Accession Number : AD0731675

Title :   Mechanism of the Bradycardia of the Diving Syndrome as Seen in Divers Using Scuba in Water of 55, 45, and 35 Degrees F.

Descriptive Note : Technical rept.,

Corporate Author : NAVY CLOTHING AND TEXTILE RESEARCH UNIT NATICK MASS

Personal Author(s) : Reins,Dale A.

Report Date : AUG 1971

Pagination or Media Count : 18

Abstract : Physiologists monitored heart rates of test subjects using SCUBA gear under water. Comparisons were made between heart rates immediately before and after subjects entered the water, and at 5-minute intervals while they were immersed in water. Data showed a difference in percent of decrease when initial heart rates were 90 and above or less than 90. However, data showed the decrease to be maximal within 5 minutes of submersion within a return towards presubmersion levels after 30 minutes. It is believed that initial heart rate changes were brought about immediately by a reflex vagal response to immersion. Increased venous return due to water pressure is the apparent cause of the longer term effect. A physiological adaptation to the pressure allowed return towards control values by the end of the 30-minute period. (Author)

Descriptors :   (*ARRHYTHMIA, *DIVING), (*CARDIOVASCULAR DISEASES, DIVING), HEART, PHYSIOLOGY, STRESS(PHYSIOLOGY), BLOOD PRESSURE, BLOOD CIRCULATION, PATHOLOGY, UNDERWATER, ELECTROCARDIOGRAPHY, PRESSURE

Subject Categories : Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE