Predictors and clinical implications of shivering during therapeutic normothermia.
BACKGROUND
Shivering during induced normothermia (IN) remains a therapeutic limitation. We investigated potential risk factors and clinical implications of shivering during IN.


METHODS
Post hoc analysis was performed on 24 patients enrolled in a clinical trial of an automated surface cooling system to achieve IN. Hyponatremia was defined as serum levels <136 mmol/L and hypomagnesaemia as levels <1.5 mg/dL. Continuous heat energy transfer (kcal/h) was averaged hourly. Glasgow Coma Scale (GCS) scores were recorded every 2 h. Shivering status was documented hourly. Mixed effects modeling was used to determine clinical measures associated with shivering. Generalized estimating equation (GEE) models were used to compare baseline-adjusted repeated-measures GCS scores.


RESULTS
About of 24 (39%) patients demonstrated shivering. Shivering was associated with men (67% vs. 21%, P = 0.03), hyponatremia (44% vs. 7%, P = 0.03), and hypomagnesaemia (56% vs. 7%, P = 0.02). The average kcal/h (158 +/- 645 kcal/h vs. 493 +/- 645 kcal/h, P = 0.03) was greater in shivering patients. Shivering was positively associated with increases in heart rate (P < 0.001), respiratory rate (P < 0.001), and kcal/h (P < 0.001). Non-shivering patients showed a greater increase from baseline GCS (GEE, P = 0.02) at 24 h. No differences in sedative doses or fever burden were noted between shiverers and non-shiverers.


CONCLUSIONS
Men, hyponatremia, and hypomagnesaemia may predispose febrile patients treated with IN to shivering. Shivering dramatically increases the amount of heat transfer required to maintain normothermia, and may be associated with adverse effects on level of consciousness.
Badjatia
Neeraj
N
Department of Neurology, Columbia University College of Physicians & Surgeons, 710 W 168th Street, New York, NY 10032, USA. nbadjatia@neuro.columbia.edu
Kowalski
Robert G
RG
Schmidt
J Michael
JM
Voorhees
Marc E
ME
Claassen
Jan
J
Ostapkovich
Noeleen D
ND
Presciutti
Mary
M
Connolly
E Sander
ES
Palestrant
David
D
Parra
Augusto
A
Mayer
Stephan A
SA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001331:Automation; D001831:Body Temperature; D017679:Cryotherapy / Q000295:instrumentation; D004735:Energy Transfer; D005260:Female; D005334:Fever / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D015600:Glasgow Coma Scale; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D007010:Hyponatremia / Q000150:complications / Q000503:physiopathology; D016014:Linear Models; D008274:Magnesium / Q000097:blood; D008297:Male; D008875:Middle Aged; D015656:Respiratory Mechanics; D012307:Risk Factors; D012737:Sex Factors; D012768:Shivering
D008274:Magnesium