Section 3. Cardiovascular System

• • Therapeutic: Impending cardiac tamponade.

  • Diagnostic.

  • • Infectious pericarditis.

    • Rule out an oncologic process.

  • Compromise in the patient’s hemodynamic status.

Relative

• • A blood dyscrasia in which a patient may have a significant bleeding complication.

  • A cutaneous infection in the area of the most feasible sights for pericardiocentesis.

  • A significantly elevated diaphragm, a grossly enlarged liver, or profound ascites, which all change the standard landmarks of inserting the pericardiocentesis needle in the subxiphoid area.

  • Under such circumstances, use the intercostal approach.

• • Povidone-iodine or equivalent sterilization substrate to cleanse the subxiphoid area.

  • 1% or 2% lidocaine or xylocaine.

  • 25-gauge, 1.5-inch-long needle.

  • 16- or 18-gauge needle, ≥ 1.5 inch.

  • Floppy tip wire that can be introduced through the needle.

  • Pigtail catheter with multiple side holes as well as an end hole.

  • Scalpel.

  • 3-way stopcock.

  • 30-mL or 60-mL syringe and suture kit.

  • ECG monitor, pulse oximeter, and blood pressure cuff.

• • Infection and bleeding can be minimized with proper technique.

  • Pneumothorax (unusual).

  • Laceration of the liver (unusual).

  • Coronary injury (unusual).

  • Cardiac perforation (unusual).

• • Ideally, a patient should be continuously monitored with echocardiography and fluoroscopy in an interventional radiology or cardiac catheterization laboratory.

  • Frequently, this is not an option, and bedside pericardiocentesis without portable fluoroscopy is performed. In this circumstance, the patient should be sedated.

  • Respiratory and hemodynamic status should be monitored by assistants, so that the physician can concentrate on performing the pericardiocentesis.

• • Prepare and drape the subxiphoid area in the usual sterile fashion.

  • If the subxiphoid approach might be difficult (due to an unusually located heart or elevated diaphragm), consider preparing the left sternal border.

  • All equipment should be readily available and an assistant should be available to help with manipulation of needles, wires, and catheters.

• • Supine position, with 10–30 degrees of reverse Trendelenburg.

  • Occasionally, the partially sitting position may be required or beneficial.

  • • Makes an orthopneic patient more comfortable.

    • May allow for most of the pericardial fluid to position inferiorly or closer to the drainage site.

• • Prepare the subxiphoid area and left sternal border.

  • Administer 1% or 2% lidocaine approximately 0.5–1 cm below the left costoxiphoid angle using a 25- or 27-gauge 1.5-inch-long needle.

  • • Infiltration of the lidocaine should be superficial as well as deep, pushing the needle superiorly, posteriorly, and leftward.

    • Withdraw fluid each time the needle is passed deeper within the skin and subcutaneous tissues.

  • To allow for easier passage of the needle, precut the skin with the scalpel before introducing the 16- or 18-gauge 1.5-inch to 2.5-inch needle.

  • Insert the larger needle at an approximate 30–45-degree angle with the abdomen with constant negative pressure on the syringe.

  • Monitor ECG very carefully for evidence of dysrhythmias or ST segment changes (evidence of coronary or myocardial injury).

  • Slowly insert the needle until fluid is withdrawn.

  • • Suspect cardiac perforation is the fluid is grossly bloody.

    • Serous fluid confirms that the needle has passed into the pericardial space.

    • It is not unusual to feel the needle pass through the pericardium.

  • Fix the needle into position once pericardial fluid is extracted.

  • Pass the floppy tip wire through the needle with the intent of passing the wire deep within the pericardium and into the posterior pericardial space (Figure 22–1).

• • Because the wire may irritate the epicardium, ventricular ectopy is not uncommon.

  • Once the wire is secured deep within the pericardium, remove the needle.

  • Make a larger incision in the skin adjacent to the wires so that the catheter can be inserted.

  • Insert the soft-tipped multiple sidehole or pigtail catheter over the wire and secure it in the posterior pericardial space.

  • Connect the catheter to a 3-way stopcock, and fluid should be extracted slowly, monitoring for blood pressure and ectopy.

  • Continuous echocardiographic monitoring is useful for location of the wire and catheter as well as for monitoring adequate extraction of pericardial fluid.

  • Once catheter position is confirmed, the catheter should be secured with sutures and the entire site covered sterilely to minimize infection.

• • Send pericardial fluid for cell count, protein, glucose, lactic dehydrogenase, cytology as well as all other studies for infectious agents.

  • Normal pericardial fluid is clear to straw colored, scant (< 50 mL) with < 500 white blood cells/mcL.

  • An elevated white blood cell count suggests either an infectious or inflammatory process.

  • Protein, glucose, and lactic dehydrogenase can be helpful in differentiating a transudate from an exudate.

  • Metastasis to the pericardial space or pericardial tumors are frequently exudative, with abnormalities seen on cytology.

  • Monitor the patient closely for rhythm disturbances and unstable blood pressure.

  • Patients may require fluid resuscitation if large amounts of fluid are extracted from the pericardial space.

  • • Remove the fluid slowly.

    • Replace with isotonic fluid, if possible.

    • Large children with nephrotic syndrome can have as much as 1–2 L of pericardial fluid and be relatively asymptomatic.

• • Compromise in the hemodynamic status.

  • Bleeding.

  • • Can be superficial and easily controlled with pressure.

    • Deeper bleeding from either a liver or splenic injury may be less obvious and more difficult to control.

  • A coronary injury is rare but potentially catastrophic (as is a cardiac perforation). These require emergent intervention by a cardiac surgeon.

  • Arrhythmias are typically transient and can be managed by repositioning the needle, wire, or catheter.

  • Occasionally, more persistent rhythm disturbances occur that require antiarrhythmic therapies.

  • A pneumoperitoneum or small pneumothorax requires careful monitoring but can be self-limited.

  • Pneumopericardium should resolve as long as the pericardiocentesis catheter is secure, in proper position, and connected to negative pressure.

• • Screening for congenital or acquired heart disease.

  • Follow-up of established cardiac disorders:

  • • Progression of chamber enlargement.

    • Hypertrophy.

    • Conduction disorders.

    • Ischemic changes.

  • Evaluation of apparent life-threatening event, syncope, chest pain, or new-onset seizure.

  • Arrhythmia detection and evaluation.

  • Evaluation of conduction disorder.

  • Monitoring cardiac effects of medication.

  • Evaluation for appropriate pacemaker or defibrillator function.

  • Evaluation of cardiac effects of electrolyte or metabolic abnormalities.

• • Disorders that limit access to skin of chest wall, such as thoracic wound.

  • Extensive bandages over chest.

  • Third-degree skin burns.

• • ECG machine, leads.

  • Electrode stickers; pediatric patches are best.

  • Alcohol pads to clean skin.

• • Improper electrical grounding may deliver electrical shock; extremely rare.

• • Improper lead positioning is a major source of abnormal tracings.

  • • Results in repeat ECGs or unnecessary further testing.

    • As many as 15–20% of pediatric ECGs performed in emergency departments or intensive care units show improper lead placement.

  • The most common recording error is limb lead reversal.

  • • White electrode should be on right arm.

    • Black electrode should be on left arm.

  • Automated ECG interpretations that read “left atrial rhythm” usually reflect limb lead reversal.

  • Negative P, QRS, and T waves in leads I and aVL are another indicator of lead reversal.

  • Make sure the initial recording is at the appropriate speed: 25 mm per second, and appropriate gain: 10 mm per mV.

  • Eliminating as much patient movement as possible is essential; blowing bubbles over young children often allows time for recording without movement.

• • Clean the area with alcohol swab.

  • Skin must be clean and dry.

  • Leads cannot be placed over bandages: either reposition bandage or omit lead.

• • Supine position is essential.

  • Some patients have T wave changes in upright positions, and decubitus positioning may slightly alter the location of the heart relative to the ECG leads.

• • Lead placement is important and must be consistent.

  • Inappropriate placement of limb or precordial leads results in interpretation errors, including hypertrophy or infarct patterns.

  • Figure 23–1 shows placement of leads.

• • • RA: Right forearm, distal to insertion of deltoid muscle.

    • LA: Left forearm, distal to insertion of deltoid muscle.

    • RL: Right leg.

    • LL: Left leg.

    • V1: Fourth intercostal space, right sternal edge.

    • V2: Fourth intercostal space, left sternal edge.

    • V3: Halfway between V2 and V4.

    • V4: Fifth intercostal space, midclavicular line.

    • V5: Same level as V4 on anterior axillary line.

    • V6: Same level as V4 on midaxillary line.

• • Place electrode stickers appropriately.

  • Attach the leads, with careful attention to limb lead placement.

  • Enter the patient data into the ECG machine. ECGs without name, age, and date cannot be officially interpreted.

  • Select gain and paper speed (standard speed 25 mm per second and standard gain 10 mm per mV).

  • Use standard settings initially.

  • Modify gain as needed.

  • Select the type of tracing desired.

  • • 12-lead ECG.

    • 12-lead rhythm strip.

    • 3-lead rhythm strip.

  • Ensure the patient is still and the tracing is stable on the monitor of the ECG machine.

  • Once there is no artifact, record.

  • Inspect the tracing before disconnecting the leads.

  • If no additional tracings are needed, disconnect the leads and remove the electrode stickers.

• • To avoid missing important information, interpret ECGs consistently and systematically.

  • Knowledge of the patient’s age is essential because standards are age-dependent.

  • ECGs in children should be interpreted by clinicians specifically trained in pediatrics because of the significant age-related differences from adult ECGs.

  • Evaluate rate, rhythm, axis, intervals, hypertrophy, ST segments.

Rate

• • Normal rates are age-dependent.

  • • Infants: 100–170 bpm.

    • Young children: 80–140 bpm.

    • Adolescents: 60–100 bpm.

Rhythm

• • Analyze P/QRS relationship and consistency.

  • Atrial rhythm.

  • • P wave before each QRS.

    • Sinus P wave has normal axis (upright in leads I and aVF).

    • Usually normal PR interval.

  • Junctional rhythm.

  • • P waves during or after QRS.

    • Usually narrow QRS complexes.

  • Ventricular.

  • • Usually wide QRS complexes, although several simultaneous leads may be needed to determine QRS duration.

    • Preceding upright P wave with 1:1 P/QRS relationship should not be present.

  • Atrioventricular (AV) dissociation.

  • • Consider conduction abnormality or accelerated junctional or ventricular rhythm.

P Wave Axis

• • Normal P wave axis is upright in leads I and aVL.

  • Left atrial rhythm, or limb lead reversal, shows negative P wave in leads I and aVL.

  • Low atrial rhythm shows negative P wave in inferior leads: II, III, aVF.

QRS Axis

• • Normal frontal QRS axis is age-dependent.

  • Neonates have relatively rightward QRS axis (+40 to +180 degrees), which gradually shifts toward left with age.

  • Left axis deviation or superior axis (0 to –90 degrees) in neonate is highly suggestive of congenital heart disease, particularly among infants with Down syndrome.

  • Left axis deviation or superior axis is also associated with the following:

  • • AV septal defects (primum atrial septal defects).

    • Tricuspid atresia.

    • Underdevelopment of right ventricle.

    • Left ventricular hypertrophy.

    • Preexcitation.

  • Right axis deviation is suggestive of right ventricular hypertrophy or underdevelopment of left ventricle.

PR Intervals

• • Measured from onset of P wave to onset of QRS.

  • Normal PR interval is age-dependent, usually < 160 msec in young children.

First-Degree AV Block

• • PR interval greater than expected for age.

  • Associated with atrial septal defects, rheumatic fever, ectopic atrial rhythms.

Second-Degree AV Block

• • Type I (Wenckebach).

  • • Successive PR lengthening until atrial impulse is not conducted (generally does not progress).

    • May be normal variant, particularly during sleep.

  • Type II.

  • • Nonconducted atrial impulse without progressive PR lengthening.

    • Not commonly seen.

    • Not usually considered a normal variant.

Third-Degree AV Block

• • Failure of an atrial impulse to be conducted to the ventricles.

  • Never a normal variant but needs to be differentiated from accelerated junctional or ventricular rhythms.

  • Congenital form associated with autoimmune disorders or complex congenital heart disease.

  • Acquired form secondary to surgical repair of congenital heart disease.

  • Congenitally corrected transposition of the great arteries.

  • Myocarditis.

  • Lyme disease.

• • Reflects ventricular depolarization.

  • Normal.

  • • Less than 90 msec in infants and young children.

    • Less than 100 msec in older children.

  • Prolonged QRS duration for age reflects right or left ventricular conduction delay or block (> 120 msec in adults).

  • Right ventricular conduction delay may be associated with atrial septal defects.

  • Right bundle branch block is seen after surgical repair of some forms of congenital heart disease, especially tetralogy of Fallot.

  • Left bundle branch block is rare and usually associated with surgical repair of lesions obstructing left ventricular outflow tract or with significant cardiomyopathy.

QT Interval

• • Measured from onset of QRS to end of T wave.

  • Reflects ventricular depolarization and repolarization.

  • The normal QT interval of 400 msec is based on a heart rate of 60 bpm.

  • Rate-corrected QT interval = QTc.

  • Bazett’s correction: Measured QT interval/square root of RR interval.

  • Normal QTc.

  • • < 460 msec for females.

    • < 450 msec for males.

  • A prolonged QT interval increases the risk for potentially life-threatening arrhythmias and may result in the long QT syndrome (a cardiac ion channelopathy) or as an acquired abnormality from drug, electrolyte, or nervous system disorders.

  • Patients with seizures, syncope, or hearing loss should be screened for QT abnormalities.

  • A prolonged QT interval may require cardiac consultation.

  • QT prolongation may be intermittent; therefore, a normal QT interval does not preclude the presence of long QT syndrome.

Atrial Enlargement

Right Atrial Enlargement

• • Tall pointed P waves.

  • Amplitude > 2.5 mm.

  • Best seen in leads II, III, V1.

  • Associated with the following:

  • • Atrial septal defects.

    • Right ventricular hypertension.

    • Pulmonary disease.

    • Cardiomyopathy.

Left Atrial Enlargement

• • Increased P wave duration (> 90–100 msec).

  • Biphasic P wave in V1 with deep negative component.

  • Associated with large left to right shunts and mitral valve disease.

Biatrial Enlargement

• • Increased amplitude and duration.

  • Associated with large left to right shunts and ventricular hypertrophy as well as cardiomyopathy.

Ventricular Hypertrophy

• • ECG diagnosis of hypertrophy is sensitive but not specific, resulting in frequent overinterpretation of hypertrophy.

  • Thin chest wall, anemia, volume overload, and athletic training may contribute to ECG appearance of ventricular hypertrophy.

Left Ventricular Hypertrophy

• • Voltage criteria include tall R waves in left precordial leads V5–V6 > 98 percentile for age, or deep S waves in V1–V2.

  • Sum of R wave in V6 and S wave in V1 or V2 > 98 percentile for age.

  • Deep Q waves in inferior limb leads or left precordial leads.

  • Seen with the following conditions:

  • • Patent ductus arteriosus.

    • Lesions obstructing left ventricular outflow tract, such as aortic stenosis or coarctation.

    • Hypertension.

    • Sickle cell anemia.

    • Cardiomyopathy.

Right Ventricular Hypertrophy

• • Voltage criteria include increased R wave amplitude in right precordial leads V1–V2 > 98 percentile for age.

  • A Q wave in V1 is never normal and suggests right ventricular hypertrophy or ventricular inversion.

  • Upright T wave in right precordial leads after the first week of life, and before “adult” ECG pattern is achieved, indicates right ventricular hypertrophy.

  • Deep S wave amplitude in V6 suggests right ventricular hypertrophy; usually > 7 mm.

  • An rSr′ pattern is a common normal variant in children; however, a tall R′ is not normal.

  • Seen when lesions obstruct right ventricular outflow tract, such as in cases of pulmonic stenosis and tetralogy of Fallot.

Biventricular Hypertrophy

• • Voltage criteria for both right and left ventricular hypertrophy.

  • Katz-Wachtel criteria for biventricular hypertrophy: Large combined voltages of R + S wave amplitude in V4 > 60 mm.

  • Associated with the following:

  • • Large patent ductus arteriosus.

    • Large ventricular septal defects.

    • AV septal defects.

    • Truncus arteriosus.

    • Single ventricle.

    • Cardiomyopathy.

ST Changes

• • Normal ST segment horizontal, isoelectric.

  • Can be normal to have 1 mm elevation or depression of ST segment in limb leads.

  • Left precordial leads may have up to 2-mm elevation or depression of ST segment.

  • Beware of calling ST changes normal if they are a change from a previous ECG or if the patient has chest pain or other cardiac symptoms.

  • J point elevation is a normal finding.

  • ST changes can be seen in the following:

  • • Myocardial ischemia.

    • Myocarditis.

    • Pericarditis.

    • Abnormal potassium levels.

    • Digitalis.

    • Left ventricular hypertrophy with “strain.”

    • Central nervous system pathology.

Preexcitation

• • Short PR interval in sinus rhythm, associated with a slurred upstroke to QRS (delta wave).

  • The term “Wolff-Parkinson-White syndrome” refers to the association of preexcitation pattern on ECG with supraventricular tachycardia.

  • Left axis deviation or the absence of a Q wave in V6 may be subtle indicators of preexcitation.

  • Preexcitation may be intermittent, and it may be associated with the development of supraventricular tachycardia in about 30–35% of cases.

  • Due to the small but present risk of life-threatening arrhythmias as the initial symptomatic event with preexcitation, patients with this finding on ECG should be referred for cardiac consultation.

Arrhythmia Detection

Rate: Too Fast or Too Slow?

• • Bradycardia may reflect the following:

  • • Sinus node dysfunction (either intrinsic or, more often, secondary to systemic disorders).

    • Blocked premature atrial beats.

    • Conduction disorders.

  • Tachycardia may be due to the following:

  • • Sinus tachycardia associated with fever, sepsis, anemia, or hemodynamic stress.

    • Pathologic rhythm (eg, supraventricular, junctional, or ventricular).

Rhythm: Regular or Irregular?

• • Irregular rhythms include the following:

  • • Sinus arrhythmia (very common in young children).

    • Sinus node dysfunction.

    • Premature beats.

    • Atrial fibrillation.

    • Ventricular fibrillation.

QRS Complex: Wide or Narrow?

• • Wide QRS rhythms are seen in the following:

  • • Supraventricular tachycardia with bundle branch block.

    • Supraventricular tachycardia conducted via an accessory connection.

    • Profound electrolyte abnormalities (hyperkalemia).

    • Drug intoxication (digoxin).

    • Toxic ingestions (yew berry).

    • Ventricular tachycardia.

What Is the P/QRS Relationship?

• • 1:1 P/QRS ratio.

  • • If P wave precedes QRS with constant PR interval, consider sinus or atrial rhythm.

    • Analyze P wave morphology to distinguish between these rhythms.

    • If QRS precedes P wave, consider ventricular or junctional rhythm, or reciprocating rhythms with retrograde conduction to atria (supraventricular tachycardia).

  • If there are more P waves than QRS complexes, consider atrial arrhythmia (ie, atrial flutter, atrial tachycardia).

  • If there are more QRS complexes than P waves, consider junctional or ventricular rhythm.

• • Rare.

  • Incorrect set-up or equipment malfunction may result in an ECG that is misinterpreted, resulting in additional (unnecessary) testing.

• • Depends on the reason the test was obtained, the patients’ clinical status, and the ECG findings.

  • Patients with abnormal ECGs should be referred to a pediatric cardiologist; the timing of referral depends on both the ECG finding and the clinical context.

• • All children aged 3 years or older who are seen in any medical setting should have their blood pressure (BP) measured.

  • BP is a primary measure of cardiac output in acute assessment of any potentially compromised patient.

  • BP change over time allows monitoring of changing hemodynamic status and of response to intervention.

  • In critical care settings, BP is best monitored by arterial line, since peripheral measures can be inaccurate when cardiac output is compromised.

Relative

• • BP measurement is not recommended as a routine in well children less than 3 years of age.

  • However, specific conditions signal the need for BP determination beginning in infancy and include the following:

  • • History of prematurity, very low birth weight, or any problem requiring neonatal intensive care.

    • Congenital heart disease (repaired or unoperated).

    • Recurrent urinary tract infections, hematuria, or proteinuria.

    • Renal or urologic disease.

    • Family history of renal disease.

    • Solid organ transplant, malignancy, or bone marrow transplant.

    • Treatment with drugs known to raise BP.

    • Systemic illnesses associated with hypertension.

    • Increased intracranial pressure.

• • BP should be measured using a standard clinical sphygmomanometer on the upper right arm and a stethoscope over the brachial artery pulse, just below the cuff.

  • Automated oscillometric BP devices are convenient and reduce observer error, but they do not provide exactly comparable results to the auscultatory method.

  • • However, because of their ease of use, these devices are valuable as a screening method and in intensive care settings.

    • Abnormal readings must be confirmed by auscultation.

  • Correct BP measurement requires a cuff size appropriate to the size of the child; this means a range of sizes, including a large adult cuff and thigh cuff, must always be available.

  • An appropriate cuff meets the following criteria:

  • • Height of the inflatable bladder is at least 40% of the arm circumference at a point midway between the olecranon and the acromion.

    • Bladder length should cover > 80% of the arm’s circumference (bladder width-to-length ratio ≥ 1:2).

  • Practically speaking, this means the cuff selected must be large enough to cover the majority of the upper arm with just room for the head of the stethoscope in the cubital fossa (Figure 24–1).

• • Whenever upper extremity hypertension is diagnosed, lower extremity BPs and pulses should be obtained and compared to exclude the possibility of coarctation of the aorta, which is the most commonly missed congenital heart diagnosis.

  • In children over 10 years of age, white coat hypertension is increasingly common.

  • • It is defined as elevated BP in medical settings but normal pressure at all other times.

    • This can be diagnosed by the use of ambulatory BP monitoring, which allows computation of mean wake and sleep pressures for comparison with published norms for age/gender/height.

  • In the presence of hypertension, left ventricular mass is increased; this measurement, obtained by echocardiography, is very useful in determining when to initiate therapy in children with high BP.

  • Through the efforts of the NIH-based Working Group on High Blood Pressure in Children and Adolescents, there is now a large national database of normal BP values throughout childhood to allow identification of children with early hypertension.

• • To determine usual BP in a nonemergent situation for comparison to norms, the child should ideally have avoided stimulant food or drugs and have been sitting quietly for 5 minutes.

• • In the nonemergent setting, the child should be seated with the back supported, feet on the floor, and right arm supported with the cubital fossa at heart level.

  • In critical care settings, consistency in position of the patient, the limb in which BP is measured and the technique of measurement should be maintained to optimize detection of physiologic change.

• • Cuff pressure should be pumped up to above anticipated systolic BP, then slowly and consistently deflated while listening with the bell of the stethoscope over the brachial artery pulse in the cubital fossa.

  • Systolic BP is the onset of the tapping sound of arterial flow, the first Korotkoff sound (K1).

  • In acute care settings where Korotkoff sounds may be difficult to appreciate, a Doppler probe over the brachial or radial pulse can optimize measurement of systolic BP.

  • Diastolic BP occurs with the disappearance of Korotkoff sounds (K5).

  • In some children, Korotkoff sounds can be heard down to 0 mm Hg.

  • • If this occurs, measurement should be repeated with less pressure on the head of the stethoscope.

  • If K5 persists down to 0, then K4, muffling of the Korotkoff sounds is recorded as diastolic BP.

Ambulatory Setting

• • In normal children, BP is determined primarily by body size and age; therefore, BP results must be compared to norms for age and height.

  • BPs are consistently higher in males beginning in early childhood; therefore, BP results must also be compared to norms for gender.

  • Revised BP tables from the 2004 report by the National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents include the 50th, 90th, 95th, and 99th percentiles by gender, age, and height.

  • • Use standard height charts to determine height percentile.

    • On appropriate gender table, follow the age row across to the intersection with the column for the height percentile for systolic and diastolic BP.

  • Classification.

  • • BP < 90th percentile is normal.

    • BP between 90th and 95th percentile is prehypertension; repeat BP measurement twice and record the average.

    • In adolescents, BP ≥ 120/80 mm Hg is prehypertension even if < 90th percentile.

    • BP > 95th percentile indicates possible hypertension; see Staging.

  • Staging.

  • • Stage 1: BP ≤ 99th percentile + 5 mm Hg, repeat BP on 2 more occasions; if high BP is confirmed, begin evaluation.

    • Stage 2: BP > 99th percentile + 5 mm Hg prompts referral for evaluation and therapy.

    • Symptomatic patients require immediate referral and treatment.

Acute Care Setting

• • Because BP measurements by cuff and auscultation are unreliable in unstable patients and automated oscillometric methods lack accuracy and reliability, arterial monitoring of BP is preferable.

  • In initial assessment of BP, mild to moderate hypotension is diagnosed when systolic BP is 20–30% below normal mean systolic BP for age; severe hypotension is diagnosed when systolic BP is < 30% of normal systolic BP for age.

  • In critical care settings, mean BP is often used to monitor BP.

  • BP results must always be interpreted in light of all available evidence for cardiac output, including mental status, skin perfusion, and urinary output, since hypotension is the last sign to develop in the failing circulation.

  • Sedation can lower BP without compromising perfusion.

• • Prolonged cuff application and inflation can lead to a transient ulnar neuropathy.

  • Petechiae can develop below the level of cuff application if initial inflation pressure is too high.