Skin mottling and an increased delta temperature (deltaT) between core and peripheral sides as measurements of microcirculatory dysfunction are associated with increased mortality in intensive care patients. We studied the effect on deltaT of ketanserin, a 5-HT2 receptor-blocking agent. MethodsA retrospective analysis was performed of all intensive care patients that received ketanserin by continuous infusion. Over four to eight consecutive hours the change in deltaT (forefoot) was determined. To exclude lead-time bias we compared with a three-hour period before the start of ketanserin. Results1875 consecutive patients received a mean total dose of 225 (SD 110) μg/kg/min ketanserini.v. The peripheral temperature rose mean 2.6° Cover eight hours and delta T declined mean 2.4°C. A repeated measures analysis showed a significant rise in peripheral temperature. Comparing three hours before with three hours after start of ketanserin, all other parameters did not significantly change. ConclusionThe microcirculation measured as peripheral temperature of critically ill patients, significantly improved with a continuous infusion of ketanserin. This increase is not associated with hypotension or the need of vasoconstrictors.