Comparison between Femoral and Superior Approach Central Venous Pressure Measurements in Critically Ill - Mechanically Ventilated Patients

Central venous catheterization is one of the most commonly used invasive procedures in critically ill patients. Internal jugular and subclavian veins are the most frequently anatomical sites used for central venous catheter (CVC) insertion. However, access through the internal jugular or subclavian veins may lead to several substantial serious and life threatening complications such as pneumothorax, haemothorax, air embolism, arterial puncture, bleeding, dysrhythmias and thoracic duct injury. In contrast, femoral route is safe, standard and popular procedure as it avoids many of the potential peri-insertion and mechanical complications of the superior approach (internal jugular & subclavian veins. In addition, the femoral route is also considered by many to be the easiest site for central venous access and can be quickly learned by inexperienced operators. Ruesch (2002), (Alzeer et al,. 1998), (Gavin M. et al., 2000 & 2008). But, does the central venous pressure (CVP), monitored via the femoral route, correlate with that measured via the subclavian or internal jugular routes? In order to answer this question, this study was conducted; it was aimed to compare the measures of central venous pressure (CVP) at two different sites (superior approach and femoral approach). Material and Methods: Prospective comparative cross - over design was used to conduct this study. Thirty consecutive adult mechanically ventilated patients admitted to intensive care unit (ICUs) from June to December 2011 and requiring femoral catheterization in addition to subclavian or internal jugular veins were recruited in this study. CVP was measured from both sites hourly for 6 consecutive hours. Positive end-expiratory pressure, mean airway pressure, and intra-abdominal pressure were recorded & measured simultaneously. Results & Conclusions: For 180-paired measurements obtained from superior approach veins and femoral vein were statistically analyzed using intra-class correlation coefficients (ICC). A statistically significant high correlation (ICC 0.868, p-value < 0.001) has been showed between the both sites. In addition, Bland and Altman Plot used for assessing agreement of femoral and superior approach. The mean difference between superior approach (subclavian and internal jugular) and femoral CVP was -1.64 mm Hg (95% CI -3.86 - 0.57). The difference was normally distributed around the mean with a standard deviation of 1.11 mm Hg. i.e., on an average, the femoral vein CVP measurements were higher than superior approach of 1.64 mm Hg.