TY - JOUR

T1 - Temporal changes in pulmonary gas exchange efficiency when breath-hold diving below residual volume

AU - Patrician, Alexander

AU - Spajić, Boris

AU - Gasho, Christopher

AU - Caldwell, Hannah Grace

AU - Dawkins, Tony

AU - Stembridge, Michael

AU - Lovering, Andrew T

AU - Coombs, Geoff B

AU - Howe, Connor A

AU - Barak, Otto

AU - Drviš, Ivan

AU - Dujić, Željko

AU - Ainslie, Philip N

N1 - (Ekstern)

PY - 2021

Y1 - 2021

N2 - Breath-hold diving involves highly integrative and extreme physiological responses to both exercise and asphyxia during progressive elevations in hydrostatic pressure. Over two diving training camps (Study 1 and 2), 25 breath-hold divers (recreational to world-champion) performed 66 dives to 57 ± 20 m (range: 18–117 m). Using the deepest dive from each diver, temporal changes in cardiopulmonary function were assessed using non-invasive pulmonary gas exchange (indexed via the O2 deficit), ultrasound B-line scores, lung compliance and pulmonary haemodynamics at baseline and following the dive. Hydrostatically induced lung compression was quantified in Study 2, using spirometry and lung volume measurement, enabling each dive to be categorized by its residual volume (RV)-equivalent depth. From both studies, pulmonary gas exchange inefficiency – defined as an increase in O2 deficit – was related to the depth of the dive (r2= 0.345; P < 0.001), with dives associated with lung squeeze symptoms exhibiting the greatest deficits. In Study 1, although B-lines doubled from baseline (P = 0.027), cardiac output and pulmonary artery systolic pressure were unchanged post-dive. In Study 2, dives with lung compression to ≤RV had higher O2 deficits at 9 min, compared to dives that did not exceed RV (24 ± 25 vs. 5 ± 8 mmHg; P = 0.021). The physiological significance of a small increase in estimated lung compliance post-dive (via decreased and increased/unaltered airway resistance and reactance, respectively) remains equivocal. Following deep dives, the current study highlights an integrated link between hydrostatically induced lung compression and transient impairments in pulmonary gas exchange efficiency.

AB - Breath-hold diving involves highly integrative and extreme physiological responses to both exercise and asphyxia during progressive elevations in hydrostatic pressure. Over two diving training camps (Study 1 and 2), 25 breath-hold divers (recreational to world-champion) performed 66 dives to 57 ± 20 m (range: 18–117 m). Using the deepest dive from each diver, temporal changes in cardiopulmonary function were assessed using non-invasive pulmonary gas exchange (indexed via the O2 deficit), ultrasound B-line scores, lung compliance and pulmonary haemodynamics at baseline and following the dive. Hydrostatically induced lung compression was quantified in Study 2, using spirometry and lung volume measurement, enabling each dive to be categorized by its residual volume (RV)-equivalent depth. From both studies, pulmonary gas exchange inefficiency – defined as an increase in O2 deficit – was related to the depth of the dive (r2= 0.345; P < 0.001), with dives associated with lung squeeze symptoms exhibiting the greatest deficits. In Study 1, although B-lines doubled from baseline (P = 0.027), cardiac output and pulmonary artery systolic pressure were unchanged post-dive. In Study 2, dives with lung compression to ≤RV had higher O2 deficits at 9 min, compared to dives that did not exceed RV (24 ± 25 vs. 5 ± 8 mmHg; P = 0.021). The physiological significance of a small increase in estimated lung compliance post-dive (via decreased and increased/unaltered airway resistance and reactance, respectively) remains equivocal. Following deep dives, the current study highlights an integrated link between hydrostatically induced lung compression and transient impairments in pulmonary gas exchange efficiency.

KW - Breath-hold

KW - Diving

KW - Immersion

KW - Lung compression

KW - Pulmonary gas exchange

KW - Residual volume

KW - Spirometry

UR - http://www.scopus.com/inward/record.url?scp=85102306739&partnerID=8YFLogxK

U2 - 10.1113/EP089176

DO - 10.1113/EP089176

M3 - Journal article

C2 - 33559974

AN - SCOPUS:85102306739

VL - 106

SP - 1120

EP - 1133

JO - Experimental Physiology

JF - Experimental Physiology

SN - 0958-0670

IS - 4

ER -