scholarly journals Prior oxygenation, but not chemoreflex responsiveness, determines breath‐hold duration during voluntary apnea

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Christina D. Bruce ◽  
Emily R. Vanden Berg ◽  
Jamie R. Pfoh ◽  
Craig D. Steinback ◽  
Trevor A. Day
Keyword(s):  
Breath Hold ◽  
Voluntary Apnea ◽  
Breath Hold Duration

Skin Cooling on Breath-Hold Duration and Predicted Emergency Air Supply Duration During Immersion

2020 ◽  
Vol 91 (7) ◽  
pp. 578-585
Author(s):  
Victory C. Madu ◽  
Heather Carnahan ◽  
Robert Brown ◽  
Kerri-Ann Ennis ◽  
Kaitlyn S. Tymko ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Hold Time ◽  
Whole Body ◽  
Breath Hold ◽  
Endurance Time ◽  
Skin Exposure ◽  
Breathing Apparatus ◽  
Air Supply ◽  
Skin Cooling ◽  
Breath Hold Duration

PURPOSE: This study was intended to determine the effect of skin cooling on breath-hold duration and predicted emergency air supply duration during immersion.METHODS: While wearing a helicopter transport suit with a dive mask, 12 subjects (29 ± 10 yr, 78 ± 14 kg, 177 ± 7 cm, 2 women) were studied in 8 and 20°C water. Subjects performed a maximum breath-hold, then breathed for 90 s (through a mouthpiece connected to room air) in five skin-exposure conditions. The first trial was out of water for Control (suit zipped, hood on, mask off). Four submersion conditions included exposure of the: Partial Face (hood and mask on); Face (hood on, mask off); Head (hood and mask off); and Whole Body (suit unzipped, hood and mask off).RESULTS: Decreasing temperature and increasing skin exposure reduced breath-hold time (to as low as 10 ± 4 s), generally increased minute ventilation (up to 40 ± 15 L · min−1), and decreased predicted endurance time (PET) of a 55-L helicopter underwater emergency breathing apparatus. In 8°C water, PET decreased from 2 min 39 s (Partial Face) to 1 min 11 s (Whole Body).CONCLUSION: The most significant factor increasing breath-hold and predicted survival time was zipping up the suit. Face masks and suit hoods increased thermal comfort. Therefore, wearing the suits zipped with hoods on and, if possible, donning the dive mask prior to crashing, may increase survivability. The results have important applications for the education and preparation of helicopter occupants. Thermal protective suits and dive masks should be provided.Madu VC, Carnahan H, Brown R, Ennis K-A, Tymko KS, Hurrie DMG, McDonald GK, Cornish SM, Giesbrecht GG. Skin cooling on breath-hold duration and predicted emergency air supply duration during immersion. Aerosp Med Hum Perform. 2020; 91(7):578–585.

Diving and swimming performance of white whales, Delphinapterus leucas: an assessment of plasma lactate and blood gas levels and respiratory rates.

1997 ◽  
Vol 200 (24) ◽  
pp. 3091-3099 ◽  
Author(s):  
S A Shaffer ◽  
D P Costa ◽  
T M Williams ◽  
S H Ridgway
Keyword(s):  
High Speed ◽  
Swimming Performance ◽  
Lactate Concentration ◽  
Delphinapterus Leucas ◽  
Breath Hold ◽  
Plasma Lactate ◽  
Post Exercise ◽  
Test Platform ◽  
Plasma Lactate Concentration ◽  
Breath Hold Duration

The white whale Delphinapterus leucas is an exceptional diver, yet we know little about the physiology that enables this species to make prolonged dives. We studied trained white whales with the specific goal of assessing their diving and swimming performance. Two adult whales performed dives to a test platform suspended at depths of 5-300 m. Behavior was monitored for 457 dives with durations of 2.2-13.3 min. Descent rates were generally less than 2 m s-1 and ascent rates averaged 2.2-3 m s-1. Post-dive plasma lactate concentration increased to as much as 3.4 mmol l-1 (4-5 times the resting level) after dives of 11 min. Mixed venous PO2 measured during voluntary breath-holds decreased from 79 to 20 mmHg within 10 min; however, maximum breath-hold duration was 17 min. Swimming performance was examined by training the whales to follow a boat at speeds of 1.4-4.2 m s-1. Respiratory rates ranged from 1.6 breaths min-1 at rest to 5.5 breaths min-1 during exercise and decreased with increasing swim speed. Post-exercise plasma lactate level increased to 1.8 mmol l-1 (2-3 times the resting level) following 10 min exercise sessions at swimming speeds of 2.5-2.8 m s-1. The results of this study are consistent with the calculated aerobic dive limit (O2 store/metabolic rate) of 9-10 min. In addition, white whales are not well adapted for high-speed swimming compared with other small cetaceans.

Utilizing flip angle/TR equivalence to reduce breath hold duration in hyperpolarized 129 Xe 1‐point Dixon gas exchange imaging

2021 ◽  
Author(s):  
Peter J. Niedbalski ◽  
Junlan Lu ◽  
Chase S. Hall ◽  
Mario Castro ◽  
John P. Mugler ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Flip Angle ◽  
Breath Hold ◽  
Breath Hold Duration

Navigator assessment of breath-hold duration: impact of supplemental oxygen and hyperventilation.

1998 ◽  
Vol 171 (2) ◽  
pp. 395-397 ◽  
Author(s):  
P G Danias ◽  
M Stuber ◽  
R M Botnar ◽  
K V Kissinger ◽  
M L Chuang ◽  
...  
Keyword(s):  
Supplemental Oxygen ◽  
Breath Hold ◽  
Breath Hold Duration

Temperature effect on the human dive response in relation to cold water near-drowning

1984 ◽  
Vol 56 (1) ◽  
pp. 202-206 ◽  
Author(s):  
J. S. Hayward ◽  
C. Hay ◽  
B. R. Matthews ◽  
C. H. Overweel ◽  
D. D. Radford
Keyword(s):  
Heart Rate ◽  
Water Temperature ◽  
Cold Water ◽  
Breath Holding ◽  
Breath Hold ◽  
Cold Stimulation ◽  
Near Drowning ◽  
Voluntary Hyperventilation ◽  
Dive Response ◽  
Breath Hold Duration

To facilitate analysis of mechanisms involved in cold water near-drowning, maximum breath-hold duration (BHD) and diving bradycardia were measured in 160 humans who were submerged in water temperatures from 0 to 35 degrees C at 5 degrees C intervals. For sudden submersion BHD was dependent on water temperature (Tw) according to the equation BHD = 15.01 + 0.92Tw. In cold water (0–15 degrees C), BHD was greatly reduced, being 25–50% of the presubmersion duration. BHD after brief habituation to water temperature and mild, voluntary hyperventilation was more than double that of sudden submersion and was also dependent on water temperature according to the equation BHD = 38.90 + 1.70Tw. Minimum heart rate during both types of submersions (diving bradycardia) was independent of water temperature. The results are pertinent to accidental submersion in cold water and show that decreased breath-holding capacity caused by peripheral cold stimulation reduces the effectiveness of the dive response and facilitates drowning. These findings do not support the postulate that the dive response has an important role in the enhanced resuscitatibility associated with cold water near-drowning, thereby shifting emphasis to hypothermia as the mechanism for this phenomenon.

The physiology and pathophysiology of human breath-hold diving

2009 ◽  
Vol 106 (1) ◽  
pp. 284-292 ◽  
Author(s):  
Peter Lindholm ◽  
Claes EG Lundgren
Keyword(s):  
Decompression Sickness ◽  
Nitrogen Pressure ◽  
Breath Hold ◽  
High Nitrogen ◽  
Diving Response ◽  
Human Breath ◽  
Physiological Limits ◽  
World Records ◽  
Physiological Reactions ◽  
Breath Hold Duration

This is a brief overview of physiological reactions, limitations, and pathophysiological mechanisms associated with human breath-hold diving. Breath-hold duration and ability to withstand compression at depth are the two main challenges that have been overcome to an amazing degree as evidenced by the current world records in breath-hold duration at 10:12 min and depth of 214 m. The quest for even further performance enhancements continues among competitive breath-hold divers, even if absolute physiological limits are being approached as indicated by findings of pulmonary edema and alveolar hemorrhage postdive. However, a remarkable, and so far poorly understood, variation in individual disposition for such problems exists. Mortality connected with breath-hold diving is primarily concentrated to less well-trained recreational divers and competitive spearfishermen who fall victim to hypoxia. Particularly vulnerable are probably also individuals with preexisting cardiac problems and possibly, essentially healthy divers who may have suffered severe alternobaric vertigo as a complication to inadequate pressure equilibration of the middle ears. The specific topics discussed include the diving response and its expression by the cardiovascular system, which exhibits hypertension, bradycardia, oxygen conservation, arrhythmias, and contraction of the spleen. The respiratory system is challenged by compression of the lungs with barotrauma of descent, intrapulmonary hemorrhage, edema, and the effects of glossopharyngeal insufflation and exsufflation. Various mechanisms associated with hypoxia and loss of consciousness are discussed, including hyperventilation, ascent blackout, fasting, and excessive postexercise O2 consumption. The potential for high nitrogen pressure in the lungs to cause decompression sickness and N2 narcosis is also illuminated.

Abstract P195: Hypertension is Associated With an Abnormal Pressor Response to Voluntary Apnea

Circulation ◽  
2015 ◽  
Vol 131 (suppl_1) ◽  
Author(s):  
Noah Jouett ◽  
Ryan Mason ◽  
Dorene Niv ◽  
Donald E Watenpaugh ◽  
Michael L Smith
Keyword(s):  
Blood Pressure ◽  
Effective Treatment ◽  
Blood Pressure Response ◽  
Pressor Response ◽  
Breath Hold ◽  
Primary Care Center ◽  
Hypertensive Patients ◽  
Control Subjects ◽  
Healthy Control ◽  
Voluntary Apnea

Background: Cardiovascular diseases are commonly associated with elevated sympathetic nerve activity (SNA). Previously, we have shown that the blood pressure response to a voluntary apnea is closely correlated with the SNA response in patients with sleep disordered breathing (SDB) and thus may serve as an index of SNA responsiveness. In the current study, we hypothesized that the pressor response to apnea is 1) reduced with effective treatment of SDB in SDB patients, and 2) that it is exaggerated in hypertensive patients (HTN) when compared to healthy control subjects. Methods: 22 OSA patients (14 treated and 8 untreated), 19 treated hypertensive patients and 23 healthy normotensive control subjects were recruited from the UNTHSC Primary Care Center and Sleep Consultants of Texas. Subjects completed a medical history questionnaire and Epworth Sleepiness survey. Blood pressure was measured by standard auscultatory assessment in the seated position. Baseline blood pressure was obtained in triplicate during quiet rest. Then after practicing a voluntary breath hold, subjects repeated three voluntary 20-second breath holds each beginning at end-expiration. Comparisons were made 1) between treated and untreated SDB patients, and 2) between HTN patients and healthy control subjects using a Student t test. Results: Importantly, as in prior studies the pressor response to apnea was not different from zero in the healthy control subjects (-1.0 ± 4.2 mmHg, p>0.05). In the SDB patients, the pressor response was significantly greater than zero in both treated (11.4 ± 3.9 mm Hg) and untreated (24.5 ± 9.8 mm Hg) SDB patients (p<0.001), and was significantly reduced in the treated SDB patients (p<0.001). In addition, the pressor response was significantly greater in the HTN patients (10.5 ± 5.3 mmHg, p<0.001) compared to the healthy control subjects. Conclusions: These data support our hypotheses that the pressor response to voluntary apnea is exaggerated in both untreated SDB and treated HTN patients and that effective treatment of SDB reduces this response, but does not normalize the response. These data suggest that the pressor response to apnea may be a simple physiologic index of exaggerated sympathetic responsiveness.

scholarly journals Shortening the preparation time of the single prolonged breath-hold for radiotherapy sessions

2021 ◽  
Author(s):  
Michael John Parkes ◽  
Stuart Green ◽  
Jason Cashmore ◽  
Qamar Ghafoor ◽  
Thomas Clutton-Brock
Keyword(s):  
Healthy Subjects ◽  
Breath Hold ◽  
Preparation Time ◽  
The Mean ◽  
Original Preparation ◽  
Thoracic And Abdominal ◽  
Clinical Adoption ◽  
Ventilator Settings ◽  
Short Breath ◽  
Breath Hold Duration

Objective: Single prolonged breath-holds of >5 min can be obtained in cancer patients. Currently, however, the preparation time in each radiotherapy session is a practical limitation for clinical adoption of this new technique. Here, we show by how much our original preparation time can be shortened without unduly compromising breath-hold duration. Methods: 44 healthy subjects performed single prolonged breath-holds from 60% O2 and mechanically induced hypocapnia. We tested the effect on breath-hold duration of shortening preparation time (the durations of acclimatization, hyperventilation and hypocapnia) by changing these durations and or ventilator settings. Results: Mean original breath-hold duration was 6.5 ± 0.2 (standard error) min. The total original preparation time (from connecting the facemask to the start of the breath-hold) was 26 ± 1 min. After shortening the hypocapnia duration from 16 to 5 min, mean breath-hold duration was still 6.1 ± 0.2 min (ns vs the original). After abolishing the acclimatization and shortening the hypocapnia to 1 min (a total preparation time now of 9 ± 1 min), a mean breath-hold duration of >5 min was still possible (now significantly shortened to 5.2 ± 0.6 min, p < 0.001). After shorter and more vigorous hyperventilation (lasting 2.7 ± 0.3 min) and shorter hypocapnia (lasting 43 ± 4 s), a mean breath-hold duration of >5 min (5.3 ± 0.2 min, p < 0.05) was still possible. Here, the final total preparation time was 3.5 ± 0.3 min. Conclusions: These improvements may facilitate adoption of the single prolonged breath-hold for a range of thoracic and abdominal radiotherapies especially involving hypofractionation. Advances in knowledge: Multiple short breath-holds improve radiotherapy for thoracic and abdominal cancers. Further improvement may occur by adopting the single prolonged breath-hold of >5 min. One limitation to clinical adoption is its long preparation time. We show here how to reduce the mean preparation time from 26 to 3.5 min without compromising breath-hold duration

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