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Results for “physiologic variables”

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At least 19 recordsLinked to original sources

PubMed1980

Oral contraceptives and physiological variables.

Physiological variables were compared among women who had never used oral contraceptives, past users, and current users. Randomly selected subjects were aged 30 to 59 years. Blood was sampled for determination of blood glucose, serum cholesterol and triglyceride, and plasma insulin concentration. Summed postchallenge glucose and insulin values were used in analyses to represent the magnitude of response. Contours of glucose and insulin curves were represented by single numerical variables termed "G-CON" and "I-CON." Current users of oral contraceptives had significantly higher values of G-CON, I-CON, triglyceride, and systolic blood pressure than women who never used oral comtraceptives. Current users also had significantly higher levels of summed glucose, G-CON, and I-CON than former users. Use of currently prescribed oral contraceptives is associated with adverse physiological changes that are reversible after discontinuing such use.

Adult↗

PubMed1983

Seasonal variables among physiological variables in elite oarsmen.

Nine members of the U.S. Men's Olympic Rowing Team were studied during the in-season (IS) and off-season (OS). Maximum power, VE, VO2, and heart rate were measured during a 6-min rowing ergometer exercise during IS and OS. Per cent body fat and isokinetic quadriceps strength were also determined. Biopsies were removed from the vastus lateralis and analyzed histochemically and morphometrically during OS only. No changes were noted for body composition between IS and OS. VEmax and VO2max increased significantly from OS to IS; absolute VO2max increased from 5.09 to 6.01 l/min and relative values increased from 56.5 to 69.1 ml . kg-1 . min-1. Power increased 14% from OS to IS while heart rate showed no difference. Leg strength increased significantly at 6 different angular velocities from IS to OS especially at the lower speeds. Biopsy data revealed an average ratio of 75% slow twitch Type I fibers and 25% fast twitch Type II fibers. Larger fiber diameters were noted for Type II fibers but this difference was not significant. Although seasonal effects were expected, the unusually large differences in metabolic and strength capacities between IS and OS reflect a high degree of training specificity.

Adult↗

PubMed1997

Estimate of physiological variability of peak latency in single sweep P300.

Among single sweep records of event-related potentials (ERPs), the peak latency of P300, which is one of the most prominent positive peaks in the ERP obtained in the oddball paradigm, may vary depending on the conditions of the subject. In the analysis of characteristics of the variability in the peak latency, it is important to know to what extent the variability of the measured peak latency (measured variability) is actually caused by physiological factors (physiological variability). In our previous study, a method was developed for judging whether the physiological variability really exists or not, and if it does exist, the developed method extracts the physiological variability from the measured variability based on a limited number of single sweep records. In the present study, based on the P300 waveforms which were detected by blinded visual inspection of the ERP data obtained by an auditory oddball paradigm from 12 healthy adults, the physiological variability was shown to exist with a confidence level of 95% for all subjects. Furthermore, its interval estimate was calculated by subtracting noise variability from the measured variability with a confidence level of 80%, and it was found to range from 17 to 57 ms for all subjects.

Adult↗

PubMed1995

Use of physiologic variables in nursing research.

In this study, the use of physiologic variables is described in research reports published 1989-1993 in four broad-based research journals. The National Institute for Nursing Research (NINR) emphasizes the need for more physiologically based nursing research. This analysis documents the current number and proportion of such research reported in four journals during a 5-year period. Each report was evaluated for the population sampled, type of physiologic variable, type of study, definitions, and reporting of reliability and validity measures. Among the 763 reports, 114 (15%) examined physiologic variables. The most frequently studied physiologic variables were blood pressure, heart rate, and body temperature. The majority of studies posed and answered a clinical nursing question, and the study populations sampled were adults. Theoretical and operational definitions were included in most reports. Evidence of reliability and validity analysis were in 36% and 60% of the reports respectively. Although most nursing research focuses primarily on psychosocial aspects of care, several conceptual and psychometric issues were also addressed in studies that examined physiologic variables.

Clinical Nursing Research↗

PubMed2002

Detecting relationships between physiological variables using graphical models.

In intensive care physiological variables of the critically ill are measured and recorded in short time intervals. The proper extraction and interpretation of the information contained in this flood of information can hardly be done by experience alone. Intelligent alarm systems are needed to provide suitable bedside decision support. So far there is no commonly accepted standard for detecting the actual clinical state from the patient record. We use the statistical methodology of graphical models based on partial correlations for detecting time-varying relationships between physiological variables. Graphical models provide information on the relationships among physiological variables that is helpful e.g. for variable selection. Separate analyses for different pathophysiological states show that distinct clinical states are characterized by distinct partial correlation structures. Hence, this technique can provide new insights into physiological mechanisms.

Critical Care↗

PubMed1987

A FORTRAN technique for correlating a circular environmental variable with a linear physiological variable in the sugar maple.

This paper deals with a computer program adapted to a statistical method for analyzing an unlimited quantity of binary recorded data of an independent circular variable (e.g. wind direction), and a linear variable (e.g. maple sap flow volume). Circular variables cannot be statistically analyzed with linear methods, unless they have been transformed. The program calculates a critical quantity, the acrophase angle (PHI, phi o). The technique is adapted from original mathematics [1] and is written in Fortran 77 for easier conversion between computer networks. Correlation analysis can be performed following the program or regression which, because of the circular nature of the independent variable, becomes periodic regression. The technique was tested on a file of approximately 4050 data pairs.

Air Movements↗

PubMed2003

Dimension reduction for physiological variables using graphical modeling.

In intensive care, physiological variables of the critically ill are measured and recorded in short time intervals. The proper extraction and interpretation of the essential information contained in this flood of data can hardly be done by experience alone. Typically, decision making in intensive care is based on only a few selected variables. Alternatively, for a dimension reduction statistical latent variable techniques like principal component analysis or factor analysis can be applied. However, the interpretation of latent components extracted by these methods may be difficult. A more refined analysis is needed to provide suitable bedside decision support. Graphical models based on partial correlations provide information on the relationships among physiological variables that is helpful for variable selection and for identifying interpretable latent components. In a comparative study we investigate how much of the variability of the observed multivariate physiological time series can be explained by variable selection, by standard principal component analysis and by extracting latent compo-nents from groups of variables identified in a graphical model.

Aged↗

PubMed2003

Subjective perceptions and physiological variables during weaning from mechanical ventilation.

BACKGROUND: As costs related to mechanical ventilation increase, clear indicators of patients' readiness to be weaned are needed. Research has not yet yielded a consensus on physiological variables that are consistent correlates of weaning outcomes. Subjective perceptions rarely have been examined for their contribution to successful weaning. OBJECTIVE: To explore the subjective perceptions of dyspnea, fatigue, and self-efficacy and selected physiological variables in patients being weaned from mechanical ventilation. METHODS: Data were collected prospectively on 68 patients being weaned from mechanical ventilation. Subjective perceptions were measured by using 3 visual analog scales; physiological variables were measured by using the Burns Weaning Assessment Program and a patient profile. Weaning outcomes were recorded 24 hours after data collection. RESULTS: Participants were primarily white women and required mechanical ventilation for a mean of less than 4 days. Participants reported mild dyspnea, moderate fatigue, and high weaning self-efficacy. High PaO2, low PaCO2, stable hemodynamic status, adequate cough and swallow reflexes, no metabolic changes, and no abdominal problems were associated with complete weaning (P = .05). Subjective perceptions were associated with physiological variables but not with weaning outcomes. CONCLUSIONS: Multidimensional assessment of both primary and secondary indicators of readiness to be weaned is necessary for timely, efficient weaning from mechanical ventilation. Primary assessments include physiological variables related to gas exchange, hemodynamic status, diaphragmatic expansion, and airway clearance. Secondary assessments include perceptions related to key physiological variables. Additional research is needed to determine the predictive value of physiological variables and perceptions of dyspnea, fatigue, and self-efficacy.

Adult↗

PubMed1999

Physiological variability of peak latency in evoked potentials: use of a property of asynchronous averaging.

A method for estimating the physiological variability of peak latency in an evoked potential, of whom the peak latency and amplitude varied, by using the property of asynchronous averaging was proposed. A point estimate of the physiological variability was obtained by minimizing the mean square error between a standard waveform and the asynchronously averaged waveform. An interval estimate was obtained by using the relationship between the signal-to-noise ratio and the standard deviation of the point estimate for the variability of peak latency. The proposed method was evaluated by using simulation data, and was successfully applied to actual P300 data of six normal subjects. The method gave accurate estimates for the physiological variability of peak latency of P300, and would also be effectively applicable to any other evoked potential records for estimating the physiological variability.

Adult↗

PubMed1991

A study on the basic nature of human biological aging processes based upon a hierarchical factor solution of the age-related physiological variables.

The purpose of this study is to determine the laws governing the aging processes based on a hierarchical factor solution of the age-related physiological variables. Healthy individuals (462) who had taken a 2-day health examination were studied. Twenty-seven physiological variables were submitted to hierarchical factor solution. The analysis revealed that there was a fixed pattern in the variations of these 27 physiological variables. In this hierarchical factor solution, three group factors as functioning at different levels of complexity composed of the 16 common factors were extracted. Of these group factors, the first and third group factors can be referred to the aging process. The first group factor, the so-called factor 1 loaded with most of physiological variables, was interpreted as a primary aging factor which presented the primary process of human aging. The third group factor, the so-called factor 6 to 16 loaded only with a few variables related to a single physiological system or organ, were interpreted as system-specific secondary aging factor. These results obtained by the hierarchical factor solution thus seem to support the notion that biological age changes can be viewed as time dependent complex integration of the primary and secondary aging processes.

Adult↗

PubMed1997

The relationship between 3 km running performance and selected physiological variables.

The aim of this study was to assess the relationship between a number of physiological variables and running velocity at 3 km (v-3km) in a group of male runners. Sixteen well-trained middle- and long-distance runners (mean +/-s: age 22.4 +/- 4.2 years, body mass 63.5 +/- 6.2 kg, VO2 max 73.3 +/- 6.7 ml kg-1 min-1) underwent laboratory treadmill tests to determine their maximum oxygen uptake (VO2 max), running economy at three submaximal velocities (12.9, 14.5 and 16.1 km h-1 or 14.5, 16.1 and 17 km h-1), predicted velocity at VO2 max (v-VO2max), velocity (v-Tlac) and VO2 (VO2-Tlac) at the lactate threshold and their velocity (v-4mM) and VO2 (VO2-4mM) at a blood lactate concentration of 4 mM. Distance running performance was determined by 3 km time-trials on an indoor 200 m track for which the average time was 9.46 +/- 0.74 min. The mean (+/-s) velocities for v-Tlac, v-4mM and v-VO2max were 16.0 +/- 1.8, 17.1 +/- 1.9 and 20.7 +/- 2.1 km h-1 respectively, all significantly different on average (all P < 0.05) from that for v-3km (19.1 +/- 1.5 km h-1). Many of these physiological variables were found to be individually (and significantly at 5%) related to v-3km. The best single predictors of v-3km were v-Tlac and v-4mM (both with a sample correlation, r2 of 0.93), while v-VO2max was slightly poorer (r = 0.86). Neither VO2 max nor running economy was strongly correlated with v-3km. A stepwise multiple-regression analysis revealed that v-Tlac alone was the best single predictor of v-3km and explained 87% of the variability in 3 km running velocity, while the addition of any of the other physiological variables did not significantly improve the prediction of v-3km. We conclude that, in a group of well-trained runners, the running velocity at the lactate threshold was all that was required to explain a large part of the variability in 3 km running performance.

Adolescent↗

PubMed1977

Effects of afternoon naps on physiological variables performance and self-reported activation.

Fluctuations in physiological variables resulting from naps and the relationship of these to previously studies changes in performance and subjective activation associated with napping were examined. The subjects were eighteen healthy male university students who habitually slept 1/2-2 hr in the afternoon. Measurements were obtained of our physiological variables, from a continuous 10-min auditory reaction time task and two factors of an Activation. Deactivation Adjective Checklist 20 min before and after a control condition and two electroencephalographically recorded afternoons of sleep. The experimental conditions comprised a 2-hr period of wakefulness, a 1/2 hr nap from 4.35-5.05 p.m., and a 2-hr nap from 3.05-5.05 p.m. Following each sleep treatment, when compared with the control condition, there were statistically significant shifts of improved reaction time performance, and elevated activation as reflected by the two self-report scales, inceased EEG frequency, heart rate, and electrodermal responses. The shifts of increased behavioral efficiency, subjective and physiological activation were approximately equivalent in extent between 2-hr and 1/2-hr naps. These findings indicate that besides the previously reported facilitation by naps of performance and mood, physiological activation is increased following accustomed episodes of afternoon sleep.

Arousal↗

PubMed2003

Effects of stage duration in incremental running tests on physiological variables.

To study the effect of stage duration on some physiological variables in an incremental running test, 8 well-trained runners underwent 3 running tests, with stage durations of 1, 3 and 6 min. To study maximal lactate steady state (maxLASS) and its corresponding speed, every subject underwent a 4th test with three 15-min stages at three speeds, based on the running speed at 4 mmol/l blood lactate (V4) in the 6 min per stage protocol. The first load in the 15 min per stage test was V4 - 0.5 km/h, the second at V4, and the third V4 + 0.5 km/h. To compare the maxLASS speed with outdoor performance, the subjects also ran 5 km at this speed on an outdoor track. Mean maximal running speed (V (max)) in the incremental test was significantly lower in the 6-min (15.1 km/h) and 3-min stage protocol (17.1 km/h), compared with the 1-min stage protocol (18.3 km/h). Mean peak VO (2) and mean peak heart rate were not different between the protocols with different stage duration. The mean V4 was significantly lower in the 6 min per stage protocol compared with the 3 min per stage protocol (12.9 vs. 14.4 km/h). Mean ventilatory threshold was not different between the 1, 3 and 6 min per stage protocols. No threshold behaviour was found in respiratory rate. MaxLASS can be estimated from V4 in the 6 min per stage protocol, and verified by three 15-min intensities being V4 - 0.5 km/h, at V4, and V4 + 0.5 km/h. The mean blood lactate concentration at the maxLASS speed was not different between treadmill running and outdoor running on a track. In conclusion, for measuring peak values of physiological variables in an incremental running test, the duration per stage is of less importance, however, when measuring blood lactate concentration as a function of running speed, the duration per stage should be at least 6 min.

Adult↗

PubMedDate not supplied

[Psychological links and coronary diseases. II. Psychological correlations of certain physiological variables (author's transl)].

In this study, correlations were tabulated between physiological and psychological measurements drawn from a group of 21 infarct patients and a matching group of 21 normal subjects. The physiological variables taken under consideration are the number of platelets, the beta-lipoproteines and the systolic blood pressure; all these variables were tested under stress and at rest. On the top, fibrinogene at rest, cortisol under stress and heart rate under conditions of "intake" and "rejection" were also measured. The psychological assessment was achieved by the MMPI. Several psychological traits link with physiological parameters to be considered as cardiovascular risks. However, these links are mostly specific; moreover, they vary under different experimental conditions. In other words, different neuro-behavioral patterns seem to operate at rest and under stress. The links between psychological and physiological variables vary also between normal subjects and infarct patients. Normal subjects as well as infarct patients show a relationship between neurotic traits and genuine physiological reactions. However, among the formers, these neurotic traits are in closer relationship with inhibitions as among heart patients. Psychological risk factors in cardiovascular disorders appear to be related with a genuine expression of conflictual affects leading to inadequate physiological responses; when these reactions are repeated in time, functional disorders may induce organic lesions.

Blood Platelets↗

PubMed2003

Changes in clinical and physiologic variables predict survival in idiopathic pulmonary fibrosis.

There is significant heterogeneity in survival time among patients with idiopathic pulmonary fibrosis. Studies of baseline clinical and physiologic variables as predictors of survival time have reported inconsistent results. We evaluated the predictive value of changes in clinical and physiologic variables over time for survival time in 81 patients with biopsy-proven idiopathic pulmonary fibrosis. Six-month changes in dyspnea score, total lung capacity, thoracic gas volume, FVC, FEV1, diffusing capacity of carbon monoxide, partial pressure of arterial oxygen, oxygen saturation, and alveolar-arterial oxygen gradient were predictive of survival time even after adjustment for baseline values. Analyses were repeated on 51 patients with 12-month change data. Twelve-month changes in dyspnea score, total lung capacity, FVC, partial pressure of arterial oxygen, oxygen saturation, and alveolar-arterial oxygen gradient were predictive of survival time after adjustment for baseline values. Evaluation of changes in clinical and physiological variables over 6 and 12 months may provide clinicians with more accurate prognostic information than baseline values alone.

Aged↗

PubMed1997

Changes in certain hematological and physiological variables following single gallium arsenide exposure in rats.

Gallium arsenide (GaAs), a group III-VA intermetallic semiconductor, possesses superior electronic and optical properties and has a wide application in electronic industry. Exposure to GaAs in the semiconductor industries could be a possible occupational risk. The aim of the present study was to determine the dose-dependent effect of single oral exposure to GaAs (500, 1000, or 2000 mg/kg) on some biochemical variables in heme synthesis pathway and few selected physiological variables at d 1, 7, and 15 following administration. The results indicate that GaAs produced a significant effect on the activity of delta-aminolevulinic acid dehydratase (ALAD) in blood and heart (particularly at d 7) following exposure to 2000 mg/kg, whereas urinary delta-aminolevulinic acid (ALA) excretion was elevated only at d 7. No marked influence of GaAs on blood hemoglobin, zinc protoporphyrin, and packed cell volume was noticed. Blood glutathione (GSH) was significantly reduced at d 7, but remained unchanged at two other time intervals. On the other hand, heart GSH contents remained uninfluenced on GaAs exposure. Most of the physiological variables, viz. blood pressure, heart and respiration rate, and twitch response, remained unchanged, except for some minor alterations observed at d 7 and 15 following exposure to GaAs at a dose of 2000 mg/kg. Blood gallium concentration was not detectable in normal animals and rats exposed to 500 mg/kg GaAs. Blood arsenic concentration was, however, detectable even at the a lower dose level and increased in a dose-dependent manner. All these changes showed a recovery pattern at d 21, indicating that the alterations are reversible.

Aminolevulinic Acid↗

PubMed2005

The effect of admission physiological variables on 30 day outcome after stroke.

INTRODUCTION: Potentially modifiable physiological variables may influence stroke prognosis but their independence from modifiable factors remains unclear. METHODS: Admission physiological measures (blood pressure, heart rate, temperature and blood glucose) and other unmodifiable factors were recorded from patients presenting within 48 hours of stroke. These variables were compared with the outcomes of death and death or dependency at 30 days in multivariate statistical models. RESULTS: In the 186 patients included in the study, age, atrial fibrillation and the National Institutes of Health Stroke Score were identified as unmodifiable factors independently associated with death and death or dependency. After adjusting for these factors, none of the physiological variables were independently associated with death, while only diastolic blood pressure (DBP) > or = 90 mmHg was associated with death or dependency at 30 days (p = 0.02). CONCLUSIONS: Except for elevated DBP, we found no independent associations between admission physiology and outcome at 30 days in an unselected stroke cohort. Future studies should look for associations in subgroups, or by analysing serial changes in physiology during the early post-stroke period.

Adolescent↗

PubMed2002

Relationship between markers of blood oxidant status and physiological variables in healthy and heaves-affected horses after exercise.

Exercise-induced oxidative stress is investigated as a potential performance-limiting factor in human sports medicine. Therefore, the present study aimed to assess whether physiological variables that change with exercise intensity were correlated with blood oxidant markers in healthy and heaves-affected horses. Seven healthy horses, 8 heaves-affected in remission and 7 heaves-affected in crisis performed a standardised exercise test (SET) of stepwise increasing intensity. Variables monitored during exercise were heart rate (HR), venous plasma lactate (LA), packed cell volume (PCV) and arterial oxygen tension (PaO2). Oxidant markers (uric acid [UA], 8-iso-PGF2alpha and reduced [GSH] and oxidised glutathione [GSSG]) were analysed in venous peripheral blood sampled at rest (R), at peak-exercise intensity (Emax), 15 (E15) and 60 (E60) min after SET. There was a significant effect of heaves on oxidant markers and, therefore, correlation analyses between physiological variables and oxidant markers were performed separately per horse group. In healthy horses, UA analysed at Emax was positively correlated with LA. Furthermore, GSH analysed at Emax and E15 was positively correlated with PaO2. In healthy and heaves-affected horses in remission, GSH and GSSG determined at Emax were negatively correlated with HR. There was no significant correlation between 8-iso-PGF2alpha and physiological variables. In conclusion, a correlation between the physiological response to exercise and some oxidant markers exists in healthy horses. However, in heaves-affected horses the blood oxidant status is probably more dependant on airway disease than on exercise. Future studies should be undertaken to assess whether antioxidant supplementation might positively influence the oxidant-antiodidant balance in exercising horses.

Animals↗