Comparison of continuous arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in conscious dogs with systemic inflammatory response syndrome

Abstract

To assess the agreement between cardiac output (CO) measured by use of arterial pressure waveform analysis (PulseCO) and lithium dilution (LiDCO) in conscious dogs with systemic inflammatory response syndrome (SIRS). 14 dogs with naturally occurring SIRS. Pulse power analysis was performed on critically ill patients with a PulseCO monitor. All measurements were obtained with an indwelling arterial line and in accordance with the manufacturer's instructions. Intermittent measurements of CO were obtained with the LiDCO method to validate the PulseCO measurements at initial calibration (baseline; time 0) and at 4, 8, 16, and 24 hours. The 2 methods for measuring CO were compared by use of Bland-Altman analysis. An error rate for the limits of agreement between the 2 methods of < 30% was defined as being acceptable. Bland-Altman analysis did not indicate good agreement between measurements obtained by use of the PulseCO and LiDCO methods, despite no significant change in cardiac index (CI) over time as measured with the LiDCO method. The percentage error for the overall difference in CI values between the PulseCO and LiDCO measurements was 122%, which indicated that the PulseCO method was not an acceptable means of CO measurement when compared with the LiDCO method for this patient population. Agreement between the PulseCO and LiDCO methods for measurement of CO was not acceptable at 4- and 8-hour intervals after calibration in conscious dogs with naturally occurring SIRS.