48 Procedures for Vascular Access
VASCULAR CANNULATION is an important procedure in the anesthetic and perioperative management of children. Its routine use was introduced in the 1950s.1 The indications are to provide routes for fluid, drug, and blood product administration, monitoring of cardiopulmonary function, and provision of access for blood sampling. Although the technique of insertion may be extremely difficult, especially in the very young or small child, no child should be denied an indicated procedure because of an operator’s inexperience; appropriate consultation should be sought, if necessary. Regardless of the procedure, gloves should be worn to maintain clean or sterile technique and to protect health care professionals from exposure to blood.2–6 An update from the Pediatric Perioperative Cardiac Arrest Registry suggests that lack of good vascular access may contribute to the underestimation of fluid or blood loss and inadequate replacement of fluid or blood in anesthetized children, emphasizing the importance of appropriate and adequate vascular access and monitoring.7,8
Indirect central venous pressure measurement; the accuracy of this method for central venous pressure measurement does not appear to vary by location of the catheter11 but does depend on ensuring direct continuity between the central and peripheral circulation.12,13 This can be assessed by providing a large, sustained inspiration or occluding the venous return of the extremity, which both cause an increase in the peripheral pressure.14–16 Hypothermia may impair the accuracy of such measurement.17
Consider the possible need for latex-free equipment. In cases of difficult access, the availability of a transillumination light source (Karl Storz, 485 B Type, Tutlingen, Germany) may improve the success rate of catheter placement.18 Ultrasonography also may be used for obtaining peripheral venous access at the basilic, cephalic, or brachial veins.19,20 Finally, new near-infrared and infrared technology is available to aid in the identification of peripheral veins (AccuVein, Accuvein, Huntington, N.Y.; VeinViewer, Christie Digital Systems, Cypress, Calif.).21
1. Awake intravenous line placement can be facilitated by any combination of good patient rapport, EMLA cream (lidocaine 2.5% and prilocaine 2.5%), lidocaine and tetracaine patch, lidocaine by iontophoresis, lidocaine by topical cream, topical tetracaine (Ametop), ethyl chloride spray, and/or pre-medication.22–31
Hematoma from a failed vascular cannulation is usually of no serious consequence. Infection or thrombosis may be limited by aseptic technique.34–36 One study of 642 Teflon catheters in 525 patients showed that the risk of catheter complications in children was extremely small and would not be reduced significantly by routine replacement of the catheters.37 Catheter life span has been found to be unrelated to insertion site, cannula size, or brand in infants younger than 12 months of age.38,39
Skin sloughing is usually caused by subcutaneous infiltration of calcium, potassium, or hypertonic solutions; it may be avoided by frequent inspection of the intravenous line before injecting medications.40 The risk of subcutaneous infiltration increases with the administration of medications versus no medications and with parenteral nutrition solutions compared with 5% or 10% dextrose solutions, but the risk of infiltration is no different with solutions that contain potassium (≤20 mEq/L vs. >20 mEq/L). In addition, there is no difference between gravity-controlled versus infusion delivery devices.41
Some studies in children and adults describe a reasonable correlation between peripheral intravenous catheters and central venous catheters, even in critically ill children. Hypothermia (peripheral vasoconstriction) decreases the accuracy of such measurements, but it is useful to understand that transducing the pressure of a peripheral vein may provide valuable information regarding right-sided cardiac filling pressures.9,10,43–46
4. Pass the next larger size intravenous catheter over the wire to dilate the vein and leave in place; stiff intravenous catheters are more effective. An alternative is to use a small dilator from a pulmonary artery catheter introducer and leave the sheath in place. The wire is removed, and the next larger size wire is inserted (0.025 inch). The catheter (or sheath) is removed, leaving this larger wire within the vein. This process may be repeated with larger catheters and wires until the desired size cannula or sheath is reached. An alternative is to leave progressively larger pulmonary artery introducer sheaths in the vein; both techniques provide a reasonably rapid method of establishing a large-bore intravenous infusion site.
Special rapid volume catheters (6F and larger, Arrow International, Reading, Pa.) allow venipuncture with a needle or small intravenous catheter, passage of a guidewire, and then introduction of a dilator and sheath, with fewer steps required (see E-Fig. 10-1).
The most common sites for insertion are the saphenous vein at the medial malleolus and the brachiocephalic vein at the antecubital fossa. This procedure may require considerable time to perform and has limited utility for emergent access.47
The saphenous vein is often a reliable point for intravenous access in infants and children that may be directly visualized or cannulated with a “blind” technique (Fig. 48-1). It is consistently found lateral to the medial malleolus of the ankle one-half to one finger breadth over the anterior quadrant.
3. Enter the skin at a 30-degree angle at the expected site of the saphenous vein at the level of the medial malleolus, with the tip of the needle directed toward the upper two thirds of the calf. If no evidence of venipuncture is seen on insertion, slowly withdraw the needle because the flash of blood may occur while exiting the vein.
In the United States, federal law requires that retractable or sheathed needles designed to reduce the potential for needlestick injury are available for use by health care personnel (see Table 48-1).48 A study that compared traditional intravenous catheters to safety devices found that a larger proportion of children younger than 3 years of age required more than one catheter to successfully gain intravenous access. The retractable intravenous catheter was associated with a nearly fourfold greater incidence of splattering and spilling of blood compared with traditional catheters.49 Retractable needles require activation of a button to trigger the safety device; therefore sheathed catheters are regarded as inherently safer because they require no action on the part of the operator to protect the needle tip. Note that the U.S. federal legislation requires that these devices be available but the ultimate decision to use them rests with the physician. Therefore the type of catheter should not be dictated by the hospital but rather by the individuals who place the catheters.
The common sites for central venous cannulation are the external and internal jugular veins, the subclavian and brachiocephalic veins, the femoral vein in infants and children, and the umbilical vein in neonates. Approaches such as the internal jugular and subclavian veins should be used with extreme caution in the presence of a bleeding diathesis as stopping bleeding may be difficult. The percutaneous approach to central venous cannulation is often successful using a modified Seldinger technique (Fig. 48-2).50,51 The advantages of this technique are that it avoids the need for a cutdown, only one venipuncture is made with a thin-walled small-gauge needle, a guidewire directs the catheter within the blood vessel, introducing a large catheter through the small venipuncture site minimizes the chances of significant hematoma formation even after systemic heparinization, and the procedure often can be accomplished when access is required emergently. Whenever a central line is inserted into the heart from above, care must be taken to ensure that the catheter tip is positioned at the junction of the superior vena cava and the right atrium, because positions within the heart have been associated with perforation of large vessels and the myocardium (Fig. 48-3) with triggering of ventricular arrhythmias.52
FIGURE 48-2 A, Seldinger technique for catheter placement. The needle is inserted into the target vessel, and the flexible end of the guidewire is passed freely into the vessel. B, The needle is then removed, leaving the guidewire in place. C, The catheter is advanced with a twisting motion into the vessel. D, The wire is removed, and the catheter is connected to an appropriate infusion or monitoring device.
(Redrawn with permission from Schwartz AJ, Coté CJ, Jobes DR, et al. Central venous catheterization in pediatrics. Scientific exhibit, American Society of Anesthesiologists, New Orleans, 1977.)
FIGURE 48-3 Proper and improper central venous pressure catheter placement. A, Normal vascular anatomy. B, Proper location for right internal jugular catheter (i.e., high right atrium or superior vena cava). C, Ventricular location of any catheter is dangerous and contraindicated. D, A short left-sided internal jugular catheter may erode through the innominate vein (arrow). E, A left-sided internal jugular catheter striking the lateral wall of the superior vena cava (arrow) may erode through it and must be partially withdrawn or advanced. F, A short right subclavian catheter may strike the lateral wall of the innominate vein (arrow) and erode through it; this catheter should be advanced or withdrawn. FIGURE 48-3, cont’d G, Proper location for a right subclavian line. H, A short left subclavian line may erode through the superior vena cava (arrow); this catheter should be advanced or withdrawn. A, Atrium; V, ventricle.
Ultrasound guidance, pressure waveform analysis, or electrocardiographic guidance may help prevent complications related to central catheter placement.53,54 Ultrasound-guided access assists successful cannulation of the internal jugular vein,53 the infraclavicular axillary vein,54 and the subclavian vein.55,56 A meta-analysis of 18 trials with 1646 participants, including infants, children, and adults, showed a benefit from the use of two-dimensional ultrasound guidance compared with the landmark method. The greatest benefit was for internal jugular vein cannulation rather than subclavian or femoral veins.57 See Chapter 42 and Video 48-1 for ultrasound-guided techniques.
Pneumothorax, arrhythmia, hematoma, bleeding, infection, thrombosis, inadvertent arterial puncture, cardiac tamponade, air embolus, thoracic duct injury, and malposition are all possible complications associated with central venous cannulation. Data in adults suggest that the smallest catheter and placement from the left subclavian approach may have the least complication rate; similar studies have not been conducted in children.58 The infection rate reported after 1056 central venous catheters were inserted into 289 children with burn injury varied from 2.0% to 7.3% for catheters in place for 11 or fewer days, but that the rate increased dramatically to 15.8% to 37.5% for catheters left in place for 12 to 14 days.59
Contamination of catheters during insertion may result in catheter colonization or bacterial infection. Evidence suggests that the use of maximum barrier precautions during placement, including the use of sterile gloves, long-sleeved gowns, full-size drape, and a nonsterile mask and cap, decrease the risk of catheter-related infection.34,36,60,61 The efficacy of chlorhexidine versus povidone-iodine for preventing bacteremia remains unclear, and the safety of chlorhexidine in infants and children has not been fully established.62 For older infants and children, chlorhexidine may be safe and effective, but it can cause severe local contact dermatitis in low-birth-weight infants.63,64 In a case-controlled, prospective, active surveillance study in a pediatric intensive care unit (ICU), independent risk factors for central line-associated bloodstream infection were the duration of central venous catheterization in the ICU, nonoperative cardiovascular disease, gastrostomy tube, parenteral nutrition, central line placement in the ICU, and red blood cell transfusion.65
3. Under aseptic conditions, venipuncture and catheter insertion are completed according to the techniques shown in Figure 48-2. A J-wire is usually more useful to circumvent the plexus of veins at the clavicle.66,67
4. Suture or tape appropriately and cover with an occlusive dressing. Many catheters will not pass beyond the clavicle or will pass into the axillary vein; success is generally more often attained on the right side.68,69 If a shorter catheter is used, infusion and pressure monitoring are very dependent on the position of the head.70 Continuous free-flowing infusion is best maintained when the head is turned away from the side of catheter insertion. This vein is particularly valuable in children with difficult peripheral venous access and in an emergent situation that suddenly develops intraoperatively that requires establishment of additional intravenous access.
Numerous approaches and techniques are used for internal jugular vein cannulation.71–74 A high approach using the apex of a triangle formed by the two bellies of the sternocleidomastoid muscle and the clavicle may be used as a landmark for insertion (Fig. 48-4). With the use of the Seldinger technique, the success rate, even in neonates, approaches 75% on the first attempt and 90% to 95% on the second attempt.50 Cannulation of the right side virtually ensures a central location because the internal jugular vein, the superior vena cava, and the right atrium are in a straight line (see Fig. 48-4). Left-sided cannulation risks injury to the thoracic duct and possible pneumothorax because the apex of the lung is more cephalad on the left. In addition, if the catheter inserted on the left is too short, it is not unusual for the tip to rest against the wall of the superior vena cava, be position dependent, and possibly erode through the wall of the vessel. Figure 48-3 illustrates less desirable sites for catheter tips that may result in perforation. The principal advantage of the high approach is that the most common complication (arterial puncture, approximately 10%) is easily recognized and usually treated uneventfully. In one study, the effect individually and in combination of the simulated Valsalva maneuver (positive inspiratory pressure of 25 mm Hg for 10 seconds), liver compression, and Trendelenburg position to increase the cross-sectional area of the right internal jugular vein was investigated.75 A maximal mean increase in cross-sectional area of the right internal jugular vein was 17.4 ± 16.1% from baseline when all three maneuvers were combined. This effect was most pronounced in children 1 to 6 years of age and was clinically negligible in infants younger than 12 months of age. The effect on ease of catheter placement was not investigated.75 For neonates, a study using skin traction in infants less than 5 kg showed that a technique using tape for skin traction combined with ultrasound guidance increased internal jugular cross-sectional area and decreased the time for catheter placement.76–78
FIGURE 48-4 A, The anatomic relationships of major chest and neck structures. Note how the internal jugular vein is in close proximity to the carotid artery. Also note that a nearly straight line is formed by the internal jugular vein, innominate vein, superior vena cava, and right atrium (yellow hatched line); thus it is rare for a right internal jugular catheter to migrate anywhere but to the right atrium. B, The relationship of external anatomic landmarks to the anatomy illustrated in A. Note the triangle formed by the two bellies of the sternocleidomastoid muscle and the clavicle. 1, The preferred point of needle insertion at the apex of this triangle for internal jugular vein puncture. 2, The point of needle insertion for subclavian vein puncture. C, The anatomic landmarks as they would appear to an anesthesiologist. The needle is introduced at the apex of the triangle outlined in C and is directed at an angle of 30 degrees to the skin toward the ipsilateral nipple. This point of entry is generally half the distance between the mastoid process and the sternal notch. C, Clavicle; M and L, medial and lateral bellies of the sternocleidomastoid muscle (SCM).
1. Position the child as for external jugular vein cannulation but with a rolled towel under the center of the back to allow the head to be slightly extended (see Fig. 48-3 and Video 48-1 for positioning and the use of ultrasound to guide insertion). The head is turned slightly away from the side of insertion; turning the head too far to the side may result in compression of the vein and moving the vein in closer proximity to the carotid artery.
2. Locate the apex of a triangle formed by the two bellies of the sternocleidomastoid muscle. This point is usually where the external jugular vein crosses the sternocleidomastoid muscle or the midpoint between the mastoid process and the sternal notch.
3. Palpate the carotid artery. Introduce the needle just lateral to this artery at an angle of 30 degrees to the skin surface. If the internal jugular vein is superficial, a less acute angle may be indicated. While continuously aspirating, advance the needle toward the ipsilateral nipple a distance of no more than 2.5 cm. If no blood is freely obtained, slowly withdraw the needle while maintaining aspiration. The needle can compress the vessel on entry, and it straightens during withdrawal, allowing free aspiration of blood.
4. Once venipuncture is accomplished, carefully remove the syringe and occlude the end of the needle (to prevent entraining air if the child is breathing spontaneously) until a flexible guidewire is inserted (see Fig. 48-2).51 The wire should advance easily. However, if the wire cannot be advanced, the needle has passed out of the vessel lumen or its tip rests against the vessel wall. In this situation, the wire and needle should be withdrawn simultaneously to avoid shearing the wire. If the wire passes without difficulty, then cannulation proceeds as demonstrated in Figures 48-2 and 48-4. Catheter tip location should be confirmed with a radiologic study and repositioned as necessary (see Fig. 48-3).
Raised intracranial pressure (Trendelenburg position and venous occlusion by the catheter may increase intracranial pressure); this is a relative contraindication and ultrasound-guided insertion may provide a great advantage because Trendelenburg position may not be required.
The subclavian vein is a site frequently used for central vein cannulation.79,80 Success rates of over 80% have been reported even in infants younger than 4 weeks of age.81–83 The advantages include fixed landmarks, ease of securing the line to children for long-term management, and patient comfort. Disadvantages include pneumothorax and hemothorax.84,85 If this site is chosen, we suggest obtaining a chest radiograph after the catheter is inserted and before surgery begins to preclude an unrecognized intraoperative tension pneumothorax. The use of the Seldinger technique (our preference) may reduce the incidence of damage to intrathoracic structures compared with other techniques. As with left-sided internal jugular vein cannulation, if a left subclavian catheter tip rests against the wall of the superior vena cava, it can erode through, resulting in hemothorax or hydrothorax (see Fig. 48-3, H). In a comparison of neutral versus lowered shoulder position in 361 adult patients, neutral position significantly reduced the incidence of misplacement of the catheter tip (ipsilateral internal jugular or brachiocephalic vein) with no difference in the rate of arterial puncture or pneumothorax.86 This maneuver remains to be tested in children.
2. Insert a needle immediately inferior to the clavicle at a point one-half to two-thirds its length from the sternoclavicular junction; while “hugging” the undersurface of the clavicle, the needle is directed toward the suprasternal notch while continuously aspirating.
If the child’s ventilation is controlled, the risk of pneumothorax may be decreased by momentarily ceasing ventilation so that the apex of the lung is away from the needle tip. While probing for the subclavian vein, once successful venipuncture has been achieved, maintaining positive end-expiratory pressure reduces the possibility of air embolism. Optimal depths for right subclavian catheterization have been studied in infants 2 to 5 kg using transesophageal echocardiography and found to be 40 to 55 mm for catheter tip placement at the junction of the superior vena cava and the right atrium.87 Contraindications are the same as for internal jugular vein catheterization (see Video 48-1 for illustration of technique).
The brachiocephalic vein offers the advantage of being far removed from the intrathoracic structures.88 The main disadvantage is that a significant number of catheters introduced at this site do not pass centrally, that is, they are caught in the axilla or pass up the jugular vein (internal or external).89–91 Other disadvantages include significant catheter migration with movement of the arm and possibly an increased incidence of infection. This approach is commonly used by radiologists and pediatric nurses for placement of peripherally inserted central catheters (PICCs), which can be used on a long-term basis.92–94 These catheters often markedly improve patient care and the quality of life for the child because of the reduced need for peripheral venous access and the reduced number of venipunctures for blood testing. The routine use of heparin to prevent catheter thrombosis and occlusion is not supported by published studies, but the data are inadequate to reach a conclusion one way or the other.95