Vascular Access




INTRODUCTION



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Although it is always best to utilize the least invasive access, central venous access is often required in the PICU. This chapter addresses central venous access and arterial access first and then addresses peripheral venous access and interosseus access. Ultrasound considerations are incorporated throughout the chapter.




CENTRAL VENOUS ACCESS



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Central versus peripheral access: Peripheral access should be used whenever possible, unless specific indications for central venous access are present.



INDICATIONS





  • Unable to achieve peripheral access



  • Large volume resuscitation



  • Need for vesicant, irritant, or hyperosmolar or highly concentrated solutions (including total parenteral nutrition [TPN], electrolyte replacement, greater than 12.5% dextrose, pH <5 or >9, or osmolarity >600 mOsm/L)



  • Need for vasoactive support



  • Need for hemodynamic monitoring, including central venous pressure, pulmonary artery pressure, or mixed venous saturation monitoring



  • Frequent blood draws



  • Need for prolonged access (chemotherapy, prolonged antibiotic course)




CONTRAINDICATIONS





  • Increased bleeding risk secondary to thrombocytopenia or coagulopathy.



  • Predisposition to sclerosis or thrombosis. Contraindicated in a vessel with a known thrombus.




RISKS/POTENTIAL COMPLICATIONS





  • Bleeding: Assessment for thrombocytopenia and coagulopathy should occur prior to line placement



  • Infection: Use sterile technique with full barrier to minimize infection



  • Embolization of intravascular thrombus, guidewire, or air



  • Vessel perforation




PREPARATION





  • Materials




    • Sterile gloves, gown, drapes



    • Surgical hat, mask



    • Catheter (see Table 8-1 for size and length considerations)



    • Caps for each catheter lumen



    • Introducer needle



    • Syringe (non-Luer Lock) to attach to introducer needle and two to three additional 3-mL syringes



    • Guidewire (at least double the length of the catheter; verify that guidewire passes through needle prior to starting procedure)



    • Scalpel



    • Tissue dilator



    • Suture



    • Kelly clamp



    • Additional syringes




  • Medications




    • Lidocaine 1% for skin numbing (and appropriate needle for superficial injection)



    • Chlorhexidine (>2 months) or iodine (<2 months) for skin preparation




  • Catheter selection





TABLE 8-1

Catheter Selection by Age





TECHNIQUE





  • Preparation




    • Sterile procedure: Use cap/mask, gown, sterile gloves



    • Prepare the area with 2% chlorhexidine (>2 months) or 10% povidine-iodine (<2 months)



    • Catheter preparation




      • Flush all ports and caps with normal saline or heparinized saline



      • Clamp lumens after flushing





  • Anesthesia




    • For use of systemic sedation or analgesia, ensure NPO status (6 hours for solids; 4 hours for clear liquids).



    • Inject local anesthetic (1% lidocaine) into the tissues at and below the venipuncture site. Withdraw prior to injection to avoid intravascular injection.




  • Seldinger technique (Figure 8-1)




    • Puncture the skin using an introducer needle attached to non-Leur Lock syringe.



    • Advance until blood return is free-flowing, then remove syringe, keeping introducer needle in place. Place finger over open lumen on needle to avoid air entry.



    • Insert guidewire through introducer needle, keeping one hand on the guidewire at all times.




      • Until the guidewire is removed, one hand should be kept on the guidewire for each subsequent step.



      • Guide wire should enter without resistance and, if met with resistance, needle or guidewire should be redirected prior to reattempting advancement.





    • When guidewire is in place, using a scalpel, make a small incision at the venipuncture site. Remove the introducer needle with the guidewire remaining in place.



    • Introduce the dilator over the guidewire. Use a twisting motion to advance through the skin as needed. Remove the dilator with the guidewire remaining in place.



    • Thread the catheter over the guidewire, retracting the guidewire through the catheter as needed until the guidewire is visible on the other side of the catheter.



    • Once the catheter is in place, remove the guidewire.



    • Aspirate blood through each port to ensure free flow. Flush each port. Take care to avoid introducing any air through the catheter.



    • Suture the catheter in place.



    • Attach caps to the catheter lumens.






FIGURE 8-1


Seldinger technique.



Reproduced with permission from Michelson K. Chapter 10. Femoral Venous Catheterization. In: Goodman DM, et al., eds. Current Procedures: Pediatrics New York, NY: McGraw-Hill; 2007.




CONFIRMATION OF PLACEMENT





  • Blood gas



  • Transduce pressure



  • Imaging




    • Chest x-ray for internal jugular (IJ) or subclavian placement to verify positioning and evaluate for pneumothorax



    • Abdominal x-ray for femoral placement to verify positioning





REMOVAL OF CATHETER





  • Remove as soon as the indication for a central venous line (CVL) is no longer present



  • Remove sutures and retract catheter with pressure at the insertion site after removal





GENERAL PRINCIPLES FOR ULTRASOUND-GUIDED VASCULAR ACCESS



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PREPARATION





  • Materials




    • Ultrasound machine



    • High-frequency linear probe



    • Ultrasound gel





TECHNIQUE





  • Preparation




    • Cover probe



    • Place gel over ultrasound probe




    • Vessel identification and confirmation




      • Veins compress more easily than arteries



      • Veins have thinner walls than arteries



      • Arteries have pulsatile flow; veins do not





    • Prescan along length of vessel to ensure its depth, course, and patency



    • Center vessel on screen



    • Confirm successful catheterization with catheter/wire visualized in vessel




  • General technique




    • Position the ultrasound machine in the operator’s direct line of site (usually on the opposite side of the patient’s bed with the cord draped across the patient)



    • Orient the probe so that the left side of the probe corresponds to the left side of the ultrasound screen



    • Ultrasound probe held in operator’s nondominant hand



    • Needle held in operator’s dominant hand




  • Short axis/transverse approach




    • Orient probe with its long axis perpendicular to the path of the vessel



    • Vessel will appear as black/anechoic circle with white/hyperechoic rim on screen



    • Brace fingers of hand holding probe on patient to ensure stability



    • Insert needle at skin at midpoint of probe of the long axis of the probe



    • Identify needle tip as bright white/hyperechoic dot on screen



    • Advance or slide ultrasound probe a few millimeters while advancing the probe



    • Adjust needle direction to ensure it is in line with the vessel



    • Ensure needle tip remains in view by tilting the probe back and forth



    • Poke needle through superficial wall into vessel



    • Shallow needle angle to allow passage of wire or catheter




  • Long axis/longitudinal approach




    • Orient probe with its long axis parallel to the path of the vessel



    • Vessel will appear as black/anechoic tube with white/hyperechoic edges on screen



    • Brace fingers of hand holding probe on patient to ensure stability



    • Insert needle into the skin proximal to and at the midpoint of the short axis of the probe



    • Identify needle tip and shaft as hyperechoic oblique line on screen



    • Keep nondominant hand in place while vessel is in view



    • Advance needle under direct ultrasound guidance



    • Poke needle through superficial wall into vessel



    • Shallow needle angle to allow passage of wire or catheter




  • Short axis vs. long axis approach




    • Short axis approach:




      • Allows simultaneous visualization of intended and neighboring vessels



      • Any point of the needle (tip and shaft) appears as a hyperechoic dot; if needle tip is not followed, one may poke inadvertently through the vessel



      • Some operators may find it difficult to manipulate the probe with their nondominant hand




    • Long axis approach:




      • Allows visualization of the entire vessel and needle



      • The hand–eye coordination necessary to keep probe still while advancing the needle along its plane may be challenging



      • Limited space of a patient’s short neck may preclude placing the probe in the long axis and a longitudinal approach







TYPES OF CENTRAL VENOUS ACCESS



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FEMORAL CENTRAL VENOUS CATHETER





  • Advantages




    • Avoids device in neck or chest



    • Able to control bleeding locally with pressure




  • Drawbacks




    • Unable to obtain a true mixed venous saturation, unless a long catheter is placed



    • Central venous pressure (CVP) monitoring affected by intra-abdominal pressure; femoral CVLs should not be placed in the setting of acute intra-abdominal process or trauma



    • Difficult when anatomic landmarks are distorted



    • Excessive stooling increases infection risk




  • Anatomy (Figure 8-2)




    • Inguinal ligament runs from anterior superior iliac spine to the pubic symphysis



    • Femoral artery and vein run in parallel and should be entered below the inguinal ligament



    • “NAVEL” describes the structures from lateral to medial of importance: nerve, artery, vein, empty space, lymphatics



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Jan 14, 2019 | Posted by in PEDIATRICS | Comments Off on Vascular Access
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