Impaired sublingual microvascular perfusion during surgery with cardiopulmonary bypass: a pilot study

Complications after cardiac surgery may involve multiple organ failure, which carries a high mortality. Development of multiple organ failure may be related to impaired microcirculatory perfusion as a result of systemic inflammation. Microcirculatory blood flow alterations have been associated with impaired outcome. We investigated whether these alterations occurred before, during, and after coronary artery bypass grafting.

We observed 25 consecutive patients who underwent elective coronary artery bypass grafting with cardiopulmonary bypass. The sublingual microcirculation was investigated using side-stream dark-field imaging. Side-stream dark-field imaging was performed before (baseline), during, and after surgery. Microvascular blood flow was estimated with a semiquantitative microvascular flow index in small, medium, and large microvessels. Changes in microvascular flow were tested with Wilcoxon signed rank test.

Median microvascular flow index of medium blood vessels decreased after starting cardiopulmonary bypass relative to that after anesthetic induction (2.6, interquartile range 1.6-3.0, vs 3.0, interquartile range 2.8-3.0, P = .02). There was a trend toward decreased microvascular flow index of small and large vessels relative to baseline (P = .08 and P = .05, respectively). Decreases in microvascular flow index occurred irrespective of changes in systemic blood pressure. After each patient's return to the intensive care unit, microvascular flow index increased and normalized in all microvessels.

For the first time, sublingual microvascular blood flow alterations have been observed during cardiopulmonary bypass-assisted coronary artery bypass grafting.