Cerebral and peripheral hemodynamics and oxygenation during maximal dry breath-holds

Palada, Ivan; Obad, Ante; Baković, Darija; Valić, Zoran; Ivančev, Vladimir; Dujić, Željko

doi:10.1016/j.resp.2007.02.002

Cited by 69 publications

(80 citation statements)

References 33 publications

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“…Prolonged apnea thus features two factors (hypoxia and hypercapnia) that together generate an extremely potent cerebral vasodilatory stimulus. 13,14 Prolonged apneas of 44 minutes may attain values of arterial partial pressures of oxygen (PaO 2 ) and carbon dioxide (PaCO 2 ) of~19 to 25 mm Hg and~30 to 50 mm Hg, respectively. 15,16 The current world record for static apnea is an outstanding 11 minutes 35 seconds.…”

Section: Introductionmentioning

confidence: 99%

Regulation of Brain Blood Flow and Oxygen Delivery in Elite Breath-Hold Divers

Willie

Ainslie

Drviš

et al. 2014

J Cereb Blood Flow Metab

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The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics were measured during maximum dry apneas in elite breath-hold divers (n = 17). To isolate the effects of apnea and IBM from the concurrent changes on ABG, end-tidal forcing ('clamp') was then used to replicate an identical temporal pattern of decreasing arterial PO 2 (PaO 2 ) and increasing arterial PCO 2 (PaCO 2 ) while breathing. End-apnea PaO 2 ranged from 23 to 37 mm Hg (30 ± 7 mm Hg). Elevation in mean arterial pressure was greater during apnea than during clamp reaching +54 ± 24% versus 34 ± 26%, respectively; however, CBF increased similarly between apnea and clamp (93.6 ± 28% and 83.4 ± 38%, respectively). This latter observation indicates that during the overall apnea period IBM per se do not augment CBF and that the brain remains sufficiently protected against hypertension. Termination of apnea was not determined by reduced cerebral oxygen delivery; despite 40% to 50% reductions in arterial oxygen content, oxygen delivery was maintained by commensurately increased CBF.

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Section: Introductionmentioning

confidence: 99%

Regulation of Brain Blood Flow and Oxygen Delivery in Elite Breath-Hold Divers

Willie

Ainslie

Drviš

et al. 2014

J Cereb Blood Flow Metab

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“…In spite of this extreme asphyxia, cerebral tissue oxygenation is well-maintained during maximal apnoea due to a compensatory cerebral hyperaemia [10]. The majority of the rise in cerebral blood flow during apnoea is achieved by vasodilation of cerebral resistance vessels, consequent to hypercapnia [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…The majority of the rise in cerebral blood flow during apnoea is achieved by vasodilation of cerebral resistance vessels, consequent to hypercapnia [11,12]. Maximal apnoea also evokes a powerful vasoconstriction of the peripheral tissues, leading to a pronounced arterial hypertension [10,13,14]. Indeed, approximately one-third of the cerebral blood flow response to brief apnoea (i.e., 20 s) is contributed by the increase in arterial blood pressure [11].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Cerebral Autoregulation Is Acutely Impaired During Maximal Apnoea In Trained Divers

Cross¹,

Kavanagh²,

Brešković³

et al. 2014

Medicine & Science in Sports & Exercise

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Aims: To examine whether dynamic cerebral autoregulation is acutely impaired during maximal voluntary apnoea in trained divers.Methods: Mean arterial pressure (MAP), cerebral blood flow-velocity (CBFV) and end-tidal partial pressures of O 2 and CO 2 (PETO 2 and PETCO 2 ) were measured in eleven trained, male apnoea divers (2862 yr; 18262 cm, 7667 kg) during maximal ''dry'' breath holding. Dynamic cerebral autoregulation was assessed by determining the strength of phase synchronisation between MAP and CBFV during maximal apnoea.Results: The strength of phase synchronisation between MAP and CBFV increased from rest until the end of maximal voluntary apnoea (P,0.05), suggesting that dynamic cerebral autoregulation had weakened by the apnoea breakpoint. The magnitude of impairment in dynamic cerebral autoregulation was strongly, and positively related to the rise in PETCO 2 observed during maximal breath holding (R 2 = 0.67, P,0.05). Interestingly, the impairment in dynamic cerebral autoregulation was not related to the fall in PETO 2 induced by apnoea (R 2 = 0.01, P = 0.75).Conclusions: This study is the first to report that dynamic cerebral autoregulation is acutely impaired in trained divers performing maximal voluntary apnoea. Furthermore, our data suggest that the impaired autoregulatory response is related to the change in PETCO 2 , but not PETO 2 , during maximal apnoea in trained divers.

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“…On the other hand, fNIRS has the shortcomings of low spatial resolution, shallow depth of penetration, and consequently, some uncertainty about the probed region. Although near-infrared spectroscopy has been successfully employed in a number of physiological measurements [3], [4], more progress is needed to establish standard methods for statistical inference of cognitive activity detection and assessment.…”

Section: Introductionmentioning

confidence: 99%

Multilevel Statistical Inference From Functional Near-Infrared Spectroscopy Data During Stroop Interference

Çiftçi

Sankur

Kahya

et al. 2008

IEEE Trans. Biomed. Eng.

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Abstract-Functional near-infrared spectroscopy (fNIRS) is an emerging technique for monitoring the concentration changes of oxy-and deoxy-hemoglobin (oxy-Hb and deoxy-Hb) in the brain. An important consideration in fNIRS-based neuroimaging modality is to conduct group-level analysis from a set of time series measured from a group of subjects. We investigate the feasibility of multilevel statistical inference for fNIRS. As a case study, we search for hemodynamic activations in the prefrontal cortex during Stroop interference. Hierarchical general linear model (GLM) is used for making this multilevel analysis. Activation patterns both at the subject and group level are investigated on a comparative basis using various classical and Bayesian inference methods. All methods showed consistent left lateral prefrontal cortex activation for oxy-Hb during interference condition, while the effects were much less pronounced for deoxy-Hb. Our analysis showed that mixed effects or Bayesian models are more convenient for faithful analysis of fNIRS data. We arrived at two important conclusions. First, fNIRS has the capability to identify activations at the group level, and second, the mixed effects or Bayesian model is the appropriate mechanism to pass from subject to group-level inference.Index Terms-General linear model (GLM), near-infrared spectroscopy, statistical inference, Stroop task.

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Cerebral and peripheral hemodynamics and oxygenation during maximal dry breath-holds

Cited by 69 publications

References 33 publications

Regulation of Brain Blood Flow and Oxygen Delivery in Elite Breath-Hold Divers

Regulation of Brain Blood Flow and Oxygen Delivery in Elite Breath-Hold Divers

Dynamic Cerebral Autoregulation Is Acutely Impaired During Maximal Apnoea In Trained Divers

Multilevel Statistical Inference From Functional Near-Infrared Spectroscopy Data During Stroop Interference

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