Cardiovascular and autonomic responses to physiological stressors before and after six hours of water immersion

Florian, John P.; Simmons, Erin E.; Chon, Ki H.; Faes, Luca; Shykoff, Barbara E.

doi:10.1152/japplphysiol.00466.2013

Cited by 34 publications

(66 citation statements)

References 64 publications

(97 reference statements)

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“…A recent study has shown that both decreased SNA and increased para-SNA followed 6 h in-water immersion when PV was significantly reduced (117). By contrast, they reported that aldosterone, ANP, AVP, and NE were unchanged postimmersion.…”

Section: Egress From Water Immersionmentioning

confidence: 96%

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Human Physiology in an Aquatic Environment

Pendergast

Moon

Krasney

et al. 2015

Comprehensive Physiology

139

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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Section: Egress From Water Immersionmentioning

confidence: 96%

“…By contrast, they reported that aldosterone, ANP, AVP, and NE were unchanged postimmersion. Importantly, they also showed that cardiovascular and autonomic control are not sufficient to prevent orthostatic intolerance postimmersion (117).…”

Section: Egress From Water Immersionmentioning

confidence: 99%

Human Physiology in an Aquatic Environment

Pendergast

Moon

Krasney

et al. 2015

Comprehensive Physiology

139

137

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“…; Florian et al. ). During WI, central blood volume increases due to fluid shifts from the intracellular and interstitial fluid compartments to extracellular compartment (Epstein ) and redistribution of blood volume from the lower extremities to the thorax (Greenleaf et al.…”

Section: Introductionmentioning

confidence: 98%

“…; Tripathi ; Florian et al. ), together with augmented excretion of fluid and electrolytes (Norsk et al. ; Epstein ).…”

Section: Introductionmentioning

confidence: 99%

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Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

et al. 2016

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Physiological compensation to postural stress is weakened after long‐duration water immersion (WI), thus predisposing individuals to orthostatic intolerance. This study was conducted to compare hemodynamic responses to postural stress following exposure to WI alone (Air WI), hyperbaric oxygen alone in a hyperbaric chamber (O2 HC), and WI combined with hyperbaric oxygen (O2 WI), all at a depth of 1.35 ATA, and to determine whether hyperbaric oxygen is protective of orthostatic tolerance. Thirty‐two healthy men underwent up to 15 min of 70° head‐up tilt (HUT) testing before and after a single 6‐h resting exposure to Air WI (N = 10), O2 HC (N = 12), or O2 WI (N = 10). Heart rate (HR), blood pressure (BP), cardiac output (Q), stroke volume (SV), forearm blood flow (FBF), and systemic and forearm vascular resistance (SVR and FVR) were measured. Although all subjects completed HUT before Air WI, three subjects reached presyncope after Air WI exposure at 10.4, 9.4, and 6.9 min. HUT time did not change after O2 WI or O2 HC exposures. Compared to preexposure responses, HR increased (+10 and +17%) and systolic BP (−13 and −8%), and SV (−16 and −23%) decreased during HUT after Air WI and O2 WI, respectively. In contrast, HR and SV did not change, and systolic (+5%) and diastolic BP (+10%) increased after O2 HC. Q decreased (−13 and −7%) and SVR increased (+12 and +20%) after O2 WI and O2 HC, respectively, whereas SVR decreased (−9%) after Air WI. Opposite patterns were evident following Air WI and O2 HC for FBF (−26 and +52%) and FVR (+28 and −30%). Therefore, breathing hyperbaric oxygen during WI may enhance post‐WI cardiovascular compensatory responses to orthostatic stress.

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Evaluation of dynamics of forehead skin temperature under induced drowsiness

Bando

Oiwa

Nozawa

2017

IEEJ Transactions Elec Engng

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Drowsiness is one of the leading causes of traffic accidents. A technique for fast and easy measurement of the level of drowsiness is desirable. The objective of the present paper is to evaluate the dynamics of forehead skin temperature (FHT) under induced drowsiness. With a precursory change associated with drowsiness from the FHT, which is a noninvasive measurement, drowsiness can be detected at an early stage and, possibly, traffic accidents can be prevented. In this study, the measured FHTs were categorized into five drowsiness levels according to facial expressions (Level 1 is awake and Level 5 is extremely drowsy). In an experiment, the thermoregulation process of drowsiness was represented by a decrease in the total peripheral resistance, elevation of the nasal skin temperature, and decline in the tympanum temperature. The experimental results showed a significant decrease in FHT for drowsiness Levels 3–5 compared to the rest state (Mann–Whitney U‐test, p < 0.01). Because FHT did not increase in accordance with the process for nasal skin temperature, FHT could represent both skin and core temperatures. The results suggest that FHT can be an indicator for predicting drowsiness. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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Cardiovascular and autonomic responses to physiological stressors before and after six hours of water immersion

Cited by 34 publications

References 64 publications

Human Physiology in an Aquatic Environment

Human Physiology in an Aquatic Environment

Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

Evaluation of dynamics of forehead skin temperature under induced drowsiness

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