Effects of age on closing volume during head-out water immersions

Derion, Toniann; Guy, H. J.

doi:10.1016/0034-5687(94)90090-6

Cited by 5 publications

(3 citation statements)

References 6 publications

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“…HOWI has been shown to increase CVs in TN water. On the other hand, ERV decreased in immersion and the alveolar plateau (Phase III) slope was less steep (86).…”

Section: Pulmonary Adjustmentsmentioning

confidence: 93%

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Human Physiology in an Aquatic Environment

Pendergast

Moon

Krasney

et al. 2015

Comprehensive Physiology

135

137

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Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues. Pulmonary artery and capillary hydrostatic pressures increase causing a decline in vital capacity with the potential for pulmonary edema. Atrial stretch and increased arterial pressure cause reflex autonomic responses which result in endocrine changes that return plasma volume and arterial pressure to preimmersion levels. Plasma volume is regulated via a reflex diuresis and natriuresis. Hydrostatic pressure also leads to elastic loading of the chest, increasing work of breathing, energy cost, and thus blood flow to respiratory muscles. Decreases in water temperature in HOWI do not affect the cardiac output compared to TN; however, they influence heart rate and the distribution of muscle and fat blood flow. The reduced muscle blood flow results in a reduced maximal oxygen consumption. The properties of water determine the mechanical load and the physiological responses during exercise in water (e.g. swimming and water based activities). Increased hydrostatic pressure caused by submersion does not affect stroke volume; however, progressive bradycardia decreases cardiac output. During submersion, compressed gas must be breathed which introduces the potential for oxygen toxicity, narcosis due to nitrogen, and tissue and vascular gas bubbles during decompression and after may cause pain in joints and the nervous system.

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“…HOWI has been shown to increase CVs in TN water. On the other hand, ERV decreased in immersion and the alveolar plateau (Phase III) slope was less steep (86).…”

Section: Pulmonary Adjustmentsmentioning

confidence: 93%

“…Arterial P O 2 is usually increased due to an increase in the ventilation to oxygen consumption ratio (V E /V O2 ) ratio (87). When CV exceeds ERV (common in older individuals), immersion is associated with an increase in right-to-left shunt (87) and a widening of the alveolar-arterial P O 2 difference (86).…”

Section: Circulatory Responses and Fluid Shiftsmentioning

confidence: 99%

Human Physiology in an Aquatic Environment

Pendergast

Moon

Krasney

et al. 2015

Comprehensive Physiology

135

137

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“…Several investigators have observed an increase in closing volume (CV) (5,19,83), consistent with some gas trapping. Also in support of gas trapping is the observation that during immersion residual volume by body plethysmography exceeds that measured by inert gas dilution (87).…”

Section: Effects Of Immersion On Ventilation and Perfusionmentioning

confidence: 98%

Pulmonary gas exchange in diving

Moon

Cherry²,

Stolp³

et al. 2009

Journal of Applied Physiology

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Moon RE, Cherry AD, Stolp BW, Camporesi EM. Pulmonary gas exchange in diving. J Appl Physiol 106: 668 -677, 2009. First published November 13, 2008 doi:10.1152/japplphysiol.91104.2008.-Diving-related pulmonary effects are due mostly to increased gas density, immersion-related increase in pulmonary blood volume, and (usually) a higher inspired PO 2. Higher gas density produces an increase in airways resistance and work of breathing, and a reduced maximum breathing capacity. An additional mechanical load is due to immersion, which can impose a static transrespiratory pressure load as well as a decrease in pulmonary compliance. The combination of resistive and elastic loads is largely responsible for the reduction in ventilation during underwater exercise. Additionally, there is a density-related increase in dead space/tidal volume ratio (VD/VT), possibly due to impairment of intrapulmonary gas phase diffusion and distribution of ventilation. The net result of relative hypoventilation and increased VD/VT is hypercapnia. The effect of high inspired PO 2 and inert gas narcosis on respiratory drive appear to be minimal. Exchange of oxygen by the lung is not impaired, at least up to a gas density of 25 g/l. There are few effects of pressure per se, other than a reduction in the P50 of hemoglobin, probably due to either a conformational change or an effect of inert gas binding. respiratory dead space; ventilation-perfusion ratio; respiratory mechanics DESPITE HAVING EVOLVED in and adapted to an atmosphere with gas density close to 1 g/l, the performance of the human lung in the diving environment is remarkable. Adequate ventilation and gas exchange have been achieved at an ambient pressure up to 71 atmospheres absolute (ATA) [701 m of sea water (msw); 2,310 ft of sea water (fsw)] with an ambient PO 2 of 0.39 ATA (49), and with a PO 2 of 0.2 ATA up to a gas density of 25 g/l (50). Adequate exchange of oxygen and carbon dioxide while diving requires the ability to maintain ventilation in the face of significantly increased resistive and elastic loads. Resistance is increased primarily by the increase in breathing gas density. Elastic load is enhanced primarily by changes in transrespiratory pressure (P TR ). Inertial mechanical load is also increased, although this has a minimal effect on the diver. Added challenges include blunted respiratory drive due to elevated partial pressures of inert gas and oxygen, and possibly impaired diffusion within the alveolus (7). While in most dives the breathing gas is hyperoxic, thus precluding hypoxemia, hypercapnia is common. Hyperoxia, particularly in the venous blood, can induce a small reduction in CO 2 solubility, and hence an increase in venous PCO 2 via the Haldane effect (27,122). Arterial PCO 2 (Pa CO 2 ) is not affected by the Haldane effect because of regulation of breathing via the chemoreceptors, although hypercapnia does occur for other reasons as discussed below.Studies of pulmonary gas exchange under hyperbaric conditions designed to simulate diving have been performed...

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Immersion in Water, Hyperbaria, and Hyperoxia Including Oxygen Therapy

Thorsen¹

2020

Cotes’ Lung Function

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Effects of age on closing volume during head-out water immersions

Cited by 5 publications

References 6 publications

Human Physiology in an Aquatic Environment

Human Physiology in an Aquatic Environment

Pulmonary gas exchange in diving

Immersion in Water, Hyperbaria, and Hyperoxia Including Oxygen Therapy

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