Matt Hansen
Children are a heterogeneous group in regard to vascular access, with unique needs in different age groups. Besides the size and depth of the vessel to be cannulated, challenges include control of the patient’s physical motion, while pain, anxiety, and parental concerns are addressed. This chapter reviews peripheral venous access, central venous access, ultrasound-guided access, and intraosseous access in children, and discusses techniques for anxiolysis and analgesia during these procedures.
PERIPHERAL VENOUS ACCESS
Peripheral venous access is a cornerstone of modern medical care. Veins in children are often of small caliber requiring narrow-gauge IV catheters. The skin can be thin, and vessels are often more superficial than in adults. Furthermore, the pain and anxiety associated with peripheral access in children is significant (1). Besides even in neonates, neural pain pathways are well developed and it is believed that pain can condition the patient’s future responses to painful events. In this context, it is ideal to obtain access as quickly and efficiently as possible, minimizing the number of IV attempts and the resulting stress to the patient and family. Placing a peripheral IV catheter in children requires more nursing resources, may take longer than in adults, and often requires active management of the patient’s position and anxiety by a second operator. Providers must consider the utility of the catheter and whether there are alternative options. For example, an IV catheter is often placed to check electrolytes and infuse fluid bolus in a child with dehydration from gastroenteritis. However, other than a bedside glucose, laboratory testing is of little utility in this situation, and oral rehydration is equally as effective as IV hydration in most circumstances.
The anatomic locations best suited for peripheral access in children are similar to those in adults, but with a few notable exceptions. First, the saphenous vein is a relatively large vein with a consistent location and can be accessed blindly using anatomic landmarks. It can often be located 1 to 2 cm superior and 1 cm medial to the medial malleolus, and then runs posteriorly toward the popliteal fossa. Use of a tourniquet and careful palpation may assist in locating the vessel. The antecubital fossa is another site which is relatively easy to cannulate in children, but it may be difficult to secure and maintain a line due to inadvertent kinking as a result of elbow flexion.
Several techniques may improve the success in difficult IV access in children. Placing a tourniquet on the extremity may also increase the caliber of the vessel and improve the likelihood of success. Transillumination of the hand or foot is a technique which can improve visualization of veins in these locations. A cool light source is needed in order to avoid damage to the skin. Several types of light source are available, including fiberoptic sources.
ULTRASOUND-GUIDED PERIPHERAL ACCESS
Ultrasound-guided peripheral access is another option in children. Ultrasound has been shown to be more accurate than external landmarks in localizing the saphenous vein in children and has been used to insert IV catheters in infants (2,3). In addition, ultrasound has been shown to reduce the time and number of attempts required in children with difficult access (4,5). However, the experience level of the sonographer l is an important factor in actual use 6. The technique for obtaining ultrasound-guided peripheral access in children are similar to those in adults and are well described (7,8). However, in small children or neonates, in whom some veins may be too close to the ultrasound probe to appropriately visualize, a stepoff pad or small bag of saline may be placed between the probe and patient to provide more distance between the probe and the target vein.
CENTRAL VENOUS ACCESS
Central venous access is rarely required in children in the emergency department (ED), largely because of the advent of powered intraosseous devices (discussed below). However, there are times where pediatric central access may be needed. The common locations for pediatric central access include the femoral vein, internal jugular vein, and subclavian vein, and the anatomic landmarks for obtaining central access in children are similar to those in adults. Complications of central access in children are similar to those in adults as well, though because of the relative proximity of important anatomic structures in children, increased vigilance is needed to avoid serious complications. Furthermore, it is frequently impossible to safely obtain central access in young children and infants who are awake or nonintubated, and in whom movement cannot be otherwise controlled.
The femoral vein is often felt to be the technically easiest location for inserting a central venous catheter and has the advantage of being distant from the heart, lungs, and carotid artery. Femoral lines are often avoided in adults because line infections are more common than with internal jugular and subclavian lines, though this is not necessarily the case in children (9).
One notable circumstance where a femoral line is relatively contraindicated is in diabetic ketoacidosis (DKA), where there is a strong association between femoral vein central line placement and subsequent deep vein thrombosis (9). Intraosseous access is the route of choice in patients with DKA in whom peripheral access cannot be established.
The use of ultrasound for central access has become routine in adults. There is evidence that, as in adults, the use of ultrasound for central access in children also lowers complication rates and improves success rates for both internal jugular and femoral sites (10–13).
INTRAOSSEOUS ACCESS
The intraosseous route provides access to a noncollapsible structure with reliable landmarks and relatively few associated contraindications. Powered intraosseous access has dramatically changed emergency access in critically ill children. Several devices are currently available, the most commonly used in the United States is the EZ-IO. Powered intraosseous access is rapidly obtained (typically in less than 1 minute) and complications are rare. The procedure can be easily learned on models or manikins by a wide variety of practitioners, from paramedic to physician (13,14). The IO has had high success rates in patients of all ages, including neonates, and has the potential to replace umbilical vein access in the ED (15). The most common location for intraosseous access is the proximal tibia, though access at the humeral head, distal femur, and distal tibia are also well described. Sternal osseous access has mostly been used in the military setting.
Proximal tibia placement via the EZ-IO will be described since the EZ-IO is the most frequently used device in the US and the proximal tibia the most common site for placement. In order to avoid the physis, the site on the proximal tibia to be accessed is approximately 2 cm distal to the tibial tuberosity. The needle is placed on the skin perpendicular to the bone. The trigger is depressed and remains engaged until the needle has been passed through the cortex of the bone. The operator should feel a sudden reduction in the pressure required to advance the needle once the needle is through the cortex. Care must be taken to not drill in an oblique manner or to go too deep as the needle could pass through the posterior cortex. After the needle is in place, the stylette is removed from the needle and an IV connector is attached. Placement can be confirmed by aspiration of bone marrow; however, the needle can be in good position and marrow not aspirated. In this situation, the catheter is flushed while palpating the area around the needle and posterior to the needle to monitor for extravasation. If the line flushes easily it is presumed to be in good position. One must be vigilant during the use of an IO for extravasation. This is the most common complication, and can occur posteriorly or lateral to the site of placement, depending on the angle and depth of the needle. The IO needle can be secured by bolstering with gauze and tape, using tape alone, using commercially available products, or other means. Regardless of the method used, it is important to be able to visualize the area near the hub of the needle and posteriorly.
Anything, including fluids and medications, that is administered by an IV can be given through an IO. Fluids infused by the IO route rapidly reach the central circulation. Although IO needles have a large bore, the medullary cavity of the bone has a somewhat high resistance, and IV pumps or pressure bags are frequently needed to aid in rapid fluid administration. In addition, rapid infusion of fluids into the medullary space can be painful, so lidocaine is often administered (0.5 mg/kg via slow push) prior to rapid fluid boluses. In general, longer use of IO access is likely to lead to more complications; thus, IO access is a temporizing means of access until a more stable route can be established.
Contraindications to IO access include infection at the site of insertion, fracture proximal to the site of insertion, suspicion of compartment syndrome in the extremity, previous IO attempt, or bone abnormalities raising the risk of fracture such as osteogenesis imperfecta. Complications include extravasation, skin necrosis, compartment syndrome, cellulitis, osteomyelitis, air embolism, and fracture (16–21). Most are directly related to extravasation of substances which can cause tissue necrosis due to misplacement or dislodgement of the needle, not due to anything inherent in the IO itself. This reinforces the need for vigilance at the site of placement.
ANALGESIA AND ANXIOLYSIS
Analgesia and anxiolysis for vascular access in children can be improved by using both behavioral and pharmacologic techniques. Behavioral techniques start before the procedure and involve providing information on the procedure in a developmentally appropriate manner. Both patients and parents can be taught coping techniques such as deep breathing. Parents can assist in providing a position of comfort and can be actively engaged in distraction, which can be an extremely powerful tool in mitigating anxiety related to a procedure. For infants, comfort may be improved by swaddling, skin to skin contact, breastfeeding, and sucrose administration. Following the procedure, encouragement and distraction are helpful to further reduce anxiety and anticipation of future events (22).
Pharmacologic techniques for analgesia and anxiolysis are myriad (1). Pharmacologic anxiolysis for IV starts may be achieved by inhaled nitrous oxide, or by midazolam, which can be administered via the intranasal, oral, or buccal routes. Pharmacologic analgesia can be achieved by local infiltration, transdermal creams, and active delivery mechanisms. Local infiltration of lidocaine is less painful than IV cannulation, but does involve a needle stick, and perhaps for this reason is not widely used. The J-Tip (National Medical Products Inc., Irvine, CA) is another option for local infiltration and uses CO2 to inject lidocaine. Several studies demonstrate that it has rapid onset and is effective, though it was associated with a reduced rate of successful cannulation in one adult study. Lidocaine and prilocaine cream 2.5%/2.5% has been shown to be effective in multiple studies at reducing the pain associated with venipuncture. The time needed for this to be optimally effective is 60 minutes, though 90 minutes is more effective. This product is not intended for use on broken skin, as it may result in systemic absorption. Tetracaine gel, not available in the United States, is also effective and requires less time to achieve its effect than the lidocaine and prilocaine mixture. Liposomal 4% lidocaine has also been shown to reduce pain in children when starting a peripheral IV, but as with similar agents, needs 30–60 minutes to achieve its desired effect. Complications are few and generally involve local skin irritation. Many other techniques have been described to facilitate delivery of local anesthetics through the skin, including heat and lasers. Finally, vapocoolant sprays have been used as analgesics and act by causing temporary (less than 1 minute) cooling of the skin in the area. Studies evaluating efficacy have been mixed, however, probably due to the extremely short duration of action, which may be insufficient for starting an IV.
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