A portable device to assess underwater changes of cardio dynamic variables by impedance cardiography

Abstract

Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea.