When measuring blood pressure indirectly, oscillations in the cuff pressure are observed. The cuff pressure for which these oscillations reach a maximum and its relationship to the true mean arterial pressure was investigated using a simple one-dimensional theoretical model of the cuff-arm-artery system. Results from this model indicate that the cuff pressure for maximal oscillation is strongly dependent on compression chamber air volume, pulse pressure, and arterial elasticity. Parallel experimental studies indicate general agreement with the theoretical model. The cuff pressure for maximal oscillations appears to provide a reasonable estimation of the true mean arterial pressure provided compression chamber air volume is kept small.

A technique for post surgical rewarming from clinical hypothermia, which utilizes a thoracic flush with heated saline solution, has been investigated experimentally and theoretically. The rewarming technique was used in conjunction with surface cooling for eighteen separate experiments using mongrel dogs, with the thermal response of the animals determined from thermocouple measurements at twelve strategic locations. Utilizing these measurements, temperature histories were established for the animals, from which representative cooling and rewarming rates have been determined. The rectal temperature was found to provide a suitable clinical reference temperature for monitoring the level of hypothermia, and the rewarming rates (from 10 to 22° C/hr) compare favorably with those obtained by other investigators using surface and extracorporeal rewarming methods. Reasonable agreement was obtained between the measured temperature histories and theoretical predictions obtained using a simple lumped parameter heat transfer model.