Non‐Invasive Pulmonary Gas Exchange Measurements Following Deep Breath‐Hold Diving

In this case study, we evaluate the unique physiological profiles of two world-champion breath-hold divers. At close-to current world record depths, the extreme physiological responses to both exercise and asphyxia during progressive elevations in hydrostatic pressure are profound. As such, these professional athletes must be highly capable of managing such stress, to maintain performing at the forefront human capacity. In both divers, pulmonary function before and after deep dives to 102 and 117 meters in the open sea were assessed using non-invasive pulmonary gas exchange (indexed via the O2 deficit, which is analogous to the traditional alveolar to arterial oxygen difference), ultrasound B-line scores, airway resistance and airway reactance. Hydrostatic-induced lung compression was also quantified via spirometry. Both divers successfully performed their dives. Pulmonary gas exchange efficiency was impaired in both divers at 10 min, but had mostly restored within a few hours. Mild hemoptysis was transiently evident immediately following the 117m dive, whereas both divers experienced nitrogen narcosis. Although B-lines were only elevated in one diver post-dive, reductions in airway resistance and reactance occurred in both divers, suggesting the compressive strain on the structural characteristics of the airways can persist for up to 3.5hrs. Marked echocardiographic dyssynchrony was evident in one diver after 10m of descent, which persisted until resolving at ~77m during ascent. In summary, despite the enormous hydrostatic and physiological stress to diving beyond 100m on a single breath, these data provide valuable insight into the extraordinary capacity of those at the pinnacle of apneic performance.

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Single breath‐hold measurement of pulmonary gas exchange and diffusion in humans with hyperpolarized 129 Xe MR

NMR in Biomedicine ◽

10.1002/nbm.4068 ◽

2019 ◽

Vol 32 (5) ◽

pp. e4068 ◽

Cited By ~ 4

Author(s):

Junshuai Xie ◽

Haidong Li ◽

Huiting Zhang ◽

Xiuchao Zhao ◽

Lei Shi ◽

...

Keyword(s):

Gas Exchange ◽

Pulmonary Gas Exchange ◽

Breath Hold ◽

Single Breath ◽

Single Breath Hold ◽

And Diffusion

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Use of a Non-Invasive Pulmonary Gas-Exchange Analyzer to Improve the Pretest Probability of Pulmonary Embolism in a Patient Classified as "Low Risk"

10.1164/ajrccm-conference.2021.203.1_meetingabstracts.a2385 ◽

2021 ◽

Author(s):

D. Sieck ◽

P. Ozon

Keyword(s):

Pulmonary Embolism ◽

Gas Exchange ◽

Pulmonary Gas Exchange ◽

Pretest Probability ◽

Low Risk ◽

Non Invasive

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Temporal changes in pulmonary gas exchange efficiency when breath‐hold diving below residual volume

Experimental Physiology ◽

10.1113/ep089176 ◽

2021 ◽

Vol 106 (4) ◽

pp. 1120-1133

Author(s):

Alexander Patrician ◽

Boris Spajić ◽

Christopher Gasho ◽

Hannah G. Caldwell ◽

Tony Dawkins ◽

...

Keyword(s):

Gas Exchange ◽

Temporal Changes ◽

Pulmonary Gas Exchange ◽

Breath Hold ◽

Residual Volume

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Non-invasive Measurement of Pulmonary Gas Exchange Efficiency: The Oxygen Deficit

Frontiers in Physiology ◽

10.3389/fphys.2021.757857 ◽

2021 ◽

Vol 12 ◽

Author(s):

G. Kim Prisk ◽

John B. West

Keyword(s):

Gas Exchange ◽

Arterial Oxygen Saturation ◽

Pulmonary Gas Exchange ◽

Oxygen Deficit ◽

Arterial Oxygen ◽

Non Invasive ◽

Arterial Blood ◽

Age Related ◽

End Tidal ◽

Serial Measurements

The efficiency of pulmonary gas exchange has long been assessed using the alveolar-arterial difference in PO2, the A-aDO2, a construct developed by Richard Riley ~70years ago. However, this measurement is invasive (requiring an arterial blood sample), time consuming, expensive, uncomfortable for the patients, and as such not ideal for serial measurements. Recent advances in the technology now provide for portable and rapidly responding measurement of the PO2 and PCO2 in expired gas, which combined with the well-established measurement of arterial oxygen saturation via pulse oximetry (SpO2) make practical a non-invasive surrogate measurement of the A-aDO2, the oxygen deficit. The oxygen deficit is the difference between the end-tidal PO2 and the calculated arterial PO2 derived from the SpO2 and taking into account the PCO2, also measured from end-tidal gas. The oxygen deficit shares the underlying basis of the measurement of gas exchange efficiency that the A-aDO2 uses, and thus the two measurements are well-correlated (r2~0.72). Studies have shown that the new approach is sensitive and can detect the age-related decline in gas exchange efficiency associated with healthy aging. In patients with lung disease the oxygen deficit is greatly elevated compared to normal subjects. The portable and non-invasive nature of the approach suggests potential uses in first responders, in military applications, and in underserved areas. Further, the completely non-invasive and rapid nature of the measurement makes it ideally suited to serial measurements of acutely ill patients including those with COVID-19, allowing patients to be closely monitored if required.

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DLCO versus DLCO/VA as predictors of pulmonary gas exchange

Yearbook of Pulmonary Disease ◽

10.1016/s8756-3452(08)70634-0 ◽

2008 ◽

Vol 2008 ◽

pp. 174-175

Author(s):

K.L. Lewis

Keyword(s):

Gas Exchange ◽

Pulmonary Gas Exchange

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Mechanisms of improvement in pulmonary gas exchange during isovolemic hemodilution

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.1.132 ◽

1999 ◽

Vol 87 (1) ◽

pp. 132-141 ◽

Cited By ~ 39

Author(s):

Steven Deem ◽

Richard G. Hedges ◽

Steven McKinney ◽

Nayak L. Polissar ◽

Michael K. Alberts ◽

...

Keyword(s):

Blood Flow ◽

Fractal Dimension ◽

Gas Exchange ◽

Spatial Correlation ◽

Pulmonary Blood Flow ◽

Minute Ventilation ◽

Flow Distribution ◽

Pulmonary Gas Exchange ◽

Normal Lung ◽

Blood Flow Distribution

Severe anemia is associated with remarkable stability of pulmonary gas exchange (S. Deem, M. K. Alberts, M. J. Bishop, A. Bidani, and E. R. Swenson. J. Appl. Physiol. 83: 240–246, 1997), although the factors that contribute to this stability have not been studied in detail. In the present study, 10 Flemish Giant rabbits were anesthetized, paralyzed, and mechanically ventilated at a fixed minute ventilation. Serial hemodilution was performed in five rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; five rabbits were followed over a comparable time. Ventilation-perfusion (V˙a/Q˙) relationships were studied by using the multiple inert-gas-elimination technique, and pulmonary blood flow distribution was assessed by using fluorescent microspheres. Expired nitric oxide (NO) was measured by chemiluminescence. Hemodilution resulted in a linear fall in hematocrit over time, from 30 ± 1.6 to 11 ± 1%. Anemia was associated with an increase in arterial [Formula: see text] in comparison with controls ( P < 0.01 between groups). The improvement in O2 exchange was associated with reducedV˙a/Q˙heterogeneity, a reduction in the fractal dimension of pulmonary blood flow ( P = 0.04), and a relative increase in the spatial correlation of pulmonary blood flow ( P = 0.04). Expired NO increased with anemia, whereas it remained stable in control animals ( P < 0.0001 between groups). Anemia results in improved gas exchange in the normal lung as a result of an improvement in overallV˙a/Q˙matching. In turn, this may be a result of favorable changes in pulmonary blood flow distribution, as assessed by the fractal dimension and spatial correlation of blood flow and as a result of increased NO availability.

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