A STUDY OF THE CARDIOVASCULAR CHANGES DURING COOLING AND REWARMING IN HUMAN SUBJECTS UNDERGOING TOTAL CIRCULATORY OCCLUSION

Journal/Book: THE JOURNAL OF THORACIC SURGERY St. LOUIS. Vol. 33 No. 6 Pages 707-718 June 1957.. 1957;

Abstract: From the Departments of Surgery and Medicine University of Colorado School of Medicine. Denver Colo. Aided in part by a grant from the U. S. Public Health Service (H-1559 C) and in part by a grant from The American Heart Association. Received for publication May 24 1956. *U. S. Public Health Service Post-Doctorate Research Fellow. SUMMARY AND CONCLUSIONS 1. The effects an the cardiovascular system of cooling and rewarming were studied in 23 patients undergoing hypothermia total circulatory occlusion and intracardiac surgery. 2. Upon cooling there was a transient elevation in blood pressure followed by a fall which was not maximum until 30 minutes after sigmoid temperature had reached its lowest point. 3. The pulse rate fell progressively with cooling and the temperature and rate reached lowest levels simultaneously. 4. Blood pressures and pulses were lost to auscultation and palpation at varying points during cooling. At the times of the "clinical disappearance both blood pressure and pulse rate were quite adequate, as demonstrated by direct measurements. The mechanism of this phenomenon is discussed. 5. The magnitude of eventual blood pressure and heart rate changes varied considerably between patients and appeared to have no direct relationship to age and type of heart disease. 6. Venous pressure rose an cooling and remained elevated. Possible mechanisms underlying this phenomenon are discussed. 7. During total circulatory occlusion, the blood pressure fell, the heart rate (following neostigmine injection) slowed abruptly, and venous pressure at first rose, then fell in some instances. 8. Following return of circulation, an immediate overshoot of blood pressure occurred, while venous pressure dropped abruptly. 9. During rewarming, all the circulatory signs have returned to within normal limits at 34° C. 10. Cardiovascular reflexes governing the circulation appear to be intact and adequate in human beings undergoing hypothermia in the range 26° to 31° C. schö

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