Air blood barrier phenotype correlates with alveolo-capillary O 2 equilibration in hypobaric hypoxia

Beretta, Egidio; Lanfranconi, Francesca; Grasso, Gabriele; Bartesaghi, Manuela; Alemayehu, Hailu Kinfu; Pratali, Lorenza; Catuzzo, Bruna; Giardini, Guido; Miserocchi, Giuseppe

doi:10.1016/j.resp.2017.08.006

Cited by 18 publications

(17 citation statements)

References 24 publications

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“…Similarly, although a reduction in SpO 2 has been thought to be related pulmonary O 2 diffusion capacity 1,2 , a previous study found greater inter-individual differences in the alveolar-capillary membrane diffusing capacity and the pulmonary capillary blood volume, which are subcomponents of total lung diffusion capacity with an inspiration of different concentration of O 2 (20-40-60% O 2 ) 35 . Similar results (i.e., greater inter-indvidual differences in lung diffusion capacity) were found under hypobaric hypoxia at rest 36 and during sub-maximal exercise 37 . In light of these previous studies, it is evident that lung diffusion capacity (which may affect SpO 2 ) causes inter-individual differences under different barometric pressure condition and/or fraction of inspired oxygen.…”

Section: Discussionsupporting

confidence: 76%

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Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation

Horiuchi

Kirihara

Fukuoka

et al. 2019

Sci Rep

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Energy expenditure (EE) during treadmill walking under normal conditions (normobaric normoxia, 21% O 2 ) and moderate hypoxia (13% O 2 ) was measured. Ten healthy young men and ten healthy young women walked on a level (0°) gradient a range of speeds (0.67–1.67 m s −1 ). During walking, there were no significant differences in reductions in arterial oxygen saturation (SpO 2 ) between the sexes. The hypoxia-induced increase in EE, heart rate (HR [bpm]) and ventilation ( [L min −1 ]) were calculated. Using a multivariate model that combined EE, , and HR to predict ΔSpO 2 (hypoxia-induced reduction), a very strong fit model both for men (r 2 = 0.900, P < 0.001) and for women was obtained (r 2 = 0.957, P < 0.001). The contributions of EE, VE, and HR to ΔSpO 2 were markedly different between men and women. and EE had a stronger effect on ΔSpO 2 in women ( : 4.1% in women vs. 1.7% in men; EE: 28.1% in women vs. 15.8% in men), while HR had a greater effect in men (82.5% in men and 67.9% in women). These findings suggested that high-altitude adaptation in response to hypoxemia has different underlying mechanisms between men and women. These results can help to explain how to adapt high-altitude for men and women, respectively.

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Section: Discussionsupporting

confidence: 76%

“…Then, the participants started to walk on the treadmill. Following preliminary tests in our laboratory and the modified protocol in the previous studies 21,36 , seven walking speeds used in ascending order (0.67, 0.83, 1.00, 1.17, 1.33, 1.50, and 1.67 m s −1 ). Each speed was maintained for four minutes.…”

Section: Methodsmentioning

confidence: 99%

Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation

Horiuchi

Kirihara

Fukuoka

et al. 2019

Sci Rep

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“…The importance of this point becomes relevant when balanced against an increase in cells metabolic requirement, namely the increased oxygen demand, as in exercise, as well as in conditions causing a limitation to oxygen delivery (environmental hypoxia and cardio-pulmonary disorders). Recent work from our group revealed considerable inter-individual differences in the adaptive response of the air-blood barrier to work in normoxia and hypoxia 1–3 and further the adaptations correlated with the morpho-functional phenotype of the air-blood barrier 4 .…”

Section: Introductionmentioning

confidence: 77%

“…As in previous study from our group 3 , standard 2D echocardiography was performed at rest in supine position using a portable echo machine with a 2.5–3.5 MHz cardiac probe (Vivid I, General Electric Healthcare Clinical System) by a single experienced cardiologist, both at SL and HA. Care was taken to ensure that the position of the participants and the transducer were similar in all examinations.…”

Section: Methodsmentioning

confidence: 99%

Differences in alveolo-capillary equilibration in healthy subjects on facing O2 demand

Beretta

Grasso

Forcaia

et al. 2019

Sci Rep

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Oxygen diffusion across the air-blood barrier in the lung is commensurate with metabolic needs and ideally allows full equilibration between alveolar and blood partial oxygen pressures. We estimated the alveolo-capillary O2 equilibration in 18 healthy subjects at sea level at rest and after exposure to increased O2 demand, including work at sea level and on hypobaric hypoxia exposure at 3840 m (PA ~ 50 mmHg). For each subject we estimated O2 diffusion capacity (DO2), pulmonary capillary blood volume (Vc) and cardiac output (). We derived blood capillary transit time and the time constant of the equilibration process (, β being the slope of the hemoglobin dissociation curve). O2 equilibration at the arterial end of the pulmonary capillary was defined as . Leq greately differed among subjects in the most demanding O2 condition (work in hypoxia): lack of full equilibration was found to range from 5 to 42% of the alveolo-capillary PO2 gradient at the venous end. The present analysis proves to be sensible enough to highlight inter-individual differences in alveolo-capillary equilibration among healthy subjects.

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“…A simple approach to estimate the inspiratory elastic power was recently proposed and proved useful to compare the energy expenditure when changing the pattern of breathing due to respiratory diseases or environmental conditions (Dellweg et al, 2008; Passoni et al, 2015; Beretta et al, 2017). Considering the linearity of the overall volume–pressure relationship of the respiratory system, between the resting respiratory capacities up to the end-inspiration, the elastic/resistive work performed by the inspiratory muscles (InW el ) can be defined as the area of the right triangle where one leg (cathetus) is the change in lung volume or tidal volume (V t ), and the other leg is the corresponding applied pulmonary pressure (ΔP), namely:…”

Section: Methodsmentioning

confidence: 99%

Impact of Hanging Motionless in Harness on Respiratory and Blood Pressure Reflex Modulation in Mountain Climbers

Lanfranconi

Ferri

Pollastri³

et al. 2019

High Altitude Medicine & Biology

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Harness hang syncope (HHS) is a risk that specifically affects safety of harness users in mountain climbing. Aims: To evaluate individual patterns of breathing resulting from deranged cardiovascular reflexes triggering a syncopal event when a mismatch between cerebral O 2 demand and supply is present. Results: Forty healthy participants [aged 39.1 (8.2) years] were enrolled in a motionless suspension test while hanging in harness. Respiratory gas exchange values were analyzed to assess the pattern of breathing (EpInW el , respiratory elastic power) and cardiovascular parameters were monitored (BP, blood pressure). Four participants experienced HHS after 30.0 (7.6) minutes, with an early manifestation of loss of control of both a sustainable EpInW el and BP, starting after 10–12 minutes. Among the other participants, two different reactions were observed during suspension: (1) group G1 tolerated 32.7 (11.4) minutes of suspension by a favorable adaptation of the EpInW el and BP parameters and (2) group G2 showed significantly shorter time of suspension 24.0 (10.4) minutes with unfavorable increase in EpInW el and BP. Conclusions: Greater resistance to HHS occurs in people developing less marked fluctuations of both respiratory and cardiovascular reflex responses. Conversely, wider fluctuations both in control of EpInW el and BP were observed in the event of decreased suspension tolerance or in syncopal events.

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Air blood barrier phenotype correlates with alveolo-capillary O 2 equilibration in hypobaric hypoxia

Cited by 18 publications

References 24 publications

Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation

Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation

Differences in alveolo-capillary equilibration in healthy subjects on facing O2 demand

Impact of Hanging Motionless in Harness on Respiratory and Blood Pressure Reflex Modulation in Mountain Climbers

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