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PubMedDate not supplied

High-speed Holter ECG analysis--what we have learned.

A system for high-speed quantitative analysis of continuous ECG (Holter) recordings has proved effective in maintaining a measured specificity of 99.67 percent and sensitivity of 99.74 percent. Practical difficulties with common ECG signal artifact, and with unusual QRS complexes, have proved that online operator monitoring of classification accuracy is required. Because of artifactual and physiological variability among patients, Holter analysis of individual recordings is meaningless unless accompanied by an indication of the degree of accuracy of the specific recording. Common definitions of specificity and sensitivity based on results from sample recordings are not sufficient to describe the characteristics of an automated ECG performance on any given recording. A quality assurance program that evaluates both the machine and its operator is discussed.

Arrhythmias, Cardiac↗

PubMed2000

Physiological predictors of flat-water kayak performance in women.

This study was conducted to investigate the relationship between selected physiological variables and 500-m flat-water kayak (K500) performance. Nine female, high-performance kayak paddlers, mean (SD) age 23 (5) years, participated in this investigation. Testing was conducted over 6 days and included anthropometric measurements (height, body mass and skinfolds), an incremental test to determine both peak VO2 and the "anaerobic threshold" (Th(an)), and a 2-min, all-out test to calculate accumulated oxygen deficit (AOD). Blood lactate concentrations were measured during the incremental test and at the completion of both tests. Subjects also completed a K500 race under competition conditions. K500 time was significantly correlated with both peak VO2 (r = -0.82, P < 0.05) and the power output achieved at the end of the incremental test (r = -0.75, P < 0.05). However, the variable most strongly correlated with K500 time was Th(an) (r = -0.89, P < 0.05). A stepwise multiple regression, for which r = 0.95 and the standard error of estimate = 1.6 s, yielded the following equation: K500time(s) = 160.6-0.154 x AOD x kg(-1) - 0.250 x Th(an). In conclusion, the results of this study have demonstrated that although K500 performance is a predominantly aerobic activity, it does require a large anaerobic contribution. The importance of both the aerobic and anaerobic energy systems is reflected by the K500 time being best predicted by a linear combination of Th(an) and AOD x kg(-1). This suggests the need to develop and implement training programmes that develop optimally both of these physiological attributes. Further research is required to elucidate the most effective means by which to develop both the aerobic and anaerobic energy systems.

Adult↗

PubMedDate not supplied

[Experimental studies in Polish psychiatric journals].

AIM: Scientific studies in psychiatry from a methodological point of view could be divided into correlational and experimental. Experimental studies are based on active selection of independent and dependent variables, attributing values of the independent variable to persons under study and measuring values of dependent variables. An example of the experimental study is a comparison of two therapeutic methods. Experiments are feeble to selection, informational and confounding bias. METHOD: This review comprises experimental papers published in journals: "Psychiatria Polska", "Postepy Psychiatrii i Neurologii", "Farmakoterapia w Psychiatrii i Neurologii", "Rocznik Psychogeriatryczny", "Wiadomości Psychiatryczne" oraz "Alkoholizm i Narkomania" from January 1998 to December 2002. RESULTS: 11 experimental publications, 6 randomised, 2 probably randomised and 3 case-control studies were found. The smallest study included 14 persons, the largest 180 persons. The number of experimental groups varied from 2 to 4. 9 studies evaluated features of specific methods of therapy and rehabilitation, among them 6 evaluated efficacy of medications. 2 studies evaluated relations between psychopathological and physiological variables. Experiments were based on groups of patients with a diagnosis of schizophrenia (3), alcohol and drug dependence (2), depression (3), insomnia (1), bronchial asthma (1), and hypertension (1). CONCLUSION: The review showed that experimental studies do not form a main-stream in Polish psychiatric journals.

Case-Control Studies↗

PubMed2002

The circadian pattern of breathing in conscious adult rats.

Recently, a circadian oscillation in pulmonary ventilation (VE) was reported in conscious, undisturbed rats [Respir. Physiol. 120 (2000) 179], with a pattern similar to that of body temperature (Tb), oxygen consumption (V(O(2))) and activity. The present study explored the relationship between the daily VE pattern and these rhythms. Adult rats (n=23) were instrumented for measurements of Tb and activity by telemetry, and placed in a chamber for measurement of VE by the barometric method and V(O(2)) by an open-flow method. Simultaneous recordings were made continuously for 3 consecutive days in a 12-h light:12-h dark (L:D) cycle. All variables showed substantial daily oscillations, with significantly higher values in the D phase, and approximately proportionate changes in VE and V(O(2)). Daily changes in tidal volume (VT) relative to inspiratory time (TI), rather than in TI relative to total breath duration, accounted for the oscillation in VE. The VT rhythm was phase-advanced relative to those of V(O(2)) and Tb. L-D differences in VE persisted when comparison between the phases was made for the same level of either very low or very high activity. We conclude that the oscillation in VE does not depend on the daily changes in activity. Rather, the daily pattern of VE is likely shaped by the oscillations of multiple physiological variables, two of which may be Tb and V(O(2)).

Animals↗

PubMed1991

Physiological characteristics of elite judo athletes.

In order to provide some understanding of the physiological capacities underlying successful judo performance, representative values for a variety of physiological variables were determined in nationally ranked male (n = 18) and female (n = 9) judo athletes. Body composition, aerobic capacity, isokinetic elbow and knee flexor and extensor strength, and muscle fiber size and composition of the vastus lateralis were examined. Comparisons across weight divisions indicate that the values of many characteristics varied as a function of size. As weight division increased, relative VO2 decreased (r = -0.53 and -0.63 for males and females, respectively), % body fat increased (r = 0.64, 0.72), and the cross sectional areas of Type I (r = 0.55, 0.77) and Type IIA (r = 0.47, = 0.76) muscle fibers increased. Among females in particular, athletes in the higher weight divisions were stronger relative to LBM than those in the lower division. These results indicate that the physiological profiles of lower and upper weight division elite judo players differ markedly. It is suggested that the factors responsible for success may be specific to each weight division and may represent a compromise between making weight and maximizing physiological capacities and performance.

Adipose Tissue↗

PubMed1994

Effects of hemodialysis on cerebral circulation evaluated by transcranial Doppler ultrasonography.

BACKGROUND AND PURPOSE: The effects of hemodialysis on the cerebral circulation of humans and the correlation between changes in blood flow velocity in the basal cerebral arteries and those of several physiological variables influenced by hemodialysis have been inadequately studied. METHODS: Blood flow velocities were obtained from the middle cerebral artery and the basilar artery by transcranial Doppler ultrasonography in 27 patients receiving chronic maintenance hemodialysis immediately before and after the procedure. Changes in body weight, hematocrit, blood pressure, and arterial blood gases were recorded simultaneously. RESULTS: There was a significant reduction in mean flow velocity in the middle cerebral artery (P < .01) and the basilar artery (P < .01) after hemodialysis. We observed a significant negative correlation between the relative change in mean flow velocity and the loss of weight after hemodialysis, the amount of fluid removed, and the increase in hematocrit in the middle cerebral artery and the basilar artery. CONCLUSIONS: Hemodialysis and the associated physiological changes can significantly affect the cerebral circulation. Blood flow velocities in the middle cerebral artery and the basilar artery decrease significantly with hemodialysis. The loss of body weight, the amount of fluid removed, and the change in hematocrit significantly correlate with the change in mean flow velocity. The transcranial Doppler method can effectively monitor rapid changes in the cerebral circulation during potentially harmful procedures.

Adult↗

PubMedDate not supplied

Use of the pigmentometer, a new device for measuring skin albedo: relating skin color with a series of physiological measures.

Use of the Pigmentometer, a new device for measuring skin albedo: Relating skin color with a series of physiological measures. An apparatus has been described for the indirect measurement of skin albedo in human subjects. This device operates on the principle of the reflectance of light as influenced by the lightness or darkness of the skin. This new equipment was used to examine the relationship between lightness or darkness of the skin and the basal level and responsivity of some autonomic nervous system physiological variables in a series of 46 black and 47 white male and female subjects. It was observed that blacks had significantly lower (darker) skin albedo (PI), a significantly higher skin resistance (SR) and amplitude of the galvanic skin response (GSR), and an insignificant higher basal heart rate (HR). Pearson Product-Movement correlations between all measures from the total population showed significant relationships between PI and SR, SR and GSR and HR and HRR (heart rate response). The further separation of the total population into subgroups of blacks, whites, males, females, and black and white male and female goups, respectively, altered some of these differences and relationships previously observed. These results appeared to support the premise that race is more responsible for influencing the measured physiological responses, particularly SR, than is the lightness or darkness of the skin.

Age Factors↗

PubMed2000

The physiological state of captive and migrating Great White Pelicans (Pelecanus onocrotalus) revealed by their blood chemistry.

The Great White Pelican Pelecanus onocrotalus is an endangered migratory bird, threatened by diminishing natural feeding sites and by persecution by fishermen. The majority of the migrating White Pelican (71000) stop-over in Israel during their autumn migration to Africa. As part of a larger study, aimed to assess the necessity of feeding during the stop-over in Israel, we examined the blood chemistry of captive and migrating White Pelicans. Blood was sampled from captive birds maintained on a fish diet, after food deprivation for 48 h and from wild birds brought from the field during migration. Food deprivation resulted in increased plasma levels of triglycerides and in lower levels of urea, potassium and calcium. In migrating birds, increased plasma levels of urea and CPK and lower levels of creatinine were revealed. In general, the coefficient of variation in the blood chemistry of migrating pelicans was higher than in the captive birds, that is to say, that these birds were in a variable physiological condition. The blood profile of migrating and wintering pelicans did not indicate a state of dehydration but did indicate energy deficiency. The less extreme changes in blood chemistry of the 48 h food-deprived compared to migrating pelicans suggest that the former did not reach a state of starvation. We conclude that for White Pelicans the stop-over in Israel is a must in order to rest and replenish their fuel reserves for completion of their autumn migration to Africa.

Animals↗

PubMed2002

[Introduction of the electronic anesthesia record keeping system].

Based on five-year experience, we have evaluated the electronic anesthesia record keeping system (DS 5300 OR, Fukuda Denshi, Tokyo), which is the first commercially available system combined with an anesthesia monitor in Japan. Although keying in of text with a keyboard on the screen remains to be improved, the user interface of touch screens is easy to use. It seems to be a great advantage that physiologic variables are automatically and accurately captured very minute. The record is more complete, legible, and accurate than a hand-written record. Both long-term storage and search for the data are much easier. The investment in this system is affordable even for small hospitals. Although there might be some areas in which improvement is needed, we are satisfied with its usefulness and reliability.

Anesthesia↗

PubMed1979

[A practicable method of polygraphic investigations in preterm and fullterm neonates (author's transl)].

Polygraphic recording techniques (simultaneous recording of several physiological variables) have been used earlier in investigations of normal newborn and preterm infants. The clinical value of prolonged polygraphic recordings in highrisk neonates is well-known. The main-purpose of this paper is to demonstrate a clinically practicable method of polygraphic recording technique, needing no more than two hours recording-time and its interpretation by means of visual analysis.

Brain Damage, Chronic↗

PubMed1994

Pharmacokinetics and pharmacodynamics of smoked heroin.

Despite the current popularity of smoking as a route of drug self-administration, there have been few human studies characterizing the pharmacokinetics and pharmacodynamics of smoked drugs of abuse. A variety of technological difficulties are encountered in the design of smoking studies, such as delivering reproducible doses and limiting the amount of pyrolysis of parent drug. As part of a concerted research effort to deliver precise, smoked doses of drug, a computer-assisted smoking device was utilized that delivered single puffs of heroin vapor to human subjects under controlled clinical conditions. Recovery studies indicated that the smoking device delivered approximately 89% of parent heroin to subjects. Although only two qualified heroin smokers could be identified as eligible volunteers, their participation provided the unique opportunity to study the pharmacokinetics and pharmacodynamics of smoked heroin. The two subjects were administered four smoked heroin doses in ascending order. In addition, four intravenous doses of heroin were administered for comparison of effects and estimation of bioavailability. Concurrent physiological, behavioral, and performance measures were collected along with blood samples. Blood was analyzed for heroin, 6-acetylmorphine, and morphine by solid-phase extraction gas chromatography-mass spectrometry. Heroin appeared rapidly in blood after administration and peaked 1-5 minutes after smoking, which is similar to that observed following intravenous administration. Heroin concentrations declined rapidly to the limit of detection (1.0 ng/mL) by 30 minutes. 6-Acetylmorphine blood concentrations also peaked and declined rapidly after smoked heroin with peak concentrations occurring at 1-2 minutes after smoking. Morphine levels rose and decayed more slowly. Mean elimination half-lives for heroin, 6-acetylmorphine, and morphine were 3.3 min, 5.4 min, and 18.8 min, respectively, by the smoked route. The bioavailability of smoked heroin was highly variable. Physiological measures such as pupil diameter demonstrated a counterclockwise hysteresis compared with heroin blood levels. The rapid onset of pharmacological effects together with the early appearance of heroin and metabolites in blood following smoked heroin demonstrated the effectiveness of this route of drug administration. It is evident that the smoking route enables individuals to obtain similar pharmacological effects as are produced by intravenous administration of heroin.

Administration, Inhalation↗

PubMed1990

Rate-adaptive cardiac pacing in children using a minute ventilation biosensor.

Chronotropic integrity is required for a normal cardiac output response to exercise. We evaluated a rate-adaptive ventricular demand pacemaker (Telectronics, META-MV) which uses minute ventilation as the sensed physiological variable for adjusting pacing rate, in seven young patients with a mean age of 11.4 years. All patients had clinically significant bradycardia related to complete heart block (n = 4) or sinus node dysfunction (n = 3). For the entire group, paced heart rates increased from 70 +/- 10 beats/min to 151 +/- 19 beats/min with exercise testing. The onset of rate adaptation took less than 30 seconds. Changes in paced rate were linearly related to workload, VO2 (5.9 to 20.7 mL/min/kg) and minute ventilation (8-65 L/min). The decline in pacing rate after exercise was related directly to the gradual decrease in minute ventilation and VO2. Our data show that minute ventilation closely and accurately reflects the metabolic demands of varying workloads in children and can be used to achieve physiological, rate-adaptive pacing.

Adult↗

PubMed1999

Laparotomy for necrotizing enterocolitis: intensive care nursery compared with operating theatre.

OBJECTIVE: To determine whether neonates requiring laparotomy for necrotizing enterocolitis (NEC) are more stable perioperatively and have less disruption of physiological parameters if surgery is performed in the neonatal intensive care unit (NICU) compared with the operating theatre (OR). METHODOLOGY: A retrospective case review was performed on 233 neonates referred for further surgical management of severe NEC in the period January 1989 to December 1997. Mortality and morbidity were compared by calculating the score for neonatal acute physiology (SNAP) and its attendant risk of mortality score. Thirty-six separate physiological variables were also compared pre- and postoperatively and the mean postoperative change was calculated. RESULTS: For neonates weighing less than 1500 g, mortality was linked to illness severity, as measured by SNAP, rather than operative location. Specific adverse events associated with secondary transfer to the OR included hypothermia, deterioration in oxygenation parameters, ventilation parameters and platelet count. The liberal use of blood products, albumin and bicarbonate in perioperative resuscitation may have obscured other effects. CONCLUSIONS: The use of the neonatal intensive care nursery for surgery on neonates weighing less than 1500 g with severe NEC can be justified and such use should be encouraged. In contrast, secondary transport of neonates weighing less than 1500 g to the OR for laparotomy is associated with significant deterioration in a number of physiological parameters, which may impact on morbidity.

Enterocolitis, Necrotizing↗

PubMed1984

Critical analysis of sensors for physiological responsive pacing.

Physiological responsive pacing includes the application of sensors to measure physiologic variables, which in turn are used to control pacemaker rate. Six such systems are evaluated based on a comparison of (1) speed of response, (2) sensor reliability, and (3) system specificity. Although there is not a clear-cut solution, and every system has some weaknesses, several sensors seem more feasible than others. Much research remains to be done, and the indications and patient benefits must be established.

Adult↗

PubMedDate not supplied

First-pass elimination. Basic concepts and clinical consequences.

First-pass elimination takes place when a drug is metabolised between its site of administration and the site of sampling for measurement of drug concentration. Clinically, first-pass metabolism is important when the fraction of the dose administered that escapes metabolism is small and variable. The liver is usually assumed to be the major site of first-pass metabolism of a drug administered orally, but other potential sites are the gastrointestinal tract, blood, vascular endothelium, lungs, and the arm from which venous samples are taken. Bioavailability, defined as the ratio of the areas under the blood concentration-time curves, after extra- and intravascular drug administration (corrected for dosage if necessary), is often used as a measure of the extent of first-pass metabolism. When several sites of first-pass metabolism are in series, the bioavailability is the product of the fractions of drug entering the tissue that escape loss at each site. The extent of first-pass metabolism in the liver and intestinal wall depends on a number of physiological factors. The major factors are enzyme activity, plasma protein and blood cell binding, and gastrointestinal motility. Models that describe the dependence of bioavailability on changes in these physiological variables have been developed for drugs subject to first-pass metabolism only in the liver. Two that have been applied widely are the 'well-stirred' and 'parallel tube' models. Discrimination between the 2 models may be performed under linear conditions in which all pharmacokinetic parameters are independent of concentration and time. The predictions of the models are similar when bioavailability is large but differ dramatically when bioavailability is small. The 'parallel tube' model always predicts a much greater change in bioavailability than the 'well-stirred' model for a given change in drug-metabolising enzyme activity, blood flow, or fraction of drug unbound. Many clinically important drugs undergo considerable first-pass metabolism after an oral dose. Drugs in this category include alprenolol, amitriptyline, dihydroergotamine, 5-fluorouracil, hydralazine, isoprenaline (isoproterenol), lignocaine (lidocaine), lorcainide, pethidine (meperidine), mercaptopurine, metoprolol, morphine, neostigmine, nifedipine, pentazocine and propranolol. One major therapeutic implication of extensive first-pass metabolism is that much larger oral doses than intravenous doses are required to achieve equivalent plasma concentrations. For some drugs, extensive first-pass metabolism precludes their use as oral agents (e. g. lignocaine, naloxone and glyceryl trinitrate).(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗

PubMed1989

ESTER: an expert system for management of respiratory weaning therapy.

The withdrawal of mechanical ventilation generally presents no problems if carried out when the values of certain predictive physiological variables suggest that the patient will be able to breathe for him or herself. In certain cases, however, a more gradual weaning procedure is necessary, in which the amount of mechanical assistance provided is in some way reduced little by little. One of the usual means of achieving this gradual reduction is by intermittent mandatory ventilation (IMV), in which short bursts of mechanical ventilation are separated by progressively longer periods of "ventilator silence" which stimulate the patient's endogenous respiration. ESTER is an expert system in which the most widely accepted criteria are systematically called upon to supply advice to the clinician who has to prescribe a respiratory therapy regime suited to the needs of the patient. After effecting a preliminary prognosis of the patient's condition, ESTER asks for certain physiological parameters to be keyed in. Analysis of these parameters reveals the patient's condition and allows a recommended respiratory therapy to be designed.

Expert Systems↗

PubMed2004

[Psychophysiological factors in high intellectual potential: comparative study in children aged from 8 to 11 years old].

UNLABELLED: Factors of intellectual talent as well as physiological and psychological characteristics are little known. However, giftedness is now a social problem and the knowledge of precocity hallmarks should permit the diagnosis in order to undertake the adequate educational orientation of these children. From questionnaires given anonymously to parents, this work showed comparative results between a population of gifted children and a control one. OBJECTIVES: The aim of this study was to present precocity hallmarks in the gifted population, following factorial analysis of socio-economic and familial parameters, as well as medical and psycho-physiological variables linked with the children's post-natal life. POPULATION: Four hundred and twelve children aged eight to 11 years, from Lyon, have been used in the survey: 217 children (control group) were included after a random selection in schools, and 195 children (gifted group, IQ >130, Wechsler test) were enrolled after clinician's diagnoses in four medical departments. RESULTS: Regression analysis allowed to draw relation between several factors and giftedness: abnormal pregnancy (CR =3.205, P =0.009), perinatal stress (CR =2.166, P =0.003), and presence of migraine (CR =3.169, P =0.001). Parents living together (married or not) (CR =2.100, P =0.080) with a good and superior level of learning (CR =5.464, P =0.0002) were also linked with giftedness. CONCLUSION: Our results indicate that precocity hallmarks are multifactorial. These data confirm some socio-economic and medical physiological features correlated with giftedness, and suggest that psychological factors may bear on the etiology of intellectual talent. We focus on the hypothesis than early stress may play a role on central nervous system maturation in these children.

Child↗

PubMed2005

Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness.

STUDY OBJECTIVES: A severely altered level of consciousness (ALC) has been considered a contraindication to noninvasive positive pressure ventilation (NPPV). We compared the clinical outcome of patients with acute respiratory failure (ARF) due to COPD exacerbations and different degrees of ALC. DESIGN: A 5-year case-control study with a prospective data collection. SETTING: Respiratory Monitoring Unit. PATIENTS: Eighty of 153 consecutive COPD patients requiring NPPV for ARF were divided into four groups, which were carefully matched for the main physiologic variables, according to the level of consciousness assessed with the Kelly-Matthay Score, in which 1 is normal (control subjects) and 6 is severely impaired. MEASUREMENT AND RESULTS: Changes from baseline in arterial blood gas (ABG) levels and Kelly score, the rate and causes of NPPV failure, the rate of nosocomial pneumonia, and the 90-day mortality rate were compared. NPPV significantly improved ABG levels and Kelly score in all groups after 1 to 2 h. NPPV failure (Kelly score 1 = 15%; Kelly score 2 = 25%; Kelly score 3 = 30%; Kelly score > 3 = 45%) and 90-day mortality rate (Kelly score 1 = 20%; Kelly score 2 = 35%; Kelly score 3 = 35%; Kelly score > 3 = 50%) significantly increased with the worsening of the level of consciousness. Using a multivariate analysis, the acute nonrespiratory component of the acute physiology and chronic health evaluation (APACHE) III score, and baseline pH independently predicted baseline Kelly score. After 1 to 2 h of NPPV, changes in the Kelly score were associated with those in pH. No correlation was found with Pa(CO2). CONCLUSIONS: This study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, whereas the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, even though better than expected, so that an initial and cautious attempt with NPPV may be performed even in this latter group. Changes in the level of consciousness induced by NPPV are not correlated with those in Pa(CO2).

Acid-Base Imbalance↗