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Gas exchange and cardiovascular responses during breath-holding in divers.

Authors :: Taboni A
Fagoni N
Moia C
Vinetti G
Ferretti G
Source :: Respiratory physiology & neurobiology [Respir Physiol Neurobiol] 2019 Sep; Vol. 267, pp. 27-34. Date of Electronic Publication: 2019 Jun 12.
Publication Year :: 2019
Abstract: To check whether the evolution of alveolar pressures of O <subscript>2</subscript> (P <subscript>A</subscript> O <subscript>2</subscript> ) and CO <subscript>2</subscript> (P <subscript>A</subscript> CO <subscript>2</subscript> ) explains the cardiovascular responses to apnoea, eight divers performed resting apnoeas of increasing duration in air and in O <subscript>2</subscript> . We measured heart rate (f <subscript>H</subscript> ), arterial pressure (AP), and peripheral resistances (TPR) beat-by-beat, P <subscript>A</subscript> O <subscript>2</subscript> and P <subscript>A</subscript> CO <subscript>2</subscript> at the end of each apnoea. The three phases of the cardiovascular response to apnoea were observed. In O <subscript>2</subscript> , TPR increase (9 ± 4 mmHg min l <superscript>-1</superscript> ) and f <subscript>H</subscript> decrease (-11 ± 8 bpm) were lower than in air (15 ± 5 mmHg min l <superscript>-1</superscript> and -28 ± 13 bpm, respectively). At end of maximal apnoeas in air, P <subscript>A</subscript> O <subscript>2</subscript> and P <subscript>A</subscript> CO <subscript>2</subscript> were 50 ± 9 and 48 ± 5 mmHg, respectively; corresponding values in O <subscript>2</subscript> were 653 ± 8 mmHg and 55 ± 5 mmHg. At end of phase II, P <subscript>A</subscript> O <subscript>2</subscript> and P <subscript>A</subscript> CO <subscript>2</subscript> in air were 90 ± 13 mmHg and 42 ± 4 mmHg respectively; corresponding values in O <subscript>2</subscript> were 669 ± 7 mmHg and 47 ± 6 mmHg. The P <subscript>A</subscript> CO <subscript>2</subscript> increase may trigger the AP rise in phase III.<br /> (Copyright © 2019 Elsevier B.V. All rights reserved.)