Accidental hypothermia and active rewarming: the metabolic and inflammatory changes observed above and below 32 degrees C.

Abstract

OBJECTIVES:

In accidental hypothermia the underlying physiological mechanisms responsible for poor outcome during rewarming through 32 degrees C remain obscure, although possible associations include changes in acid-base balance, divalent cations, and inflammatory markers. This study investigated the metabolic and inflammatory changes that occur during the rewarming of hypothermic patients.

METHODS:

Eight patients, four men and four women, age 45 to 85 years, admitted with core temperatures <35 degrees C were included in the study. Patients were rewarmed with dry warm blankets and fluid replaced by crystalloid at 40 degrees C. Bloods for pH, ionised calcium (Ca(2+)) and magnesium (Mg(2+)), parathyroid hormone (PTH), interleukin 1 (IL1), interleukin 6 (IL6), tissue necrosis factor alpha (TNFalpha), were collected at presentation, during rewarming, and at 24 hours.

RESULTS:

Four patients were admitted with mild (32 degrees -35 degrees C) and four with moderate (28 degrees -32 degrees C) hypothermia. Rewarming to 32 degrees C had no significant effect on the presenting acidosis (p=0.1740), although above 32 degrees C pH increased with temperature (p<0.0001). There was a negative correlation between pH and both Ca(2+) (p=0.0005) and Mg(2+) (p=0.0488) below 32 degrees C; above this temperature the relation was significant only for Ca(2+) (p=0.0494). PTH and Ca(2+) correlated positively (p=0.0041) and negatively (p=0.0039) below and above 32 degrees C respectively. There was no relation between IL1 or TNFalpha with Ca(2+) during rewarming, but IL6 and Ca(2+) correlated positively (p=0.0039) and negatively (p=0.0018) when presentation temperature was below and above 32 degrees C respectively.

CONCLUSIONS:

During rewarming pH remains unchanged until patient temperature approaches 32 degrees C. Ca(2+) and Mg(2+) decline is associated with the pH increase above 32 degrees C. Poor outcome is associated with presentation temperature (<32 degrees C), non-physiological correlation between IL6-PTH-Ca(2+), and age (>or=84 years).

• Authors: J J McInerney, A Breakell, W Madira, T G Davies, P A Evans
• Journal: Emergency medicine journal : EMJ (Emerg Med J) Vol. 19 Issue 3 Pg. 219-23 (May 2002) ISSN: 1472-0205 [Print] England
• PMID: 11971831 (Publication Type: Journal Article)

Chemical References

• Magnesium
• Calcium

Topics

• Aged
• Aged, 80 and over
• Calcium (blood)
• Female
• Humans
• Hydrogen-Ion Concentration
• Hypothermia (physiopathology, therapy)
• Magnesium (blood)
• Male
• Middle Aged
• Rewarming
• Severity of Illness Index