Two patients sustained severe circulatory inadequacy before and during thoracotomy for coronary surgery. Both patients were promptly cote cooled to between 20 degrees and 25 degrees C. After coronary surgery, each patient was rewarmed and the operation was terminated uneventfully in each case, No important cerebral deficit was apparent despite periods of circulatory insufficiency and arrest which were well beyond the usually accepted limits. It is suggested that prompt core cooling may exert a protective effect in this context.
