The effect of ketanserin on post-anaesthetic vasoconstriction and shivering

Two homogeneous groups of 20 healthy women submitted to elective gynaecological surgery, who presented after anaesthesia with peripheral vasoconstriction and shivering, were included in a randomized, double-blind study. The first group received 10 mg ketanserin, a new pure antagonist of serotoninergic S2 receptors. The second group received 10 ml saline as placebo. Blood pressure, heart rate, pulse wave amplitude, and rectal and cutaneous temperatures were measured before and 5, 15 and 30 min after treatment. Vasoconstriction, shivering and discomfort were classified as intense, moderate or absent at these times. Venous and arterial blood gases were determined before and 15 min after treatment. Blood pressure and heart rate decreased slightly after ketanserin administration and this decrease was statistically significant. Increases in rectal temperature were similar in both groups. Peripheral temperature, measured in the big toe, significantly decreased in the placebo group but did not change after ketanserin. Vasoconstriction, shivering, discomfort and pulse wave amplitude improved significantly following ketanserin. We conclude that ketanserin may be effective in treating this post-operative complication, the possible mechanism being the vasodilatation it causes; a central serotoninergic blockade could also be implied.