Comparison of water manometry to 2 commercial electronic pressure monitors for central venous pressure measurement in horses

Background: Central venous pressure (CVP) customarily has been measured in veterinary patients with water manometry. However, many institutions are now using stallside electronic monitors in both anesthesia and intensive care units for many aspects of patient monitoring. Hypothesis: Electronic stall side monitoring devices will agree with water manometry for measurement of CVP in horses. Animals: Ten healthy adult horses from the university research herd. Methods: Central venous catheters were placed routinely, and measurements were obtained in triplicate with each of the 3 methods every 12 hours for 3 days. Data were analyzed by a Lin concordance correlation coefficient and modified Bland-Altman limits of agreement, with all devices compared pairwise. Results: Compared with water manometry, agreement (bias) of the Passport was −1.94 cmH2O (95% limits of agreement, −8.54 to 4.66 cmH2O) and of the Medtronic was −1.83 cmH2O (95% limits of agreement, −8.60 to 4.94 cmH2O). When compared with the Passport, agreement of the data obtained with the Medtronic was 0.27 cmH2O (95% limits of agreement, −4.39 to 4.93 cmH2O). Conclusions and Clinical Importance: These data show that both electronic monitors systematically provide measurements that are approximately 2 cmH2O lower than water manometry, but differences between the 2 electronic devices are small enough (< 0.5 cmH2O) to be considered clinically unimportant. This discrepancy should be taken into account when interpreting data obtained with these monitoring devices.