98 SECTION II Pediatric Critical Care Tools and Procedures blood is seen in the hub, the needle and catheter are advanced further, through the posterior wall of the artery transfixing the vessel to th[.]
98 S E C T I O N I I Pediatric Critical Care: Tools and Procedures blood is seen in the hub, the needle and catheter are advanced further, through the posterior wall of the artery transfixing the vessel to the underlying structures The needle is removed, leaving the catheter in place The catheter is then slowly withdrawn until the tip is again intraluminal with blood flowing into the hub The catheter is then advanced into the artery to its hub Catheter advancement can be facilitated by attaching a Luer-Lok connecter with a heparinized flush-filled syringe on it and gently flushing as the catheter is advanced The final and most successful percutaneous method for catheter placement in critically ill patients involves the use of the Seldinger technique.33 A needle is used to pierce the anterior wall of the artery When arterial blood return is seen, a guidewire is placed through the introducer needle The wire should meet little to no resistance If resistance is met, the wire is retracted and pulsatile blood flow is assured at the hub of the needle The depth or angle of the needle may need to be adjusted if blood is not flowing If the guidewire glides in easily on insertion, it is advanced into the lumen of the vessel, the needle removed, and the catheter threaded over the guidewire into the arterial lumen This method can also be used with the over-the-needle catheter technique Improved success rates and shorter time to insertion characterize pediatric arterial catheters placed using a guidewire compared with no wire guide.34 However, an adult study found no difference in success rate or insertion times between the two groups.35 Ultrasound-assisted placement of arterial catheters is becoming increasingly popular (see Chapter 15) Ultrasound guidance significantly increases the first attempt success rate of radial arterial cannulation and decreases hematoma complication rates compared with the palpation or Doppler technique.36 Studies have also demonstrated decreased time to insertion and decreased number of attempts at catheter placement using ultrasoundguided techniques.36–40 However, in the hands of physicians who are inexperienced in performing arterial cannulations via ultrasound guidance (yet proficient in traditional methods), no difference in success rates was observed between the ultrasound-assisted and palpation-based techniques.37 The study shed light on the importance of experience and frequent practice in the use of ultrasound-guided arterial cannulation to develop competency A cutdown approach serves as an alternative if percutaneous attempts are unsuccessful A superficial incision of the skin is made perpendicular to the artery The subcutaneous tissues are bluntly dissected parallel to the vessel using a hemostat When the artery is identified, the posterior wall is gently dissected away from the adjacent structures Two loops are placed around the vessel, one proximal and one distal These loops are used to elevate the artery during cannulation; they should never be used to tie off the vessel The artery is then cannulated under direct visualization using the over-the-needle technique The catheter is secured with a suture through the skin, and the wound is closed with interrupted sutures If excessive bleeding persists, gentle traction can be applied to the proximal loop in an attempt to control the hemorrhage Maintenance of an Arterial Catheter To prolong the patency of an arterial catheter, heparinized fluid is most commonly infused through the catheter A common practice is to infuse 0.9% sodium chloride containing heparin U/mL at mL/h; slower infusion rates may be used in small infants requiring fluid restriction There is conflicting literature supporting the use of heparin to positively impact patency and mitigate the risk of thrombus formation in peripheral arterial catheters.41,42 More recent adult studies call into question the benefit of heparin and spotlight the need for more rigorous clinical investigation.43,44 However, these studies not take into account the smaller vessel size and prolonged monitoring common in critically ill children A randomized controlled trial demonstrated that the addition of papaverine (120 mg/L) to routine arterial catheter fluids significantly lowered the rate of catheter failure.45 This study recommended avoiding the use of papaverine in neonates owing to a perceived increase in risk of intraventricular hemorrhage However, a more recent study of neonates 25 to 36 weeks’ gestational age did not confirm this concern.45 Despite these results, some institutions routinely avoid the use of papaverine in arterial catheter fluids in preterm neonates and patients with traumatic brain injury or other preexisting intracranial hemorrhage Arterial catheters should always be visible so that any bleeding around the catheter site or inadvertent disconnection of the tubing from the catheter can be immediately identified to avoid significant hemorrhage Securing the catheter with suture and using Luer-Lok connectors decrease the possibility of accidental detachment The site of catheter insertion should be closely monitored for signs of infection or compromised perfusion Mottling of the skin proximal or distal to the catheter may be indicative of intraarterial thrombus formation, and discoloration of fingers or toes distal to a catheter may result from emboli If these complications occur, the catheter must be removed Children with femoral artery catheters are at a higher risk of thrombus formation, particularly newborns and children with low body weight, low cardiac output, and elevated hematocrit.46 Transducing an arterial catheter is performed by placing the transducer at the level of the right atrium and zeroing to atmospheric pressure for accurate measurements.47 Studies in animal models have demonstrated that positioning the transducer to be level with the aortic root results in accurate measurement of mean arterial pressure (MAP) regardless of position or catheter site This is in contrast to the significant error in MAP measurement that occurs when the transducer is level with the catheter tip.48 Arterial fluids and tubing are currently recommended to be changed every 96 hours.49 The overlying dressing is also changed on a scheduled basis and any time it becomes soiled or nonocclusive Inability to draw blood from a catheter or flattening of the waveform on the monitor is suggestive of either a kinked catheter or thrombus formation at the end of the catheter If no evidence of compromised perfusion is present distal to the catheter, the catheter may be exchanged over a guidewire However, strong consideration should be given to removing the existing catheter and placing a new arterial catheter at a different site, as exchanging a catheter over a guidewire has been associated with an increased risk of catheter-related bloodstream infection (CRBSI) in central venous catheters.50 Complications Complications related to arterial catheters include hemorrhage, thrombus formation, emboli, distal ischemia, and infection Permanent ischemic complications related to radial artery catheters in adult patients are rare.28 A multi-institutional diagnostic code database study demonstrated that 10.3% of patients with arterial catheters also had a code associated with infection or inflammation, and 7.5% had a thrombotic- or embolic-associated complication code These complications were more common in younger children and longer hospitalizations.51 An uncommon but wellrecognized complication of arterial catheter placement is growth CHAPTER 14 Pediatric Vascular Access and Centeses arrest due to physeal injury from extravasation, aneurysm formation, or ischemia.52 Catheter-related infections can be local or systemic The risk of catheter-related infection was previously thought to be lower for arterial catheters than for central venous catheters However, a meta-analysis indicated that arterial catheters are an underrecognized source of CRBSI.53 Risks for an arterial catheter infection are related to the duration of catheter use and catheter placement in the femoral artery.53–56 The presence of an arterial catheter has been noted to be a risk for CRBSI, but it has been suggested that a positive culture is more likely to be a surrogate marker for greater illness severity.57 Nevertheless, an arterial catheter should be considered a potential source of sepsis, and strong consideration should be given to removing an arterial catheter when it is no longer needed for optimal care Summary Arterial catheters are an important way to monitor hemodynamics and gain valuable laboratory data in order to proactively provide interventions and manage critically ill children The potential risks and benefits of arterial catheter placement should be weighed carefully prior to performing the procedure Rigorous studies investigating the complications associated with arterial catheterization are lacking for critically ill children; thus, further study is needed.51 Central Venous Line Placement Central venous catheter (CVC) placement and use are frequently required in caring for critically ill patients The need for central access should be anticipated so that circumstances surrounding the procedure, such as aseptic technique and patient safety, can be optimized Indications and Contraindications Indications for CVCs include the following: • Need for reliable and durable venous access • Lack of or inadequate peripheral venous access • Administration of vasoactive infusions, total parenteral nutrition, and medications that require central venous delivery • Need for frequent blood sampling • Monitoring of central venous pressure and central venous oxygen saturation • Provision of access for extracorporeal support modalities, such as continuous renal replacement therapy and apheresis Contraindications to central access are not absolute and are primarily related to specific CVC placement sites In the presence of coagulopathy or systemic anticoagulation, operators should consider avoiding sites where bleeding may be difficult to control (e.g., subclavian vein) Generally, CVC insertion sites with intravascular hardware (e.g., pacemaker, ventriculoatrial shunt, hemodialysis catheter) or adjacent to permanent hardware (e.g., cerebral ventricular shunt catheters subcutaneously tunneled along the neck) should be avoided owing to risks of infection, hardware puncture, and venous stasis CVCs placed at a time of bacteremia will likely become colonized with the pathogen.58 Catheters should not be inserted through overtly infected skin In traumatic brain injury management, it is reasonable to abstain from CVC placement in the neck vessels to avoid obstruction of jugular venous drainage from the brain and exacerbating intracranial 99 hypertension.59 The relative risks and benefits of CVC placement should be carefully weighed prior to each procedure Technique Critically ill pediatric patients range greatly in size Being aware of vessel dimensions as well as the proximity and anatomic relation of the respective artery to the vein are important in central vein cannulation Central vein diameters vary across the pediatric age groups (eTable 14.1); based on this measurement, an appropriately sized catheter should be selected for CVC placement These catheters are commonly made of a plastic polymer and available in a variety of diameters, lengths, and number of lumens CVCs are often packaged with the introducer needle, guidewire, and tissue dilator that correspond to the selected catheter diameter and length Maximal sterile barrier precautions should be used whenever a CVC is placed in the pediatric intensive care unit (PICU) This includes mask, cap, sterile gown and gloves, and sterile full-body drape.60,61 Additionally, the following should be performed: thorough hand hygiene (which may involve the use of surgical antiseptic handwash or scrub brush), skin preparation at the insertion site using chlorhexidine antiseptic solution (covering an extensive area and allowing adequate dry time), and creation of a large sterile field with sterile drapes and towels to cover the patient’s entire body and bed (in order to minimize the risk of inadvertent contamination of sterile equipment and surfaces) Chlorhexidine is superior to povidone-iodine for skin disinfection.62,63 Adequate sedation and analgesia along with local anesthesia should be used to provide patient comfort during the procedure Patient movement will also be minimized, diminishing the risk of sterile field disruption and allowing the procedure to be performed more easily and safely Adherence to CVC insertion and maintenance bundles will minimize the risk of CRBSI Most CVCs employed in the PICU are placed using the Seldinger technique, in which the clinician places an introducer needle into the desired vein while aspirating with a slip tip syringe When the lumen of the needle is fully within the vein lumen, blood freely flows into the syringe The needle is held in place with the nondominant hand while the syringe is disconnected with the other hand Blood should continue to passively flow from the needle hub but not be pulsatile A J-tipped guidewire is inserted into the open hub of the needle and advanced into the vein with little to no resistance (Fig 14.3) If resistance is felt, further advancement of the wire should be avoided Adjusting the needle position by slightly altering its depth or changing the angle of entry may facilitate guidewire insertion If there continues to be resistance, the wire is carefully withdrawn, and the syringe is reattached to the needle in order to reidentify the vein’s lumen If the wire is not easily retracted, the needle and wire should be removed as a unit, reducing the risk of breaking the wire Once the guidewire is well within the lumen of the vein, a small nick in the skin adjacent to the needle is made using a No 11-blade scalpel, enlarging the puncture site to more easily accommodate the dilator and catheter The introducer needle is carefully withdrawn along the wire, maintaining control of the wire at all times either by holding it directly or intermittently using a sterile hemostat to clamp the end of the wire to ensure that it is not lost into the patient or onto the floor A dilator is advanced along the wire and then twisted through the puncture site, dilating the tissue planes that lead to the lumen of the vessel; the vein itself should not be dilated Following withdrawal of the 99.e1 Approximate Mean Femoral and Internal eTABLE Jugular Vein Diameters Across the Pediatric 14.1 Age Interval Mean IJV Diameter (mm) Mean FV Diameter (mm) 25–27 wk PCAa 2.1 1.5 a 3.3 1.9 a 37–39 wk PCA 4.2 2.3 mo 5.5b 4.5c b 5.4c Age 31–33 wk PCA 1y 6.2 yd 6.7 6.3 d 7.8 yd 8.9 7.7 4y yd 10 8.5 d 11.1 9.2 d 12.8 10.4 d 16 y 14.5 11.5 19 yd 16.2 12.6 10 y 13 y a Data from Tailounie M, McAdams LA, Frost KC, et al Dimension and overlap of femoral and neck blood vessels in neonates Pediatr Crit Care Med 2012;13:312–317 b Data from Alderson PJ, Burrows FA, Stemp LI, Holtby HM Use of ultrasound to evaluate internal jugular vein anatomy and to facilitate central venous cannulation in paediatric patients Br J Anaesth 1993;70:145–148 c Data from Warkentine FH, Clyde Pierce M, Lorenz D, Kim IK The anatomic relationship of femoral vein to femoral artery in euvolemic pediatric patients by ultrasonography: implications for pediatric femoral central venous access Acad Emerg Med 2008;15:426–430 d Data from Steinberg C, Weinstock DJ, Gold JP, et al Measurements of central blood vessels in infants and children: normal values Cathet Cardiovasc Diagn 1992;27:197–201 FV, Femoral vein; IJV, internal jugular vein; PCA, postconception age 100 S E C T I O N I I Pediatric Critical Care: Tools and Procedures A neck, and the face is turned to the contralateral side Most commonly, the middle approach is used, in which the introducer needle enters the skin at a 30-degree angle at the apex of the triangle formed by the clavicle and the heads of the sternocleidomastoid muscle and is directed toward the ipsilateral nipple (Fig 14.4A) For the anterior approach, the introducer needle enters the skin along the anterior margin of the sternocleidomastoid halfway between the mastoid process and the sternum and is directed at the ipsilateral nipple (Fig 14.4B) Using the posterior approach, the needle enters the skin along the posterior border of the sternocleidomastoid halfway between the mastoid process and the clavicle and is directed toward the suprasternal notch (Fig 14.4C).64 Subclavian Vein Cannulation Following Trendelenburg positioning of the supine patient, a narrow cloth roll is placed beneath the patient, between the scapulae The introducer needle enters the skin inferior to the junction of the middle and lateral thirds of the clavicle and is directed toward the suprasternal notch The needle passes along the inferior surface of the clavicle until it enters the subclavian vein (Fig 14.5).64 Femoral Vein Cannulation B C • Fig 14.3 Seldinger technique (A) Guidewire is placed through the introducer needle into the lumen of the vein (B) Catheter is advanced into the vein lumen along the guidewire (C) Wings of the catheter are secured to the skin with suture dilator, the catheter is advanced into position over the wire (see Fig 14.3) The guidewire is removed, leaving the catheter in place Blood should be easily aspirated from each lumen; then, the lumens should be completely cleared of blood by flushing with sterile heparinized saline to reduce the chance of clot formation Several systems for securing the catheter are commercially available, but it may also be secured with suture A large loop of suture is placed in the skin, attached through the wings of the catheter, and tied down The suture should be taut, preventing catheter movement without causing skin necrosis within the loop of suture A chlorhexidine-impregnated patch can be applied and a transparent adhesive film placed over the catheter, creating an occlusive dressing Internal Jugular Vein Cannulation Multiple approaches can be used to cannulate the internal jugular vein The patient is placed supine in slight Trendelenburg position A roll of bed linen is placed under the shoulders to extend the Following flat or slight reverse Trendelenburg positioning of the supine patient, a towel is placed under the hips to slightly raise them, to enhance exposure of the inguinal crease insertion site The leg is abducted and externally rotated The arterial pulse is palpated just distal to the inguinal ligament, halfway between the anterior iliac crest and the pubic symphysis The femoral vein is approximately mm medial to the artery in infants and toddlers and cm in adolescents and adults The introducer needle enters the skin to cm distal to the inguinal ligament at a 30-degree angle in line with the course of the vein and parallel to the axis of the thigh (Fig 14.6).64 Use of Ultrasound for Central Venous Line Placement Ultrasonography has been increasingly used to facilitate the placement of CVCs in the PICU Anatomic variation of the central veins is not uncommon, reported in 7% to 18% of pediatric patients, and can make cannulation more difficult using landmarks alone.65,66 Bedside ultrasonography offers direct visualization of the vessel before and during the intervention Use of ultrasound reduces insertion-related complications in children67–70 and CVC placement success rates are improved with the use of ultrasound.71 As familiarity with real-time ultrasound guidance is improving, novel techniques, including subclavian access, are successfully being implemented in pediatrics.72 Routine use of real-time ultrasound guidance for CVC placement is recommended and reflects best practice, particularly for internal jugular catheterization (see Chapter 15) Complications CRBSI is the most common complication related to CVCs (see Chapter 109) In children, the location of the insertion site is not related to infection risk.73 The risk of infection is decreased by the use of a bundle of practices during insertion and ongoing maintenance of the CVC The insertion bundle includes strict maximal sterile barrier precautions and aseptic technique Dressing changes CHAPTER 14 Pediatric Vascular Access and Centeses 101 Carotid artery Sternocleidomastoid muscle Sternocleidomastoid muscle Internal jugular vein Internal jugular vein Ipsilateral nipple Ipsilateral nipple A B Sternocleidomastoid muscle Internal jugular vein External jugular vein Sternal notch C • Fig 14.4 Approaches to the internal jugular vein The patient is supine, in slight Trendelenburg position, with the neck extended over a shoulder roll and the head rotated to the contralateral side (A) Middle approach: The introducer needle enters the skin at a 30-degree angle at the apex of the triangle formed by the heads of the sternocleidomastoid muscle and clavicle, directing it toward the ipsilateral nipple. (B) Anterior approach: The carotid pulse is palpated and may be slightly retracted medially The introducer needle enters along the anterior margin of the sternocleidomastoid, about halfway between the suprasternal notch and mastoid process, while being directed toward the ipsilateral nipple (C) Posterior approach: The introducer needle enters at the posterior margin of the sternocleidomastoid, just superior to where the external jugular vein crosses, and is directed under its heads toward the suprasternal notch with chlorhexidine skin prep, minimizing catheter access, and daily assessment of the need of the catheter are all recommended as a part of CVC maintenance.74 Antimicrobial-impregnated catheters may decrease the risk of catheter-related infection, but more pediatric studies are needed.75 Pneumothorax may result if the lung is punctured during jugular or subclavian vein CVC placement This complication is less likely with careful patient positioning, attention to anatomic landmarks, and real-time use of ultrasonography as the introducer needle is advanced Chest radiography should be performed after these approaches are attempted to document absence of pneumothorax and verify CVC position Thrombosis may occur in the vessel surrounding the catheter and is associated with malignancies and diabetic ketoacidosis.76,77 Ectopy may ensue when the guidewire or catheter, positioned too deeply, stimulates the right heart Prompt retraction of the guidewire or catheter typically resolves the ectopic arrhythmia Bleeding at the skin puncture site from an inadvertent arterial puncture is usually controlled by direct pressure However, hemorrhage can be difficult to control and may be potentially lifethreatening if there is injury to deeper vascular structures or when coagulopathy is present Veins and arteries may be perforated far from the intended puncture site by the introducer needle, guidewire, dilator, or catheter Injury to the femoral or iliac vessels may ... cannulation Central vein diameters vary across the pediatric age groups (eTable 14.1); based on this measurement, an appropriately sized catheter should be selected for CVC placement These catheters... precautions should be used whenever a CVC is placed in the pediatric intensive care unit (PICU) This includes mask, cap, sterile gown and gloves, and sterile full-body drape.60,61 Additionally,... the desired vein while aspirating with a slip tip syringe When the lumen of the needle is fully within the vein lumen, blood freely flows into the syringe The needle is held in place with the nondominant