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A number of procedures are used to gain vascular access.
Most patients’ needs for IV fluid and drugs can be met with a percutaneous peripheral venous catheter. Venous cutdown can be used when percutaneous catheter insertion is not feasible. Typical cutdown sites are the cephalic vein in the arm and the saphenous vein at the ankle. However, venous cutdown is rarely needed because of the recent popularity of peripherally inserted central catheter (PICC) lines and intraosseous lines in both adults and children.
Common complications (eg, local infection, venous thrombosis, thrombophlebitis, interstitial fluid extravasation) can be reduced by using a meticulous sterile technique during insertion and by replacing or removing the catheters within 72 h.
Patients needing secure or long-term vascular access (eg, to receive antibiotics, chemotherapy, or TPN) and those with poor peripheral venous access require a central venous catheter (CVC). CVCs allow infusion of solutions that are too concentrated or irritating for peripheral veins and allow monitoring of central venous pressure (CVP—see Central venous pressure).
CVCs can be inserted through the jugular, subclavian, or femoral veins or via the upper arm peripheral veins (PICC line). Although the type of catheter and site chosen are often determined by individual clinical and patient characteristics, a jugular CVC or PICC line is usually preferred to a subclavian CVC (associated with a higher risk of bleeding and pneumothorax) or femoral CVC (associated with a higher risk of infection). During cardiac arrest, fluid and drugs given through a femoral vein CVC often fail to circulate above the diaphragm because of the increased intrathoracic pressure generated by CPR. In this case, a subclavian or internal jugular approach may be preferred.
Ultrasound guidance for placement of internal jugular lines and PICC lines is now standard care and reduces the risk of complications. Coagulopathy should be corrected whenever feasible prior to CVC insertion, and the subclavian approach should not be used in patients with uncorrected coagulopathy because the venipuncture site cannot be monitored or compressed.
CVCs are inserted using sterile technique and a local anesthetic (eg, 1% lidocaine) and a series of well-defined steps:
The catheter is flushed with saline and sutured in place, and an occlusive dressing is applied. For jugular and subclavian vein CVCs, a chest x-ray is done to confirm that the tip of the CVC is at the junction between the superior vena cava and the right atrium (the catheter can be advanced or retracted if not in the appropriate position) and to confirm that pneumothorax has not occurred. To prevent cardiac arrhythmias, clinicians should withdraw catheters in the right atrium or ventricle until the tip is within the superior vena cava.
Percutaneous femoral lines must be inserted below the inguinal ligament. Otherwise, laceration of the external iliac vein or artery above the inguinal ligament may result in retroperitoneal hemorrhage; external compression of these vessels is nearly impossible.
To reduce the risk of venous thrombosis and catheter sepsis, clinicians should remove CVCs as soon as possible. The skin entry site must be cleansed and inspected daily for local infection; the catheter must be replaced if local or systemic infection occurs. Some clinicians feel it is beneficial to change CVC catheters at regular intervals (eg, every 5 to 7 days) in patients with sepsis who remain febrile; this approach may reduce the risk of bacterial colonization of the catheter. (See also Guidelines for Prevention of Intravascular Catheter-Related Infections at the CDC web site.)
CVCs can cause many complications (see Table: Complications Associated With Central Venous Catheters). Pneumothorax occurs in 1% of patients after CVC insertion. Atrial or ventricular arrhythmias frequently occur during catheter insertion but are generally self-limited and subside when the guide wire or catheter is withdrawn from within the heart. The incidence of catheter bacterial colonization without systemic infection may be as high as 35%, whereas that of true sepsis is 2 to 8%. (See also Guidelines for Prevention of Intravascular Catheter-Related Infections at the CDC web site.) Rarely, accidental arterial catheterization requires surgical repair of the artery. Hydrothorax and hydromediastinum may occur when catheters are positioned extravascularly. Catheter damage to the tricuspid valve, bacterial endocarditis, and air and catheter embolism occur rarely.
Complications Associated With Central Venous Catheters
The use of automated noninvasive BP devices has diminished the use of arterial catheters simply for pressure monitoring. However, these catheters are beneficial in unstable patients who require minute-to-minute pressure measurement and in those requiring frequent ABG sampling. Indications include refractory shock and respiratory failure. BP is frequently somewhat higher when measured by an arterial catheter than by sphygmomanometry. Initial upstroke, maximum systolic pressure, and pulse pressure increase the more distal the point of measurement, whereas the diastolic and mean arterial pressures decline. Vessel calcification, atherosclerosis, proximal occlusion, and extremity position can all affect the value of arterial catheter measurements.
Arterial catheters are inserted using sterile technique and a local anesthetic (eg, 1% lidocaine). They are typically inserted percutaneously into the radial, femoral, axillary, brachial, dorsalis pedis, and (in children) temporal arteries. The radial artery is most frequently used; insertion into the femoral artery has fewer complications but should be avoided after vascular bypass surgery (due to potential injury to the bypass graft) and in patients with distal vascular insufficiency (to avoid precipitating ischemia). Ultrasound guidance may be beneficial in difficult cases.
Before radial artery catheterization, the Allen test (digital compression of both ulnar and radial arteries causes palmar blanching followed by hyperemia when either artery is released) can determine whether there is sufficient ulnar collateral flow to perfuse the hand in the event of radial artery occlusion. If reperfusion does not occur within 8 sec of releasing the compressed ulnar artery, arterial catheterization should not be done or another arterial site is chosen.
At all sites, bleeding, infection, thrombosis, and distal embolism may occur. Catheters should be removed if signs of local or systemic infection are present.
Radial arterial complications include ischemia of the hand and forearm due to thrombosis or embolism, intimal dissection, or spasm at the site of catheterization. The risk of arterial thrombosis is higher in small arteries (explaining the greater incidence in women) and with increased duration of catheterization. Occluded arteries nearly always recanalize after catheter removal.
Femoral arterial complications include atheroembolism during guide wire insertion. The incidence of thrombosis and distal ischemia is much lower than that for radial arterial catheterization.
Axillary arterial complications include hematomas, which are infrequent but may require urgent care because brachial plexus compression can result in permanent peripheral neuropathy. Flushing the axillary arterial catheter may introduce air or a clot. To avoid neurologic sequelae of these emboli, clinicians should select the left axillary artery for catheterization (the left axillary artery branches further distal to the carotid vessels than does the right).
Any fluid or substance routinely given IV (including blood products) may be given via a sturdy needle inserted in the medullary cavity of select long bones. Fluids reach the central circulation as quickly as with venous infusion. This technique is used more commonly in infants and young children, whose bony cortices are thin and easily penetrated and in whom peripheral and central venous access can be quite difficult, particularly in shock or cardiac arrest. However, this technique can be used in older patients at various sites (eg, sternum, proximal tibia, humerus) via special devices (eg, pressure-loaded puncture device, drilling device) that are now more readily available. Thus, intraosseus infusion is becoming more common in adults.
Intraosseous delivery systems should be removed within 24 h of insertion or as soon as practical after peripheral or central IV access has been achieved.
Intraosseous (IO) Needle Insertion.
A special-purpose intraosseous needle with stylet is used. The preferred insertion sites in children are the proximal tibia and distal femur; both areas are given a sterile preparation and are included in the operative field. For tibial insertion, the needle is placed on the broad, flat anteromedial surface 1 to 2 cm distal to the tibial tubercle. For the femur, the site is 3 cm above the lateral condyle in the midline. For older children, the medial surface of the distal tibia 2 cm above the medial malleolus may be easier. For adults, the upper humerus also can be used.
For all sites, the needle is inserted with a rotary, coring motion. Stabilizing the needle shaft at the skin surface with a gloved fingertip aids control, allowing advancement to be stopped once the cortex is penetrated. On entering the medullary cavity, the stylet is removed and infusion is begun. Several semiautomatic insertion devices are available, including spring-powered and battery-powered devices.
Poor control during insertion may result in the needle exiting the opposite cortex; then, subsequent infusion largely enters the soft tissues, so a site on another bone should be tried. Osteomyelitis may occur but is uncommon (eg, < 2 to 3%). Growth plate damage has not been reported. Other complications include bleeding and compartment syndrome.
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