SEARCH · PubMed Health

Results for “physiologic variables”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources

PubMed1991

Base deficit as a sensitive indicator of compensated shock and tissue oxygen utilization.

To determine the relationship of the arterial base deficit (BD) to physiologic indicators of shock and resuscitation--heart rate, mean arterial pressure (MAP), cardiac output (CO), arteriovenous oxygen difference (AVO2), mixed venous oxygen saturation (VSAT) and oxygen delivery to consumption ratio (RATIO)--16 swine were monitored invasively, bled 40 per cent of their calculated blood volume and resuscitated with crystalloid and blood. During hemorrhage, the MAP, CO, VSAT and RATIO decreased and the BD and AVO2 increased. One hour after hemorrhage, but before crystalloid infusion, the MAP, VSAT and RATIO had increased significantly from previous levels and the AVO2 had narrowed significantly, while the BD showed no significant change. All parameters returned to baseline with resuscitation. BD accurately reflected the hemodynamic and tissue perfusion changes associated with hemorrhagic shock and resuscitation in this model. BD can be used as an indicator of the severity of the shock state and the efficacy of resuscitation when invasive monitoring is impractical or not available. BD was more reflective of the true volume deficit during compensated shock than other physiologic variables in this study.

Acid-Base Imbalance↗

PubMed1982

Digital and sampled-data control of arterial blood pressure during halothane anesthesia.

A control system that maintains mean arterial pressure (MAP) at a desired level by automatically controlling halothane input has been developed. The control system is a discrete, digital type and is implemented with a small desk-top programmable calculator. Essentially, if MAP decreases, the inspired concentration of halothane will decrease; if MAP increases, the system will compensate by increasing inspired halothane concentration. The control system was tested in two ways: with a hybrid computer model of uptake and distribution of halothane and with dog experiments. The results indicate that (a) the model can be used to predict the response of the animal-anesthesia machine control system, and (b) the proposed algorithm is successful in controlling one anesthetic agent with one physiologic variable.

Anesthesiology↗

PubMed2006

Spatial exploration behaviour in an extended labyrinth in patients with panic disorder and agoraphobia.

Finding one's way through a labyrinth is both stressful and panicogenic for individuals suffering from panic disorder with agoraphobia (PDA), whilst normal subjects experience no stress. In this study the spatial exploratory behaviour of 15 subjects suffering from PDA, together with 15 patients with generalised anxiety disorder (GAD) and a further 15 normal control subjects - all female - was analysed during a walk through a labyrinth-like basement in an attempt to find the exit. The study covered behavioural variables, i.e., anxiety levels whilst route-searching and exploration-related movements (the frequency and intensity of trunk and head rotation, touching oneself and folding one's arms across the chest) and also physiological variables (blood pressure, heart rate) before and after the labyrinth walk. Data obtained in the PDA subjects were compared with those of the GAD and control subjects, and it was found that the PDA subjects' high blood pressure was associated with disturbed exploratory activity, which restricted their contact to the environment. As a consequence, they did not detect navigation signals to find the right route to the labyrinth exit. The interpretation focused on the analysis of the structure of human extraterritorial fear.

Adult↗

PubMed2000

Nasal proportional assist ventilation unloads the inspiratory muscles of stable patients with hypercapnia due to COPD.

This study was undertaken to assess the physiological effects of proportional assist ventilation (PAV), administered noninvasively through a nose mask, on ventilatory pattern, arterial blood gases, lung mechanics, and inspiratory muscle effort in stable, hypercapnic patients with chronic obstructive pulmonary disease. In 15 patients, PAV was set by adjusting volume assist (VA) and flow assist (FA) according to the "run-away" technique and the patient's comfort respectively. The level of support was fixed at 80% of the total possible assistance and averaged 13.9+/-4.1 cmH2O x L(-1) and 4.1+/-1.3 cmH2O x L(-1) x s for VA and FA, respectively. Continuous positive airway pressure (CPAP) was established at 2 cmH2O and then increased to 5 cmH2O. Physiological measurements were made during spontaneous breathing (SB), after more than 40 min of PAV, and 20 min after the rise in CPAP. On average, PAV improved ventilation (10.3+/-2.1 to 12.5+/-2.0 L x m(-1)), tidal volume (0.60+/-0.11 to 0.76+/-0.24 L), arterial oxygen tension and arterial carbon dioxide pressure (from 6.7+/-0.7 to 7.1+/-0.9 and from 7.6+/-1.0 to 7.2+/-1.2 kPa, respectively). During SB, pulmonary resistance and dynamic lung elastance averaged 15.0+/-7.6 cmH2O x L(-1) s and 15.8+/-8.0 cmH2O x L(-1), respectively. Assuming a normal chest wall elastance (5 cmH2O x L(-1)), VA and FA relieved respectively approximately 70% of the elastic and 30% of the resistive burden, with PAV set with the procedure of this study. The overall magnitude of the patients' inspiratory effort, measured by means of the oesophageal and diaphragmatic pressure time product in 10 patients was significantly reduced by PAV, on average, 328+/-122 to 226+/-118 (-31%) and 361+/-119 to 254+/-126 (-30%) cmH2O x min(-1), respectively. In 10 patients the electrical activity of the diaphragm (Edi) was also reduced by PAV to approximately 70%, on average, of the SB activity. The rise of CPAP 25 cmH2O did not cause any further significant change in the physiological variables. In all instances there was a good patient-ventilator interaction, the ventilatory breath never entering into the patient's neural expiratory time. These data show that nasal proportional assist ventilation can provide physiological benefits to the stable hypercapnic chronic obstructive pulmonary disease patients. In fact, proportional assist ventilation, which was well tolerated by all patients, unloaded the inspiratory muscles and improved arterial blood gases. Further studies can clarify whether these beneficial physiological effects of nasal proportional assist ventilation can bear profitable consequences in the overall clinical management of chronic obstructive pulmonary disease patients with chronic carbon dioxide retention.

Aged↗

PubMed2004

Changes of jugular venous blood temperature associated with measurements of cerebral blood flow using the transcerebral double-indicator dilution technique.

BACKGROUND AND OBJECTIVE: The transcerebral double-indicator dilution technique is a recently developed method to measure global cerebral blood flow at bedside. It is based on bolus injection of ice-cold indocyanine green dye and simultaneous recording of resulting thermo- and dye-dilution curves in the aorta and the jugular bulb. However, with this method 40 mL of ice-cold solution is administered as a bolus. Therefore, this prospective clinical study was performed to elucidate the effects of repeated administration of indicator on absolute blood temperature and on cerebral blood flow and metabolism. METHODS: The investigation was performed in nine male patients scheduled for elective coronary artery bypass grafting. Absolute blood temperature was measured in the jugular bulb and in the aorta before and after repeated measurements using the transcerebral double-indicator dilution technique. RESULTS: During the investigated time course, the blood temperature in the jugular bulb, compared to the aorta, was significantly higher with a mean difference of 0.21 degrees C. The administration of an ice-cold bolus reduced the mean blood temperature by 0.06 degrees C in the jugular bulb as well as in the aorta. After the transcerebral double-indicator dilution measurements a temperature recovery to baseline conditions was not observed during the investigated time period. Cerebral blood flow and cerebral metabolism did not change during the investigated time period. CONCLUSIONS: Repeated measurements with the transcerebral double-indicator dilution technique do not affect absolute jugular bulb blood temperatures negatively. Global cerebral blood flow and metabolism measurements remain unaltered. However, accuracy and resolution of this technique is not high enough to detect the effect of minor changes of physiological variables.

Aged↗

PubMed2002

Effects of exercise on physiological and psychological variables in cancer survivors.

PURPOSE: The primary purpose of this study was to examine the effect of aerobic exercise on physiological and psychological function in patients rehabilitating from cancer treatment. A second purpose was to evaluate the differential effects of low- and moderate-intensity exercise on these variables. METHODS: Eighteen survivors of breast or colon cancer (15 female and 3 male, 40-65 yr of age) served as subjects. The subjects were matched by aerobic capacity and scores on a Quality of Life questionnaire, and then randomly assigned to a control, low- (25-35% heart rate reserve (HRR)), or a moderate- (40-50% HRR) intensity exercise group. The exercise groups performed lower-body aerobic exercise three times a week for 10 wk. After the exercise training, there were no statistically significant differences between the two exercise groups on any of the physiological variables. Therefore, the exercise groups were combined into one group for the final analysis. RESULTS: The results revealed statistically significant increases in aerobic capacity (P < 0.001) and lower-body flexibility (P = 0.027), a significant decrease in body fat (P < 0.001), and a significant increase in quality of life (P < 0.001) and a measure of energy (P = 0.038) in the exercise group when compared with the control group. CONCLUSION: Low- and moderate-intensity aerobic-exercise programs were equally effective in improving physiological and psychological function in this population of cancer survivors. Aerobic exercise appears to be a valuable and well-tolerated component of the cancer-rehabilitation process.

Adult↗

PubMed2000

Risks for developing critical illness with GI hemorrhage.

STUDY OBJECTIVES: To define risk factors, identifiable on initial presentation, that predict subsequent physiologic derangements that are consistent with critical illness in patients presenting to hospital with GI hemorrhage (GIH). DESIGN: Observational, cohort study. SETTING: Fourteen-bed medical ICU in a 300-bed community teaching hospital. PATIENTS: One hundred ninety-three patients were studied during 199 separate hospital admissions for GIH. METHODS AMD MEASUREMENTS: Demographic and physiologic variables were extracted from the medical records of patients admitted with GIH. Comprehensive data, from after 2 h in the emergency department to the time of discharge or death, were used to determine whether patients met established ICU admission criteria. Physiologic and demographic data from the initial 2-h period were then compared for patients who subsequently met and for those who did not meet ICU admission criteria. Independent predictors of meeting ICU admission criteria were identified using multiple logistic regression analyses. Sensitivity and specificity associated with the combined use of these predictors were assessed. RESULTS: Thirty-four patients satisfied ICU admission criteria after the initial 2-h period in the emergency department. Sixty-five patients, including 29 of 34 patients who met ICU admission criteria, were actually admitted to the ICU. Among those who never fulfilled ICU admission criteria, the duration of hospital stay was longer for those admitted to the ICU than for those not admitted to ICU (6.6 +/- 0.6 days vs 5.2 +/- 0.3 days; p = 0.04). The admission prothrombin time (international normalized ratio > 1.2), hypotension (systolic BP < 90 mm Hg), acute neurologic changes, and initial APACHE (acute physiology and chronic health evaluation) II score ( > or =15) were the best independent predictors for meeting the defined criteria for admission to ICU. The presence of one or more of these in the first 2 h of presentation was associated with a sensitivity of 88% and specificity of 74% for predicting subsequent critical instability. The area under the receiver operator characteristic curve for use of these four variables was 86% for predicting whether patients met ICU admission criteria. CONCLUSIONS: Many patients with GIH were admitted to the ICU who never met local criteria for admission, and these patients experienced a significantly longer length of hospital stay than other, similarly ill patients. Coagulopathy, hypotension, neurologic dysfunction, and a higher (> or = 15) APACHE II score in the first 2 h of hospitalization were the best independent predictors of the subsequent development of critical illness.

APACHE↗

PubMed1990

From phenomenon to mechanism: an investigational strategy.

1. The author describes an investigational strategy useful in the field of psychopharmacology. 2. This strategy is based on the ability of a multi-disciplinary team first to measure significant changes in a behavioral or physiological variable in response to an experimental manipulation. 3. This initial measurement allows investigators to identify a phenomenon but not its underlying mechanism. 4. Study then proceeds to assess the anatomical substratum essential to mediating the physiologic change and receptology. 5. Finally, changes in second messenger mechanisms are determined. 6. Study of the neurobiologic effects of bright light is used as an illustration.

Animals↗

PubMed1994

Assessment of neutrophil aggregation by Coulter STKR and STKS haematological analysers.

We have studied an alternative method to aggregometry for the assessment of human polymorphonuclear (PMN) leucocyte aggregation. This simple, rapid and reliable procedure counts unaggregated cells on both Coulter STKS and STKR haematological analysers by the impedance principle. Aggregation of PMN was induced by 15 min incubation with fresh autologous serum (FAS) after a 10 min phorbol myristate acetate (PMA) activation of neutrophils in small aliquots (0.25 ml) of suspension containing about 4.0 x 10(9) PMN/1. Differences (x 100) between count of resting and PMA+FAS treated neutrophils/count of resting PMN reflect percent aggregation. By this procedure, PMN aggregation did not occur in autologous plasma from EDTA anticoagulated whole blood; it was partially inhibited by hydrocortisone, whereas inactivated or Zymosan activated sera gave values similar to those from FAS induced aggregation. PMA aggregation was dependent on Ca2+ + Mg2+ concentration. Intra-assay analytical variability did not exceed 4% on either instrument. Reference values (n = 20) of percent PMN aggregation were 50.7 +/- 4.7 on STKS and 47.1 +/- 4.8 on STKR. Most probably, the interindividual variance was due to the physiological variability of Mg2+ and/or Ca2+ concentrations in FAS. Thus, this procedure reflects the true PMN aggregability status in a given subject, and in a given electrolyte environment.

Adult↗

PubMed1991

Nutritional, physiological, genetic, sex, and age effects on fat-free dry matter composition of the body in avian, fish, and mammalian species: a review.

The purpose of this review is to outline and interpret the effects of nutrition, physiological state, sex, genetics, and age on composition of the fat-free dry matter of birds, mammals, and fishes in order to test the hypothesis that the protein:ash ratio in the body is constant. Calculations from a broad array of published data revealed that nutritional factors, including mineral, protein and amino acid nutriture, frequency and level of feeding, and energy intake and nonnutritional factors, including physiological state, sex, genetic background, and age of animal, may each alter the ratio of protein:ash in the body. All or part of the response may be associated with changes in accretion of body protein and(or) skeletal development and mineralization imposed by these nutritional and nonnutritional factors. In most cases of amino acid or protein deficiency, the protein:ash ratio was decreased relative to the control because the deposition of protein in muscle and viscera was reduced more than the growth and mineralization of the skeleton. In other cases, the protein:ash ratio was increased relative to a control because the dietary Ca or P intake or absorption limited skeletal mineralization. More knowledge is needed of how skeletal development and protein:ash ratio in the body is regulated, especially under the influence of nutritional, ontogenetic, and physiological variables among different genotypes of mammals, birds, and fishes. Documentation that the protein:ash ratio in the whole body of representative mammals, birds, and fishes is not constant, but is subject to manipulation, has important physiological and economic implications for developing food animals for the efficient production of lean meat.

Age Factors↗

PubMed2001

Markers for work disability in rheumatoid arthritis.

Work disability is common in rheumatoid arthritis (RA), and accounts for a large fraction of its costs. People with RA who are work disabled have more joint involvement, radiographic damage, and/or laboratory abnormalities than people who are working. However, analysis of predictive and associative markers in 15 studies of work disability indicate that the demographic variables, such as age, occupation, level of education, and duration of disease, as well as functional status in activities of daily living (ADL) identified on a patient questionnaire, appear to identify work status more than physiological variables. Work disability results from complex interactions of a medical disease, demographic variables, social conditions, and government policies. Some patients with RA are work disabled before they see a rheumatologist. Improved work disability outcomes in RA will require attention to social, economic, and political issues, and wider physician and public education concerning RA, in addition to improved medical management of disease.

Activities of Daily Living↗

PubMedDate not supplied

[Neonatal reflexes variability in the normal full term neonate during the neurological exam].

It has been stated that findings in neonatal neurological examinations can play a role as a pointer to adverse developmental outcome. The description of the examinations, and their presence or absence differed among authors without clear reference to their physiological variability ranges. We approached the study of some neonatal behaviours and reflexes in 143 examinations made on 113 healthy newborn babies from the maternity wards by looking at the influence that perinatal environmental factors which are considered normal, can play in these examinations. The results showed that the flexion answer of the Babinski reflex increased significantly between the first and third day of life (c2= 4.4478; p= 0.03495) in the same way there was an increase in the stepping reflex (c2= 3.999; p= 0.04552) in the righting reflex (c2= 4.9342; p= 0.02633) and in the supporting reaction (c2= 11.7874; p= 0.0006). This was significantly reduced in the caesarean section deliveries (c2= 7.1209; p= 0.0076). Head reaction was only detectable during the Brazelton behavioural states 1 to 3 (c2= 3.8911; p= 0.04854) and the same thing happened with the stepping reflex (c2= 4.9370; p= 0.02629). We discuss the utility of neonatal reflexes scoring scales in predicting the neurodevelopmental outcome of the newborn baby.

Female↗

PubMed2004

The two-process model of sleep regulation revisited.

The two-process model of sleep regulation posits that the interaction of its two constituent processes, a sleep/wake dependent homeostatic Process S and a circadian Process C, generates the timing of sleep and waking. The time course of Process S was derived from a physiological variable, EEG slow-wave activity. In addition to the timing of sleep, changes of daytime vigilance are accounted for by the interaction of the two processes. The attractiveness of the model derives from its physiological basis and its mathematical simplicity. The two-process model stimulated the establishment of other models of neurobehavioral functions. The background of the model is reviewed and simulations of alertness and sleepiness are discussed.

Circadian Rhythm↗

PubMed1993

Properties of the upper airway during sleep.

Research efforts to date have identified that both anatomic and physiologic variables may contribute to the pathophysiology of obstructive sleep apnea. Whether specific factors within either of these two categories will be shown to predominate remains to be seen. Surely, experience with sleep apnea patients teaches us that different variables are important in different OSA patients. In the area of anatomy, investigators are just beginning to try surgical approaches designed specifically for the pharyngeal site of obstruction found in a given patient. Possible new physiologic and pharmacologic treatments are being explored. Hopefully, such treatments will be as effective and more convenient than continuous positive airway pressure.

Humans↗

PubMed2000

Metabolic and cardiorespiratory responses to continuous box lifting and lowering in nonimpaired subjects.

STUDY DESIGN: A within-subject experimental design. OBJECTIVES: To compare the magnitude of metabolic and cardiorespiratory changes produced during box lifting and lowering among combinations of lift technique (leg lift and leg-torso lift) and lift weight (10.8 and 15.4 kg). BACKGROUND: Continuous box lifting and lowering can be used as an exercise in a low-back rehabilitation program. Awareness of the possible cardiovascular stress of this activity is important to the clinician because some patients may have existing cardiovascular pathologies or possess unknown risk factors for cardiovascular disease. METHODS AND MEASURES: A group of 17 nonimpaired men 26 +/- 8 years of age (mean +/- SD) performed the 4 experimental trials on different days in a counterbalanced order determined by a Latin Square design. Lifting and lowering was performed for 6 continuous minutes at a rate of 12 cycles per minute. Physiologic variables were oxygen uptake, minute ventilation, heart rate, systolic blood pressure, diastolic blood pressure, metabolic equivalent, and rate-pressure product. RESULTS: There were stepwise increases in the values for oxygen uptake, minute ventilation, heart rate, metabolic equivalent, and rate-pressure product from the leg-torso lift to the leg lift and from 10.8 to 15.4 kg of weight within each lift technique (with the exception that minute ventilation and heart rate did not differ between the leg-torso lift at 15.4 kg and the leg lift at 10.8 kg). For the 4 lifts, values (mean +/- SD) varied from 20.3 +/- 5.4 to 28.8 +/- 5.8 mL x kg x min(-1) for oxygen uptake, 42.2 +/- 11.1 to 66.4 +/- 15.2 L x min(-2) for minute ventilation,129 +/- 20.6 to 156 +/- 16.5 beats x min(-1) for heart rate, 5.8 +/- 1.6 to 8.2 +/- 1.6 for metabolic equivalent, and 197 +/- 49.4 to 245 +/- 41.2 for rate-pressure product (x10(-2)). CONCLUSION: The leg lift with the 15.4-kg weight produced the greatest physiologic stress. Because of the magnitude of the increase in the variables measured for all 4 types of lifts, clinicians should closely monitor patients' response to this type of exercise.

Adult↗

PubMed2005

Neuroendocrine-immune relationships between emotion regulation and health in patients with rheumatoid arthritis.

OBJECTIVES: Emotion regulation is hypothesized to be related to health through neuroendocrine-immune changes. This study examined the role of the neuroendocrine variables 24-h urinary cortisol and noradrenaline, and the immune variable serum interleukin 6 as mediators between emotion regulation styles and health (perceived health and disease activity: erythrocyte sedimentation rate (ESR) and Thompson joint score). METHODS: Sixty patients with rheumatoid arthritis (mean age 59.0+/-11.2 yr; 38 female) participated. RESULTS: Emotion regulation was not associated with immune functioning or disease activity, but it was somewhat related to neuroendocrine functioning: one of the emotion regulation styles, ambiguity, was related to noradrenaline in women (r = 0.39) but not in men. The indicators of neuroendocrine functioning (cortisol and noradrenaline) were correlated (r = 0.40), as were indicators of immune functioning (interleukin 6) and inflammatory activity (ESR; r = 0.53), but analyses did not indicate a role of these physiological variables in mediating between emotion regulation and health: neuroendocrine variables were not related to interleukin 6 or ESR, and none of the physiological parameters was correlated with joint score or perceived health. CONCLUSIONS: To examine whether the proposed mediational processes apply to individual patients, a longitudinal within-subjects design is needed. In our cross-sectional study, emotion regulation was somewhat related to neuroendocrine functioning, but our study did not uncover a potential mediational role of cortisol, noradrenaline or interleukin 6 in the relationship between emotion regulation and health in rheumatoid arthritis.

Adult↗

PubMed1991

Production of reliability proven physiological data for use in automated monitoring and diagnostic systems.

In recent years manufacturers of intensive care monitoring systems have introduced complex digital processing architectures that theoretically have enormous processing power. This power should allow the realization of many useful processing methodologies that up to now have only been research tools, e.g. the generation of reliable alarms, the implementation of predictive monitoring strategies and reliable diagnostic and treatment guidance to the clinical staff. However, before any of these methodologies can be successfully initiated, each must have accurate and reliable derived physiological data available to them, e.g. beat-by-beat heart rate and blood pressure. From the very nature of monitoring physiological quantities there will be much misinformation or 'noise' superimposed on the raw signal obtained from the patient. The major source of noise (as far as electrocardiogram (ECG) monitoring is concerned) is internal to the body and is electromyographic noise. This results from the contraction of skeletal muscles producing action potentials of similar magnitude and frequency to that of the ECG. Fortunately, nursing staff are very good at 'filtering out' any misinformation before recording any data (on a ward chart for instance). However, in completely automated systems, if this noise is not detected and eliminated or compensated for at an early stage in the processing chain, misinformation will result with potentially serious consequences. The recognition and elimination of such noise cannot be readily achieved using standard filtering techniques without serious degradation of information. This paper discusses the potential of modern digital system architectures developed for ECG monitoring. It analyses the noise that occurs on this physiological variable and demonstrates a novel method of eliminating such noise.

Electrocardiography↗

PubMed2004

Evaluation of a pulmonary graphical display in the medical intensive care unit: an observational study.

We developed a pulmonary graphic display that depicts pulmonary physiological variables for intubated, mechanically ventilated patients in a graphical format. The pulmonary graphical display presents multiple respiratory variables and changes are depicted by alterations in shape and color. Learning how this new technology will be integrated and accepted by users is an important step before it is introduced into the clinical arena. This study observed use and acceptance of the pulmonary graphical display by health care providers in an intensive care unit. Investigators noted that physicians, respiratory therapists, and nurses observed the pulmonary graphical display on average six, three, and one times, respectively, per patient room entry. Based on questionnaires, the pulmonary graphical display was perceived as useful, a desirable addition to current ICU monitors, and an accurate representation of respiratory variables.

Attitude of Health Personnel↗