الفهرس 
? Pathophysiology of ShiveringOnly 14 pages are availabe for public view
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Abstract
Post-anesthetic shivering is hyperactivity which increases metabolic heat production up to 600% after general or regional anesthesia.
Shivering is not only subjectively spontaneous, involuntary, rhythmic, oscillating and tremor-like muscle 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.
The aim of this work is to compare the efficacy of prophylactic i.v dexmedetomidine vs. tramadol for control of post spinal shivering during knee arthroscopy.
This prospective randomized double blinded study was carried in Ain Shams University hospitals on 75 patients scheduled for knee arthroscopy. Patients were randomized into three groups 25 patients each:
group D patients received i.v dexmedetomidine (0.5 mcg/kg, group T patients received i.v tramadol 0.5mg/kg while group C patients received 0.9% sodium chloride (normal saline).
All drugs were given immediately before intra-thecal injection of the anesthetic drugs and returning to the supine position by 20 mins.
Comparisons were done between the three groups as regards: incidence of shivering, onset and grade of shivering, hemodynamics (MAP, HR, temperature, respiratory rate, and oxygen saturation) sedation scores, and the incidence of shivering and grade of shivering, incidence of nausea and vomiting.
The study revealed that the incidence of shivering was less in the D group (8%) and T group (12%) compared to the C group (36%)(P<0.031) with no significant difference between D group and T group as regard the incidence of shivering. Grade of shivering was significantly different between D group and other groups.
There was no significant difference among the three groups as regards hemodynamics (HR, SBP, DBP ,MAP), oxygen saturations and axillary temperature. The incidence of nausea and vomiting was significantly highest in T group (24%) followed by C group and D group.
The current study revealed that both prophylactic i.v dexmedetomidine 0.5mcq/kg and tramadol 0.5mg/kg were effective in prevention of post spinal shivering in patients undergoing knee arthroscopy.