Arousal responses of the newborn piglet to airways obstruction and rebreathing during normothermia and hyperthermia

1996 ◽  
Vol 8 (3) ◽  
pp. 365 ◽  
Author(s):  
BC Galland ◽  
NS Wehner ◽  
DP Bolton ◽  
BJ Taylor
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Experimental Studies ◽  
Thermal Conditions ◽  
Nrem Sleep ◽  
Sleep State ◽  
Adverse Conditions ◽  
Airways Obstruction ◽  
Respiratory Variables ◽  
Thermal States

Most experimental studies of arousal to respiratory stressors have been performed under neutral thermal conditions. The present study focussed on arousal responses with the added challenge of heat stress. The subjects were two groups of 10 sedated piglets aged 4-6 days and 2-6 days respectively. Respiratory stimuli (partial and total airways obstruction (AO) or rebreathing (RB) expired gases) were applied during non-rapid-eye-movement (NREM) sleep. Measurements of heart rate, SaO2, intra-pleural pressure or inspired CO2 and O2 were recorded during tests in normothermia and hyperthermia. Hyperthermia significantly shortened the time to arousal. Thus, arousal times from partial and total AO and from RB were: in normothermia, 40.3 +/- 5.8, 9.2 +/- 0.7 and 94.9 +/- 14.7 s respectively; in hyperthermia, 17.8 +/- 3.7, 7.6 +/- 0.9 and 68.5 +/- 9.1 s respectively. Cardio-respiratory variables at arousal were similar in both thermal states. Seven non-sedated piglets were challenged with RB stimuli during normothermia only to determine the influence of sleep state on arousal. Arousal in REM sleep was delayed approximately 2-3-fold (NREM, 41.2 +/- 8.2 s; REM, 88.5 +/- 18.1 s), occurring at a lower SaO2 and higher inspired CO2. It is concluded that arousal from NREM sleep under adverse conditions of hyperthermia shortens the arousal time from asphyxial stimuli induced by AO and RB with no change in the arousal threshold.

scholarly journals Combined heat and mental stress alters neurovascular control in humans

2010 ◽  
Vol 109 (6) ◽  
pp. 1880-1886 ◽  
Author(s):  
Jenna C. Klein ◽  
Craig G. Crandall ◽  
R. Matthew Brothers ◽  
Jason R. Carter
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Mental Stress ◽  
Muscle Sympathetic Nerve Activity ◽  
Thermal Conditions ◽  
Venous Occlusion ◽  
Vascular Conductance ◽  
Vascular Responses ◽  
Time Condition ◽  
Forearm Skin

This study examined the effect of combined heat and mental stress on neurovascular control. We hypothesized that muscle sympathetic nerve activity (MSNA) and forearm vascular responses to mental stress would be augmented during heat stress. Thirteen subjects performed 5 min of mental stress during normothermia (Tcore; 37 ± 0°C) and heat stress (38 ± 0°C). Heart rate, mean arterial pressure (MAP), MSNA, forearm vascular conductance (FVC; venous occlusion plethysmography), and forearm skin vascular conductance (SkVCf; via laser-Doppler) were analyzed. Heat stress increased heart rate, MSNA, SkVCf, and FVC at rest but did not change MAP. Mental stress increased MSNA and MAP during both thermal conditions; however, the increase in MAP during heat stress was blunted, whereas the increase in MSNA was accentuated, compared with normothermia (time × condition; P < 0.05 for both). Mental stress decreased SkVCf during heat stress but not during normothermia (time × condition, P < 0.01). Mental stress elicited similar increases in heart rate and FVC during both conditions. In one subject combined heat and mental stress induced presyncope coupled with atypical blood pressure and cutaneous vascular responses. In conclusion, these findings indicate that mental stress elicits a blunted increase of MAP during heat stress, despite greater increases in total MSNA and cutaneous vasoconstriction. The neurovascular responses to combined heat and mental stress may be clinically relevant to individuals frequently exposed to mentally demanding tasks in hyperthermic environmental conditions (i.e., soldiers, firefighters, and athletes).

scholarly journals Heat stress alters hemodynamic responses during the Valsalva maneuver

2010 ◽  
Vol 108 (6) ◽  
pp. 1591-1594 ◽  
Author(s):  
Scott L. Davis ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Phase Ii ◽  
Valsalva Maneuver ◽  
Late Phase ◽  
Thermal Conditions ◽  
Whole Body ◽  
Hemodynamic Responses ◽  
Arterial Blood

The Valsalva maneuver can be used as a noninvasive index of autonomic control of blood pressure and heart rate. The purpose of this investigation was to test the hypothesis that sympathetic mediated vasoconstriction, as referenced by hemodynamic responses during late phase II (phase IIb) of the Valsalva maneuver, is inhibited during whole body heating. Seven individuals (5 men, 2 women) performed three Valsalva maneuvers (each at a 30-mmHg expiratory pressure for 15 s) during normothermia and again during whole body heating (increase sublingual temperature ∼0.8°C via water-perfused suit). Each Valsalva maneuver was separated by a minimum of 5 min. Beat-to-beat mean arterial blood pressure (MAP) and heart rate were measured during each Valsalva maneuver, and responses for each phase were averaged across the three Valsalva maneuvers for both thermal conditions. Baseline MAP was not significantly different between normothermic (88 ± 11 mmHg) and heat stress (84 ± 9 mmHg) conditions. The change in MAP (ΔMAP) relative to pre-Valsalva MAP during phases IIa and IIb was significantly lower during heat stress (IIa = −20 ± 8 mmHg; IIb = −13 ± 7 mmHg) compared with normothermia (IIa = −1 ± 15 mmHg; IIb = 3 ± 13 mmHg). ΔMAP from pre-Valsalva baseline during phase IV was significantly higher during heat stress (25 ± 10 mmHg) compared with normothermia (8 ± 9 mmHg). Counter to the proposed hypothesis, the increase in MAP from the end of phase IIa to the end of phase IIb during heat stress was not attenuated. Conversely, this increase in MAP tended to be greater during heat stress relative to normothermia ( P = 0.06), suggesting that sympathetic activation may be elevated during this phase of the Valsalva while heat stressed. These data show that heat stress does not attenuate this index of vasoconstrictor responsiveness during the Valsalva maneuver.

Neurocirculatory consequences of abrupt change in sleep state in humans

1996 ◽  
Vol 80 (5) ◽  
pp. 1627-1636 ◽  
Author(s):  
B. J. Morgan ◽  
D. C. Crabtree ◽  
D. S. Puleo ◽  
M. S. Badr ◽  
F. Toiber ◽  
...  
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Pressor Response ◽  
Muscle Sympathetic Nerve Activity ◽  
Intrathoracic Pressure ◽  
Nrem Sleep ◽  
Auditory Stimuli ◽  
Sleep State ◽  
Healthy Humans ◽  
Pressor Responses

The arterial pressure elevations that accompany sleep apneas may be caused by chemoreflex stimulation, negative intrathoracic pressure, and/or arousal. To assess the neurocirculatory effects of arousal alone, we applied graded auditory stimuli during non-rapid-eye-movement (NREM) sleep in eight healthy humans. We measured muscle sympathetic nerve activity (intraneural microelectrodes), electroencephalogram (EEG; C4/A1 and O1/A2), arterial pressure (photoelectric plethysmography), heart rate (electrocardiogram), and stroke volume (impedance cardiography). Auditory stimuli caused abrupt increases in systolic and diastolic pressures (21 +/- 2 and 15 +/- 1 mmHg) and heart rate (11 +/- 2 beats/min). Cardiac output decreased (-10%). Stimuli that produced EEG evidence of arousal evoked one to two large bursts of sympathetic activity (316 +/- 46% of baseline amplitude). Stimuli that did not alter EEG frequency produced smaller but consistent pressor responses even though no sympathetic activation was observed. We conclude that arousal from NREM sleep evokes a pressor response caused by increased peripheral vascular resistance. Increased sympathetic outflow to skeletal muscle may contribute to, but is not required for, this vasoconstriction. The neurocirculatory effects of arousal may augment those caused by asphyxia during episodes of sleep-disordered breathing.

scholarly journals Heat stress attenuates the increase in arterial blood pressure during the cold pressor test

2010 ◽  
Vol 109 (5) ◽  
pp. 1354-1359 ◽  
Author(s):  
Jian Cui ◽  
Manabu Shibasaki ◽  
David A. Low ◽  
David M. Keller ◽  
Scott L. Davis ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Arterial Blood Pressure ◽  
Blood Pressure Response ◽  
Cold Pressor Test ◽  
Thermal Conditions ◽  
Cold Pressor ◽  
Pressor Test ◽  
Arterial Blood

The mechanisms by which heat stress impairs the control of blood pressure leading to compromised orthostatic tolerance are not thoroughly understood. A possible mechanism may be an attenuated blood pressure response to a given increase in sympathetic activity. This study tested the hypothesis that whole body heating attenuates the blood pressure response to a non-baroreflex-mediated sympathoexcitatory stimulus. Ten healthy subjects were instrumented for the measurement of integrated muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate, sweat rate, and forearm skin blood flow. Subjects were exposed to a cold pressor test (CPT) by immersing a hand in an ice water slurry for 3 min while otherwise normothermic and while heat stressed (i.e., increase core temperature ∼0.7°C via water-perfused suit). Mean responses from the final minute of the CPT were evaluated. In both thermal conditions CPT induced significant increases in MSNA and MAP without altering heart rate. Although the increase in MSNA to the CPT was similar between thermal conditions (normothermia: Δ14.0 ± 2.6; heat stress: Δ19.1 ± 2.6 bursts/min; P = 0.09), the accompanying increase in MAP was attenuated when subjects were heat stressed (normothermia: Δ25.6 ± 2.3, heat stress: Δ13.4 ± 3.0 mmHg; P < 0.001). The results demonstrate that heat stress can attenuate the pressor response to a sympathoexcitatory stimulus.

Experimental studies of iodine stationary plasma thruster

2019 ◽  
pp. 81-90
Author(s):  
Boris A. Sokolov ◽  
Pavel A. Shcherbina ◽  
Ivan B. Sishko ◽  
Aleksandr V. Shipovskiy Aleksandr ◽  
Aleksandr A. Lyapin ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Thermal Conditions ◽  
Economic Viability ◽  
Electron Drift ◽  
Experimental Facility ◽  
Operational Mode ◽  
Stationary Plasma Thruster ◽  
Stationary Plasma ◽  
Plasma Thruster ◽  
Closed Electron

The paper demonstrates the feasibility of using iodine as propellant for thrusters with closed electron drift and its economic viability. It describes a test setup for running experiments. It provides the results of experimental studies of the stationary plasma thruster using iodine as its propellant with xenon gas-passage hollow cathode, as well as of the operational mode of the thruster where a mixture of xenon and iodine is used. During tests gas dynamic and electrical properties of the thruster were analyzed. Thermal conditions in the iodine storage and supply system were studied. Conclusions were drawn on how the test object could be improved and upgraded. The paper describes the option to use a thermionic non-flow cathode as the compensator cathode for the operation of the iodine thruster. The paper provides the results of an experimental study of the prototype non-flow compensator cathode in diode mode. Based on the results of the studies an experimental facility was built for testing a thruster with non-flow compensator cathode. Key words: cathode, compensator cathode, thruster with closed electron drift, stationary plasma thruster, iodine.

scholarly journals The Effect Of Outside Corridor’s Orientation to Interior Thermal Condition at Lawang Sewu Semarang.

2018 ◽  
Vol 73 ◽  
pp. 01011
Author(s):  
Benediktus Yosef Arya Wastunimpuna ◽  
Wahyu Setia Budi ◽  
Erni Setyowati
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Thermal Condition ◽  
Natural Ventilation ◽  
Thermal Conditions ◽  
Standard Theory ◽  
Hot Wire ◽  
Air Movement ◽  
Dutch Colonial

The outside corridor of Dutch Colonial Building in Indonesia was made to make the temperature of the room more comfortable. Lawang Sewu Building in Semarang is one example of a building that has an outside corridor along the building and until now still use natural ventilation. This study focuses on finding out whether there is a difference on the thermal conditions of each room’s orientation, so after that we know the effect of orientation of the outdoor corridor to the temperature of the interior. In this study the experiment based on measurement using Heat Stress WBGT Meter for Wet Bulb Temperature, Dry Bulb Temperature, Relative Humidity, and KW0600653 Hot Wire Anemometer for the air movement. The data will be analysed using thermal standard theory to find out which point has the most comfortable thermal conditions.. At the end of this study will be found the effect of corridor’s orientation to thermal condition of the interior in Lawang Sewu Semarang.

A preliminary systematic review and meta-analysis on the effects of heart rate variability biofeedback on heart rate variability and respiration of athletes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jeffrey Cayaban Pagaduan ◽  
Yung-Sheng Chen ◽  
James William Fell ◽  
Sam Shi Xuan Wu
Keyword(s):  
Systematic Review ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Web Of Science ◽  
Meta Analysis ◽  
Academic Research ◽  
Experimental Studies ◽  
Quantitative Review ◽  
Heart Rate Variability Biofeedback ◽  
Randomized Control

Abstract To date, there is no quantitative review examining the influence of heart rate variability biofeedback (HRV BFB) on the athlete population. Such an undertaking may provide valuable information on the autonomic and respiration responses of athletes when performing HRV BFB. Thus, purpose of this preliminary systematic review and meta-analysis on the effects of HRV BFB on HRV and respiration of athletes. Searches of Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect were conducted for studies that met the following criteria: (1) experimental studies involving athletes that underwent randomized control trial; (2) availability of HRV BFB as a treatment compared with a control (CON)/placebo (PLA); (3) any pre and post HRV variable and/or breathing frequency as dependent variable/s; and, (4) peer-reviewed articles written in English. Four out of 660 studies involving 115 athletes (25 females and 90 males) ages 16–30 years old were assessed in this review. Preliminary findings suggest the promising ability of HRV BFB to improve respiratory mechanics in athlete population. More work is needed to determine the autonomic modulatory effect of HRV BFB in athletes.

250 AI-Supported Sleep Staging from Activity and Heart Rate

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A101-A101
Author(s):  
Samadrita Chowdhury ◽  
TzuAn Song ◽  
Richa Saxena ◽  
Shaun Purcell ◽  
Joyita Dutta
Keyword(s):  
Heart Rate ◽  
Network Architecture ◽  
Class Imbalance ◽  
Nrem Sleep ◽  
Sleep Time ◽  
Deep Sleep ◽  
Sleep Staging ◽  
Temporal Correlations ◽  
Stage Classification ◽  
Small Form Factor

Abstract Introduction Polysomnography (PSG) is considered the gold standard for sleep staging but is labor-intensive and expensive. Wrist wearables are an alternative to PSG because of their small form factor and continuous monitoring capability. In this work, we present a scheme to perform such automated sleep staging via deep learning in the MESA cohort validated against PSG. This scheme makes use of actigraphic activity counts and two coarse heart rate measures (only mean and standard deviation for 30-s sleep epochs) to perform multi-class sleep staging. Our method outperforms existing techniques in three-stage classification (i.e., wake, NREM, and REM) and is feasible for four-stage classification (i.e., wake, light, deep, and REM). Methods Our technique uses a combined convolutional neural network coupled and sequence-to-sequence network architecture to appropriate the temporal correlations in sleep toward classification. Supervised training with PSG stage labels for each sleep epoch as the target was performed. We used data from MESA participants randomly assigned to non-overlapping training (N=608) and validation (N=200) cohorts. The under-representation of deep sleep in the data leads to class imbalance which diminishes deep sleep prediction accuracy. To specifically address the class imbalance, we use a novel loss function that is minimized in the network training phase. Results Our network leads to accuracies of 78.66% and 72.46% for three-class and four-class sleep staging respectively. Our three-stage classifier is especially accurate at measuring NREM sleep time (predicted: 4.98 ± 1.26 hrs. vs. actual: 5.08 ± 0.98 hrs. from PSG). Similarly, our four-stage classifier leads to highly accurate estimates of light sleep time (predicted: 4.33 ± 1.20 hrs. vs. actual: 4.46 ± 1.04 hrs. from PSG) and deep sleep time (predicted: 0.62 ± 0.65 hrs. vs. actual: 0.63 ± 0.59 hrs. from PSG). Lastly, we demonstrate the feasibility of our method for sleep staging from Apple Watch-derived measurements. Conclusion This work demonstrates the viability of high-accuracy, automated multi-class sleep staging from actigraphy and coarse heart rate measures that are device-agnostic and therefore well suited for extraction from smartwatches and other consumer wrist wearables. Support (if any) This work was supported in part by the NIH grant 1R21AG068890-01 and the American Association for University Women.

scholarly journals Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans

2012 ◽  
Vol 47 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Masaki Iguchi ◽  
Andrew E. Littmann ◽  
Shuo-Hsiu Chang ◽  
Lydia A. Wester ◽  
Jane S. Knipper ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Heat Shock ◽  
Body Temperature ◽  
Controlled Trial ◽  
Whole Body ◽  
Cord Injury ◽  
Whole Body Heat Stress ◽  
Body Heat

Context: Conditions such as osteoarthritis, obesity, and spinal cord injury limit the ability of patients to exercise, preventing them from experiencing many well-documented physiologic stressors. Recent evidence indicates that some of these stressors might derive from exercise-induced body temperature increases. Objective: To determine whether whole-body heat stress without exercise triggers cardiovascular, hormonal, and extra-cellular protein responses of exercise. Design: Randomized controlled trial. Setting: University research laboratory. Patients or Other Participants: Twenty-five young, healthy adults (13 men, 12 women; age = 22.1 ± 2.4 years, height = 175.2 ± 11.6 cm, mass = 69.4 ± 14.8 kg, body mass index = 22.6 ± 4.0) volunteered. Intervention(s): Participants sat in a heat stress chamber with heat (73°C) and without heat (26°C) stress for 30 minutes on separate days. We obtained blood samples from a subset of 13 participants (7 men, 6 women) before and after exposure to heat stress. Main Outcome Measure(s): Extracellular heat shock protein (HSP72) and catecholamine plasma concentration, heart rate, blood pressure, and heat perception. Results: After 30 minutes of heat stress, body temperature measured via rectal sensor increased by 0.8°C. Heart rate increased linearly to 131.4 ± 22.4 beats per minute (F6,24 = 186, P &lt; .001) and systolic and diastolic blood pressure decreased by 16 mm Hg (F6,24 = 10.1, P &lt; .001) and 5 mm Hg (F6,24 = 5.4, P &lt; .001), respectively. Norepinephrine (F1,12 = 12.1, P = .004) and prolactin (F1,12 = 30.2, P &lt; .001) increased in the plasma (58% and 285%, respectively) (P &lt; .05). The HSP72 (F1,12 = 44.7, P &lt; .001) level increased with heat stress by 48.7% ± 53.9%. No cardiovascular or blood variables showed changes during the control trials (quiet sitting in the heat chamber with no heat stress), resulting in differences between heat and control trials. Conclusions: We found that whole-body heat stress triggers some of the physiologic responses observed with exercise. Future studies are necessary to investigate whether carefully prescribed heat stress constitutes a method to augment or supplement exercise.

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