Cardiovascular changes induced by cold water immersion during hyperbaric hyperoxic exposure

• Published in: Clinical Physiology and Functional Imaging 2007-09, Vol.27 (5), p.268-274
• Main Authors: Boussuges, Alain, Molenat, Florence, Grandfond, Aliocha, Regnard, Jacques, Wolf, Jean-Pierre, Galland, François, Robinet, Claude
• Format: Article
• Language: English
• Subjects: Adult; Arteries; Arteries - physiopathology; Biological and medical sciences; Blood Pressure; Blood Volume; cardiac function; Cardiac Output; Cardiovascular System; Cardiovascular System - diagnostic imaging; Cardiovascular System - physiopathology; Cold; cold exposure; Cold Temperature; Compliance; Diving; Echocardiography, Doppler, Pulsed; echocardiography-Doppler; Fundamental and applied biological sciences. Psychology; healthy volunteers; Heart Rate; Human health and pathology; Humans; hyperbaric hyperoxia; Hyperbaric Oxygenation; Hyperoxia; Hyperoxia - diagnostic imaging; Hyperoxia - physiopathology; Immersion; Life Sciences; Male; Myocardial Contraction; Stroke Volume; Time Factors; Ventricular Function, Left; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water
• ISSN: 1475-0961; 1475-097X; 1475-097X; 1365-2281
• DOI: 10.1111/j.1475-097X.2007.00747.x

Summary 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 PiO2 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.