Pharmacokinetic Study of Effect of Cardiac Output on the Uptake of Isoflurane

The effect of cardiac output on the uptake of isoflurane is yet to be quantified. This study aims to obtain a quantifiable relationship between isoflurane uptake and cardiac output. The study patients will be cardiac patients in whom anesthesia is induced with fentanyl , propofol and maintained on isoflurane . The baseline cardiac index from the pulmonary artery catheter as displayed on the continuous cardiac output monitor will be used to classify the patients into two groups with cardiac index of 2.1 liters per minute per square meter as the differentiating criteria. No change in the anesthesia protocol will be done for the two groups.The study is designed such that all vascular catheterisations and the dose of isoflurane administered is as per prevailing institutional protocols and that no other intervention particular or unique to the study is done. As such the data that the study will use is also routinely acquired during the procedure but not systematically stored, which is what the study will do. This, we suggest, makes the study an observational study.The continuous cardiac output data and the inspired and expired concentration of isoflurane as displayed on the monitor will be recorded online. Data will be collected from the start of isoflurane till 30 minutes or till the surgeon starts cannulating the great vessels. The data so obtained will be analysed in two groups based on the baseline cardiac index using Statistical Package for the Social Sciences (SPSS) for difference in uptake between the groups.

Inclusion criteria

• Presence of valve stenosis / valvular regurgitant lesion/ coronary artery disease with Ejection fraction >40%
• Posted for open cardiac surgery under general endotracheal anesthesia

Exclusion criteria

• Shunt lesion
• Allergy to propofol
• Psychotropic drug use
• Preinduction hemodynamic instability