Reliability of continuous cardiac output determination by pulse-contour analysis in porcine septic shock.

BACKGROUND: Pulse-contour analysis represents a technique for cardiac output (CO)-measurement and allows continuously monitoring trends in CO. We evaluated reliability of pulse-contour CO (COpc) in septic shock.

METHODS: Seventeen anaesthetized and mechanically ventilated pigs were investigated. After baseline measurements, 14 animals received 0.75 g/kg body weight faeces into the abdominal cavity to induce sepsis and were observed over 9 h, three animals served as controls. A central venous catheter was inserted into the jugular vein and an arterial catheter for thermodilution was inserted into the femoral artery. Two bedside computers were used for COpc. After induction of sepsis, COpc-computer No. 1 (COpcCAL) was recalibrated hourly. No further calibrations were performed in computer No. 2 (COpcNoCAL). We directly compared COpcCAL hourly before recalibration with COpcNoCAL. One hundred and seventy parallel triplicate determinations of CO were analysed using the method of Bland-Altman.

RESULTS: Three hours after sepsis induction, correlation between recalibrated and non-recalibrated CO was r = 0.74, P < 0.01, at 5 h r = 0.59, P < 0.05 and 9 h r = 0.02, NS. Three hours after sepsis induction, bias +/- SD (limits of agreement) between both groups was 1.6 +/- 15.5 (-29.4-32.6) ml/kg/min, at 5 h -15.0 +/- 24.3 (-63.6-33.7) ml/kg/min and at 9 h -87.0 +/- 90.8 (-268.5-94.6) ml/kg/min.

CONCLUSION: Continuous CO determination using pulse-contour analysis is a reliable method of assessing CO up to 5 h without recalibration in porcine septic shock. Thus, COpc may be a useful tool for assessment of unpredictable haemodynamic changes in sepsis.