scholarly journals Evaluation of 2 Heat-Mitigation Methods in Army Trainees

2016 ◽  
Vol 51 (11) ◽  
pp. 936-945 ◽  
Author(s):  
JoEllen M. Sefton ◽  
J. S. McAdam ◽  
David D. Pascoe ◽  
K. R. Lohse ◽  
Robert L. Banda ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Core Temperature ◽  
Control Treatment ◽  
Controlled Clinical Trial ◽  
Humid Climate ◽  
Physically Active ◽  
Perceived Temperature ◽  
Fort Benning ◽  
Mitigation Methods

Context: Heat injury is a significant threat to military trainees. Different methods of heat mitigation are in use across military units. Mist fans are 1 of several methods used in the hot and humid climate of Fort Benning, Georgia. Objectives: To determine if (1) the mist fan or the cooling towel effectively lowered participant core temperature in the humid environment found at Fort Benning and (2) the mist fan or the cooling towel presented additional physiologic or safety benefits or detriments when used in this environment. Design: Randomized controlled clinical trial. Setting: Laboratory environmental chamber. Patients or Other Participants: Thirty-five physically active men aged 19 to 35 years. Intervention(s): (1) Mist fan, (2) commercial cooling towel, (3) passive-cooling (no intervention) control. All treatments lasted 20 minutes. Participants ran on a treadmill at 60% V̇o2max. Main Outcome Measure(s): Rectal core temperature, heart rate, thermal comfort, perceived temperature, perceived wetness, and blood pressure. Results: Average core temperature increased during 20 minutes of cooling (F1,28 = 64.76, P < .001, ηp2 = 0.70), regardless of group (F1,28 = 3.41, P = .08, ηp2 = 0.11) or condition (F1,28 < 1.0). Core temperature, heart rate, and blood pressure did not differ among the 3 conditions. Perceived temperature during 20 minutes of cooling decreased (F1,30 = 141.19, P < .001, ηp2 = 0.83) regardless of group or condition. Perceived temperature was lower with the mist-fan treatment than with the control treatment (F1,15 = 7.38, P = .02, ηp2 = 0.32). The mist-fan group perceived themselves to be cooler even at elevated core temperatures. Conclusions: The mist fan and cooling towel were both ineffective at lowering core temperature. Core temperature continued to increase after exercise in all groups. The mist fan produced feelings of coolness while the core temperature remained elevated, possibly increasing the risk of heat illness.

Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

2008 ◽  
Vol 294 (2) ◽  
pp. F309-F315 ◽  
Author(s):  
Joo Lee Cham ◽  
Emilio Badoer
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Core Temperature ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Body Core Temperature ◽  
Control Group ◽  
Body Core

Redistribution of blood from the viscera to the peripheral vasculature is the major cardiovascular response designed to restore thermoregulatory homeostasis after an elevation in body core temperature. In this study, we investigated the role of the hypothalamic paraventricular nucleus (PVN) in the reflex decrease in renal blood flow that is induced by hyperthermia, as this brain region is known to play a key role in renal function and may contribute to the central pathways underlying thermoregulatory responses. In anesthetized rats, blood pressure, heart rate, renal blood flow, and tail skin temperature were recorded in response to elevating body core temperature. In the control group, saline was microinjected bilaterally into the PVN; in the second group, muscimol (1 nmol in 100 nl per side) was microinjected to inhibit neuronal activity in the PVN; and in a third group, muscimol was microinjected outside the PVN. Compared with control, microinjection of muscimol into the PVN did not significantly affect the blood pressure or heart rate responses. However, the normal reflex reduction in renal blood flow observed in response to hyperthermia in the control group (∼70% from a resting level of 11.5 ml/min) was abolished by the microinjection of muscimol into the PVN (maximum reduction of 8% from a resting of 9.1 ml/min). This effect was specific to the PVN since microinjection of muscimol outside the PVN did not prevent the normal renal blood flow response. The data suggest that the PVN plays an essential role in the reflex decrease in renal blood flow elicited by hyperthermia.

11 Circadian Rhythm of Core Temperature, Blood Pressure and Heart Rate in Hypothyroid and Normal Rats

2015 ◽  
pp. 55-59
Author(s):  
P De Remigis ◽  
P Cugini ◽  
F Halberg ◽  
S Sensi ◽  
D Scavo
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Circadian Rhythm ◽  
Core Temperature

scholarly journals Efficacy of Intravenous Ondansetron on Hemodynamic Complications in Women Undergoing Spinal Anesthesia for Cesarean Section: A Randomized Placebo Controlled Clinical Trial

2016 ◽  
Vol 5 (1) ◽  
pp. 13-18
Author(s):  
Pouran Hajian ◽  
Bita Malekianzadeh ◽  
Maryam Davoudi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Placebo Group ◽  
Cesarean Section ◽  
Spinal Anesthesia ◽  
Nausea And Vomiting ◽  
Elective Cesarean Section ◽  
Controlled Clinical Trial ◽  
Sterile Water ◽  
Elective Cesarean

Background: Several methods are used for the prevention or decreasing the incidence of spinal anesthesia hemodynamic complications. Ondansetron is a 5HT3 receptor antagonist with known efficacy on preventing nausea and vomiting and probably on intrathecal opioid-induced pruritus. The present study aims to evaluate the effects of intravenous Ondansetron on the attenuation of blood pressure and heart rate, by 5HT3 blocking in vagal nerve endings and effect on Bezold Jarish reflex. Material and Methods: One hundred and two candidates for elective cesarean section were randomized into 2 groups of 51 cases, the Ondansetron group received 4mg Ondansetron intravenously before performing spinal anesthesia, and placebo group received 2cc sterile water. Hypotension was defined: Systolic blood pressure less than 100 MmHg or fall more than 20% from primary BP which was treated by administration of Ephedrine in case of any. In both groups, Ondansetron effect was studied on hypotension occurrence, bradycardia, consumed Ephedrine amount, pruritus, nausea and vomiting. Results: There were no statistically significant differences in systolic/diastolic blood pressure, Mean Arterial Pressure, heart rate and pruritus in both groups (P=0.081).Nausea and vomiting in the first 10 minutes after spinal anesthesia were lesser in Ondansetron group (P= 0.001). Mean consumed Ephedrine was significantly lesser in Ondansetron group (5.8 mg in Ondansetron and 10.7 mg in placebo group, P=0.009). Conclusion: Ondansetron  given  intravenously  with  antiemetic  dose  (4  mg)  decreases  mean consumed Ephedrine and nausea and vomiting after spinal anesthesia, but does not have an influence on blood pressure, heart rate and pruritus.[GMJ. 2016;5(1):13-18]

Abstract 200: Glycopyrrolate Does Not Ameliorate Bradycardia During Prolonged Cooling in Awake Subjects

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_2) ◽  
Author(s):  
Jon C Rittenberger ◽  
Alex Weissman ◽  
Kate Flickinger ◽  
Francis X Guyette ◽  
Melissa Repine ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Core Temperature ◽  
Mean Arterial Blood Pressure ◽  
Anticholinergic Drugs ◽  
Surface Cooling ◽  
Vessel Occlusion ◽  
Arterial Blood ◽  
Dexmedetomidine Infusion

Introduction: Hypothermia may help improve outcomes in patients with large vessel occlusion cerebrovascular accidents or other reversible ischemia. Dexmedetomidine infusion reduces shivering in awake subjects undergoing hypothermia but has dose-limiting bradycardia. If vagally mediated, anticholinergic drugs might reduce bradycardia. Hypothesis: Glycopyrrolate prevents bradycardia during dexmedetomidine-assisted prolonged hypothermia. Methods: Eight healthy subjects were randomly assigned to 0.4mg glycopyrrolate bolus, glycopyrrolate rescue (0.01mg every 3 minutes as needed for heart rate <50), or no glycopyrrolate during three separate sessions of 3 hours cooling. Following 1mg/kg dexmedetomidine bolus, subjects received 20cc/kg of (4 0 C) cold saline and surface cooling (EM COOLS, Weinerdorf Austria). Dexmedetomidine infusion was titrated to suppress shivering but allow arousal to verbal stimuli. After 3 hours of cooling, we allowed subjects to rewarm. We compared heart rate, core temperature, and mean arterial blood pressure between groups using Kruskal-Wallis test and ANOVA. Results: Mean age was 27 (SD 6) years and most (N=6, 75%) were male. Mean pre-treatment resting heart rate was 73 [SD 13] bpm. Neither heart rate nor core temperature differed between the groups during the stable hypothermia period (p>0.05). (Figure) Mean arterial blood pressure was higher in the glycopyrrolate bolus group than the other two groups during the study period (p<0.048). Conclusions: Glycopyrrolate did not prevent the bradycardic response to hypothermia and dexmedetomidine. Mean arterial blood pressure was higher in subjects receiving a bolus of glycopyrrolate before induction of hypothermia.

Effect of Different Types of Lower-limb Exercise on Blood Pressure in Hypertensive People: A Randomized, Double-blind Controlled Clinical Trial

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Rozita Hedayti ◽  
Salimeh Mahmoodi ◽  
Rasool Bagheri ◽  
Marjan Biglary ◽  
Amir Hoshang Bakhtiary ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Diastolic Blood Pressure ◽  
Controlled Clinical Trial ◽  
Maximum Oxygen Consumption ◽  
Exercise Interventions ◽  
Concentric Exercise ◽  
Significant Difference

Objectives: The current study aimed at determining the immediate and long-lasting effects of eccentric and concentric exercises on hypertension in individuals with high blood pressure. Methods: A total of 45 hypertensive volunteers were randomly assigned to three intervention groups as eccentric exercise (n = 15), concentric exercise (n = 15), and control (n = 15) groups. All the volunteers underwent exercise interventions for four weeks, three sessions per week (12 sessions in total) as treadmill walking with +10% gradient (concentric group), -10% gradient (eccentric group), or neutral gradient. Before the intervention, immediately after the first session of the intervention, after the end of the intervention, and 48 hours after the end of the intervention, systolic and diastolic blood pressure, heart rate, and maximum oxygen consumption were measured and compared between the groups. Results: The positive gradient group had higher diastolic blood pressure 48 h after the intervention than the negative and neutral gradient groups (P < 0.05). There was no significant difference in the other study variables between eccentric and concentric exercise groups (P > 0.05). Statistical analysis showed that eccentric exercises immediately reduced systolic and diastolic blood pressure (P < 0.05). Eccentric and constrictive exercises reduced systolic and diastolic blood pressure for the long term (P < 0.05). Exonerative and constrictive exercises improved the heart rate, maximum oxygen consumption, and systolic blood and diastolic blood pressure in the short and long term (P < 0.05). Conclusions: Eccentric and concentric exercises with immediate and long-lasting effects improved systolic and diastolic blood pressure, as well as heart rate and maximum oxygen consumption. No significant difference was found between the two types of exercises in terms of the variables studied.

scholarly journals Blood pressure, heart rate, and rate pressure product behavior during interval and continuous aerobic exercise (Comportamiento de la presión arterial, frecuencia cardíaca y doble producto durante el ejercicio aeróbico a intervalos y continuo)

Retos ◽  
2021 ◽  
Vol 43 ◽  
pp. 579-585
Author(s):  
Victor Gonçalves Corrêa Neto ◽  
Juliana Augusto Do Rosário ◽  
Nathaniel Bodell ◽  
Gleisson Da Silva Araujo ◽  
Luiz Guilherme Da Silva Telles ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Aerobic Exercise ◽  
Rate Pressure Product ◽  
Maximum Heart Rate ◽  
Physically Active ◽  
Athletic Population ◽  
Experimental Protocols ◽  
Study Participants ◽  
Practical Implications

The purpose of the present study was to compare the blood pressure, heart rate, and rate pressure product behavior during interval and continuous aerobic exercise in physically active women. Eight physically active women with prior indoor cycling experience were recruited for the present study. Participants visited the laboratory for three sessions, the first visit was used for familiarization and the remaining two visits were to perform the experimental protocols in a randomized order: 1) Twenty-one minutes of continuous indoor cycling at 70% of maximum heart rate (CONT), and 2) Twenty-one minutes of interval indoor cycling, alternating one minute at 90% and two minutes at 60% of maximum heart rate (INT). To assess the hemodynamic behavior, blood pressure, heart rate, and rate pressure product were also measuring at 6-minute (During-6), 12-minute (During-12), 18-minute (During-18), and 21-minute (During-21) intervals. Both protocols (continuous and interval) showed significant increases in blood pressure, heart rate, and rate pressure product in three out of four moments (During-6, During-12, and During-21), with the interval protocol showing higher values compared to the continuous protocol. The results of this study have practical implications for both prescription and cardiac rehabilitation and may be used in an athletic and non-athletic population, since a hypotension effect and lower cardiac workload is advantageous to one’s fitness.  Resumen. El propósito del presente estudio fue comparar lo comportamiento de la presión arterial, la frecuencia cardíaca y doble producto durante el ejercicio aeróbico continuo y a intervalos en mujeres físicamente activas. Para el presente estudio se reclutaron ocho mujeres físicamente activas con experiencia previa en ciclismo indoor. Los participantes visitaron el laboratorio durante tres sesiones, la primera visita se utilizó para familiarizarse y les das visitas restantes fueron para realizar los protocolos experimentales en un orden aleatorio: 1) Veintiún minutos de ciclismo indoor continuo al 70% de la frecuencia cardíaca máxima (CONT), y 2) Veintiún minutos de ciclismo indoor a intervalos, alternando un minuto al 90% y dos minutos al 60% de la frecuencia cardíaca máxima (INT). Para evaluar el comportamiento de la presión arterial, la frecuencia cardíaca y doble producto también se midieron a los 6 minutos (Durante-6), 12 minutos (Durante-12), 18 minutos (Durante-18) y 21 minutos (durante-21) durante la actividad. Ambos los protocolos (CONT y INT) mostraron aumentos significativos en la presión arterial, la frecuencia cardíaca, y el doble producto en tres de cuatro momentos (Durante-6, Durante-12 y durante-21), con el protocolo INT que muestra los valores más altos en comparación al protocolo CONT. Los resultados de este estudio tienen implicaciones prácticas tanto para la prescripción médica como para la rehabilitación cardíaca y pueden usarse en una población atlética y no atlética, ya que un efecto de hipotensión y una menor carga de trabajo cardíaco son ventajosos para la aptitud física.

scholarly journals Multicap to improve adherence after acute coronary syndromes: results of a randomized controlled clinical trial

2020 ◽  
Vol 14 ◽  
pp. 175394472091207
Author(s):  
Javier Mariani ◽  
Andrés Rosende ◽  
Maximiliano De Abreu ◽  
Gabriel Gonzalez Villa Monte ◽  
Heraldo D’Imperio ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Blood Pressure ◽  
Heart Rate ◽  
Platelet Aggregation ◽  
Fixed Dose ◽  
Control Group ◽  
Controlled Clinical Trial ◽  
Adherence To Treatment ◽  
C Reactive Protein ◽  
Reactive Protein

Background: Adherence to treatment after a myocardial infarction (MI) is poor, even in the early postinfarction period. Combining evidence-based drugs into a multicap could improve adherence in this population. No previous randomized trial assessing fixed-dose combination therapy has included patients early after a MI. We aimed to assess if a multicap containing four secondary prevention drugs increases adherence to treatment at 6 months after MI hospitalization. The study was designed as a randomized, parallel, open-label, controlled trial. Methods: Patients were randomized within 7 days of a MI to either multicap or control group. The multicap group received a capsule containing aspirin, atenolol, ramipril, and simvastatin. The control group received each drug in separate pills. The primary outcome was adherence at 6 months. We also measured blood pressure, heart rate, serum cholesterol levels, C-reactive protein, and platelet aggregation. Results: The study was stopped prematurely when 100 patients were included for futility. At 6 months, 92 (95.8%) patients were adherent to medical treatment: 98.0% in the multicap group and 93.5% in the control group [relative risk (RR) 1.05; 95% confidence interval (CI) 0.96–1.14; p = 0.347]. There were no differences between groups in systolic blood pressure ( p = 0.662), diastolic blood pressure ( p = 0.784), heart rate ( p = 0.533), total cholesterol ( p = 0.760), LDL-c ( p = 0.979), C-reactive protein ( p = 0.399), or in the proportion of patients with adequate platelet aggregation inhibition ( p = 0.600). Conclusions: The study did not find any improvement in the adherence at 6 months after a MI with a multicap-based strategy (Multicap for Increase Adherence After Acute Myocardial Infarction; [ ClinicalTrials.gov identifier: NCT02271178]).

Hypoxia-induced metabolic and core temperature changes in the squirrel monkey

1977 ◽  
Vol 42 (2) ◽  
pp. 273-278 ◽  
Author(s):  
D. H. Horstman ◽  
L. E. Banderet
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Core Temperature ◽  
Heat Production ◽  
Squirrel Monkeys ◽  
Experimental Conditions ◽  
Temperature Changes ◽  
Arterial Blood ◽  
Arterial Ph ◽  
Skin Temperatures

To identify components of reduced core temperature (Tre) with exposure to hypoxia, oxygen uptake (VO2) and skin temperatures were measured in chair-restrained squirrel monkeys during conditions of 21% O2, 11% O2, and 11% O2 + 5% CO2. Exposure to 11% O2 resulted in a 20% decrease in VO2 and a 1.8 degrees C reduction of Tre with skin temperatures closely paralleling Tre. The addition of 5% CO2 to 11% O2 effectively blocked the decrease of both VO2 and Tre. The responses of one monkey (LD) exhibiting decreased Tre (greater than 2.0 degrees C) and 20% decrease in VO2 were compared to those of another (SD) exhibiting decreased Tre (less than 0.5 degrees C) and little change of VO2 under the same experimental conditions. Increased mean arterial blood pressure (BPa) and heart rate (HR) occurred for monkey SD, while for monkey LD BPa decreased and HR increased slightly. Arterial pressure of oxygen (PaO2) and calculated arterial saturation of oxygen (SaO2) were higher, while PaCO2 was lower for monkey SD than for monkey LD. When 5% CO2 was added to 11% O2 both animals exhibited decreased PaO2, little change of Tre, VO2, PaCO2, arterial pH, and calculated SaO2, and increased BPa and HR. These data suggest that decreased Tre resulted from reduced heat production and reduced oxygen transport was primarily responsible for reduction of heat production.

Contribution of brown adipose tissue to central PGE1-evoked hyperthermia in rats

1991 ◽  
Vol 260 (1) ◽  
pp. R59-R66 ◽  
Author(s):  
D. M. Fyda ◽  
K. E. Cooper ◽  
W. L. Veale
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Adipose Tissue ◽  
Systolic Blood Pressure ◽  
Brown Adipose Tissue ◽  
Core Temperature ◽  
Tissue Temperature ◽  
Whole Body ◽  
Central Administration ◽  
Brown Adipose

The relative contribution of several effector systems to a prostaglandin E1-(PGE1) evoked hyperthermia was examined. Infusion of 150 ng of PGE1 into a lateral cerebral ventricle increased core temperature and whole body metabolic rate, brown adipose tissue temperature, systolic blood pressure, and heart rate. Pretreating the animals with a nonselective beta-antagonist propranolol (1 mg/kg iv in 0.3 ml followed by 3 mg.kg-1.h-1 in 0.3 ml/h) not only attenuated the rise in metabolism observed after the central administration of 150 ng PGE1 but also diminished the elevation in both core and brown fat tissue temperatures as well as the increase in heart rate. Pretreating the animals with the alpha-antagonist prazosin (2 mg/kg im followed by 50 micrograms.kg-1.h-1 iv in 0.3 ml/h) somewhat reduced the rise in whole body metabolism, suppressed the elevation in core temperature, but failed to alter the rise in brown adipose tissue temperature normally seen after the central administration of PGE1. Moreover, both the rise in systolic blood pressure and heart rate were attenuated when the PGE1 administration was preceded by prazosin. These results suggest that brown adipose tissue is an important effector organ responsible for mediating the hyperthermic response observed after the intracerebral injection of PGE1. In addition, the results indicate that alterations in vasomotor tone may also be important in producing or sustaining the elevated core temperature found after a pyrogen administration.

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