Key result
Cold water immersion during a 6-hour hyperbaric hyperoxic exposure maintained stroke volume and left ventricular diameters compared to dry conditions, though cardiac output decreased by ~20% in both.
Why the study?
Does cold water immersion alter cardiac hemodynamics compared with dry conditions during prolonged hyperbaric and hyperoxic exposure in healthy volunteers?
Does cold water immersion alter cardiac hemodynamics compared with dry conditions during prolonged hyperbaric and hyperoxic exposure in healthy volunteers?
Cold water immersion during hyperbaric exposure preserves stroke volume and left ventricular contractility compared to dry conditions, likely due to hydrostatic redistribution of blood volume.
May warrant study in diving medicine; hypothesis-generating and should not yet change practice.
The present study was designed to assess the cardiac changes induced by cold water immersion compared with dry conditions during a prolonged hyperbaric and hyperoxic exposure (ambient pressure between 1.6 and 3 ATA and PiO(2) between 1.2 and 2.8 ATA). Ten healthy volunteers were studied during a 6 h compression in a hyperbaric chamber with immersion up to the neck in cold water while wearing wet suits. Results were compared with measurements obtained in dry conditions. Echocardiography and Doppler examinations were performed after 15 min and 5 h. Stroke volume, left atrial and left ventricular (LV) diameters remained unchanged during immersion, whereas they significantly fell during the dry session. As an index of LV contractility, percentage fractional shortening remained unchanged, in contrast to a decrease during dry experiment. Heart rate (HR) significantly decreased after 5 h, although it had not changed during the dry session. The changes in the total arterial compliance were similar during the immersed and dry sessions, with a significant decrease after 5 h. In immersed and dry conditions, cardiac output was unchanged after 15 min but decreased by almost 20% after 5 h. This decrease was related to a decrease in HR during immersion and to a decrease in stroke volume in dry conditions. The hydrostatic pressure exerted by water immersion on the systemic vessels could explain these differences. Indeed, the redistribution of blood volume towards the compliant thoracic bed may conceal a part of hypovolaemia that developed in the course of the session.
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Boussuges et al. (2007) studied Healthy volunteers (n=10). Cold water immersion during hyperbaric hyperoxic exposure vs. Dry conditions during hyperbaric hyperoxic exposure was evaluated on Cardiac changes (stroke volume, left atrial and left ventricular diameters, fractional shortening, heart rate, cardiac output). Cold water immersion during a 6-hour hyperbaric hyperoxic exposure maintained stroke volume and left ventricular diameters compared to dry conditions, though cardiac output decreased by ~20% in both.
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