The effect of major abdominal surgery on the sublingual microcirculation: an observational study

It remains unknown whether the sublingual microcirculation is impaired during noncardiac surgery. We, therefore, aimed to investigate the sublingual microcirculation in patients undergoing major abdominal surgery. Specifically, we sought to test the primary hypothesis that the sublingual microcirculation is persistently impaired during major abdominal surgery.

In this prospective observational study, we assessed the sublingual microcirculation using vital microscopy before induction of general anesthesia, at the time of surgical incision, every 20 min during surgery, and on the first postoperative day in 46 patients undergoing major abdominal surgery. The primary endpoint was the area under a proportion of perfused vessels (PPV) of 92% as a measure of the duration and severity of capillary red blood cell flow impairment.

The median [interquartile range (IQR)] intraoperative area under a PPV of 92% was 71%⋅min [2%⋅min-278%⋅min], and the median [IQR] time-weighted average PPV < 92% was 0.3% [0%-0.9%]. Twelve patients (26%) had an area under a PPV of 92% of 0%⋅min, and five patients (11%) had an area under a PPV of 92% of 400%⋅min or higher. The duration of surgery had no clinically important persistent effect on intraoperative PPV or any other sublingual microcirculation variable. The lowest intraoperative PPV was lower than the PPV at incision (estimated difference, -5.3%; 95% confidence interval, -6.3 to -4.4; P < 0.001).

The area under a PPV of 92% during elective major abdominal surgery was small, indicative of little impairment of sublingual microcirculation. The duration of surgery had no clinically important effect on sublingual microcirculatory variables.