Effects on dogs of surface-induced hypothermia and rewarming on the right heart function and pulmonary circulation |
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Authors: | M Palo T Lauri J Timisjärvi |
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Institution: | (1) University of Oulu, Department of Physiology, Kajaanintie 52A, P.O. Box 5000 FIN-90014, Oulu, Finland Fax: +358-8-5375153, FI;(2) Oulu University Hospital, Department of Internal Medicine, Oulu, Finland , FI |
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Abstract: | Hypothermia is commonly found in accidents on land and at sea, yet its pulmonary circulatory effects have not been studied
before. To study the effects of hypothermia on the right heart function and pulmonary circulation, cardiac catheterization
was carried out on nine anaesthetized beagle dogs. The dogs were cooled between ice bags until the temperature in the pulmonary
artery was 25°C and then rewarmed using a heating box especially constructed for this purpose. Heart rate decreased significantly
(P < 0.01) during cooling. Cardiac output also diminished mainly because of decreased heart rate. Total pulmonary resistance
increased in the cold (P < 0.05) and returned to the initial level during rewarming. The peak rate of increase in pressure (dP/dtmax) of the right ventricular pressure curve did not show any significant change. Retardation in relaxation in hypothermia was
indicated by an increase (P < 0.01) in the peak negative dP/dt of the right ventricular pressure curve. According to our results, the contraction rate
did not change, but the relaxation rate decreased significantly during cooling. No signs of heart failure were observed and
all parameters returned to normal during rewarming. In conclusion, right ventricular function was not compromized even during
deep hypothermia.
Accepted: 19 November 1999 |
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Keywords: | Dog Heart Hypothermia Pulmonary circulation |
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