title: Spontaneous intraoperative hypothermia and cerebral protection in aneurysmal subarachnoid hemorrhage.
abstract: BACKGROUND
  In patients with aneurysmal subarachnoid hemorrhage (SAH), a trend towards cerebral protection has been demonstrated with intraoperative mild hypothermia. Mild to moderate spontaneous hypothermia occurs intraoperatively if no active measures are taken to warm the patient. The present study investigated the cerebral protective role of such spontaneous intraoperative hypothermia in patients with aneurysmal SAH.
  
  
  METHODS
  In 50 patients undergoing surgery for aneurysmal subarachnoid hemorrhage, nasopharyngeal temperatures were monitored from the time of endotracheal intubation till the end of surgery. The patients were observed for any neurological deterioration during the first 24 h postoperatively. The temperatures of the deteriorated and nondeteriorated patients, at different stages during surgery, were compared.
  
  
  RESULTS
  Ten out of the 50 patients showed neurological deterioration within the first 24 h after surgery. The nondeteriorated patients had significantly lower nasopharyngeal temperatures compared to the deteriorated group at the time of dural opening, temporary vessel occlusion (TVO), dural closure and the end of surgery (p < or = 0.05). They also had a significantly lower temperature for 2 h starting from the time of temporary vessel occlusion (p < or = 0.05). When the patients were divided into hypothermic (< 34.5 degrees C) and normothermic groups (> 34.5 degrees C) on the basis of their nasopharyngeal temperature at the time of TVO, the normothermic group tended to have a higher incidence of postoperative neurological deterioration (p = 0.07). When the aneurysms were classified according to their anatomical location, a significant intraoperative temperature difference between the deteriorated and nondeteriorated groups was evident only in patients with anterior communicating artery aneurysms (p < or = 0.02) and not others. Infective complications were more frequent in hypothermic patients (p = 0.02).
  
  
  CONCLUSIONS
  The findings of the current study suggest that mild spontaneous intraoperative hypothermia offers cerebral protection in patients undergoing surgery for aneurysmal subarachnoid hemorrhage. This protective role of seems to be related to the anatomical location of the aneurysm.
authors.affiliation: Department of Neuroanaesthesia, National Institute of Mental Health and Neurosciences, Bangalore, India.
authors.forename: Hanuman S
authors.initials: HS
authors.lastname: Murthy
authors.forename: Muthugaduru N
authors.initials: MN
authors.lastname: Chidanandaswamy
authors.forename: Ganne S Umamaheswara
authors.initials: GS
authors.lastname: Rao
authors.forename: Sastry
authors.initials: S
authors.lastname: Kolluri
mesh_terms: D000704:Analysis of Variance; D000758:Anesthesia / Q000379:methods; D017542:Aneurysm, Ruptured / Q000601:surgery*; D001831:Body Temperature / Q000502:physiology*; D005260:Female; D006801:Humans; D007035:Hypothermia / Q000209:etiology*; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009422:Nervous System Diseases / Q000517:prevention & control*; D011183:Postoperative Complications / Q000517:prevention & control; D011446:Prospective Studies; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000601:surgery*; D013997:Time Factors