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Oxygen-conserving effect of the diving response in the immersed human
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
Responsible organisation
2009 (English)In: Diving and hyperbaric medicine, ISSN 1833-3516, Vol. 39, no 4, 193-199 p.Article in journal (Refereed) Published
Abstract [en]

Research involving the human diving response has often simulated diving by apneic face immersion. However, no comparisons of cardiovascular responses and their oxygen- conserving function have been made between simulated diving and apneic face immersion when the body is constantly immersed as during diving. We compared the diving response and its effects on arterial oxygen saturation during apneas in horizontal dry body and immersed body positions. Both air and water temperatures were 23ºC. Twelve near-maximal apneas of the same duration were completed by 17 subjects. Four series of 3 apneas each were conducted: dry body apnea (DA), dry body, face-immersion apnea (DFIA), immersed body apnea (IA), and immersed body, face-immersion apnea (IFIA). Heart rate, skin capillary blood flow, arterial blood pressure, arterial hemoglobin saturation, lung volume and end-tidal PACO2 and PAO2 were recorded non-invasively and responses during apneas were compared among series. Cardiovascular responses showed similar patterns in all series. Face immersion led to a greater reduction in heart rate during apnea, regardless of body immersion. Both DFIA and DA resulted in a transient skin vasoconstriction, more pronounced during DFIA (p<0.001). During body immersion skin vasoconstriction was constant, and neither IA nor IFIA reduced blood flow further. Less arterial desaturation occurred after both FIA series, suggesting an oxygen-conserving effect of the more powerful diving response associated with face immersion in both body positions. We conclude that a similar oxygen-conserving diving response is triggered by apnea and face immersion during full-body immersion in cool water, as in the dry body model.

Place, publisher, year, edition, pages
2009. Vol. 39, no 4, 193-199 p.
Keyword [en]
Apnea, bradycardia, oxygen conservation, vasoconstriction, immersion
National Category
Microbiology
Identifiers
URN: urn:nbn:se:miun:diva-6186ISI: 000273113700004Scopus ID: 2-s2.0-75149148221Local ID: 1903OAI: oai:DiVA.org:miun-6186DiVA: diva2:31225
Available from: 2009-01-29 Created: 2009-01-29 Last updated: 2010-06-14Bibliographically approved
In thesis
1. Cardiovascular and hematological responses to voluntary apnea in humans
Open this publication in new window or tab >>Cardiovascular and hematological responses to voluntary apnea in humans
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with cardiovascular and hematological responses to voluntary apnea in

humans, with a special focus on O2 usage and storage. Humans, and many other air‐breathing

animals, respond to apnea (breath holding) with a collection of interacting cardiovascular

reflexes, which are collectively called the diving response. In humans, the main characteristics of

the diving response are a reduction in heart rate (bradycardia), decreased cardiac output,

peripheral vasoconstriction and increased arterial blood pressure. Another response during

apnea in mammals, more recently also observed in man, is a transient increase in hemoglobin

concentration across a series of apneas, probably due a reduction in spleen size. There may also

be long‐term effects on erythropoiesis in the apneic diver, as suggested by high hemoglobin

levels observed in divers. The focus of the included studies are the short transient diving

response (I), the more slowly occurring transient hematological changes to apnea, most likely

related to a reduction in spleen size (II), and the possible effects of repeated apnea on serum

erythropoietin concentration (III).

I) The aim was to study the effects of body immersion on the O2‐conserving effect of the

human diving response. The results showed that, regardless of body immersion, apnea with face

immersion causes a stronger cardiovascular diving response compared to during apnea alone,

leading to a smaller reduction in arterial oxygen saturation levels. Thus the diving response is

triggered and conserves O2 even during whole‐body immersion, which has previously only been

observed during apnea without whole‐body immersion.

II) The aim was to study hematological responses to voluntary repeated maximal‐duration

apneas in divers and non‐divers. Increases in hemoglobin concentration were found across a

series of 3 apneas in elite breath‐hold divers, elite cross‐country skiers and untrained subjects.

However a larger increase in hemoglobin was found in divers compared to non‐divers, which

suggests a possible training effect of their extensive apnea‐specific training. In contrast, physical

endurance training does not appear to affect the hematological response to apnea.

III) The aim was to study the effects of serial voluntary apnea on the serum erythropoietin

concentration. In a comparison between elite breath‐hold divers and subjects untrained in apnea,

divers were found to have a 5% higher resting hemoglobin concentration. An average maximum

increase in erythropoietin of 24 % was found in untrained subjects after 15 maximal duration

apneas, preceded by 1 min of hyperventilation. This suggests a possible erythropoietic effect of

apnea‐induced hypoxia, which may connect the increased resting hemoglobin found in divers to

their apnea‐specific training.

It was concluded from these studies that man responds to apnea with a series of different

adjustments in order to limit O2 usage and increase O2 storage: The classical diving response is

effectively restricting O2‐consumption also during full immersion, the spleen related hemoglobin

increase occurs in both divers and non‐divers with different levels of physiological training, but

is more prominent in divers, and finally, the observed high levels of hemoglobin concentration in

divers may be related to enhanced erythropoiesis during dive training.

Place, publisher, year, edition, pages
Sundsvall: Mittuniversitetet, 2007. 47 p.
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 28
National Category
Microbiology
Identifiers
urn:nbn:se:miun:diva-9328 (URN)978-91-85317-70-7 (ISBN)
Presentation
(English)
Available from: 2009-07-10 Created: 2009-07-10 Last updated: 2011-04-05Bibliographically approved

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de Bruijn, RobertRichardson, MatthewSchagatay, Erika

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