Adjustments in oxygen transport during head-out immersion in water at different temperatures

Abstract

Respiratory gas exchange was investigated in human subjects immersed up to the shoulders in water at different temperatures (Tw = 25, 34, and 40 degrees C). Cardiac output (Qc) and pulmonary tissue volume (Vti) were measured by a rebreathing technique with the inert gas Freon 22, and O2 consumption (VO2) was determined by the closed-circuit technique. Arterial blood gases (PaO2, PaCO2) were analyzed by a micromethod, and alveolar gas (PAO2) was analyzed during quiet breathing with a mass spectrometer. The findings were as follows. 1) Immersion in a cold bath had no significant effect on Qc compared with the value measured at Tw = 34 degrees C, whereas immersion in a hot bath led to a considerable increase in Qc. Vti was not affected by immersion at any of the temperatures tested. 2) A large rise in metabolic rate VO2 was only observed at Tw = 25 degrees C (P less than 0.001). 3) Arterial blood gases were not significantly affected by immersion, whatever the water temperature. 4) O2 transport during immersion is affected by two main factors: hydrostatic pressure and temperature. Above neutral temperature, O2 transport is improved because of the marked increase in Qc resulting from the combined actions of hydrostatic counter pressure and body heating. Below neutral temperature, O2 transport is altered; an increase in O2 extraction of the tissue is even calculated.

The human diving response, its function, and its control

“…The hydrostatic counter-pressure occurring with water immersion causes an increase in . Q, central blood volume, and pulmonary arterial pressure (Choukroun & Marene, 1990). Central hypervolemia occurring with water immersion results in a delayed .…”

Water immersion delays the oxygen uptake response to sitting arm-cranking in humans

“…Water immersion has been shown to induce several cardiopulmonary changes, including increases in c and stroke volume (Choukroun and Varene 1990;Farhi and Linnarsson 1977;Rowell 1993). On the other hand, it has been suggested that the oxygen transport response by the circulation alters the O 2 response (Hughson 1984;Hughson et al 1991).…”

Maximal Physiological Responses to Deep Water Running at Thermoneutral Temperature.

“…Craig and Dvorak (1968) showed that the water temperature required for thermoneutrality was lower during dynamic exercises than at rest. Water temperature of between 29 C and 33 C is thought to be thermoneutral during dynamic exercises (Choukroun and Varene, 1990;Israel et al, 1989;Choukroun and Varene, 1989;McArdle et al, 1976). WI below thermoneutral water temperature causes peripheral vasoconstriction resulting in an increase of the central blood volume (McArdle et al, 1976), which then leads to a decrease of HR and an increase of stroke volume (SV).…”