Difficult vascular access is often the rate-limiting step in resuscitation of children. Although intraosseous access may serve as a bridge to vascular access, it is temporary. P-POCUS improves the success of placement of both peripheral and central venous catheters.
By using the high-frequency linear probe, one identifies the vessel of interest and its surrounding relationships.14 The vein should be compressible, nonpulsatile, and increase with valsalva or positioning maneuvers that increase venous pooling. The use of real-time guidance of the vascular access procedure is the preferred method, ideally with one-operator technique such that fine adjustment of the probe can be made as the catheter is being inserted. However, the static view or two-operator techniques are better than landmark or blind techniques if operators are not yet adept at one-operator real-time ultrasound guidance.15
When a central line is needed, the femoral vein is the most apparent candidate as it is away from the neck or chest where other life-saving maneuvers may be in progress, such as cervical spine immobilization, securing the airway, or chest compressions. The traditional technique of palpating the femoral artery and inserting the needle medial to this to access the femoral vein can be unreliable. By using ultrasound to guide central venous access, numerous adult studies have demonstrated that it improves time to cannulation, first-time success rate, while decreasing complications of arterial punctures and failure to cannulate the vein.15,16 Acronyms describing the medial to lateral relationship of vein, artery, and nerve (Fig. 15-5A) have been demonstrated to be inconsistent. The femoral artery and vein overlap in 12% to 45% of children17,18 and in up to 88% of children just 1 cm distal the inguinal ligament in the frog-legposition18 (Fig. 15-5B). Another study demonstrated faster and safer femoral vein catheterization using ultrasound during cardiopulmonary resuscitation (CPR) in adults.19 In particular, they noted that the pulsations felt in the groin during CPR was venous in origin.
A. Right inguinal view of an infant in which the most common anatomic relationship of the femoral vein and artery from medial to lateral is seen. Inset shows the compressibility of the femoral vein and not the artery. B. Right inguinal view in a school-aged child in which the femoral artery overlaps by 50% of the femoral vein.
Peripheral intravenous (IV) placement is one of the most common and distressing procedures performed in pediatric hospitals, often being the leading sources of pain during their ED visit. POCUS can be used to visualize and guide peripheral IV placement. Studies to date have yielded mixed results.20,21 However, when performed by ED nurses in an adult population with difficult IV access, it led to an improved success rate and fewer complications,22,23 as well as improved patient satisfaction.24
In one study, children with difficult venous access were randomized to an ultrasound group, in which the vein was visualized and marked by a physician through which the nurse would attempt the IV, but there was no significant benefit demonstrated with this static, two-operator–based technique.25 Subsequently, Doniger et al.26 studied whether two-operator real-time ultrasound-guided IV placement resulted in improved success in children. The physician performed the ultrasound visualization of the vein and the nurse performed the IV catheterization and resulted in reduced time to successful IV placement and fewer numbers of skin punctures. More recently, one-operator real-time ultrasound-guided IV placements among children less than 3 years old with difficult IV access undergoing general anesthesia was performed in which the use of ultrasound resulted in a shorter time to IV placement (seven times faster) compared with traditional technique, along with fewer skin punctures and a higher first-attempt success rate.27 An adult ED study demonstrated that an ultrasound-guided peripheral IV access program significantly reduced the number of central venous catheters placed in the ED, particularly in noncritically ill patients.28 Another study similarly demonstrated that nurse-performed ultrasound-guided IV placements led to significant improvements in patient care and fewer physician vascular access interventions.24 A meta-analysis of IV placement in difficult IV access patients confirmed that ultrasound more than doubled the likelihood of successful cannulation.29
Because peripheral veins are easily compressible, pressure is minimized by applying generous amounts of sterile gel. The larger peripheral veins located between 0.3 and 1.6 cm deep are those that will be cannulated most successfully with ultrasound guidance (Fig. 15-6).30 Maneuvers such as blood pressure cuff or tourniquet application can increase the size of the vein to improve the likelihood of success.31
A. Peripheral vascular access on an 18-month-old in which the basilic vein is easily identified (arrow). B. Forearm vein identified in the same child (arrow) with the inset demonstrating vein compressibility.