Plasma Fibronectin Levels: Effect Of Obtaining Blood For Assay VIA Indwelling Plastic Catheters

Plasma fibronectin (PFN) concentrations are reported to be decreased in patients with sepsis and disseminated intravascular coagulation. In such critically ill patients vascular access is often limited, and the indwelling plastic catheters inserted for clinical monitoring are often used for obtaining blood samples. Despite slow continuous infusion of heparinized saline, these catheters often become coated with fibrin. Since PFN is known to be precipi table by heparin and to be bound to fibrin(ogen), levels of PFN obtained from blood drawn through such indwelling catheters may be artifactually depressed. To provide data, levels of PFN were determined from blood samples drawn simultaneously through the distal port of Swan-Ganz (110 cm length), plastic arterial (3.2 cm length) or central venous pressure(CVP 20.3 cm length) catheters, and compared with those levels obtained after a percutaneous venipuncture. All catheters were in situ for 24-48 hours prior to blood sampling. The arterial and Swan-Ganz lines were flushed with heparinized saline continuously (2 units/ml;3 ml/hour). Prior to sample collection, 5 ml of blood was aspirated through the catheter and discarded. Plasma was frozen at -80C until assay. PFN concentration was determined using an electroimmunoassay.

We conclude that PFN levels determined from blood drawn through any of the plastic catheters studied were equivalent to those levels obtained from a percutaneous venipuncture. In critically ill patients in whom vascular access is limited, PFN concentration may be reliably obtained from blood samples collected through indwelling catheters.