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de Bruijn, Robert
Alternative names
Publications (10 of 17) Show all publications
Richardson, M., de Bruijn, R. & Schagatay, E. (2009). Hypoxia augments apnea-induced increase in hematocrit and hemoglobin concentration. European Journal of Applied Physiology, 105(1), 63-68
Open this publication in new window or tab >>Hypoxia augments apnea-induced increase in hematocrit and hemoglobin concentration
2009 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, no 1, p. 63-68Article in journal (Refereed) Published
Abstract [en]

Increased hemoglobin concentration (Hb) and hematocrit (Hct) attributable to spleen contraction raises blood gas storage capacity during apnea, but the mechanisms that trigger this response have not been clarified. We focused on the role of hypoxia in triggering these Hb and Hct elevations. After horizontal rest for 20 min, 10 volunteers performed 3 maximal apneas spaced by 2 min, each preceded by a deep inspiration of air. The series was repeated using the same apneic durations but after 1 min of 100% oxygen breathing and oxygen inspiration prior to apneas. Mean apneic durations were 150s, 171s, and 214s for apneas 1, 2, and 3, respectively. Relative to pre-apnea values, the mean post-apneic arterial oxygen saturation nadir was 84.7% after air and 98% after oxygen. A more pronounced elevation of both Hb and Hct occurred during the air trial: after apnea 1 with air, mean Hb had increased by 1.5% (P<0.01), but no clear increase was found after the first apnea in with oxygen. After the third apnea with air Hb had increased by 3.0% (P<0.01), and with oxygen by 2.0% (P<0.01). After the first apnea with air Hct had increased by 1.9% (P<0.01) and after 3 apneas by 3.0% (P<0.01), but Hct did not change significantly in the oxygen trial. In both trials, Hb and Hct were at pre-apneic levels 10 min after apneas. Diving bradycardia during apnea was the same in both trials. We concluded that hypoxia is essential in inducing spleen-related Hb and Hct increase during apnea.

Keywords
Breath-hold, apnea, hematocrit, spleen contraction, diving response, diving reflex
National Category
Biological Sciences Microbiology
Identifiers
urn:nbn:se:miun:diva-4364 (URN)10.1007/s00421-008-0873-9 (DOI)000262411500010 ()18839204 (PubMedID)2-s2.0-58549090876 (Scopus ID)5598 (Local ID)5598 (Archive number)5598 (OAI)
Available from: 2008-11-29 Created: 2008-11-29 Last updated: 2017-12-12Bibliographically approved
de Bruijn, R., Richardson, M. & Schagatay, E. (2009). Oxygen-conserving effect of the diving response in the immersed human. Diving and hyperbaric medicine, 39(4), 193-199
Open this publication in new window or tab >>Oxygen-conserving effect of the diving response in the immersed human
2009 (English)In: Diving and hyperbaric medicine, ISSN 1833-3516, Vol. 39, no 4, p. 193-199Article 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.

Keywords
Apnea, bradycardia, oxygen conservation, vasoconstriction, immersion
National Category
Microbiology
Identifiers
urn:nbn:se:miun:diva-6186 (URN)000273113700004 ()2-s2.0-75149148221 (Scopus ID)1903 (Local ID)1903 (Archive number)1903 (OAI)
Available from: 2009-01-29 Created: 2009-01-29 Last updated: 2010-06-14Bibliographically approved
de Bruijn, R., Richardson, M. & Schagatay, E. (2008). Increased erythropoietin concentration after repeated apneas in humans. European Journal of Applied Physiology, 102(5), 609-613
Open this publication in new window or tab >>Increased erythropoietin concentration after repeated apneas in humans
2008 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 102, no 5, p. 609-613Article in journal (Refereed) Published
Abstract [en]

Hypoxia-induced increases in red blood cell production have been found in both altitudeadapted populations and acclimatized lowlanders. This process is mediated by erythropoietin (EPO) released mainly by the hypoxic kidney. We have previously observed high hemoglobin concentrations in elite breath-hold divers and our aim was to investigate whether apnea-induced hypoxia could increase EPO concentration. Ten healthy volunteers performed 15 voluntary maximal duration apneas, divided into three seriesof five apneas, each series separated by 10 min of rest. Apneas within series were separated by 2 min and preceded by 1 min of hyperventilation to increase apnea duration and arterial oxygen desaturation. When EPO concentration after serial apneas was compared to baseline values, an average maximum increase of 24% was found (P<0.01). No changes in EPO concentration were observed during a control day without apnea, eliminating possible effects of a diurnal rhythm or blood loss. We therefore conclude that serial apneas increase circulating EPO concentration in humans.

Keywords
Erythropoiesis, breath holding, desaturation, diving response, bradycardia
National Category
Microbiology Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-3335 (URN)10.1007/s00421-007-0639-9 (DOI)000252540300015 ()18097682 (PubMedID)2-s2.0-38649119768 (Scopus ID)3340 (Local ID)3340 (Archive number)3340 (OAI)
Note
VR-Medicine, ExternalAvailable from: 2008-11-29 Created: 2008-11-13 Last updated: 2017-12-12Bibliographically approved
de Bruijn, R. (2007). Cardiovascular and hematological responses to voluntary apnea in humans. (Licentiate dissertation). Sundsvall: Mittuniversitetet
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. p. 47
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
Schagatay, E., Richardson, M., de Bruijn, R. & Andersson, J. (2006). Cardiovascular and hematological adjustments to apneic diving in humans. -Is the 'spleen-response' part of the diving response?. In: Breath-hold diving 2006: UHMS proceedings, Orlando, USA, June 20-24 (pp. 20-24).
Open this publication in new window or tab >>Cardiovascular and hematological adjustments to apneic diving in humans. -Is the 'spleen-response' part of the diving response?
2006 (English)In: Breath-hold diving 2006: UHMS proceedings, Orlando, USA, June 20-24, 2006, p. 20-24Conference paper, Published paper (Refereed)
Keywords
apnea
National Category
Microbiology
Identifiers
urn:nbn:se:miun:diva-4039 (URN)5023 (Local ID)1-930536-36-4 (ISBN)5023 (Archive number)5023 (OAI)
Available from: 2008-09-30 Created: 2009-07-16Bibliographically approved
Richardson, M., de Bruijn, R., Pettersson, S., Reimers, J. & Schagatay, E. (2006). CORRELATION BETWEEN SPLEEN SIZE AND HEMATOCRIT DURING APNEA IN HUMANS. In: Proceedings of the Undersea and Hyperbaric Medical Society/Divers Alert Network 2006 June 20-21 Workshop. Durham, NC.
Open this publication in new window or tab >>CORRELATION BETWEEN SPLEEN SIZE AND HEMATOCRIT DURING APNEA IN HUMANS
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2006 (English)In: Proceedings of the Undersea and Hyperbaric Medical Society/Divers Alert Network 2006 June 20-21 Workshop. Durham, NC, 2006Conference paper, Published paper (Other academic)
Keywords
apnea EPO
National Category
Microbiology Sport and Fitness Sciences Physiology
Identifiers
urn:nbn:se:miun:diva-4011 (URN)4483 (Local ID)1-930536-36-4 (ISBN)4483 (Archive number)4483 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2018-01-12Bibliographically approved
de Bruijn, R., Richardson, M., Haughey, H., Björklund, G., Pettersson, S. & Schagatay, E. (2005). High hemoglobin levels in divers may be a result of apnea induced EPO-production. In: FASEB JOURNAL. Paper presented at Experimental Biology 2005 Meeting/35th International Congress of Physiological Sciences, Mar 31-Apr 06, 2005, San Diego CA (pp. A211-A212).
Open this publication in new window or tab >>High hemoglobin levels in divers may be a result of apnea induced EPO-production
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2005 (English)In: FASEB JOURNAL, 2005, p. A211-A212Conference paper, Published paper (Refereed)
Abstract [en]

Oxygen storage capacity is important for apneic duration and affects performance in endurance sports. We studied if hemoglobin concentration (Hb) was different in divers compared to endurance athletes and untrained subjects and if any differences could be connected to training-induced erythropoietin (EPO) -production. We first compared Hb in 3 groups of subjects: 13 elite apneic divers (35±4 years), 13 elite cross-country skiers (20±1 years) and 23 untrained subjects (29±1 years) with similar weight and height. After 20 min of horizontal rest blood samples were drawn and analysed for Hb using standard methods. In a second experiment, we compared EPO levels before and after a series of 15 maximal apneas in air in 9 previously untrained volunteers (302 years). Apneas were spaced by 2 minutes, the last minute with hyperventilation to produce durations long enough to induce hypoxia. Values were also compared to the EPO levels of a control day without apneas. The apneic divers had higher Hb than untrained subjects (P<0.05) and skiers (P<0.01). After apnea training in untrained subjects EPO levels increased in all subjects, with a mean peak value after 3 h, where the increase was 135 % of the pre apnea value (P<0.05). No increase was observed during the same time period of the control day. We concluded that higher Hb levels in apneic divers may be a result of enhanced EPO-production due to the apnea training.

Series
FASEB JOURNAL, ISSN 0892-6638 ; 19-4
Keywords
EPO
National Category
Microbiology Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-2789 (URN)000227610701334 ()2313 (Local ID)2313 (Archive number)2313 (OAI)
Conference
Experimental Biology 2005 Meeting/35th International Congress of Physiological Sciences, Mar 31-Apr 06, 2005, San Diego CA
Available from: 2008-09-30 Created: 2009-07-27 Last updated: 2011-04-12Bibliographically approved
Richardson, M., de Bruijn, R. & Schagatay, E. (2005). Hypoxia - A trigger for spleen contraction?. In: EUBS 2005.
Open this publication in new window or tab >>Hypoxia - A trigger for spleen contraction?
2005 (English)In: EUBS 2005, 2005Conference paper, Published paper (Other scientific)
Abstract [en]

Several mechanisms involving oxygen conservation or increased blood gas storage capacity serve to facilitate prolonged diving in mammals. Two such mechanisms present in humans are the cardiovascular �diving response� and the blood boosting spleen contraction. Repeated diving may elicit these adaptive responses by similar or different mechanisms. Increased hematocrit (Hct) attributable to spleen contraction raises blood gas storage capacity during human apneic diving or simulated diving, but the underlying mechanisms have not been clarified. The time course for development of the Hct response is slower than for the cardiovascular diving response: The development of spleen contraction is progressive across 3 serial apneas, and recovery takes 8-9 minutes. Also, while the diving response is initiated by apnea and fortified by facial chilling, the stimulus eliciting Hct increase is related to apnea alone. Thus apnea itself or its consequences appear to be the main stimulus. In this study we focused on the role of hypoxia in triggering spleen induced elevations in Hct. After horizontal rest for 20 min, nine volunteers performed 3 maximal apneas spaced by 2 min of rest, preceeded by an inspiration of normal air. The series was repeated at a different day using the same apneic durations but after 60 s of 100% oxygen breathing and oxygen inspiration prior to apneas. Relative to pre-apnea values, the post apneic arterial oxygen saturation nadir averaged 84% after the air trial and 99% after the oxygen trial. The Hct rose in both protocols, but with about twice the magnitude after apneas with air. A relative increase of 2.7% was found after three apneas with air (p<0.01), and 1.4% increase after three apneas with oxygen (p<0.05). Values returned to pre-apneic levels within 10 minutes. We conclude that hypoxia may be an important modifying factor influencing the magnitude of hematocrit increase during apnea.

Keywords
hypoxia apnea
National Category
Microbiology
Identifiers
urn:nbn:se:miun:diva-3305 (URN)3233 (Local ID)3233 (Archive number)3233 (OAI)
Available from: 2008-09-30 Created: 2008-09-30Bibliographically approved
Schagatay, E., de Bruijn, R. & Richardson, M. (2005). Increase in hematocrit after short and long term apnea training. In: Blue 2005. Human Behaviour and Limits in Underwater Environments. Abstract book: International Conference organised by: CNR Institute of Clinical Physiology, Pisa - Italy Apnea Academy - Italy University of Chieti - Italy. Pisa December 1-4 2005. (pp. 57-58). Pisa: CNR Institute of Clinical Physiology
Open this publication in new window or tab >>Increase in hematocrit after short and long term apnea training
2005 (English)In: Blue 2005. Human Behaviour and Limits in Underwater Environments. Abstract book: International Conference organised by: CNR Institute of Clinical Physiology, Pisa - Italy Apnea Academy - Italy University of Chieti - Italy. Pisa December 1-4 2005., Pisa: CNR Institute of Clinical Physiology , 2005, p. 57-58Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Pisa: CNR Institute of Clinical Physiology, 2005
Keywords
apnea
National Category
Microbiology Sport and Fitness Sciences Physiology
Identifiers
urn:nbn:se:miun:diva-4040 (URN)5024 (Local ID)5024 (Archive number)5024 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2018-01-12Bibliographically approved
Richardson, M., de Bruijn, R., Holmberg, H.-C., Björklund, G., Haughey, H. & Schagatay, E. (2005). Increase of hemoglobin concentration after maximal apneas in divers, skiers and untrained humans. Canadian Journal of Applied Physiology, 30(3), 276-281
Open this publication in new window or tab >>Increase of hemoglobin concentration after maximal apneas in divers, skiers and untrained humans
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2005 (English)In: Canadian Journal of Applied Physiology, ISSN 1066-7814, Vol. 30, no 3, p. 276-281Article in journal (Refereed) Published
Abstract [en]

Apnea is physiologically stressful and can within a short time frame pose a threat to survival. To sustain prolonged apnea, oxygen use should be minimized and its storage maximized. Two mechanisms known to have this effect are the cardiovascular diving response, directing the available oxygen selectively to the heart and brain, and spleen contraction increasing the circulating erythrocyte volume and thereby gas storage capacity. Spleen contraction is also observed after maximal exercise, and is thought to enhance aerobic performance. While the cardiovascular diving response is known to be more pronounced after apnea training, spleen contraction has not been studied in conjunction with apnea training or other types of training. The aim of the present investigation is to study the hematological responses to apnea performed during rest by elite apneic divers, by elite cross-country skiers and by untrained subjects. After 20 min of rest, subjects performed 3 maximal apneas spaced by 2 min normal breathing intervals. Blood samples were drawn before, directly after, and 10 min after the apnea series and hemoglobin concentration was measured. All groups responded to maximal apneas with an increase in hemoglobin concentration, which had disappeared after 10 min of recovery. The increase in hemoglobin concentration was more pronounced in the apneic divers (4g/L) than in skiers (3g/L) and untrained subjects (2g/L; P < 0.05). All groups prolonged their apneic times through the series, but the increase was most evident for the divers versus both the skiers (P < 0.05) and untrained subjects (P < 0.01). The results suggest that these responses could be more pronounced as a result of apnea training.

Keywords
apnea, hemoglobin, endurance training, cross country skiing, spleen contraction
National Category
Microbiology Biological Sciences Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-1688 (URN)000229602800002 ()1516 (Local ID)1516 (Archive number)1516 (OAI)
Note
VR-Medicine, ExternalAvailable from: 2008-09-30 Created: 2009-07-27 Last updated: 2011-04-06Bibliographically approved
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