The management of temperature during hypothermic cardiopulmonary bypass: II — Effect of prolonged hypothermia

  • Howard J. Nathan
  • Tom Polis
Reports of Investigation

Abstract

In animals mild hypothermia (32–35°C) reduces ischaemic brain injury, but this has not been investigated in humans. During hypothermic cardiopulmonary bypass (CPE) patients are made hypothermie (usually to 30–32° C) but are then rewarmed at a time when they are still at risk of ischaemic brain injury. We investigated the feasibility and safety of maintaining mild hypothermia throughout the CPB period. Thirty adult cardiac surgical patients were randomized to either rewarming to 36–37° C or to maintaining temperature at 34° C without rewarming. On arrival in the recovery room, patients in the hypothermie group had a mean bladder temperature of 33.8 ± 0.45° C compared with 35.4 ± 0.58° C (mean ± SD, P < 0.05) in the rewarmed patients. There were no differences between groups in intra-or postoperative blood loss or blood use, inotrope use, dysrhythmias, or myocardial infarction. The hypothermic group received more muscle relaxant for the treatment of shivering postoperatively. Our results suggest that mild hypothermia following CPB did not increase morbidity although larger studies are needed for confirmation.

Key words

temperature: hypothermia, hypothermie surgery: cardiac, cardiopulmonary bypass complications: neurological 

Résumé

Chez l’animal, l’hypothermie légère atténue le dommage cérébral causé par l’ischémie, ce qui n’a jamais été vérifié chez l’humain. Sous circulation extracorporelle (CEC) hypothermique, la température corporelle est abaissée (ordinairement à 30–32° C) mais les patients sont réchauffés alors qu’ils sont toujours à risque de dommage cérébral ischémique. Nous avons étudié la faisabilité et la sécurité offertes par l’hypothermie légère pendant la CEC. En chirurgie cardiaque, trente adultes sont répartis au hasard soit pour le réchauffement à 36°–37° C soit pour le maintien de la température à 34° C sans réchauffement. A l’admission à la salle de réveil, les patients du groupe hypothermique présentent une température vésicale moyenne de 33,8 ± 0,45° C comparativement à 35,4 ± 0,58° C (moyenne ± ET, P < 0,05) pour les patients réchauffés. On ne trouve pas de différence entre les groupes pour ce qui est des pertes sanguines per- et postopératoires, l’utilisation des inotropes, les troubles du rythme et l’infarctus du myocarde. Le groupe hypothermique reçoit plus de curarisants pour le traitement des frissons postopératoires. Nos résultats suggèrent que l’hypothermie légère après CEC n’augmente pas la morbidité bien que des études plus vastes soient nécessaires pour le confirmer.

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Copyright information

© Canadian Anesthesiologists 1995

Authors and Affiliations

  • Howard J. Nathan
    • 1
  • Tom Polis
    • 1
  1. 1.Departments of AnaesthesiaUniversity of Ottawa Heart Institute and The Ottawa Civic HospitalOttawaCanada

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