Complications of invasive monitoring: central venous catheter

Abstract

Insertion of a central venous catheter has been increasingly recommended as an effective monitoring device in the critically ill patient. A simple central venous catheter (CVC) can yield significant information concerning volume status of the patient as well as function of the right and, by extension, the left heart. It allows continuous monitoring of therapy in real time as fluid boluses and cardiac function can be evaluated in real time. In contrast, other monitors such as echocardiography cannot provide hours of monitoring but are limited to small epochs of time during a patient’s therapeutic course. Finally, a CVC can be converted to an insertion point from which a pulmonary artery catheter can be floated to evaluate more specifically pulmonary pressures and left heart function. Central venous access has remained the staple of intensive care therapy for decades. However, controversy exists regarding the risks and benefits of indwelling CVCs, particularly in light of recent intolerance of complications from the ever increasingly used devices. Infectious complications are particularly devastating, with internal jugular cannulation being associated with a higher infection rate than lines inserted via a subclavian approach. This may be a consequence of the insertion technique or, more likely, a combination of increased use of CVCs in patients as well as a relative willingness to leave these CVP catheters in situ for a prolonged period of time in the intensive care unit. These internal venous lines may be used for infusion of therapeutics as well as for monitoring, resulting in a complex picture in the control of infectious complications. A second aspect of CVCs is the insertion technique. With the increasing use of ultrasound, many clinicians now advocate using ultrasound routinely as an adjunct to central line insertion. Proponents argue that the structures are easily identified, making complications due to unusual anatomy rare to non-existent. However, using ultrasound involves the ability to have an ultrasound machine available when line insertion is needed, and necessitates the training of personnel to use ultrasound appropriately. Additionally, a second experienced person is required to hold the probe if ultrasound is to be used to guide in real-time the insertion of a CVC into the venous structure. Many clinicians still rely, successfully, on anatomic landmarks to guide insertion of CVCs. The most common, and most feared, complication of CVC insertion is the misplacement of a CVC into an artery. IT has been estimated that the incidence of such a complication, with insertion of a dilator into the artery, occurs at a less than 1% rate, surprisingly low for a complex procedure. However, such a complication is devastating and can result in death or permanent injury. It is unknown what the actual incidence is, as many events may be unreported. A recent report highlighted the use of manometry during the process of CVC insertion, prior to the dilation of the vein to accept the CVC, with no reported incidence of complications in over 10,000 insertions over a 15 year period. However, it is recognized that no technique, manometry or ultrasound guidance, is foolproof, as reports of complications despite using techniques designed to eliminate such mishaps continue to be published.