Title:	Effect of 0.5% heavy bupivacaine at room temperature vs body temperature on shivering after spinal anaesthesia in patients undergoing Caesarean section
Author(s):	Saed B.
Institute(s):	Khoula Hospital, Dept of Anaesthesiology, Muscat, Oman
Text:	Background and Goal of Study:
 Shivering is very common unwanted effect associated with spinal block with incidence up to 40-60% (1).Etiology is still not proven with no definitive treatment (2).
Mirzaie et al. Have shown that bupivacaine administered at room temperature was associted with significantly lower incidence of shivering than that given at 4 c 
In our study we evaluate the effect of warm (at body temperature 37 c ) versus cold (room temperature 23 c) 0.5%heavy bupivacaine on post spinal shivering(PAS) in women undergoing caesarean section.

Materials and methods:
 In this prospective randomized double blinded study ; after getting the ethical issue committee, 100 patients selected in tow groups 50 each , randomized using closed envelop technique, body temperature group (BT) received local anaesthetic warmed using tissle kit warmer machine to 37 c, the room temperature (RT) received medications with usual methods. Patient core temperature recorded with tympanic probe; block height ,blood pressure and heart rate, shivering intesity grades (1-4) according to scale developed by Crossley and Mahajan (3); side effects like nausea and vomiting, itching, Apgar score and blood loss recorded. Chi-square test used with p< 0.05 was considered statistically significant.

Results and discussion:
 Out of 50 patients in each group, shivering was seen in 7 (14%) and 31(62%) patients in BT and RT group respectively, intensity of shivering >3% observed in 15 (30%) patients of RT group and 5(10%) patients in BT group ; no difference in the amount of blood loss , heart rate and blood pressure and Apgar score. Pruritus was significantly higher in RT group with p< 0.05.Dermatomal level achieved was slightly higher in RT group.
The thermoregulatory control is impaired with spinal block by blocking the tonic vasoconstriction which is essential for temperature regulation; spinal block causes redistribution of core heat from the trunk to peripheral tissues which leads to hypothermia and shivering, Thermosensitive receptors in spinal cord has been studied,and the effect of warming on baricity was investigated before; no effect observed on density and baricity  of hyperbaric bupivacaine .

Conclusion(s):
 Warming heavy bupivacaine 0.5%to body temperature is associated with less incidence and intensity of shivering compared to room temperature local anaesthetics

References: 

(1) NSY et al , p.op anesthesia shivering -Natal 2013 no.15 
(2) Mirzaie et al regional anaesthesia & pain medicine 2008 ; 241-52
(3) Crossly ;intensity of shivering

Effect of 0.5% heavy bupivacaine at room temperature vs body temperature on shivering after spinal anaesthesia in patients undergoing Caesarean section