Biomaterial Database

Changes in body core temperatures and heat balance after an abrupt release of lower body negative pressure in humans. 1994

M Tanabe, and O Shido

Department of Physiology, School of Medicine, Kanazawa University, Japan.

Changes in body core temperature (T(cor)) and heat balance after an abrupt release of lower body negative pressure (LBNP) were investigated in 5 volunteers under the following conditions: (1) an ambient temperature (Ta) of 20 degrees C or (2) 35 degrees C, and (3) Ta of 25 degrees C with a leg skin temperature of 30 degrees C or (4) 35 degrees C. The leg skin temperature was controlled with water perfusion devices wound around the legs. Rectal (T(re)), tympanic (T(ty)) and esophageal (T(es)) temperatures, skin temperatures (7 sites) and oxygen consumption were measured. The intensity of LBNP was adjusted so that the amount of blood pooled in the legs was the same under all conditions. When a thermal balance was attained during LBNP, application of LBNP was suddenly halted. The skin temperatures increased significantly after the release of LBNP under all conditions, while oxygen consumption hardly changed. The release of LBNP caused significant falls in T(cor)s under conditions (1) and (3), but lowered T(cor)s very slightly under conditions (2) and (4). The changes in T(es) were always more rapid and greater than those of T(ty) and T(re). The falls in T(ty) and T(re) appeared to be explained by changes in heat balance, whereas the sharp drop of T(es) could not be explained especially during the first 8 min after the release of LBNP. The results suggest that a fall in T(cor) after a release of LBNP is attributed to an increase in heat loss due to reflexive skin vasodilation and is dependent on the temperature of venous blood returning from the lower body.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008150	Lower Body Negative Pressure	External decompression applied to the lower body. It is used to study orthostatic intolerance and the effects of gravitation and acceleration, to produce simulated hemorrhage in physiologic research, to assess cardiovascular function, and to reduce abdominal stress during childbirth.	Abdominal Decompression,Decompression, Abdominal,LBNP
D008297	Male		Males
D011187	Posture	The position or physical attitude of the body.	Postures
D001833	Body Temperature Regulation	The processes of heating and cooling that an organism uses to control its temperature.	Heat Loss,Thermoregulation,Regulation, Body Temperature,Temperature Regulation, Body,Body Temperature Regulations,Heat Losses,Loss, Heat,Losses, Heat,Regulations, Body Temperature,Temperature Regulations, Body,Thermoregulations
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D012867	Skin	The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.
D017704	Baroreflex	A response by the BARORECEPTORS to increased BLOOD PRESSURE. Increased pressure stretches BLOOD VESSELS which activates the baroreceptors in the vessel walls. The net response of the CENTRAL NERVOUS SYSTEM is a reduction of central sympathetic outflow. This reduces blood pressure both by decreasing peripheral VASCULAR RESISTANCE and by lowering CARDIAC OUTPUT. Because the baroreceptors are tonically active, the baroreflex can compensate rapidly for both increases and decreases in blood pressure.	Reflex, Baroreceptor,Baroreceptor Reflex,Baroreceptor Reflexes,Baroreflexes,Reflexes, Baroreceptor