Influence of port site on central venous pressure measurements from triple-lumen catheters in critically ill adults

BACKGROUND: Measurements of central venous pressure are generally obtained through one of the three ports of centrally placed triple-lumen catheters. However, no scientifically based literature is available that guides clinical practice and indicates which of the lumens is most appropriate for obtaining these measurements. OBJECTIVE: To determine if a difference exists between measurements of central venous pressure obtained via the proximal, medial, and distal ports of a triple-lumen catheter. METHODS: Measurements of central venous pressure in 48 adult ICU patients were obtained via each of the three ports of a triple-lumen catheter. Catheters were placed in either the right or left subclavian vein or the right or left internal jugular vein. The flush system was single-transducer, trifurcated pressure tubing system. Data were evaluated for variation among the three ports of the catheter for readings taken at a single point. RESULTS: A repeated-measures analysis of variance showed significant differences across port sites. Post hoc univariate F tests showed significant differences between the proximal and distal ports and between the medial and distal ports. In some patients, the difference between central venous pressure obtained from the distal port and pressure obtained from the proximal or the medial port may be clinically significant. CONCLUSION: Because measurements of central venous pressure may not always be comparable for all three ports of a triple-lumen catheter, care should be taken to distinguish when changes in pressure readings are a result of a change in port site rather than in the patient's condition.