Are venous pressures obtained from femoral central lines comparable with pressure readings from neck lines?

Objective

To evaluate whether femoral (femoro-iliac) venous pressures are comparable with the central venous pressures (CVP) obtained from neck lines. We hypothesised that there would not be a clinically significant difference in the readings, in the absence of intra-abdominal hypertension

Methods

Simultaneous measurements were taken from ICU patients who had both femoral and neck (superior veno-caval) central catheters in situ. Only 20 cm femoral lines were considered for the study. Hemodialysis catheters were included in the study. On each occasion, measurements were taken by two independent observers and recorded separately. Intra-abdominal pressures were also measured by the intra-vesical method. We estimated a difference > 2 cmH₂O to be clinically significant

Results

Thirty sets of readings were taken from 25 patients. Only two sets had a difference > 2 cm. There was no statistically significant difference between the two groups (P = 0.054, paired t test). The femoro-iliac venous pressures correlated well with the superior vena-caval CVP (r² = 0.721, P < 0.01).

Conclusions

Venous pressures from femoro-iliac central lines correlated well with CVP taken from neck lines.