Catheter Information and Courses from MediaLab, Inc.

Francois P. Vaudaux P. Foster TJ. Lew DP.: Host-bacteria interactions in foreign body infections. Infection Control & Hospital Epidemiology. 17:514-20, 1996 Persistent staphylococcal infections are a major medical problem, especially when they occur on implanted materials or intravascular catheters. This review describes some of the recently discovered molecular mechanisms of Staphylococcus aureus attachment to host proteins coating biomedical implants. These interactions involve specific surface proteins, called bacterial adhesins, that recognize specific domains of host proteins deposited on indwelling devices, such as fibronectin, fibrinogen, or fibrin. Elucidation of molecular mechanisms of S. aureus adhesion to the different host proteins may lead to the development of specific inhibitors blocking attachment of S. aureus, which may decrease the risk of bacterial colonization of indwelling devices.

Venous BloodVenous blood is deoxygenated blood that flows from tiny capillary blood vessels within the tissues into progressively larger veins to the right side of the heart. Venous blood is the specimen of choice for most routine laboratory tests. The blood is obtained by direct puncture to a vein, most often located in the antecubital area of the arm or the back (top) of the hand. At times, venous blood may be obtained using a vascular access device (VAD) such as a central venous pressure line or Hickmann Catheter or an IV start. Most laboratory reference ranges for blood analytes are based on venous blood.Arterial BloodDeoxygenated blood is pumped from the right side of the heart to the lungs where it takes up oxygen. The now oxygenated blood is pumped through the left side of the heart via arteries.The most common reason for collection of arterial blood is the evaluation of arterial blood gases. Arterial blood may be obtained directly from the artery (most commonly, the radial artery) by personnel who are trained to perform this procedure and are knowledgeable about the complications that could occur as a result of this procedure. Arterial blood may also be obtained from a vascular access device (VAD) inserted in an artery such as a femoral arterial line or Swan-Gantz catheter. Capillary BloodCapillary blood is obtained from capillary beds that consist of the smallest veins (venules) and arteries (arterioles) of the circulatory system. The venules and arterioles join together in capillary beds forming a mixture of venous and arterial blood. The specimen from a dermal puncture will therefore be a mixture of arterial and venous blood along with interstitial and intracellular fluids.Capillary blood is often the specimen of choice for infants, very young children, elderly patients with fragile veins, and severely burned patients. Point-of-care testing is often performed using a capillary blood specimen. Specimen Type Method of Collection Common Use Venous Direct puncture of vein by venipuncture; vascular access device Routine laboratory tests Arterial Direct puncture of artery; vascular access device Arterial blood gases Capillary Dermal puncture of fingertip or heel Infants and young children Elderly patients with fragile veins Severly burned patients Point-of-care testing

Venous blood specimens for coagulation assays should be collected into a tube containing 3.2% buffered sodium citrate tube (blue top tube), yielding a whole blood sample with a 9:1 blood to anticoagulant ratio. Inadequate filling of the collection tube will decrease this ratio, and may affect test results.A blue top tube used for coagulation testing should be drawn before any other tubes containing additives. This includes tubes containing other anticoagulants and/or plastic serum tubes containing clot activators. A serum tube that does not contain an additive can be collected before the blue top tube.If a winged blood collection set is used in drawing a specimen for coagulation testing, a discard tube should be drawn first. The discard tube must be used to fill the blood collection tubing dead space to assure that the proper anticoagulant/blood ratio is maintained, but the discard tube does not need to be completely filled. The discard tube should be a nonadditive or a coagulation tube.If a blood specimen used for coagulation testing must be collected from an indwelling line that may contain heparin, the line should be flushed with 5 mL of saline, and the first 5 mL of blood, or 6 times the line volume (dead space volume of the catheter), be drawn off and discarded before the coagulation tube is filled.

Avoid the following sites:Scarred, abraded, or inflamed skin.Arms containing IV catheters.Edematous armsArms with casts.