Inaccuracies in manometric central venous pressure measurement

Manometric measurement of CVP was compared to electronic measurement in ten patients. Manometric measurement was found to give readings of up to 5 cmH2O greater than electronic, with a mean difference of 2.4 cmH2O. This was shown to be due to two factors. Firstly, a meniscus effect caused an error of 1.07 cmH2O in the manometers used. Secondly, an error attributed to the way mean values of CVP are commonly read from manometers caused a further over estimate of 1.33 cmH2O. In intensive care units, where it is important to recognise and treat small changes in CVP, the use of electronic transducers to measure CVP is recommended.