Intravenous dexmedetomidine vs intravenous tramadol for control of postspinal shivering in patients undergoing knee arthroscopy: a randomized double-blind placebo controlled trial

Abstract

Post-anesthetic shivering is spontaneous, involuntary, rhythmic, oscillating and tremor-like muscle hyperactivity which increases metabolic heat production up to 600% after general or regional anesthesia. Shivering is not only subjectively unpleasant but is physiologically stressful because it elevates blood pressure, heart rate, oxygen consumption, and plasma catecholamine concentrations. Moreover, shivering may aggravate pain and wound closure by simply stretching surgical incisions. The mechanism for shivering after spinal anesthesia may be related to disruption of normal temperature regulation resulting from the redistribution of body heat from the center of the body to the periphery. As a result, the afferent temperature signal in the anesthetized area is not transmitted to the thermoregulation center located in the hypothalamus.