Section 2: Resuscitation & Stabilization

INDICATIONS

• Respiratory

  • Apnea

  • Hypoventilation

  • Severe respiratory distress/respiratory muscle weakness

  • Acute respiratory failure (PaO₂ <50 mmHg in patient with FiO₂ >0.5 and PaCO₂ >55 mmHg acutely)

  • Need to control oxygen delivery (e.g., institution of positive end-expiratory pressure [PEEP], accurate delivery of FiO₂ >0.5)

  • Need to control ventilation (e.g., to decrease work of breathing, to control PaCO₂, to provide muscle relaxation)

• Neurologic

  • Inadequate chest wall function (e.g., in patient with Guillain-Barre syndrome, poliomyelitis)

  • Absence of protective airway reflexes (loss of cough, gag)

  • Glasgow Coma Score <8

• Airway

  • Upper airway obstruction

  • Infectious processes (epiglottis, croup)

  • Trauma to the airway

  • Burns (concern for airway edema)

• Cardiac

  • Cardiopulmonary failure/arrest

  • Low cardiac output states (reduced oxygen demand/consumption)

• Other

  • Transport of a patient with potential for respiratory failure

CONTRAINDICATIONS

• Absolute

  • Nasotracheal intubation is contraindicated in patients with nasal fractures or basilar skull fractures

• Relative

  • None

RISKS

• Bradycardia

• Hypoxemia/desaturation

• Hypotension

• Inability to intubate

EQUIPMENT-SEE FIGURES 6-1 AND 6-2

• Suction – source, catheters; should have a tonsil-tipped suction device or a large-bore suction catheter, as well as a suction catheter of appropriate size that fits into the endotracheal tube (ETT)

• Oxygen – source

• Ventilation bags – flow inflating bags and self-inflating bags

• Masks – appropriate sizes for ventilation

• Laryngoscope – blade (straight or curved), handle, bulb, battery

  • Handle with battery and blade with light source

  • Adult and pediatric handles fit all blades and differ only in handle diameter

• Video laryngoscope if available

• Endotracheal tubes – appropriate sizes, cuffed, uncuffed

• Forceps

• Oropharyngeal airway

• Tongue blade

• Bite block

• Tape – to secure tube or tube securement device

• Stylet – appropriate sizes

• CO₂ detector device – colorimetric detection device or capnography

• Syringe to inflate the endotracheal tube balloon on cuffed tubes

• Laryngeal mask airways (LMA) – appropriate sizes

• Medications (see medication section later)

• Normal saline or Lactated Ringer’s for fluid resuscitation

GUIDELINES FOR LARYNGOSCOPE, ETT, SUCTION CATHETERS BASED ON AGE AND WEIGHT – SEE TABLE 6-1

• Historically, uncuffed tubes were recommended for children <8 years of age; however, current research shows that cuffed tubes are safe in all patients except in the newborn period.

• If a difficult intubation is anticipated due to altered supraglottic anatomy, absolutely no irreversible anesthetics or muscle relaxants should be administered.

• Such patients should generally be intubated awake or in the operating room with inhaled anesthetic.

• For difficult intubations, other techniques, such as fiber-optic intubation, may be used.

DISTINGUISHING FEATURES OF THE INFANT AND CHILD AIRWAY COMPARED WITH ADULTS

• The larynx is more cephalad.

• The epiglottis is omega shaped.

• In children younger than 8 years, the cricoid is the narrowest part of the airway.

• The infant larynx is one-third the size of the adult larynx.

• The vocal cords are short and concave.

• Aligning the mouth, pharynx, and glottis to create a visual field is difficult.

• The endotracheal tube size relates to the cricoid ring.

• In children, the lower airways are smaller, have less supporting cartilage, and may easily obstruct.

• A small reduction in diameter results in a large reduction in the cross-sectional area and therefore increased airway resistance.

PROCEDURE

Checklists are helpful to ensure all team members are prepared for the procedure.

See Table 6-2

PATIENT PREPARATION

• Preoxygenate with 100% FiO₂.

• In an older child, explain each step as it is done.

PATIENT POSITIONING

• A neutral “sniffing” position without hyperextension of the neck is usually appropriate for infants and toddlers.

• Avoid extreme hyperextension in infants, because it may produce airway obstruction.

• It is sometimes helpful to place a towel under the patient's shoulders.

• In patients with head or neck injuries, the neck must be maintained in a neutral position.

SET UP PRIOR TO INTUBATION

• Check the intubation equipment before beginning.

• Attach the blade to the handle and be sure that the bulb illuminates.

• Attach suction to a suction machine and be sure that suction is turned on.

• If using a stylet, insert the stylet into the endotracheal tube. The tip of the stylet should be 1 to 2 cm proximal to the distal end of the endotracheal tube, ensuring that the stylet does not go through the Murphy eye.

• Prepare to monitor the patient's heart rate, oxygen saturation levels, and blood pressure.

INITIAL STEPS IN PROCEDURE

1. Preoxygenate with 100% oxygen

2. Administer atropine in certa in situations.

   • Infants and children can exhibit bradycardia due to vagal nerve stimulation.

   • Atropine may not be indicated in patients with significant tachycardia.

3. Administer IV sedation (e.g. fentanyl, morphine, midazolam, etomidate, ketamine, propofol; see medication section later).

4. Apply cricoid pressure in certain situations if indicated.

   • The cricoid cartilage is the first tracheal ring, located by palpating the prominent horizontal band inferior to the thyroid cartilage and cricothyroid membrane.

   • Cricoid pressure occludes the proximal esophagus by displacing the cricoid cartilage posteriorly. See Figure 6-3.

   • The esophagus is compressed between the rigid cricoid ring and the cervical spine.

   • Cricoid pressure can limit gastric distension in unconscious patients and may also prevent regurgitation and aspiration of gastric contents.

   • Avoid excessive cricoid pressure because it may produce tracheal compression and obstruction or distortion of the upper airway anatomy.

   • Use of cricoid pressure is controversial. There is insufficient evidence to recommend routine use.

5. Perform bag mask ventilation with 100% oxygen.

   • Bag mask ventilation gives the clinician time to prepare for more definitive airway management.

   • Good technique involves preserving good mask–face seal, inflating the chest with minimal required pressure, and maintaining the optimal patency of the upper airway through manipulation of the mandible and cervical spine.

   • The clinician should only use the force and tidal volume necessary to cause the chest to rise visibly.

   • The mask should extend from the bridge of the nose to the cleft of the chin, enveloping the nose and mouth but avoiding compression of the eyes.

   • The mask should provide an airtight seal.

   • The goal of ventilation with a bag and mask should be to approximate normal ventilation.

   • Sequence for bag mask ventilation:

     1. Open the airway via chin lift/jaw thrust maneuver.

     2. Seal the mask to the face.

     3. Deliver a tidal volume that makes the chest rise.

   • E-C clamp technique. See Figure 6-4.

     1. Tilt the head back and place a towel beneath the head.

     2. If head or neck injury is suspected, open the airway with the jaw thrust technique without tilting the head.

        • If a second person is present, have that person immobilize the spine.

     3. Apply the mask to the face.

     4. Lift the jaw, using the third, fourth, and fifth fingers from the left hand, under the angle of the mandible; this forms the “E.”

     5. When lifting the jaw, the tongue is also lifted away from the posterior pharynx.

     6. Do not put pressure on the soft tissues under the jaw because this may compress the airway.

     7. Place the thumb and forefinger of the left hand in a “C” shape over the mask and exert downward pressure.

     8. Create a tight seal between the mask and the patient's face using the left hand and lifting the jaw.

     9. Compress the ventilation bag with the right hand.

     10. Be sure the chest rises visibly with each breath.

   • If two people are present, then one person can hold the mask to the face, while the other person ventilates with the bag.

   • One person uses both hands to open the airway and maintain a tight mask-to-face seal, while the second person compresses the ventilation bag. See Figure 6-5.

   • If there is difficulty with bag mask ventilation, an oropharyngeal airway can be inserted. See Figure 6-6.

   • Oropharyngeal airways provide a conduit for airflow through the mouth to the pharynx.

   • Oropharyngeal airways prevent mandibular tissue from obstructing the posterior pharynx.

   • Oropharyngeal airways may be used in the unconscious infant or child if procedures to open the airway (head tilt–chin lift, or jaw thrust) fail to provide and maintain a clear, unobstructed airway.

   • An oropharyngeal airway should not be used in conscious or semiconscious patients because it may stimulate gagging and vomiting.

   • Measure the distance from the central incisors to the angle of the mandible to approximate the correct size oral airway.

SEQUENCE FOR INTUBATION CONTINUED

• 6. Administer IV muscle relaxant (e.g. rocuronium, succinylcholine; see medication section later).

• 7. Never give patients a muscle relaxant until you are sure that you are able to bag-mask the patient and until a person capable of performing endotracheal intubation is present.

• 8. Open the mouth and insert the laryngoscope.

  Laryngoscopes (see Figures 6-2 and 6-7):

  • A straight blade provides greater displacement of the tongue into the floor of the mouth and visualization of a cephalad and anterior larynx.

  • With a straight blade, the tip of the blade lifts the epiglottis directly.

  • A curved blade may be used in the older child. The broader base and flange allow easier displacement of the tongue.

  • With a curved blade, the tip of the blade is placed in the vallecula.

• 9. Avoid positioning the blade against the teeth, gums, or lips.

• 10. Visualize the glottic opening; see Figure 6-8.

• 11. Suction any secretions that may obscure visualization.

• 12. Insert the endotracheal tube, and observe the tube as it passes through the glottic opening.

• 13. Remove the stylet while holding the tube securely in place and ventilate the patient.

• 14. Secure the tube to the face.

CONFIRMING CORRECT POSITION OF ENDOTRACHEAL TUBE PLACEMENT

• Observe the ETT going through the glottic opening

• Auscultation for symmetrical breath sounds

• Good chest excursion

• Effective oxygenation

• Disposable colorimetric capnometer (color should change from purple to yellow if patient has a perfusing rhythm) or capnograph

• Obtain chest radiograph

• Absence of breath sounds over the upper abdomen

• If unilateral breath sounds are heard on the right, pull back the tube slowly while ventilating and listen for breath sounds on the left (probable intubation of right mainstem bronchus)

MEDICATIONS

Atropine – 0.02 mg/kg, IV (minimum dose 0.1 mg, maximum dose 0.5 mg) in certain circumstances

Sedation and analgesia medications should be given before the neuromuscular blocking medications

• Benzodiazepines

  • Most commonly used medications

  • Provide amnesia, not analgesia

  • Examples include midazolam and lorazepam

  • Flumazenil reverses the effects of benzodiazepines – dose: 0.01 mg/kg/dose, IV (maximum dose 0.2 mg/dose; may repeat every minute to cumulative dose of 0.05 mg/kg or 1 mg, whichever is lower)

  • Flumazenil is contraindicated in patients with seizure disorder, tricyclic antidepressant ingestion, or long-term benzodiazepine use

1. Midazolam

   • Dose: 0.1 mg/kg, IV

   • Onset of action: within 3 to 5 minutes

   • Maximal depression may not be achieved for 5 to 7 minutes

   • Duration of effect: approximately 20 to 30 minutes

   • May cause apnea in some patients

   • Cautious use in patients with hepatic or kidney injury

2. Lorazepam

   • Dose: 0.05 to 0.1 mg/kg, IV

   • Onset of action: 15 to 30 minutes

   • Duration of effect: 8 to 12 hours

   • Metabolized in the liver to inactive compounds

   • Excreted in the urine

   • May not be optimal for intubation because of prolonged onset

• Opioids

  • Second most commonly used medications

  • Provides analgesia, not amnesia

  • Differences among drugs include chemical structure, half-life, potency, cardiovascular effects, and metabolic products

  • Naloxone reverses the effects of opioids – dose: 0.01 to 0.1 mg/kg/dose, IV; up to maximum 2 mg/dose; may repeat every 3 to 5 minutes

1. Morphine

   • Dose: 0.1 mg/kg, IV

   • Onset of action: peak 20 minutes

   • Duration of effect: 3 to 5 hours

   • Metabolized in the liver to inactive and active compounds

   • Excreted in the urine

   • Cardiovascular effects: peripheral vasodilation

   • Respiratory depression may occur

2. Fentanyl

   • Dose: 2 to 3 mcg/kg, IV, maximum dose 100 mcg

   • Peak onset of respiratory depression is approximately 15 minutes

   • Onset of action: almost immediate

   • Duration of effect: 30 to 60 minutes

   • Respiratory depression may last longer than analgesia

   • May provide adequate anesthesia (and analgesia), especially in combination with other drugs and in patients with serious cardiovascular limitations

   • Unlike morphine, fentanyl rarely decreases blood pressure, even in patients with poor left ventricular function (no histamine release)

   • Incidence of chest wall rigidity from 0% to 100%; rigidity usually begins as patient is losing consciousness—succinylcholine reliably and rapidly terminates rigidity; rigidity is related to both dose and rate of infusion

• Ketamine

  • Dose: 1 mg/kg, IV, maximum dose 100 mg

  • Onset of action: within 30 seconds

  • Duration of effect: 5 to 10 minutes

  • Recovery: 1 to 2 hours

  • Provides amnesia and analgesia

  • A “dissociative anesthetic”; may cause hallucinations in older children and adults, should pretreat with a benzodiazepine

  • Increases blood pressure and heart rate

  • Ventilation is maintained

  • Bronchial smooth muscle tone is relaxed

  • Preferred in patients with heart disease and may be the drug of choice in patients with asthma

  • Disadvantages include increased secretions (should always give a vagolytic agent, such as atropine), dysphoria, and increased skeletal muscle tone, often requiring muscle relaxation

  • Contraindications include elevated intracranial pressure, hypertension, and increased intraocular pressure

• Etomidate

  • Dose: 0.1 to 0.4 mg/kg, IV, maximum dose 20 mg

  • Onset of action: 30 to 60 seconds

  • Duration of effect: 4 to 10 minutes

  • Nonbarbiturate, anesthetic agent

  • Decreases cerebral metabolic rate and intracranial pressure

  • Maintains cerebral perfusion pressure

  • Minimal changes in mean arterial pressure, cardiac output, or systemic vascular resistance

  • Disadvantages include pain on injection, myoclonus, nausea and vomiting, and adrenal suppression

• Propofol

  • Dose: 1.5 to 2 mg/kg, IV

  • Onset of action: 30 to 40 seconds

  • Duration of effect: 3 to 10 minutes

  • Lipophilic sedative hypnotic

  • May cause hypotension, vasodilatation, myocardial depression

  • Metabolized in the liver to inactive metabolites

  • Excreted in the urine

  • Unsafe to use in patients with allergies to eggs or soybeans

• Neuromuscular blocking agents

  • No analgesic or amnestic properties

  • Must be able to manage the airway

• Depolarizing neuromuscular blocking agent

• Succinylcholine

  • Dose: 1 mg/kg, IV; can be given IM 3 mg/kg, maximum dose IV/IO/IM 100 mg

  • Onset of action: 30 to 60 seconds

  • Duration of effect: 4 to 6 minutes

  • Major disadvantage is vagal stimulation; can result in bradycardia and cardiac arrest, especially after second dose

  • Should always be preceded by atropine

  • Metabolized by plasma pseudocholinesterase

  • Contraindications include:

    • Traumatic and burn injuries (increased receptor density 24 hours to 6 months after injury; note: not contraindicated at time of injury)

    • Hyperkalemia

    • Neuromuscular disease (including muscular dystrophy but not cerebral palsy)

    • Renal failure

    • Severe intraabdominal infection

    • Raised intraocular pressure

    • Personal or family history of malignant hyperthermia

• Nondepolarizing neuromuscular blocking agent

• Rocuronium

  • Dose: 0.6 to 1.2 mg/kg, IV, maximum dose 50 mg

  • Dose for rapid sequence intubation: 1.2 mg/kg, IV

  • Onset of action: 30 to 60 seconds

  • Duration of effect: 30 to 60 minutes

  • Excretion primarily biliary with some renal

MONITORING

• Continuous monitoring of oxygen saturation

• Continuous monitoring of capnography

• Continuous monitoring of heart rate

• Frequent monitoring of blood pressure

• The importance of monitoring is to make sure that the endotracheal tube remains in the correct position and is not obstructed

If an intubated patient's condition deteriorates, consider the following possibilities (DOPE):

• Displacement of the tube from the trachea

• Obstruction of the tube

• Pneumothorax

• Equipment failure

COMPLICATIONS

• Esophageal intubation

• Perforation of trachea, tracheal tear or rupture

• Intubation of right mainstem bronchus

• Aspiration

• Dental damage

• Laceration of lips or gums

• Injury to oropharynx

• Pneumothorax

SPECIAL CONSIDERATIONS

• If difficult intubation anticipated due to altered supraglottic anatomy, NO PARALYTICS should be given.

• Intubate awake or in operating room with inhaled anesthetic.

• Consider notifying anesthesia and/or otolaryngology if an airway is anticipated to be difficult.

RAPID SEQUENCE INTUBATION

• There is a risk of aspiration in patients who:

  • Have eaten less than 4 to 8 hours prior to intubation

  • Have undergone a traumatic event

  • Have gastroesophageal reflux

  • Have abdominal distention (ileus, ascites, pregnancy)

  • Are obese

• In these situations, patients should be intubated either awake (the patient may protect his or her own airway) or using a rapid sequence induction

• Rapid sequence induction

  1. Preoxygenation with 100% oxygen

  2. Administer atropine if indicated

  3. Apply cricoid pressure to prevent regurgitation

  4. Apply oxygen without active mask ventilation (apneic preoxygenation)

  5. Administer a rapid-acting anesthetic

  6. Administer a rapid-acting muscle relaxant

SUGGESTED READINGS

BACKGROUND

• Cardiac arrest is defined by a triad of derangements:

  • Pulselessness

  • Apnea

  • Unresponsiveness

• This state leads to progressive tissue ischemia and organ dysfunction, which, if not rapidly corrected, can result in irreversible deterioration of cardiac and neurologic function.

• Cardiac arrest occurs in 2% to 6% of pediatric patients who are admitted to the pediatric intensive care unit.

• Cardiac arrest occurs in approximately 16,000 children out of hospital in the United States each year.

• Because of the relative infrequency of out-of-hospital events, pediatric resuscitations are not common for providers outside of the pediatric intensive care unit.

• There continues to be a significant difference in outcomes (e.g., favorable vs. nonfavorable) between patients with in-hospital vs. out-of-hospital events.

ETIOLOGY

• In general, the cause of cardiac arrest falls into one of three categories:

  • Asphyxia

  • Ischemia

  • Arrhythmia

• Adults with cardiac arrest often have sudden, unexpected ventricular fibrillation and often have underlying coronary artery disease, which leads to myocardial ischemia.

• In contrast, pediatric cardiac arrest is rarely caused by a sudden coronary event or arrhythmia.

• Cardiac arrest in children is most often caused by progressive asphyxia from acute hypoxia or hypercarbia, which leads to acidosis and nutrient depletion.

• Ischemic events are the second most common etiology in pediatrics.

• Ischemic events occur secondary to inadequate myocardial oxygen delivery, which in children occurs most commonly in the setting of sepsis, hypovolemia, or myocardial dysfunction.

• Arrhythmias account for the smallest number of cardiac arrest events in pediatric patients, comprising only 10% of events.

PHASES OF CARDIAC ARREST

• Cardiac arrest can be broken down into four phases:

  • Prearrest

  • No flow (untreated cardiac arrest)

  • Low flow (cardiopulmonary resuscitation [CPR])

  • Postresuscitation

PREARREST

• Pediatric patients with in-hospital cardiac arrest may have physiologic changes in the hours leading up to their arrest.

• Because the majority of pediatric cardiac arrests occur secondary to progressive asphyxia or ischemia, recognition and treatment of respiratory failure and shock states may prevent a number of arrest events from occurring.

• The Pediatric Advanced Life Support (PALS) course was designed to reduce the number of cardiac arrests by improving the early recognition of these conditions.

• Care during this phase should focus on:

  • Identifying and treating reversible conditions

  • Optimizing patient monitoring

  • Providing rapid emergency response for patients not already in a health care setting

NO FLOW (UNTREATED CARDIAC ARREST)

• During untreated cardiac arrest, circulation has stopped.

• Responders to cardiac arrest should minimize time in this state in order to optimize patient outcomes.

• Interventions should focus on the initiation of Basic and Advanced Life Support techniques.

LOW FLOW (CPR)

• The low-flow phase begins with the initiation of resuscitation measures (chest compressions).

• Effective CPR improves coronary perfusion pressure and provides cardiac output to support organ viability.

• Even with optimal CPR, cardiac output is only 10% to 25% of normal. Basic Life Support (BLS) and PALS guidelines should be followed during the resuscitation phase.

• Responders should push hard and fast and should allow for complete chest recoil to maximize cardiac filling.

• Care should be taken to minimize interruptions to CPR and to avoid overventilation.

• Code medications should be administered according to PALS guidelines. See Table 7-1.

• Further research on goal-directed endpoints (end tidal CO₂, etc.) is necessary, but a sudden increase in end-tidal CO₂ suggests return of spontaneous circulation.

POSTRESUSCITATION

• The postresuscitation period involves the management of the physiologic derangements that occur after cardiac arrest.

• Cardiac issues:

  • During the initial period after cardiac arrest, patients are at high risk for ventricular arrhythmias and reperfusion injuries.

  • Additionally, the myocardium may be stunned and require support with inotropes to maintain cardiac output.

• Neurologic issues:

  • The brain is at high risk of reperfusion injury, and care should be taken to minimize further neurologic injury during the recovery period.

  • Neuroprotection consists of maintaining:

    • Euglycemia

    • Normothermia

    • Normotension

    • Normocarbia

    • Normonatremia

    • Normoxia

  • Care should be taken to avoid hyperoxia to minimize the risk of further oxidative damage to the brain.

  • Standard guidelines do not exist regarding the length of optimal neuroprotection, but many centers maintain strict control of these parameters for 48 to 72 hours following cardiac arrest.

  • Electroencephalogram (EEG) monitoring may be used to monitor for subclinical seizures in comatose patients.

  • Seizures should be treated to minimize further neurologic injury.

  • Cerebral edema may develop in the 48 to 72 hours following a prolonged cardiac arrest.

  • Treatment should focus on maintaining cerebral perfusion pressure and may require the use of hyperosmolar therapy (e.g., mannitol or hypertonic saline).

OUTCOMES

• Improved likelihood of ROSC (Return of Spontaneous Circulation) is associated with:

  • Short time to initiation of adequate CPR

  • High-quality CPR

  • Shorter overall duration of resuscitation

  • Witnessed cardiac arrest

• Achievement of ROSC is not necessarily predictive of a favorable neurologic outcome.

• Further research is necessary to identify clinical data (biomarkers or radiographic data) that is predictive of patient outcome.

SUGGESTED READINGS

INTRODUCTION

Although it is always best to utilize the least invasive access, central venous access is often required in the PICU. This chapter addresses central venous access and arterial access first and then addresses peripheral venous access and interosseus access. Ultrasound considerations are incorporated throughout the chapter.

CENTRAL VENOUS ACCESS

Central versus peripheral access: Peripheral access should be used whenever possible, unless specific indications for central venous access are present.

INDICATIONS

• Unable to achieve peripheral access

• Large volume resuscitation

• Need for vesicant, irritant, or hyperosmolar or highly concentrated solutions (including total parenteral nutrition [TPN], electrolyte replacement, greater than 12.5% dextrose, pH <5 or >9, or osmolarity >600 mOsm/L)

• Need for vasoactive support

• Need for hemodynamic monitoring, including central venous pressure, pulmonary artery pressure, or mixed venous saturation monitoring

• Frequent blood draws

• Need for prolonged access (chemotherapy, prolonged antibiotic course)

CONTRAINDICATIONS

• Increased bleeding risk secondary to thrombocytopenia or coagulopathy.

• Predisposition to sclerosis or thrombosis. Contraindicated in a vessel with a known thrombus.

RISKS/POTENTIAL COMPLICATIONS

• Bleeding: Assessment for thrombocytopenia and coagulopathy should occur prior to line placement

• Infection: Use sterile technique with full barrier to minimize infection

• Embolization of intravascular thrombus, guidewire, or air

• Vessel perforation

PREPARATION

• Materials

  • Sterile gloves, gown, drapes

  • Surgical hat, mask

  • Catheter (see Table 8-1 for size and length considerations)

  • Caps for each catheter lumen

  • Introducer needle

  • Syringe (non-Luer Lock) to attach to introducer needle and two to three additional 3-mL syringes

  • Guidewire (at least double the length of the catheter; verify that guidewire passes through needle prior to starting procedure)

  • Scalpel

  • Tissue dilator

  • Suture

  • Kelly clamp

  • Additional syringes

• Medications

  • Lidocaine 1% for skin numbing (and appropriate needle for superficial injection)

  • Chlorhexidine (>2 months) or iodine (<2 months) for skin preparation

• Catheter selection

TECHNIQUE

• Preparation

  • Sterile procedure: Use cap/mask, gown, sterile gloves

  • Prepare the area with 2% chlorhexidine (>2 months) or 10% povidine-iodine (<2 months)

  • Catheter preparation

    • Flush all ports and caps with normal saline or heparinized saline

    • Clamp lumens after flushing

• Anesthesia

  • For use of systemic sedation or analgesia, ensure NPO status (6 hours for solids; 4 hours for clear liquids).

  • Inject local anesthetic (1% lidocaine) into the tissues at and below the venipuncture site. Withdraw prior to injection to avoid intravascular injection.

• Seldinger technique (Figure 8-1)

  • Puncture the skin using an introducer needle attached to non-Leur Lock syringe.

  • Advance until blood return is free-flowing, then remove syringe, keeping introducer needle in place. Place finger over open lumen on needle to avoid air entry.

  • Insert guidewire through introducer needle, keeping one hand on the guidewire at all times.

    • Until the guidewire is removed, one hand should be kept on the guidewire for each subsequent step.

    • Guide wire should enter without resistance and, if met with resistance, needle or guidewire should be redirected prior to reattempting advancement.

  • When guidewire is in place, using a scalpel, make a small incision at the venipuncture site. Remove the introducer needle with the guidewire remaining in place.

  • Introduce the dilator over the guidewire. Use a twisting motion to advance through the skin as needed. Remove the dilator with the guidewire remaining in place.

  • Thread the catheter over the guidewire, retracting the guidewire through the catheter as needed until the guidewire is visible on the other side of the catheter.

  • Once the catheter is in place, remove the guidewire.

  • Aspirate blood through each port to ensure free flow. Flush each port. Take care to avoid introducing any air through the catheter.

  • Suture the catheter in place.

  • Attach caps to the catheter lumens.

CONFIRMATION OF PLACEMENT

• Blood gas

• Transduce pressure

• Imaging

  • Chest x-ray for internal jugular (IJ) or subclavian placement to verify positioning and evaluate for pneumothorax

  • Abdominal x-ray for femoral placement to verify positioning

REMOVAL OF CATHETER

• Remove as soon as the indication for a central venous line (CVL) is no longer present

• Remove sutures and retract catheter with pressure at the insertion site after removal

GENERAL PRINCIPLES FOR ULTRASOUND-GUIDED VASCULAR ACCESS

PREPARATION

• Materials

  • Ultrasound machine

  • High-frequency linear probe

  • Ultrasound gel

TECHNIQUE

• Preparation

  • Cover probe

  • Place gel over ultrasound probe

  • Vessel identification and confirmation

    • Veins compress more easily than arteries

    • Veins have thinner walls than arteries

    • Arteries have pulsatile flow; veins do not

  • Prescan along length of vessel to ensure its depth, course, and patency

  • Center vessel on screen

  • Confirm successful catheterization with catheter/wire visualized in vessel

• General technique

  • Position the ultrasound machine in the operator's direct line of site (usually on the opposite side of the patient's bed with the cord draped across the patient)

  • Orient the probe so that the left side of the probe corresponds to the left side of the ultrasound screen

  • Ultrasound probe held in operator's nondominant hand

  • Needle held in operator's dominant hand

• Short axis/transverse approach

  • Orient probe with its long axis perpendicular to the path of the vessel

  • Vessel will appear as black/anechoic circle with white/hyperechoic rim on screen

  • Brace fingers of hand holding probe on patient to ensure stability

  • Insert needle at skin at midpoint of probe of the long axis of the probe

  • Identify needle tip as bright white/hyperechoic dot on screen

  • Advance or slide ultrasound probe a few millimeters while advancing the probe

  • Adjust needle direction to ensure it is in line with the vessel

  • Ensure needle tip remains in view by tilting the probe back and forth

  • Poke needle through superficial wall into vessel

  • Shallow needle angle to allow passage of wire or catheter

• Long axis/longitudinal approach

  • Orient probe with its long axis parallel to the path of the vessel

  • Vessel will appear as black/anechoic tube with white/hyperechoic edges on screen

  • Brace fingers of hand holding probe on patient to ensure stability

  • Insert needle into the skin proximal to and at the midpoint of the short axis of the probe

  • Identify needle tip and shaft as hyperechoic oblique line on screen

  • Keep nondominant hand in place while vessel is in view

  • Advance needle under direct ultrasound guidance

  • Poke needle through superficial wall into vessel

  • Shallow needle angle to allow passage of wire or catheter

• Short axis vs. long axis approach

  • Short axis approach:

    • Allows simultaneous visualization of intended and neighboring vessels

    • Any point of the needle (tip and shaft) appears as a hyperechoic dot; if needle tip is not followed, one may poke inadvertently through the vessel

    • Some operators may find it difficult to manipulate the probe with their nondominant hand

  • Long axis approach:

    • Allows visualization of the entire vessel and needle

    • The hand–eye coordination necessary to keep probe still while advancing the needle along its plane may be challenging

    • Limited space of a patient's short neck may preclude placing the probe in the long axis and a longitudinal approach

TYPES OF CENTRAL VENOUS ACCESS

FEMORAL CENTRAL VENOUS CATHETER

• Advantages

  • Avoids device in neck or chest

  • Able to control bleeding locally with pressure

• Drawbacks

  • Unable to obtain a true mixed venous saturation, unless a long catheter is placed

  • Central venous pressure (CVP) monitoring affected by intra-abdominal pressure; femoral CVLs should not be placed in the setting of acute intra-abdominal process or trauma

  • Difficult when anatomic landmarks are distorted

  • Excessive stooling increases infection risk

• Anatomy (Figure 8-2)

  • Inguinal ligament runs from anterior superior iliac spine to the pubic symphysis

  • Femoral artery and vein run in parallel and should be entered below the inguinal ligament

  • “NAVEL” describes the structures from lateral to medial of importance: nerve, artery, vein, empty space, lymphatics

• Approach

  • Patient positioning

    • Supine position

    • Lift hips with leg on the side of the approach in slightly flexed, “frogleg” position

  • Palpate the femoral artery; the femoral vein will be just medial to the artery

  • With ultrasound:

    • Identify the femoral vein as the nonpulsatile, thinner-walled structure

    • Adjust leg position while visualizing the femoral vein and artery so as to minimize femoral vein overlap of the femoral artery and reduce risk of inadvertent femoral artery puncture

  • Enter the skin 1 to 2 cm inferior to the inguinal ligament at a 30- to 45-degree angle aimed toward the umbilicus

  • Place the line using the Seldinger technique

• Specific complications

  • Impaired lower extremity venous return with lower extremity swelling

  • Thrombus

  • Misplacement of the catheter; placement into the lumbar venous plexus can result in mortality

INTERNAL JUGULAR (IJ) CENTRAL VENOUS CATHETER

• Advantages

  • Avoids femoral access

  • Allows for more reliable hemodynamic monitoring (CVP, mixed venous saturation)

  • Better control of bleeding than subclavian

  • Potential access point for pacing wire

• Drawbacks

  • Difficult with tracheostomy stoma and ties

  • May impair cerebral venous drainage in the setting of increased intracranial pressure

• Anatomy (Figure 8-3)

  • Triangle formed by clavicle and two bellies of the sternocleidomastoid

• Approach

  • Patient positioning

    • Supine and head slightly down (Trendelenburg) 15 to 30 degrees

    • Roll under shoulders

    • Head turned contralateral to puncture site

  • Right IJ preferred to avoid injury to thoracic duct, left brachiocephalic vein, or superior vena cava (SVC)

  • With ultrasound:

    • Identify the internal jugular vein as the nonpulsatile, thinner-walled structure

    • Adjust neck position while visualizing the internal jugular vein and carotid artery so as to minimize overlap of the internal jugular vein and carotid artery and reduce the risk of inadvertent arterial puncture

  • Three approaches (the middle is the most common)

    • Anterior – introduce the needle along the anterior margin of the sternocleidomastoid between the mastoid process and sternum; aim for the ipsilateral nipple

    • Middle

      • Enter apex of triangle formed by two muscle bellies and clavicle

      • Enter at 30-degree angle

      • Aim for ipsilateral nipple

    • Posterior

      • Introduce the needle along the posterior border of the sternocleidomastoid cephalad to the division into anterior and sternal heads

      • Aim toward the suprasternal notch

• Complications

  • Pneumothorax or hemothorax

  • Arrhythmia

  • Pericardial tamponade

  • Left-sided approach can lead to thoracic duct injury or injury to the SVC or left brachiocephalic vein

SUBCLAVIAN CENTRAL VENOUS CATHETER

• Advantages

  • Avoids femoral access or neck access

  • Better hemodynamic monitoring than femoral

• Drawbacks

  • Coagulopathy – more difficult to control bleeding because cannot apply direct pressure to the artery or vein

• Anatomy (Figure 8-3)

  • Entry point is at the junction of the middle and medial thirds of the clavicle

• Approach

  • Patient positioning

    • Head down (Trendelenburg) 30 degrees

    • Neck may be extended with neck roll, neutral, or slightly flexed with head turned to direction of needle entry

    • Shoulders neutral with arms beside patient

  • Introduce needle at the inferior aspect of the clavicle at the junction of the middle and medial thirds of the clavicle and advanced while applying negative pressure to attached syringe

  • With ultrasound:

    • Supraclavicular and infraclavicular approaches are options

    • Adjust neck position while scanning to maximize visualization of subclavian vein

    • Identify pleura just deep to the subclavian vein

  • Insert needle parallel to patient and direct medially and slightly cephalad toward finger placed in the sternal notch

  • Introduce guidewire during inspiration on ventilator and on expiration in spontaneously breathing patient to avoid air embolus

  • Complete placement using Seldinger technique

• Complications

  • Pneumothorax – risk is reduced by using expiratory hold or hemothorax

  • Arrhythmia

  • Pericardial tamponade

ARTERIAL ACCESS

INDICATIONS

• Continuous blood pressure monitoring when noninvasive blood pressure monitoring is inaccurate (morbidly obese, very thin, burns)

• Frequent blood laboratory sampling

• Frequent arterial blood gas sampling

CONTRAINDICATIONS

• Absent pulse

• Full-thickness burn

• Inadequate circulation, including Raynaud's

• Relative: anticoagulation, partial-thickness burn, inadequate collateral flow, local infection at insertion site, vascular graft, surgical site at insertion site

PREPARATION

• For Seldinger technique

  • Arterial catheter

  • Finder needle

  • Guidewire

• For non-Seldinger technique use an IV catheter or arterial catheter with a catheter over the needle technique

• Chlorhexidine solution

• Gauze

• Sterile towels/drape

• Sterile gloves, gown, hat

PROCEDURE

• Identify site for cannulation

  • Radial artery most common (Figure 8-4). Allen test (Figure 8-5) should be performed to evaluate for dual perfusion to the hand. The patient opens and closes the hand multiple times and then squeezes tightly. The examiner then compresses over both the radial and ulnar arteries and then releases the ulnar artery. The hand should reperfuse when the artery is released. This should be repeated with the radial released to ensure dual hand perfusion and can be compared to the contralateral side.

  • Other sites include ulnar, posterior tibialis, dorsalis pedis, axillary, and femoral (for central arterial cannulation). Brachial is not recommended due to absence of collateral circulation.

• Prepare and drape the area as described earlier for central venous cannulation.

• Feel arterial pulsation prior to inserting catheter.

• For Seldinger technique.

  • Insert finder needle until blood return is obtained. Alternatively, the needle can be advanced fully through the vessel until flow stops (to transfix the vessel) and then the needle pulled back until flow starts again.

  • Advance the wire through the needle. Rotate the needle 90 to 180 degrees if difficulty with passing wire to avoid blockage from an intimal flap.

  • Once wire is in place, advance catheter over wire. No dilation of the vessel is generally required (unless central cannulation is performed).

• For the catheter over needle technique, once the needle is introduced with blood return, advance the catheter over the needle.

• Attach catheter to arterial line pressure monitoring system and secure with sterile dressing (procedure similar to dressing of peripheral IV lines for peripheral arterial lines and central venous lines for central arterial line).

Complications (most are rare with proper technique)

• Hematoma/bleeding

• Local site infection

• Sepsis

• Ischemic damage (may be permanent)

• Thrombosis

• Air embolism

• Compartment syndrome

• Nerve injury

• For femoral cannulation, femoral artery dissection, pseudoaneurysm

Ultrasound considerations (see General Principles for Ultrasound-Guided Vascular Access for complete description of technique)

• Indications

  • Ultrasound-guided placement improves success rate and reduces complications

  • Inability to palpate artery secondary to obesity, edema, or multiple prior attempts

• Preparation, materials, and technique

  • Cover ultrasound probe with sterile sheath

  • Use sterile gel outside the sheath

  • Scan at site of insertion to ensure artery is free of clots

  • Either short axis/transverse approach or long axis/longitudinal approach may be used (see General Principles for Ultrasound-Guided Vascular Access for details)

  • Insert needle at appropriate angle to ensure sufficient catheter length

PERIPHERAL VENOUS ACCESS

INDICATIONS

• IV fluid or medication administration

• Blood sampling

• Peripheral IV nutrition

• Blood product administration

• Contrast administration for imaging

• There are no absolute contraindications, but should avoid placement in an injured, infected, or burned extremity

PROCEDURE

• Preparation

  • Choose a catheter size appropriate for the indication. Smaller catheters will risk less damage to vessels. Larger catheters are preferred for high volume or resuscitation.

  • Venous engorgement will aid cannulation and can be accomplished by placing the target vein in a dependent position, tourniquets, and “pumping” the muscle to create contractions around the vessel.

  • Transillumination with a cold light source (usually fiber-optic) in a dark room can help to illuminate veins in neonates and infants.

• Materials

  • Chlorhexidine or alcohol to decontaminate the skin

  • IV cannula

  • Sterile syringe with normal saline

  • Three-way connector or T-connector

  • Sterile dressing (e.g., Tegaderm)

  • Tape

  • Gauze

  • Board to secure/immobilize extremity following placement

  • Blood tubes if needed to send blood

  • Gloves

• Technique (Figure 8-6)

  • Stabilize extremity at joints above and below entry site if necessary

  • Apply tourniquet if needed with care not to compress arterial flow

  • Decontaminate using chlorhexidine or alcohol; do not touch site after decontamination

  • Insert needle at a 10- to 15-degree angle, advancing the needle 1 to 2mm after entering the vessel

  • Advance the catheter over the needle into the vessel

  • Secure the hub of the needle at the skin entry point

  • Attach saline-filled three-way connector and flush IV

  • Consider placing a small piece of gauze under the hub of the needle to avoid pressure on the skin

  • Attach using tape crossed over the cannula and at the hub with the skin entry point remaining visible

  • Place a clear dressing over the catheter

  • Secure extremity to board or place immobilizer around extremity as needed

Ultrasound Considerations (see General Principles for Ultrasound-Guided Vascular Access for complete description of technique)

• Indications

  • Difficult access secondary to edema, obesity, multiple prior vascular attempts, or inability to visualize veins

  • Desire to avoid/limit central access

• Preparation and materials

  • Cover ultrasound probe with adhesive dressing or sterile sheath

  • Superficial vessels are preferred, as they are associated with a higher success rate of cannulation

  • Choose longer (>2 inches) catheters, as they have less risk of premature failure secondary to dislodgement as compared to shorter catheters

• Technique

  • Scan at site of insertion to ensure vein is free of clots and valves

  • Either short axis/transverse approach or long axis/longitudinal approach may be used (see General Principles for Ultrasound-Guided Vascular Access for details)

  • Insert needle at appropriate angle to ensure sufficient catheter length

INTRAOSSEOUS ACCESS

• General considerations

  • An intraosseous (IO) line may be used for venous access whenever a peripheral IV is needed and cannot be accomplished.

  • IO lines should be removed within hours of placement or earlier as soon as peripheral or central access is achieved.

  • Special IO needles with stylets should be used.

• Procedure (Figure 8-7)

  • Identify site for placement

    • Infants: Distal femur, proximal tibia

    • Children/adolescents: Distal femur, proximal tibia, distal tibia

    • Other sites: Anterior superior iliac spine, calcaneus, humerus, radius, sternum (adults)

  • Stabilize the extremity without placing hand behind the area where the IO line will be inserted.

  • For proximal tibia, insertion should be on the flat anteromedial surface, 1 to 2 centimeters distal to the tibial tuberosity.

  • For distal femur, insertion should be 3 cm above the lateral condyle in the midline.

  • For distal tibia in older children, insertion should be on the medial surface 2 cm above the medial malleolus.

  • The needle is held firmly in the palm of the hand not being used to stabilize the extremity and inserted using moderate pressure and a rotary motion aimed away from the direction of the joint, stopping when a “pop” marks penetration of the cortex. Semi-automatic (spring- or battery-powered) devices may be used to aid insertion.

  • The needle should be stabilized once the cortex has been penetrated and the needle is in the medullary cavity to avoid crossing the cortex on the other side of the bone.

  • Once the cavity is entered, the stylet is removed and the IO can be used.

• Complications

  • Advancing the needle too far can result in exiting the opposite cortex and soft tissue infusion of IV products

  • Osteomyelitis

  • Bleeding

  • Compartment syndrome

  Ultrasound Considerations (see General Principles for Ultrasound-Guided Vascular Access for complete description of technique)

  • Confirmation of placement

  • Place high-frequency linear probe proximal or distal to IO needle in transverse or longitudinal orientation (with respect to bone)

  • The accessed bone will appear as a hyperechoic line

  • Use color Doppler or power Doppler for placement confirmation

  • Appropriate placement will reveal flow within the IO channel (visualized deep to the bony cortex)

  • Placement failure will be seen as flow superficial or lateral to bone

SUGGESTED READINGS

INTRODUCTION

The aim of this chapter is to introduce the reader to commonly deployed patient monitoring devices in critical care medicine. It is necessary to have a basic understanding of how these devices work to have an ability to recognize potential pitfalls in interpretation of the data they generate.

HEMODYNAMIC MONITORING

Invasive hemodynamic monitoring remains the accepted reference standard for blood pressure monitoring of hemodynamically unstable patients.

• Transducers: Integral to monitoring of all pressure waveforms is the transducer. Transducers contain a fluid-filled interface that detects changes in pressure. The transducer contains a diaphragm that interfaces with a column of fluid extending from the cannula inserted into the blood vessel, through the pressure tubing, to the transducer.

• How it works: Changes in intravascular pressure result in pulsations in the column of saline in the tubing between the cannula in the blood vessel and the transducer. The pulsations displace the diaphragm on the transducer, which transmits the waveform to the monitor and converts this waveform into an electrical signal displaying the pressure.

• Zeroing/positioning: All transducers must be zeroed and placed in the appropriate location relative to the patient.

  • Zeroing negates the influence of external pressures (like atmospheric pressure) and occurs when the stopcock connecting the cannula to the noncompressible pressure tubing is opened to ambient atmospheric pressure. Consequently, all pressures displayed account for the external pressures like atmospheric pressure.

  • Transducer position is often aligned either with the blood vessel or cavity against which the pressure will be measured or at the level of cannula insertion. For example, the central venous pressure (CVp) transducer should be aligned with the upper fluid level of the right atrium (typically 5 cm posterior to the right sternal border at the fourth intercostal space). If the transducer changes position, then the blood pressure will be incorrect secondary to the effects of hydrostatic pressure from the tubing. For example, if the transducer is too low, the fluid in the tubing above the transducer will exert a greater pressure on the transducer than at the location at which it was zeroed, resulting in a falsely high blood pressure.

INVASIVE ARTERIAL PRESSURE MONITORING (SEE FIG. 9-1)

• Indications include the following: Blood pressure monitoring in the hemodynamically unstable patient, frequent sampling of arterial blood gases or other laboratory tests.

• Potential complications of arterial cannulation: Infection, pain, bleeding, embolus, impaired arterial circulation in the extremity cannulated. Retroperitoneal hematoma may occur in femoral arterial line placement.

• Locations for arterial cannulation: Radial, dorsalis pedis, and posterior tibial arteries are most commonly the first sites accessed. If unable to cannulate these areas, alternative areas to consider include ulnar (smaller, more challenging, and less desirable if the radial artery is in the same side previously cannulated, as this would compromise blood flow to that hand), femoral, or axillary arteries. Brachial arterial lines are often avoided, as compromise to this artery may result in impaired blood flow to the distal part of that limb and possible limb loss in extreme cases.

• Waveform artifacts due to technical errors include damping (overdamping vs. underdamping), fling (whip). See normal arterial waveform in Figure 9-1.

  • Damping is when the waveform amplitude is reduced. Some amount of damping is desired in order to reduce the inherent resonant frequency of the monitoring system or to eliminate the contributions of the physical forces of the system and only measure the patient's pressure waveform. If the system is overdamped (See Fig. 9-2) (by an air bubble, partially closed stopcock, or soft tubing that absorbs the pressure waves), then the pressure will be underestimated with a low-amplitude waveform. An underdamped system occurs when there is too high a frequency response in the system, causing a large-amplitude waveform and an overestimation of the systolic blood pressure.

  • Arterial catheter fling (whip) (See Fig. 9-3) occurs when the peak pressure “overshoots,” resulting in a falsely high systolic blood pressure. This can result from significant catheter tip movement or overfilling of the transducer.

  • Resonance: The arterial waveform is composed of multiple sine waves with each wave having a specific frequency. If any of these frequencies are the same as the resonant frequency inherent in the transduction system, distortion of the signal will occur, leading to erroneous measurements. The equipment used is specifically designed to maintain a natural frequency above the frequencies of the arterial waveforms to eliminate this problem.

CENTRAL VENOUS PRESSURE (CVp) MONITORING (SEE FIG. 9-4)

• Indications: In patients with hemodynamic instability, CVp monitoring provides an assessment of intravascular volume as well as an assessment of right ventricular end diastolic pressure (RVEDp) in patients without tricuspid stenosis. Central lines also offer stable vascular access for infusion of vesicants, inotropes, and parenteral nutritional support, as well as a means of obtaining blood samples for laboratory testing.

• Potential complications: Infection, pain, bleeding, vascular injury, pulmonary embolus, air embolus, hemothorax, and pneumothorax.

• Sites: Femoral, internal jugular, subclavian. Note: Due to line characteristics that lead to inaccuracy (i.e., length and distensibility), peripherally inserted central catheter (PICC) lines are generally undesirable for CVp monitoring.

• Waveforms:

An understanding of the components of the CVp is crucial, as the waveform undergoes characteristic changes in certain pathologic states:

Central venous vessels are very sensitive to changes in intrathoracic pressure during the respiratory cycle. This respiratory variation in the CVp tracing is accentuated in conditions that promote an excessively negative intrathoracic pressure (like upper airway obstruction) and in patients experiencing positive pressure ventilation.

NONINVASIVE BLOOD PRESSURE (BP) MEASUREMENT

• Methods include auscultation, palpation, and oscillometry.

• Auscultation: Auscultation over the brachial artery while a cuff is inflated. Systolic pressure is identified when Korotkoff sounds occur. Diastolic blood pressure is identified by the loss of all sounds. This methodology is often inaccurate and often user dependent. Diastolic values are less accurate than systolic values.

• Palpation: A cuff is inflated to above systolic pressure, preventing arterial pulsations from occurring. The cuff is then deflated to the point where pulsations are palpated. This is the systolic blood pressure. No diastolic blood pressure is obtained. This methodology is easy to perform, though often inaccurate. Shown to underestimate systolic blood pressure.

• Oscillometer: This is an automatic measurement using a self-inflating cuff. The cuff inflates above systolic pressure, eliminating arterial pulsations, then deflates either continuously or in steps until pulsations reappear. The electronic transducer detects this and notes the pressure at which the oscillations (pulsations) occurring within the artery are greatest, and this is systolic pressure. The cuff continues to deflate, and when the oscillations are the smallest, this is noted as diastolic pressure. Mean arterial pressure and systolic pressure are the most accurate in this method. These values are compared to standard BP calculation equations included in the system by the manufacturer where:

  • $MeanBP=[SystolicBP+(2×DiastolicBP)]/3$

CARBON DIOXIDE AND OXYGEN MONITORING

• Transcutaneous carbon dioxide (CO₂) monitoring:

  • Measures the skin-surface partial pressure of CO₂ as an estimate of the partial pressure of arterial CO₂ (PaCO₂).

  • Mechanism: The monitor is placed on an adhesive ring containing saline or glue and causes the capillaries to dilate by increasing the temperature of the skin at the site where it is applied using a heating electrode. This allows the skin to become more permeable to gases. Using a temperature correction factor, it calculates the CO₂ value electrochemically by detecting a change in the pH of the solution present between the skin and the electrode.

  • Limitations: Device must be calibrated and allowed several minutes to begin reading accurately. Can cause damage to skin due to local increases in skin temperature. Trapped air bubbles in the solution between the skin and monitor will result in inaccurate readings. Vasoconstriction due to hypothermia, shock states, etc., will reduce system accuracy.

• Near-Infrared Spectroscopy (NIRS)

  • NIRS is a spectroscopic method that relies on the relative transparency of the skin to the near-infrared region of the electromagnetic spectrum (700–2500 nm) to determine tissue oxygenation. By monitoring absorption at wavelengths where oxyhemoglobin, deoxyhemoglobin, and cytochrome aa3 differ, it is possible to calculate local hemoglobin–O₂ saturation.

  • Although both pulse oximetry and NIRS monitors use near-infrared light to determine O₂ saturation, due to differences in how the strong pulsatile (the focus of pulse oximetry) and weaker nonpulsatile (the focus of NIRS) signals of the waveform are processed, NIRS monitors are less susceptible to errors from poor perfusion.

  • The designation of the regional saturation being measured depends on where the probe is placed. If measuring a specific tissue saturation (e.g., limb), the value is designated StO₂ (tissue); if cerebral venous saturation is being measured, the value is recorded as ScO₂ (cerebral), and rSO₂ (regional) if used to estimate splanchnic perfusion by placement on the patient's flank.

  • Somanetics devices in clinical practice are not very accurate when compared to a weighted average of absolute tissue oxygenation (10%–15% error), but are more accurate in measuring a change in saturation (+/− 5%) and are therefore best interpreted as a trend rather than an absolute value.

• Pulse Oximetry

  • Transmissive pulse oximetry involves the placement of a sensor that has small light-emitting diodes (LEDs) facing a photodetector and a processor. Two wavelengths (660 nm and 940 nm) of light that are differentially absorbed by oxyhemoglobin and deoxyhemoglobin are passed through the tissue, and changing absorbance at each wavelength allows determination of absorbances due to arterial pulsation with correction for tissue absorbance. The ratio of red to infrared measurement is calculated by the processer and converted to the SpO₂ by reference to tables of empiric observation.

    $SpO2=HbO2​/totalHb$

  • Limitations: Accurate readings are very dependent on perfusion and movement. Pulse oximetry is not a measure of circulatory sufficiency; significant anemia with tissue hypoxia can exist in spite of high measured oxygen saturations. Because oximetry is only measuring the percentage of bound hemoglobin, false readings occur when hemoglobin binds something other than oxygen.

    • Falsely high values occur with carbon monoxide poisoning and cyanide exposure

    • Falsely low readings occur with methemoglobinemia (classically 80%–85%)

• End Tidal Capnography (EtCO₂) (See Fig. 9-8)

  EtCO₂ refers to the graphical measurement of the partial pressure of CO₂ (mmHg) during exhalation.

  • Indications: Monitoring of adequacy of ventilation, verifying correct placement of an endotracheal tube, measuring efficacy of CPR, assessing for return of spontaneous circulation, and assessment of pulmonary pathology (obstruction, shunt thrombosis, pulmonary embolus).

  • Measurement: Measurement can involve either mainstream (in line with the endotracheal tube) or sidestream techniques (which are more appropriate for extubated patients).

  • Interpretation: An elevated end tidal CO₂ could indicate inadequate ventilation (i.e., a generous paCO₂) or an increase in deadspace ventilation. An abrupt decrease in the measured partial pressure of CO₂ by capnography could indicate a sudden decrease in pulmonary blood flow, as would occur with pulmonary embolism or shunt thrombosis. A gradual decrease in EtCO₂ likely indicates overgenerous minute ventilation. It is necessary to also note the morphology of the EtCO₂ waveform, as this provides additional information about pathologic processes as indicated by Figures 9-8 and 9-9.

INTRACRANIAL PRESSURE MONITORING

• Indications: Continuous measurement of intracranial pressure (ICP) in the critically ill patient with brain injury (for example, patients with closed head injury).

• ICP waveforms: The ICP wave is a combination of two pulsatile waves. The first is secondary to arterial pulsations from vessels within the brain. This results in an ICP waveform similar to the arterial waveform. The second waveform is a result of respirations altering the central venous pressure waveform. This represents intrathoracic pressure. The two patterns are superimposed and result in an overall ICP wave form.

• Methodology: Two common forms of continuous ICP measurement are used currently: an intraventricular drain (commonly referred to as an external ventricular drain [EVD]) and the catheter-tip transducer (bolt).

  • Intraventricular drain, commonly referred to as the external ventricular drain (EVD): This is considered to be the gold standard of ICP measurement. The drain is connected to an external pressure transducer (see Transducers earlier) with the reference point at the foramen of Monro or at the midway point between the two external auditory canals.

    • Benefits include the ability to drain cerebrospinal fluid (CSF) while transducing ICP and calculating cerebral perfusion pressure (CPP), as well as the ability to rezero the system (has an external transducer).

    • Limitations include injury of nearby regions of brain, increased risk of infection, overdrainage of CSF, bleeding with placement, and difficulty with insertion if small ventricle size (i.e., in setting of significant cerebral edema).

    • 

  • Catheter-tip transducer (bolt): There are three kinds: parenchymal (inserted into brain parenchyma; reduced risk of hemorrhage and infection), subdural (inserted into subdural space; may not reflect pressure changes within brain), and ventricular (inserted into ventricle; can drain CSF and measure ICP).

    • Limitations include inability to rezero after insertion due to internal transducer (vs. external transducer with EVD), leading to possibly false estimates of ICP (drift). Drift is loss of measurement accuracy usually after approximately 5 days. Also ICP may not be uniform throughout the brain; thus measurements from one location may not reflect ICP elsewhere.

INDIRECT CALORIMETRY

• Indications: Accurate assessment of resting energy expenditure (REE) in patients to determine precise fluid and nutritional needs.

• Methodology: Calorimetry classically measures heat transfer as a means of registering changes in state. In living organisms, metabolic processes generate heat. Due to the challenges associated with the direct measurement of heat production, indirect measurement of metabolic activity by consumption of oxygen or elimination of carbon dioxide and nitrogen waste have become the gold standard. Respiratory indirect calorimetry (IC) has an error rate of <1% and is a highly reproducible method that measures oxygen consumed (VO₂) and carbon dioxide produced (VCO₂). Measured values are then entered in the modified Weir equation to calculate REE.

  $Restingenergyexpenditure(REE)=[(3.94×VO2​)+(1.1×VCO2​)]×1440min/​day$

• This technique also allows for calculation of the respiratory quotient: RQ = VCO₂/VO₂. Normal values of the RQ range from ∼0.7 for pure fat oxidation, to 0.8 for pure protein oxidation, to 1.0 for pure carbohydrate oxidation in states of metabolic balance.

• Considerations:

  • REE usually accounts for 75% to 90% of total energy expenditure, but does not accommodate activity.

  • Brain, heart, liver, and kidney metabolism account for 60% to 70% of REE.

  • REE increases up to 13% per degree (C) of fever.

  • Illness affects REE, but not always predictably (∼60% of critically ill patients are hypermetabolic with the other ∼40% being evenly divided between normometabolic and hypometabolic).

  • REE should not be performed in patients on high FiO₂ (>0.6), patients on high positive end-expiratory pressure (PEEP) (>14), or in patients with known circuit leaks or chest tubes due to pneumothorax, as these conditions lead to inaccuracy in measurement.

SUGGESTED READINGS

NEEDLE CRICOTHYROTOMY

This procedure involves the creation of a communication between airway and skin via the cricothyroid membrane. An over-the-needle catheter is then passed through the membrane. This procedure provides a temporary secure airway to oxygenate and ventilate a patient in severe respiratory distress when less invasive measures have failed or are unlikely to be successful.

A high pressure gas source such as Jet Ventilation or percutaneous transtracheal ventilation (PTV) is then used to deliver oxygen to the lungs through the catheter. The gas source attaches to the inserted catheter through an improvised device. One can attach the catheter to a 3-mL syringe with the plunger removed and then attach the syringe to the proximal connection piece of a 7.5-mm internal diameter endotracheal tube (Figure 10-1). Alternatively, one can insert an endotracheal tube into the barrel of the 3-mL syringe and inflate the cuff.

Needle cricothyrotomy is considered preferable in children less than 12 years of age because of the membrane's small size and close proximity of vascular structures

Advantages over tracheostomy:

• Simplicity

• Speed

• Bloodless field

• Minimal training required

• Avoidance of hyperextension of neck

Indications:

• Inability to intubate

• Inability to ventilate

• Rescue laryngeal mask airway cannot be inserted/passed

Contraindications:

• Injury to larynx with damage to cricoid cartilage

• Laryngeal fracture

• Tracheal rupture

• Relative contraindications include anterior neck swelling that distorts anatomic landmarks, anatomic anomalies that distort the larynx or trachea, and bleeding disorders.

• In most cases, the need for securing an airway will outweigh the risks involved in this procedure.

TECHNIQUE

1. Position patient supine with neck extended, if possible

2. Identify surface landmarks: thyroid cartilage, cricoid cartilage, and cricothyroid membrane (Figure 10-2)

3. Clean and sterile drape (universal precautions)

4. If time, inject 1% lidocaine into the skin, through the cricothyroid membrane and into airway, to anesthetize the airway and suppress the cough reflex

5. Palpate landmarks; fix thyroid cartilage with the first and third fingers of the nondominant hand, leaving the second finger to locate/palpate the cricothyroid membrane

6. With the dominant hand, pass a 12- or 14-gauge intravenous cannula attached to a syringe filled with sterile saline through the membrane, angling the needle caudally or inferiorly at 45-degree angle (Figure 10-3)

7. Apply negative pressure to the syringe; if in the trachea, escaping air should create air bubbles in the syringe

8. Advance the cannula and remove the needle

9. Secure catheter

10. Attach Jet ventilator and ventilate at 15 L/min

11. Monitor adequacy of ventilation by chest wall movement and breath sound auscultation. Can also interpose ETCO₂ in the circuit to monitor exhalation

• Complications:

  • Pneumothorax

  • Subcutaneous and mediastinal emphysema

  • Bleeding

  • Esophageal puncture

  • Respiratory acidosis secondary to hypoventilation

• Caveats:

  • Cricothyroidotomy is typically performed as an emergency procedure that is temporizing only:

    • Ventilation via needle cricothyrotomy is only effective for approximately 45 minutes secondary to inadequate ventilation and CO₂ accumulation. This can be particularly injurious to head injury patients, as hypoventilation will lead to intracranial pressure (ICP) increase.

    • The patient should be intubated (if possible) or formal tracheostomy performed within 24 hours to avoid glottic or subglottic stenosis.

    • Complete upper airway obstruction proximal to the cricothyrotomy is a contraindication because of the risk of devastating barotrauma to the lungs.

PERICARDIOCENTESIS

Pericardiocentesis is the aspiration of fluid from the pericardial space that surrounds the heart. It is typically performed in patients experiencing cardiac tamponade and may be lifesaving.

Echocardiography is now the most facile way to identify pericardial effusions, characterize their size and location, and assess dynamic findings associated with tamponade. Hemodynamic effects can be assessed by determining abnormal septal motion, right atrial or right ventricular inversion, and decreased respiratory variation of the inferior vena cava (IVC) diameter.

INDICATIONS

Emergent pericardiocentesis:

• The presence of life-threatening hemodynamic alterations in a patient with suspected cardiac tamponade.

Nonemergent pericardiocentesis:

• The aspiration of pericardial fluid in hemodynamically stable patients may be used for diagnostic, palliative, or prophylactic reasons. This procedure should be performed under ultrasonography, fluoroscopic visualization, or computerized tomography.

Contraindications:

• No absolute contraindications exist in the hemodynamically unstable patient. Even the aspiration of small amounts of fluid may improve the patient's status and prevent arrest.

Relative contraindications:

• Uncorrected bleeding disorders and traumatic cardiac tamponade. Some experts believe that tamponade caused by trauma should be treated via emergency thoracotomy.

Materials:

• Antiseptic solution

• Sterile drapes, gown, mask

• 1% lidocaine

• Small and large syringes

• Needles

• Pericardiocentesis kit

EMERGENT NEEDLE PERICARDIOCENTESIS POSITIONING AND TECHNIQUE

The patient can be positioned either supine or in a semirecumbent position at a 30- to 45-degree angle. This brings the heart closer to the anterior chest wall.

The patient should have at least one intravenous line, should be receiving supplemental oxygen, and should be connected to a cardiac monitor and continuous pulse oximetry. If time permits, placement of a nasogastric tube is advised to decompress the stomach and decrease the chance of gastric perforation.

Identify the anatomic landmarks, including the xiphoid process and the fifth and sixth ribs, and select a site for needle insertion. The subxiphoid approach is most commonly used, followed by the left sternocostal margin. See Figure 10-4.

Sterilely clean and drape the subxiphoid area using universal precautions (if time allows).

Create a skin wheal with local anesthetic solution, and use that wheal to infiltrate and anesthetize subcutaneous and deeper tissue and sternocostal margins.

Connect a large syringe (20 or 60 mL) to the spinal needle, and aspirate 5 mL of normal saline into the syringe. Occasional injection of small amounts of saline can help keep your needle patent and free of clots or debris. If time allows, connect an alligator clip to the base of the spinal needle and connect it to the V1 lead of an electrocardiogram (ECG) machine (see Figure 10-4).

Insert the spinal needle at the subxiphoid area at a 45-degree angle to the abdominal wall and direct toward the left shoulder at 45 degrees off the midline sagittal plane. If time permits, needle insertion should be done under ultrasonographic guidance.

While applying negative pressure on the syringe, slowly advance the needle until there is return of fluid, cardiac pulsations are felt, or there is a change in ECG waveform. If the ECG waveform is consistent with myocardial injury (ST segment elevation), this may mean the needle is in direct contact with the myocardium; slowly withdraw the needle until the tracing returns to normal.

Withdraw as much fluid as possible. One may want to configure a setup using a three-way stopcock in order to limit movement of the needle and syringe if there is a need to remove a large volume/effusion.

Remove the needle once fluid can no longer be aspirated.

CONFIRMATION TESTS TO DETERMINE IF FLUID IS PERICARDIAL VS. INTRACARDIAC

Pericardial aspirate should not form a clot, whereas intracardiac blood will clot.

Pericardial aspirate should have a lower hemoglobin concentration than peripheral blood.

Fluorescein test: Intracardiac injection of fluorescein should cause a fluorescent flush when examining a patient's conjunctiva.

CHEST TUBE INSERTION

Chest tubes are used to remove air (pneumothorax), fluid (pleural effusion, blood), or pus (empyema) in the thoracic space. To accomplish this task, either a needle thoracentesis or percutaneous thoracostomy can be performed.

INDICATIONS

• Pneumothorax (spontaneous, iatrogenic, tension)

• Hemothorax

• Parapneumonic effusion (if complex)

• Empyema

• Recurrent malignant effusion

• Chylothorax

• Penetrating chest trauma

• Bronchopleural fistula

NEEDLE THORACENTESIS

Equipment

• Needle size (dependent on patient size)

• Infant: #23 to 25 gauge butterfly needle or #22 to 24 gauge IV catheter

• Child: #18 gauge needle or #18 gauge angiocath

• Young adult: #14 gauge needle (2″ catheter-over-needle)

• Approved cleansing solution (chlorhexidine, povidone-iodine)

• Sterile gown, gloves, mask, and cap/sterile drapes

• Three-way stopcock, “T” connector/extension tubing

• 20 mL syringe

• 1% lidocaine

• Sterile 2″ × 2″ gauze pads

• Paper tape

Patient preparation

1. Place the patient in the supine position (ensure thermoregulation is maintained in infants).

2. Augment oxygen concentration and delivery and/or ventilation as needed.

3. Monitor heart rate, color, and oxygen saturation.

TECHNIQUE

(Needle decompression in emergent situations)

1. Locate landmarks on the chest to find the second intercostal space (Figure 10-5).

2. Cleanse the insertion site with cleansing solution. Work from the identified site of insertion and clean in a concentric pattern outward. Allow ∼1 minute to dry. Drape with sterile field/towels.

3. Using 1% lidocaine, initially anesthetize the insertion site subcutaneously (above the rib to avoid the neurovascular bundle) and then advance to anesthetize the costal margins and deeper to the muscle and parietal pleura.

4. Insert the needle firmly into the second intercostal space, midclavicular line, just above the top of the third rib (again, inserting the needle at the superior edge of the rib avoids the neurovascular bundle) (Figure 10-6).

5. The operator can connect the needle/angiocath to extension tubing and a three-way stopcock set up with a 20-mL syringe attached to facilitate safe drainage.

6. As the needle is being advanced into the pleural cavity, a small amount of negative pressure should be exerted on the syringe plunger. Advance the needle until a “pop” is felt, signifying pleural entry. Air or fluid may rapidly flow into the syringe. Once the pleural space has been entered, the needle should be held steady and advanced no farther. If aspiration is not successful, then imaging (typically ultrasound) should be obtained.

7. For a tension pneumothorax, the inserted thoracentesis needle hub should be connected to extension tubing that is attached to a water seal/Pleur-evac. This will prevent air from being entrained and entering the pleural cavity and allows any trapped air to escape.

8. Needle thoracentesis is typically a temporary measure (unless being performed for diagnostics). A chest tube should be placed for more definitive treatment when the patient is stable.

9. Once the withdrawal of air or fluid is complete, withdraw the needle. Monitor the patient vigilantly for any signs of reaccumulation.

PERCUTANEOUS THORACOSTOMY

Equipment

• Sterile gloves, gown, mask, and cap

• Sterile surgical drapes

• Chest tube tray that contains (at minimum):

  • - Scalpel and blade

  • - Two straight hemostats

  • - Suture scissors

  • - Needle driver

  • - Two curved Kelly hemostats

• 3.0 silk suture

• Chest tubes of age-appropriate size

• Antiseptic skin preparation

• 1% lidocaine

• 3 mL sterile syringe

• Occlusive dressing

• Sterile gauze pads (4 × 4)

• Chest drainage device (e.g., Heimlich one-way flutter valve, Pleur-evac)

CHEST NEEDLE AND CHEST TUBE INSERTION

• Preparation

  1. Administer sedation as required.

  2. Place the patient in a supine position. The patient's arm can be raised/taped above the head on the insertion side to facilitate exposure.

  3. Augment oxygen concentration and delivery and/or ventilation as needed. Monitor heart rate, color, and oxygen saturation.

  4. For chest tubes placed along the anterior axillary line, the head of the bed can be elevated 30 to 60 degrees, lowering the diaphragm and decreasing the risk of injury to the diaphragm, liver, or spleen.

• Technique

  1. Apply mask, perform sterile scrub, and don sterile gown and gloves.

  2. Estimate insertion distance. Using the chest tube, measure the distance from the insertion site to the lung apex and make a note of this.

  3. Identify appropriate landmarks on the chest

     • The nipple is an anatomic landmark for the fourth intercostal space. Avoid the pectoralis muscle and the axillary artery.

     • Choose the appropriate insertion site at the fourth or fifth intercostal space at the midaxillary line.

  4. Prepare the catheter for insertion. Close the hemostat or forceps around the insertion end of the chest tube. Clamp the end of the chest tube that will be connected to the Pleur-evac so that air cannot enter the pleural cavity once the chest tube is inserted.

  5. Cleanse the identified insertion site with chlorhexidine 2%, cleaning from the insertion site outward in concentric circles. Allow to dry for 1 to 2 minutes.

  6. Drape the desired anatomic region with a sterile drape or towels to create a surgical field. Make sure you can still view the patient's head and neck.

  7. Using 1% lidocaine, anesthetize the insertion site. Some operators create a wheal. Infiltrate subcutaneous tissue first and then proceed to muscle, periosteum, and pleura. Infiltrating the pleura is vital to minimize discomfort in the awake patient.

  8. Create a 2-cm superficial skin incision immediately above the rib, parallel to the rib and intercostal space. This will avoid injury to the neurovascular bundle if your incision extends more deeply than intended.

  9. Insert a forceps or Kelly clamp into the incision to perform blunt dissection down to the intercostal space. This process may require several scissoring and separating maneuvers. Once the operator has dissected down to the pleura, gently advance the forceps in the closed position until the pleura is penetrated. Once pleural penetration is achieved, open the forceps to spread and dissect, creating a subcutaneous tunnel in the parietal pleura and intercostal muscles (Figure 10-7).

  10. After penetrating the pleura with the instrument, a rush of air/fluid is often audible.

  11. Grasp the curved hemostat that is holding the catheter and direct the catheter through the incision into the pleural cavity. Once this is achieved, stabilize the catheter with the opposite hand and release it from the hemostat. Slowly remove the hemostat from the chest and advance the catheter to the desired position. Condensation in the lumen of the tube indicates that it has entered the pleural space. Its entry site should be palpated to ensure that it is not in the subcutaneous tissue.

  12. In most cases, the catheter will need to be directed anteriorly and superiorly. Advance the chest tube after releasing the hemostat. Ensure that the eyes/holes of the catheter are within the pleural space. Moisture that is present within the tube usually confirms its proper placement within the pleural space.

  13. A purse string suture may be placed around the tube and the chest tube secured by wrapping and then tying the skin suture around the tube.

  14. Cover the insertion site with an occlusive dressing. The use of Tegaderm over the insertion site permits visualization of the field.

  15. After securing the chest tube, connect the chest tube to a Pleur-evac or similar device. If the chest tube is draining fluid, the operator may want to control the volume of drainage with intermittent clamping to avoid rapid fluid shifts and re-expansion pulmonary edema, especially in smaller children.

Do not unclamp the chest tube until the drainage system is attached. This will prevent the inspiration of air into the pleural space.

PARACENTESIS

Abdominal paracentesis is a bedside procedure in which a needle is inserted into the peritoneal cavity and ascitic fluid is obtained. Diagnostic paracentesis involves the removal of a small amount of fluid for testing. Diagnostic peritoneal lavage is usually performed by a surgeon to rule out internal bleeding after a trauma and will not be explained here in detail. Therapeutic paracentesis typically involves the removal of a large volume of ascitic fluid to reduce intra-abdominal pressure and its associated symptoms (abdominal pain, dyspnea, feeding intolerance).

Indications:

• Evaluation of new-onset ascites

• Diagnostic sampling of ascitic fluid (rule out bleeding, chyle leak, malignancy, or infection)

• Therapeutic removal of ascitic fluid

CONTRAINDICATIONS

Absolute

• Patient instability (unstable airway or hemodynamics)

• Intestinal perforation

Relative

• Potential sites on abdomen infected or compromised

• Coagulopathy or bleeding diathesis

• Recent intestinal tract surgery (<1 month)

Equipment

• Sterile gloves, gown, mask, and cap

• Sterile surgical drapes

• Antiseptic skin preparation

• Local anesthetic (1% lidocaine)

• 21 or 23 gauge needles

• Angiocatheters with syringes

• Large-bore needle with plastic catheter

• Sterile gauze pads (4 × 4)

• Sterile containers for fluid collection

• Culture tubes for samples

Risks

• Perforation of bowel or solid organs

• Bleeding

• Infection

• Pneumoperitoneum

• Ascites leak

TECHNIQUE

Place the patient in a supine or side position.

Cleanse the insertion site with cleansing solution. Work from the identified site of insertion and clean in a concentric pattern outward. Allow ∼1 minute to dry. Drape with sterile field/towels.

Ultrasound guidance is recommended (if available) to locate the optimal pocket of fluid.

Using 1% lidocaine, initially anesthetize the insertion site; injecting the skin first and then deeper into the subcutaneous layer.

The anterosuperior iliac spine should be located and a site chosen that is ∼3 cm medial and ∼ 3 cm cephalad to this landmark (Figure 10-8). The inferior epigastric arteries run from a point just lateral to the pubic tubercle cephalad within the rectus sheath and should be avoided due to the risk of bleeding. Insert the tap needle into the anesthetized area. In most children, depending on size and body habitus, fluid can be obtained by inserting the needle 1 to 2 inches into the abdomen. To prevent ascites leak after the procedure, the Z-track technique can be utilized, which creates a nonlinear track to prevent direct connection between the ascitic fluid in the peritoneal cavity and the skin (Figure 10-9).

If a large volume of paracentesis is required, connecting the insertion needle to a three-way stopcock may facilitate removal so that the operator does not need to disconnect the syringe from the needle and risk migration of the needle/catheter setup.

Obtain as much fluid as desired for laboratory sampling or therapeutic relief.

Remove the needle and place a pressure dressing at the insertion site.

Colloid replacement is controversial and likely unnecessary unless removing more than 5 liters of fluid in larger children. Some studies suggest the use of colloid replacement when draining >200 mL/kg (dry weight) in children to prevent circulatory changes and potential renal compromise.

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