AIM: Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath-hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black-out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well as a decrease in overall oxygen uptake. METHODS: To test this hypothesis, the apnoea response was studied in BHDs and non-divers (NDs) during static and dynamic apnoeas (SA, DA). Heart rate, arterial oxygen saturation (SaO(2)), and popliteal artery blood flow were recorded to investigate the oxygen-conserving effect of apnoea response, and the internal carotid artery blood flow was used to examine the mechanisms of cerebral protection. RESULTS: The bradycardia and peripheral vasoconstriction were accentuated in BHDs compared with NDs (P < 0.01), in association with a smaller SaO(2) decrease (-2.7% vs. -4.9% during SA, P < 0.01 and -6% vs. -11.3% during DA, P < 0.01). Greater increase in carotid artery blood flow was also measured during apnoea in BHDs than in controls. CONCLUSION: These results confirm that elite divers present a potentiation of the well-known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records.
AIM: Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath-hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black-out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well as a decrease in overall oxygen uptake. METHODS: To test this hypothesis, the apnoea response was studied in BHDs and non-divers (NDs) during static and dynamic apnoeas (SA, DA). Heart rate, arterial oxygen saturation (SaO(2)), and popliteal artery blood flow were recorded to investigate the oxygen-conserving effect of apnoea response, and the internal carotid artery blood flow was used to examine the mechanisms of cerebral protection. RESULTS: The bradycardia and peripheral vasoconstriction were accentuated in BHDs compared with NDs (P < 0.01), in association with a smaller SaO(2) decrease (-2.7% vs. -4.9% during SA, P < 0.01 and -6% vs. -11.3% during DA, P < 0.01). Greater increase in carotid artery blood flow was also measured during apnoea in BHDs than in controls. CONCLUSION: These results confirm that elite divers present a potentiation of the well-known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records.
Authors: Lars Eichhorn; Florian Kessler; Volker Böhnert; Felix Erdfelder; Anja Reckendorf; Rainer Meyer; Richard K Ellerkmann Journal: J Vis Exp Date: 2016-12-22 Impact factor: 1.355