Article Text

Download PDFPDF

Accidental hypothermia and active rewarming: the metabolic and inflammatory changes observed above and below 32°C
  1. J J McInerney1,
  2. A Breakell1,
  3. W Madira2,
  4. T G Davies2,
  5. P A Evans1
  1. 1Accident and Emergency Department, The Leicester Royal Infirmary, Leicester, UK
  2. 2Clinical Biochemistry Department, The Leicester Royal Infirmary
  1. Correspondence to:
 Mr P A Evans, Accident and Emergency Department, University Hospitals of Leicester NHS Trust, The Leicester Royal Infirmary, Infirmary Close, Leicester, LE1 5WW, UK;


Objectives: In accidental hypothermia the underlying physiological mechanisms responsible for poor outcome during rewarming through 32°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°C were included in the study. Patients were rewarmed with dry warm blankets and fluid replaced by crystalloid at 40°C. Bloods for pH, ionised calcium (Ca2+) and magnesium (Mg2+), parathyroid hormone (PTH), interleukin 1 (IL1), interleukin 6 (IL6), tissue necrosis factor α (TNFα), were collected at presentation, during rewarming, and at 24 hours.

Results: Four patients were admitted with mild (32°–35°C) and four with moderate (28°–32°C) hypothermia. Rewarming to 32°C had no significant effect on the presenting acidosis (p=0.1740), although above 32°C pH increased with temperature (p<0.0001). There was a negative correlation between pH and both Ca2+ (p=0.0005) and Mg2+ (p=0.0488) below 32°C; above this temperature the relation was significant only for Ca2+ (p=0.0494). PTH and Ca2+ correlated positively (p=0.0041) and negatively (p=0.0039) below and above 32°C respectively. There was no relation between IL1 or TNFα with Ca2+ during rewarming, but IL6 and Ca2+ correlated positively (p=0.0039) and negatively (p=0.0018) when presentation temperature was below and above 32°C respectively.

Conclusions: During rewarming pH remains unchanged until patient temperature approaches 32°C. Ca2+ and Mg2+ decline is associated with the pH increase above 32°C. Poor outcome is associated with presentation temperature (<32°C), non-physiological correlation between IL6-PTH-Ca2+, and age (≥84 years).

  • hypothermia
  • pH
  • divalent cations
  • parathyroid hormone
  • interleukins
  • PTH, parathyroid hormone
  • IL1, interleukin 1
  • IL6, interleukin 6
  • TNFα
  • tissue necrosis factor α
View Full Text

Statistics from


    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.