Prediction of postoperative cardiac surgical morbidity and organ failure within 4 hours of intensive care unit admission using esophageal Doppler ultrasonography

Abstract

Objective: To compare esophageal Doppler ultrasonography with standard hemodynamic variables used in postoperative care for the prediction of postoperative complications after cardiac surgery.

Design: Prospective, observational pilot study.

Setting: University hospital, multidisciplinary intensive care unit

Patients: Postoperative cardiac surgical patients.

Interventions: Standard postoperative management as guided by routinely measured hemodynamic variables.

Measurements: An esophageal Doppler ultrasound probe was inserted for measurement of stroke volume (SV), cardiac output (CO), and other flow-related variables. Both these and routine hemodynamic variables (mean arterial pressure, central venous pressure, heart rate, arterial base deficit, urine output, core-toe temperature difference) were recorded at half-hourly intervals for the first 4 postoperative hrs. The incidence of systemic inflammatory response syndrome at 24 hrs, Acute Physiology and Chronic Health Evaluation II, and multiple organ failure scores, postoperative complications, and length of ICU and hospital stays were recorded.

Main results: Twenty consecutively admitted patients were studied: eight after emergency bypass grafting and 12 after elective bypass grafts and/or valve replacement. Of the nine patients who developed postoperative complications, two died. At admission, significant differences were seen between patients with a complicated and those with an uncomplicated surgical procedure for SV, heart rate, and standard base excess, but not for cardiac output. By using receiver operator characteristic curves, SV was the best marker for predicting postoperative complications during the initial postoperative period.

Conclusions: A low SV and a high heart rate, both at ICU admission and during the subsequent 4 hrs, were the best prognostic factors for development of complications after cardiac surgery. Cardiac output values were not useful. This pilot study suggests that the minimally invasive technique of esophageal Doppler ultrasonography may be a useful tool to assist early prognostication.