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At least 1,747 records · Page 97Linked to original sources
PubMed1991

Plasma volume shifts with immersion at rest and two exercise intensities.

Eight men were studied to determine the effect of cycling exercise on plasma volume (PV) during water immersion to the xiphoid process (WIX). In all protocols the subjects were seated upright. After 30 min of rest, subjects were immersed in 34.5 degrees C water and seated on a cycling ergometer. During three 1 h WIX protocols, subjects either remained at rest (No Ex) or pedaled from minutes 20 to 30 at 38% (Ex1) or 62% (Ex2) of peak oxygen consumption (VO2peak). Hematocrit (Hct) and hemoglobin concentration [( Hb]) from venous blood samples were compared pre-WIX and at minutes 20, 30, 40, and 60. Percent change in PV (delta PV) was calculated from pre-WIX Hct and [Hb] within each protocol. Hct and [Hb] decreased after 20 min of resting WIX (P less than 0.017). In the No Ex protocol, there were no further significant changes in these variables, with delta PV values of +10.4% at minute 20 and at a peak of +13.5% at minute 40. In Ex1 and Ex2, cycling increased Hct and [Hb] (P less than 0.01, minute 30 vs No Ex), with delta PV values at minute 30 of +3.7% and -0.9%, respectively, vs +12.8% in No Ex. Minute 60 values between protocols were not significantly different (mean delta PV of +10.8 +/- 0.6% SD). The hemodilution associated with WIX was either partially or completely attenuated by cycling exercise; the degree of hemoconcentration was related to exercise intensity. The exercise-induced hemoconcentration was reversed by 30 min of resting WIX. Exercise during WIX appears to cause similar decreases in PV, as does exercise in air provided that postural hemoconcentration prior to exercise is not already maximal.

Adult↗
PubMed1990

The effect of almitrine on the steady-state ventilatory response to carbon dioxide at rest and during exercise in man.

Almitrine has potential as a tool for testing the physiological role of the peripheral chemoreceptor. The effects of almitrine on CO2 chemosensitivity were studied at rest and during light exercise using a constant inflow technique that avoids the hyperoxia of rebreathing methods. The steady-state ventilatory response to CO2 was measured in two groups of six normal men before and 150 min after 100 mg oral almitrine bismesylate or placebo. One group was studied at rest, the other while pedalling at 50 W. The resting group showed a significant increase in CO2 response slope after almitrine when compared with placebo but there was no significant change in the response intercept. During exercise the individual results were very variable and after almitrine no significant change was seen in either the response slope or intercept. Control ventilation was not affected by almitrine in either group. Even in the absence of marked hyperoxia the effect of almitrine on CO2 sensitivity at rest in small. The lack of effect at 50 W is against any important role for the peripheral chemoreceptor during light exercise but other interpretations are possible.

Adult↗
PubMed1990

[Regional myocardial blood flow measurements in resting and dipyridamole induced vasodilative state by Xenon-133 clearance method].

Myocardial imaging with Xenon-133 and a gamma camera was employed to evaluate the relationship between angiographically demonstrated coronary artery stenosis and regional myocardial blood flow (r-MBF) in 22 patients with ischemic heart disease and 9 control subjects. After a left anterior oblique cineangiogram was obtained, the cinecamera was replaced by the mobile gamma camera in the same plane and location over the pericardium of patients. Then, 370 MBq (10 mCi) of 133Xe was injected into the left coronary artery as a bolus. After the first measurement of r-MBF in resting state, a second injection was made 3 minutes after intravenous injection of 0.56 mg/kg of dipyridamole for 4 minutes. The r-MBF in different regions of the heart was calculated by Kety formula. Coronary flow reserve (CFR) was defined the rMBF ratio between resting and dipyridamole induced vasodilative state. In the resting state, good correlation (r = 0.711) was observed between pressure rate product and the r-MBF at the areas perfused by non stenotic vessels. The r-MBF of the areas perfused by severe stenotic vessels (greater than 90%) was smaller than that of the areas perfused by non stenotic vessels, however there was overlapping of flow. In the dipyridamole induced vasodilative state, the r-MBF of the areas perfused by intact vessels increased approximately 2.4 times of the resting state, and showed good correlation with pressure rate product. In contrast, the r-MBF of the areas perfused by stenotic vessels did not correlate with pressure rate product, but depended on the degrees of coronary stenosis (50-75% stenosis; 1.9 times, greater than 90% stenosis; 1.3 times, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Perfusion and function at rest and treadmill exercise using technetium-99m-sestamibi: comparison of one- and two-day protocols in normal volunteers.

The purpose of this study was to explore the feasibility of performing rest and exercise technetium-99m-sestamibi (99mTc-sestamibi) studies on the same day. We prospectively studied 34 asymptomatic volunteers using two different protocols (17 patients studied using one-day protocol and 17 patients studied using two-day protocol). For the one-day protocol, the rest study was performed first. For the two-day protocol, the exercise study was performed first followed by a second-day rest study. Left and right ventricular ejection fractions, myocardium/lung, myocardium/liver, myocardium/spleen, and myocardium/gallbladder count ratios were similar for the one- and two-day groups. No significant difference was observed in any variable measured. These data suggest that 99mTc-sestamibi can be used for rest and treadmill exercise studies performed on the same day to provide assessment of ventricular function and perfusion similar to studies performed on separate days.

Abdomen↗
PubMed1989

[Correlation between Selvester's QRS score and left ventricular function at rest and during effort in patients who survived myocardial infarction].

This study was carried out in order to determine if there is any correlation between QRS score and left ventricular function at rest and during exercise after single myocardial infarction. Selvester's QRS scoring system to determine infarct size by observing Q and R standard 12-lead ECG was independently applied by three cardiologists. Left ventricular function was determined using the resting angiographic LVEF, the pulmonary wedge pressure in supine position and during exercise. The total work performed and the heart rate and systolic blood pressure percentage increase (delta) were also considered. Forty-eight male pts (mean age 52.3 +/- 8.7) were studied within 2 months after acute myocardial infarction. The site of the myocardial infarction was anterior in 13, inferior in 20, inferior plus posterior in 15. There were poor correlations between QRS score and left ventricular ejection fraction (r = -0.44) and pulmonary wedge pressure in supine position and during exercise, total work performed, delta heart rate and delta systolic blood pressure. There was no significant difference in mean QRS score between pts with abnormal (greater than 12 mmHg) and normal resting pulmonary wedge pressure in supine position (10.8 +/- 8.4 vs 7.3 +/- 5.8) or between pts with abnormal (greater than 20 mmHg) and normal exertional pulmonary wedge pressure (10.5 +/- 8.4 vs 7.4 +/- 5.7). In conclusion, the QRS score, obtained up to 30 days following an acute myocardial infarction, is not useful in determining left ventricular function at rest or during exercise.

Blood Pressure↗
PubMed1989

[Current views on bed rest in pediatrics].

The author reviews the method of laying and bed rest that has been used for several centuries, describes the aim and assumed advantages of this therapeutic precautions. The criticism concerning the inflexible prescriptions are dealt with. Some disease groups where concerning laying and bed rest new viewpoints were brought up and discussed in the literature are dealt with in details. Studying the literature the author advises to weight the assumed positive effect of bed rest against the not always favourable effect that a "confinement to bed" means for a child. The author is of the opinion that the sometimes inflexible principles learned and applied in connection with laying and bed rest should be reconsidered and reassessed and if necessary changed.

Bed Rest↗
PubMed1988

A comparative study of continuous ultrasound, placebo ultrasound and rest in epicondylalgia.

In this study the pain alleviating effects of continuous ultrasound treatment in epicondylalgia has been compared to placebo ultrasound and to rest. Of 99 patients 33 were randomly allocated to receive continuous ultrasound treatment, 33 to placebo ultrasound treatment and 33 were recommended only rest. The 66 patients treated were each given 10 treatments over 5 to 6 weeks. The condition was significantly improved in the group treated with continuous ultrasound in 36%, in 30% given placebo, and in 24% of those recommended rest. A significant improvement was noted when the effect of continuous ultrasound was compared with rest, but continuous ultrasound treatment was not significantly better than placebo ultrasound.

Adult↗
PubMed1988

Hemodynamics in essential hypertension at rest and during exercise--a 20-year follow-up study.

In connection with a mass screening of the Bergen population 93 patients with essential hypertension and 48 normotensive controls were studied in 1965-66. Blood pressure (BP) was recorded intraarterially, cardiac output (CO), by dilution method, heart rate (HR) by ECG and oxygen consumption (VO2) by Douglas bag/Scholander technique. Studies were performed during rest and 50, 100 and 150 watt steady state exercise. The most important initial findings were: Although CO and HR were higher in the youngest hypertensive group (17-29 yrs) than in normotensive age matched controls VO2 was also increased and no true luxury perfusion was demonstrated. Exercise stroke index (SI) did not increase to the same level as in normotensives and total peripheral resistance index (TPRI) during exercise was increased. Cross-sectional data showed a reduction in SI and CI and an increase in TPRI with increasing age - at rest as well as during exercise. 10-year follow-up: 28 subjects initially below 40 years were completely untreated. During the first 10 years there was a fall in CI and SI of approximately 15% and TPRI increased by 20%. The same changes were seen at rest as well as during exercise. Resting blood pressure was practically unchanged. Nearly all patients greater than 40 yrs were treated. 20-year follow-up: Between the 10 year and 20 year follow-up DAP rose to 100 mmHg or more in most of the subjects less than 40 yrs and treatment had to be started. Generally diuretics, betablockers or a combination of the 2 were used. Before the 20 year follow-up, treatment was withdrawn for 2 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

[Study of myocardial perfusion at rest using technetium Tc 99m methoxy-isobutylisonitrile: comparison with labeled microspheres and thallium 201].

In order to evaluate the potential usefulness of 99m technetium (Tc)-methoxy-isobutyl-isonitrile (MIBI) as a myocardial perfusion tracer in man, its myocardial distribution at rest was compared with that of 201thallium (TI). Perfusion images obtained with 99mTc-labelled microspheres, whose myocardial distribution is exclusively coronary flow dependent, were used as reference. The study was performed on twelve patients (10 males and 2 females, mean age 55.4 +/- 6.4) with suspected effort angina and without a history of previous myocardial infarction. In the space of two weeks patients underwent rest and exercise 99mTc-MIBI myocardial scintigraphy, exercise-redistribution 201TI myocardial scintigraphy, 99mTc-labelled microsphere scintigraphy after microsphere injection in the left ventricle at rest during catheterization before performing left ventriculography and coronary angiography. The comparison with microsphere distribution was limited to rest 99mTc-MIBI scintigraphy and redistribution 201TI images. Single photon emission tomography (SPECT) was employed. SPECT was performed using a double-head Rotacamera with a 360 degrees rotation arc. Ninety projections of 20 seconds each were acquired; subsequently image reconstruction was performed using an iterative algorithm. To evaluate regional perfusion the left ventricular wall was divided into 18 segments; the uptake pattern of each segment was graduated according to a qualitative score (0: severe defect; 1: moderate defect; 2: normal uptake). The quality of tomographic myocardial 99mTc-MIBI and 99mTc-microspheres images was higher than that of 201TI tomograms in account of the different physical characteristics of the two radionuclides.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1977

Forearm and splanchnic blood flow at rest and during exercise in relation to the systemic arteriovenous oxygen difference in cardiac patients.

In eleven patients with chronic heart failure forearm blood flow (FBF) was measured by plethysmography with a mercury-in-silastic strain gauge and splanchnic blood flow (SBF) with indocyanine green (ICG) infusion clearance at rest during right heart catheterization. The measurements were repeated during 8 min supine exercise on a bicycle ergometer, SBF during exercise being calculated from the changes of the brachial artery to hepatic vein oxygen differences and the ICG values at rest. Close correlations were found between cardiac output and FBF, and cardiac output and SBF at rest. During exercise forearm and splanchnic vascular resistances were both closely correlated with the brachial to pulmonary artery oxygen difference. It is concluded that in patients with heart failure vasoconstriction occurs during exercise in resting limbs and visceral organs, both closely related to the circulatory strain.

Adult↗
PubMed1988

Bed rest versus activity ad lib in the treatment of small hyphemas.

The management of small hyphemas remains controversial. Some authors advocate hospitalization, strict bed rest, and medical therapy with aminocaproic acid. Others are less conservative and recommend treatment on an ambulatory basis without the drug. In order to establish the overall rebleed rate for small hyphemas and to assess whether or not strict bed rest improves the prognosis, we studied 73 patients with small hyphemas occupying less than one third of the anterior chamber. Thirty-seven patients, during the first year of the study, were hospitalized and treated with strict bed rest while 36 patients, during the second year, were hospitalized but allowed to ambulate freely. The overall incidence of rebleeds was 15% (11 of 73). The incidence of rebleeds and other complications was not statistically different between the two study groups. Additionally, the final visual acuity in both groups was essentially identical. We conclude that bed rest does not improve the prognosis in cases of small hyphemas.

Atropine↗
PubMedDate not supplied

[Neurophysiological characteristics of the resting forms of primary sleep and hypobiosis in the frog Rana temporaria].

Neurophysiological studies have been made on natural resting forms of the primary sleep, wakefulness and hypobiosis in the frog. New method of presentation of the distribution density of EEG signal by a frequency spectrum was used. New data were presented concerning seasonal changes in the frequency parameters of one of the resting forms of the primary sleep, SLS-2. The role of this form of rest in the origin of hypobiosis in the frog Rana temporaria is discussed. Besides, new data were obtained which confirm that the resting form, SLS-3, of the primary sleep is an evolutionary precursor of the intermediate form of the sleep in reptiles and slow wave and activated phase of the sleep in warm-blooded vertebrates.

Animals↗
PubMedDate not supplied

[Psychophysiological characteristics of the organization and regulation of the daily work-rest cycles for the crew on a prolonged space flight].

This paper presents the results of analysis of work-rest cycles of the Salyut-6 and Salyut-7 prime crewmembers. The distribution of work-rest cycles within the day, week, month and the flight as a whole, their relation with other components of the time schedule, the effect of various factors involved on the health status and work capacity were studied. It was shown that specified work-rest cycles should be rigorously adhered to. It was demonstrated that proper planning and realization of work-rest cycles, as well as their correction during actual flight with respect to psychophysiological and biorhythmological variations are required to maintain good health condition and high work capacity of crewmembers.

Circadian Rhythm↗
PubMedDate not supplied

Cardiac performance at rest and during exercise in normal subjects.

Hemodynamic profiles at rest and during bicycle exercise are described in 50 normal male subjects. In nine of these, the hemodynamics at rest and during exercise in the supine position have been compared to those in the sitting position. In the supine position, the observed and derived hemodynamic parameters at rest and during exercise (mean +/- standard deviation) were: heart rate 77 +/- 11 vs 127 +/- 17 beats . min-1, brachial arterial mean pressure, 12.4 +/- 1.2 vs 15.0 +/- 1.6 kPa (93 +/- 9 vs 113 +/- 12 mmHg), pulmonary arterial mean pressure 1.9 +/- 0.5 vs 3.2 +/- 0.8 kPa (14 +/- 4 vs 24 +/- 6 mmHg), left ventricular end-diastolic pressure 1.2 +/- 0.4 vs 1.7 +/- 0.7 kPa (9 +/- 3 vs 13 +/- 5 mmHg), cardiac output 6.3 +/- 1.5 vs 12.0 +/- 3.0 1 . min-1, stroke volume 88 +/- 22 vs 95 +/- 23 cm3, and left ventricular stroke work 0.93 +/- 0.27 vs 1.26 +/- 0.34 J . beats-1. Comparison of hemodynamic data in the supine and sitting position showed that pulmonary capillary wedge pressure, left ventricular end-diastolic pressure, cardiac output, stroke volume, and left ventricular stroke work were lower and heart rate higher in the sitting position, while brachial arterial and pulmonary arterial mean pressures were similar in the two positions. During exercise, the absolute values of pulmonary capillary wedge pressure, left ventricular end-diastolic pressure and stroke volume were lower and heart rate higher in the sitting position, while cardiac output and left ventricular stroke work were similar in the two positions. Comparison of changes from rest to exercise in the supine and sitting postures revealed similar increases in heart rate, pulmonary capillary wedge pressure, left ventricular end-diastolic pressure, cardiac output, and stroke volume in the two positions.

Adult↗
PubMed1979

Validity of left-ventricular ejection fractions measured at rest and peak exercise by equilibrium radionuclide angiography using short acquisition times.

To validate ejection fraction (EF) calculations from 5 and 2 minutes of multiple-gated equilibrium radionuclide angiographic data and to establish its utility during alterations in cardiac performance, we studied 38 patients with chest pain suggestive of coronary artery disease. Twenty-four patients underwent contrast ventriculography (CV) as well as first-pass (FP) and equilibrium (EQ) radionuclide angiography at rest, and 14 additional patients had both radionuclide tests performed at rest as well as during peak supine bicycle exercise. The resting 5-min acquisition ejection fractions were compared between each method and the following correlations were generated: r = .92, n = 24 (CV-EQ), r = .92, n = 24 (CV-FP), and r = .95, n = 38 (FP-EQ). The variability of EQ-EF calculations between two independent observers was less than 2%; the mean absolute difference between two sequential 2-min acquisitions and the 5-min recordings was -.1 +/- 1.6%, and the reproducibility of sequential 2-min ejection fractions was excellent (r = .98). EQ and FP ejection fractions at symptom-limited exercise correlated well (r = .96, n = 14). We conclude that equilibrium radionuclide angiography is a valid method to measure EF both at rest as well as during peak exercise even when 2-min acquisition periods are used.

Adult↗
PubMedDate not supplied

[Work and rest organization for the cosmonauts on a long flight].

Proper arrangement of work-rest cycles of crewmembers in long-duration space flight is a practically important task of space ergonomics, a field of science studying man's work capacity and methods of its increase. The basic principle of space ergonomics assuring high efficiency of space crewmembers is to cover every aspect of their activities. Of particular importance is the use of laws of biorhythmology, in order to select candidates least susceptible to desynchronosis and closely resembling each other in their biorhythmological status. At the present time, work-rest cycles in a prolonged space flight should be arranged on a 24-hour basis with a normal day-night alternation, including 8-hour night sleep and 2-hour day rest. Optimization of cosmonauts' activities in space demands that they strictly adhere to the recommended work-rest cycle; this can be achieved through their highly motivated desire only.

Activities of Daily Living↗
PubMedDate not supplied

Prizidilol in essential hypertension: long-term effects on plasma volume, extracellular fluid volume, and central hemodynamics at rest and during exercise.

We studied the long-term hemodynamic effect of prizidilol (a precapillary vasodilator and beta-adrenoceptor blocker) in 14 men aged 25-66 years with mild and moderate essential hypertension (EH). Cardiac output (by Cardiogreen) and intraarterial blood pressure (BP) were measured at rest and during exercise before and after 8 months of therapy. Changes in body fluid volumes were measured by isotope dilution techniques. After 8 months on prizidilol, eight of the 14 patients were normotensive, and the mean casual BP was lowered by 23/17 mm Hg to 140/91 mm Hg. The intraarterial systolic and diastolic pressures fell by 15-20% of the pretreatment levels at rest supine, sitting, and during 50, 100 and 150 W exercise. The fall in BP was due to a marked reduction in total peripheral resistance ranging from 17 to 23% at rest and during exercise. Cardiac output was unchanged at all work loads, whereas heart rate fell. The stroke volume increased in all settings; at maximum work load by 30%. Body weight and body fluid volumes did not change significantly. Except for some coldness in hands and feet in one patient, which disappeared after 2-3 months, no side effects were observed. We conclude that, in mild and moderate EH, prizidilol induces a substantial fall in BP with an excellent hemodynamic profile both at rest and during exercise.

Adrenergic beta-Antagonists↗
PubMed1983

Effects of various levels of hypoxia on plasma catecholamines at rest and during exercise.

The purpose of this study was to investigate the relationship between hypoxia and heart rate (HR), pulmonary ventilation, plasma epinephrine (E) and norepinephrine (NE) at rest and during exercise at 40% of maximal oxygen uptake. Six subjects were exposed to inspired gas mixtures containing 21%, 19%, 17%, 15%, and 13% O2. The duration of exposure to each mixture was 10 continuous min at rest, followed by 10 continuous min during exercise. The order of the inspired gas mixtures was randomized. During the exercise test, HR was elevated with exposure to 15% and 13% O2 (p less than 0.001). Pulmonary ventilation was higher at 13% O2 than at the higher O2 percents (p less than 0.001). There were no significant changes in plasma E or NE at rest or during exercise in response to the gas treatments. These results indicate that acute exposure to hypoxic gas mixtures at rest and during light work does not result in significant increases in sympathetic nervous system activity, as judged by the plasma E and NE response.

Adult↗