Hypercapnia in diving: a review of CO2 retention in submersed exercise at depth

Dunworth, Sophia; Natoli, Michael J.; Cooter, Mary; Cherry, Anne D.; Peacher, Dionne F.; Potter, Michael Q.; Wester, Tracy E.; Freiberger, JJ; Moon, Richard E.

doi:10.22462/5.6.2017.1

Cited by 14 publications

(16 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Along these lines, we used PETCO 2 as a marker of arterial CO 2 pressure since previous reports demonstrate that PETCO 2 and arterial CO 2 pressure are not significantly different during water immersion (Dunworth et al. ). However, PETCO 2 may underestimate arterial CO 2 pressure during instances of increased dead space (i.e., water immersion) (Liu et al.…”

Section: Discussionmentioning

confidence: 99%

“…PETCO 2 was used as a marker of arterial CO 2 pressure since it reflects arterial CO 2 pressure during water immersion (Dunworth et al. ) and throughout a wide range of physiological dead space (McSwain et al. ), which may be increased during water immersion (Cherry et al.…”

Section: Methodsmentioning

confidence: 99%

“…The sample rate of the capnograph was 4 Hz. PETCO 2 was used as a marker of arterial CO 2 pressure since it reflects arterial CO 2 pressure during water immersion (Dunworth et al 2017) and throughout a wide range of physiological dead space (McSwain et al 2010), which may be increased during water immersion ). Inspired and expired ventilation was measured using a heated pneumotachometer (Hans Rudolph, Inc., Shawnee, KS, USA) that was attached to a silicone mouthpiece (Hans Rudolph, Inc., Shawnee, KS, USA).…”

Section: Instrumentation and Measurementsmentioning

confidence: 99%

“…However, it was apparent that the increases in PETCO 2 were sensed by the chemoreceptors during Dry + CO 2 , evidenced by the rise in minute ventilation. Along these lines, we used PETCO 2 as a marker of arterial CO 2 pressure since previous reports demonstrate that PETCO 2 and arterial CO 2 pressure are not significantly different during water immersion (Dunworth et al 2017 immersion) (Liu et al 1995;Williams and Babb 1997). Thus, using PETCO 2 as a surrogate of arterial CO 2 pressure is a conservative approach, such that calculated differences in dead space ventilation and alveolar ventilation to cardiac output ratio would be exacerbated if we were to observe a higher value for arterial CO 2 pressure via direct measurements.…”

Section: Considerationsmentioning

confidence: 99%

See 3 more Smart Citations

The effect of water immersion and acute hypercapnia on ventilatory sensitivity and cerebrovascular reactivity

et al. 2018

View full text Add to dashboard Cite

The partial pressure of end tidal carbon dioxide (PETCO 2), ventilatory sensitivity to CO 2, and cerebral perfusion are augmented during thermoneutral head out water immersion (HOWI). We tested the hypotheses that HOWI and acute hypercapnia augments minute ventilation, ventilatory sensitivity to CO 2, cerebral perfusion, and cerebrovascular reactivity to CO 2. Twelve subjects (age: 24 ± 3 years, BMI: 25.3 ± 2.9 kg/m2, 6 women) participated in two experimental visits: a HOWI visit (HOWI) and a matched hypercapnia visit (Dry + CO 2). A rebreathing test was conducted at baseline, 10, 30, 60 min, and post HOWI and Dry + CO 2. PETCO 2, minute ventilation, expired gases, blood pressure, heart rate, and middle cerebral artery blood velocity were recorded continuously. PETCO 2 increased throughout HOWI (baseline: 42 ± 2 mmHg; maximum at 10 min: 44 ± 2 mmHg, P ≤ 0.013) and Dry + CO 2 (baseline: 42 ± 2 mmHg; maximum at 10 min: 44 ± 2 mmHg, P ≤ 0.013) and was matched between conditions (condition main effect: P = 0.494). Minute ventilation was lower during HOWI versus Dry + CO 2 (maximum difference at 60 min: 13.2 ± 1.9 vs. 16.2 ± 2.7 L/min, P < 0.001). Ventilatory sensitivity to CO 2 and middle cerebral artery blood velocity were greater during HOWI versus Dry + CO 2 (maximum difference at 10 min: 2.60 ± 1.09 vs. 2.20 ± 1.05 L/min/mmHg, P < 0.001, and 63 ± 18 vs. 53 ± 14 cm/sec, P < 0.001 respectively). Cerebrovascular reactivity to CO 2 decreased throughout HOWI and Dry + CO 2 and was not different between conditions (condition main effect: P = 0.777). These data indicate that acute hypercapnia, matched to what occurs during HOWI, augments minute ventilation but not ventilatory sensitivity to CO 2 or middle cerebral artery blood velocity despite an attenuated cerebrovascular reactivity to CO 2.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Instrumentation and Measurementsmentioning

confidence: 99%

Section: Considerationsmentioning

confidence: 99%

See 2 more Smart Citations

The effect of water immersion and acute hypercapnia on ventilatory sensitivity and cerebrovascular reactivity

et al. 2018

View full text Add to dashboard Cite

show abstract

“…When breathing gas with a fixed oxygen concentration, alveolar and arterial oxygen partial pressures increase with depth. This tends to attenuate ventilatory chemosensitivity ( Dunworth et al, 2017 ) and facilitate CO 2 retention. Seasoned divers indeed become less sensitive to high CO 2 partial pressures.…”

Section: Man and Watermentioning

confidence: 99%

Environmental Physiology and Diving Medicine

et al. 2018

Self Cite

View full text Add to dashboard Cite

Man’s experience and exploration of the underwater environment has been recorded from ancient times and today encompasses large sections of the population for sport enjoyment, recreational and commercial purpose, as well as military strategic goals. Knowledge, respect and maintenance of the underwater world is an essential development for our future and the knowledge acquired over the last few dozen years will change rapidly in the near future with plans to establish secure habitats with specific long-term goals of exploration, maintenance and survival. This summary will illustrate briefly the physiological changes induced by immersion, swimming, breath-hold diving and exploring while using special equipment in the water. Cardiac, circulatory and pulmonary vascular adaptation and the pathophysiology of novel syndromes have been demonstrated, which will allow selection of individual characteristics in order to succeed in various environments. Training and treatment for these new microenvironments will be suggested with description of successful pioneers in this field. This is a summary of the physiology and the present status of pathology and therapy for the field.

show abstract

Diving ergospirometry with suspended weights: breathing- and fin-swimming style matter

Koch¹,

Kramkowski²,

Holzum

et al. 2022

Eur J Appl Physiol

View full text Add to dashboard Cite

Purpose Scuba diving is a complex condition including elevated ambient pressure, limited air supply, increased breathing work, and unfamiliar fin-swimming. Earlier approaches to assess diving specific data did not comprehensively address these aspects. We first present an underwater ergospirometry system and then test the hypothesis that both breathing characteristics and fin-swimming style affect the air consumption. Methods/Participants A suspended-weights ergospirometry system was mounted inside a hyperbaric chamber. Ergo group: 25 divers (24.6 ± 4.1 years); three set-ups: dry normobaric cycling (75–225 W), dry cycling at 20 m simulated depth (75–225 W), fin-swimming at 20 m (5–8 kg suspended weights). Style group: 20 other divers (24.6 ± 4.1 years): fin-swimming at 20 m (5–8 kg) with regard to ventilation ($$\dot{V}$$ V ˙ E) and fin-swimming style. Results Ergo group: linear heart rate and oxygen uptake ($$\dot{V}$$ V ˙ O2) increases with both 50 W-bicycle steps and suspended-weights ergometry (r = 0.97). During hyperbaric conditions, $$\dot{V}$$ V ˙ E was less increased versus normobaric conditions. Style group: the more efficient hip/thigh-oriented style shifted towards the knee/calf-oriented style. $$\dot{V}$$ V ˙ E and $$\dot{V}$$ V ˙ O2 were higher in beginners (< 100 dives) versus advanced divers (≥ 100 dives). Significant differences on the 5 kg-step: $$\dot{V}$$ V ˙ E: 31.5 ± 7.1 l/min vs. 23.7 ± 5.9 l/min and $$\dot{V}$$ V ˙ O2: 1.6 ± 0.3 l/min vs. 1.2 ± 0.3 l/min. A comparison is presented, in addition to illustrate the impact of differences in breathing characteristics and fin-swimming style. Conclusions Diving ergospirometry with suspended weights in a hyperbaric chamber allows for comprehensive studies. Little diving experience in terms of breathing characteristics and fin-swimming style significantly increases $$\dot{V}$$ V ˙ E thereby increasing the risk of running-out-of-air.

show abstract

Hypercapnia in diving: a review of CO2 retention in submersed exercise at depth

Cited by 14 publications

References 77 publications

The effect of water immersion and acute hypercapnia on ventilatory sensitivity and cerebrovascular reactivity

The effect of water immersion and acute hypercapnia on ventilatory sensitivity and cerebrovascular reactivity

Environmental Physiology and Diving Medicine

Diving ergospirometry with suspended weights: breathing- and fin-swimming style matter

Contact Info

Product

Resources

About