An Observational Comparative Study of Cardiac Index Estimated ByFloTrac and Intermittent Thermo Dilution in Off-Pump Coronary ArteryBypass Grafting

Objective: The purpose of this study was to determine the correlation between cardiac index (CI) measurements made using intermittent thermodilution (ITD) technique by pulmonary artery catheter (PAC) and arterial pulse-contour analysis by FloTrac. Design: Prospective observational study. Setting: Cardiac surgery unit in a 350 bedded tertiary care hospital in India. Participants: 31 adult patients undergoing elective off-pump coronary artery bypass grafting (OPCABG) Interventions: CI measurements performed by the two different methods at six time points during the surgery (before skin incision, during grafting of left anterior descending artery, obtuse marginal artery and right coronary/ posterior descending artery, after protamine administration and after shifting the patient to recovery room). Measurements and results: The techniques a weak correlation at all six time points during the OPCABG. The mean bias of 0.85 L/min/m2 and precision of 0.55 was found in the study population. The percentage error calculated using Critchley s criteria was found to be 46%. Conclusion: CI measurements obtained using FloTrac showed a limited correlation with those acquired by ITD technique at different stages of OPCABG. Further studies are required in other patient populations and clinical situations.