SEMICONTINUOUS VERSUS INJECTATE CARDIAC-OUTPUT MEASUREMENT IN INTENSIVE-CARE PATIENTS AFTER CARDIAC-SURGERY

Objective: Commercially available semi-continuous cardiac output (SCCO ) monitoring systems are based on the pulsed warm thermodilution techn ique. There is evidence that SCCO fails to correlate with standard int ermittent bolus cardiac output (ICO) in clinical situations with therm al instability in the pulmonary artery. Furthermore, ventilation may p otentially influence thermodilution measurements by enhanced respirato ry variations in pulmonary artery blood temperature and by cyclic chan ges in venous return. Therefore, we evaluated the correlation, accurac y and precision of SCCO versus ICO measurements before and after extub ation. Design: Prospective cohort study. Setting: Intensive care unit (ICU) of a university hospital. Patients and participants: 22 cardiac surgical ICU patients. Interventions: None. Measurements and results: SCCO and ICO data were obtained at nine postoperative time points whil e the patients were on controlled mechanical ventilation. Further sets of measurements were taken during the weaning phase 20 min before ext ubation, and 5 min, 20 min and Ih after extubation. SCCO and ICO measu rements yielded 286 data pairs with a range of 1.8 - 9.9 1/min for SCC O and 1.9 - 9.8 1/min for ICO. The correlation between SCCO and ICO wa s highly significant (r = 0.92; p<0.01), accompanied by a bias of -0.0 521/min and a precision of 0.561/min. Correlation, accuracy and precis ion were not influenced by the mode of respiration. Conclusions: Our r esults demonstrate excellent correlation, accuracy and precision betwe en SCCO and ICO measurements in postoperative cardiac surgical ICU pat ients. We conclude that SCCO monitoring offers a reliable clinical met hod of cardiac output monitoring in ICU patients following cardiac sur gery.