Alterations of mesenteric blood flow after cardiopulmonary bypass: a Doppler sonographic study

Mesenteric ischemia after cardiopulmonary bypass is a serious complication associated with high mortality. It was the aim of this study to investigate mesenteric blood flow with the help of Doppler sonography in asymptomatic patients before and after cardiopulmonary bypass and cardiac surgery.

Observational study of consecutive patients.

Nonuniversity cardiac center.

Twenty-five patients undergoing elective coronary revascularization with normal left ventricular function and stable postoperative circulations with no need for catecholamines.

Preoperative and postoperative color and CW-Doppler sonography of the superior mesenteric artery. Diameter of the superior mesenteric artery and the Doppler flow profile were analyzed. Preoperative and postoperative hemodynamic data were measured by using a pulmonary artery thermodilution catheter. Mesenteric systolic flow velocity was 135 +/- 11 cm/s preoperatively and 193 +/- 13 cm/s postoperatively (p < 0.05). The corresponding preoperative and postoperative values of diastolic flow velocity were 14 +/- 4 and 4 +/- 2 cm/s (p < 0.05) and the values of mean flow velocity were 24 +/- 3 and 17 +/- 2 cm/s (p < 0.05), respectively. The preoperative Pourcelot resistive index was 0.87 +/- 0.05, and the preoperative Gosling pulsatility index was 4.6 +/- 0.5. Both indices increased postoperatively to values of 0.98 +/- 0.04 and 9.5 +/- 0.7, respectively (p < 0.05). Preoperative and postoperative hemodynamic data did not differ significantly.

The postoperative changes in the flow velocities and the increases of the resistive and pulsatility index are indications of rigidity of the mesenteric vascular bed and decreased mesenteric perfusion after cardiopulmonary bypass.