Feasibility of measuring myocardial performance index of the right ventricle in anesthetized patients

Objective: Myocardial performance index, the sum of the 2 isovolumic times divided by the ejection time, contains information on global systolic and diastolic function. This study was performed to determine the feasibility of right ventricular myocardial performance index measurements if measured by transesophageal echocardiography in patients under general anesthesia and positive-pressure ventilation.

Design: A prospective cohort study.

Setting: A tertiary care university hospital.

Participants: Twenty patients undergoing elective coronary artery bypass graft surgery.

Interventions: None.

Measurements and main results: The feasibility of the right ventricular myocardial performance index measurements was assessed in awake patients by using transthoracic echocardiography and reassessed in the same patients under general anesthesia and positive-pressure ventilation using transesophageal echocardiography. The time from the cessation to the onset of 2 consecutive right ventricular inflows was measured as time A; the time from the onset to the cessation of right ventricular ejection was measured as time B. Myocardial performance index was calculated as follows: (time A-time B)/time B. A first reader independently measured all recordings twice to assess intrareader variability and a second reader once to assess interreader variability. Variability (%) was calculated as the mean absolute difference between 2 readings divided by their mean. The myocardial performance index could be measured for all patients. The point estimates of inter- and intraobserver variability of the right ventricular myocardial performance index measurements were 4.3% to 5% in awake patients and 17.8% to 19.6% in anesthetized patients.

Conclusions: This finding questions the use of right ventricular myocardial performance index measurements in anesthetized patients under positive-pressure ventilation.