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Results for “physiologic variables”

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PubMed1999

The anesthetic record: accuracy and completeness.

PURPOSE: To evaluate if anesthesia training and experience influenced chart completion and accuracy. METHODS: One hundred and twenty-four subjects, including medical students, anesthesia residents and community and university based clinical anesthesiologists, were given a standardized patient in a simulator environment and asked to conduct induction and maintenance of anaesthesia. Three critical events were introduced resulting in changes in BP, HR, PETCO2 and SpO2. Subjects were instructed to manage the patient and the anesthetic chart, as was their customary practice. Discrepancy, calculated as the difference between the actual and charted values divided by the actual physiological value was compared by level of training with a two-way repeated measures analysis of variance (ANOVA) for all four physiological variables. The completeness of charting, defined as at least one data point recorded for each of the four physiological variables of the three critical events, was compared across level of training, age of participants and number of years in practice. RESULTS: The overall completeness of charting remained low (< 37%) with no relationship based on the anesthesiologist's age, level of training or number of years in practice. There was discrepancy in charting for all physiological variables (HR, BP, PETCO2 and SpO2, P < 0.0001), with a marked difference in the degree of discrepancy within each level of training. Training resulted in no differences in charting discrepancy. CONCLUSION: Charting of data to the anesthetic record remained incomplete and inaccurate in all groups based on level of training, age and number of years in practice.

Adult↗

PubMed2005

Physiological thresholds for irreversible tissue damage in contusional regions following traumatic brain injury.

Cerebral ischaemia appears to be an important mechanism of secondary neuronal injury in traumatic brain injury (TBI) and is an important predictor of outcome. To date, the thresholds of cerebral blood flow (CBF) and cerebral oxygen utilization (CMRO(2)) for irreversible tissue damage used in TBI studies have been adopted from experimental and clinical ischaemic stroke studies. Identification of irreversibly damaged tissue in the acute phase following TBI could have considerable therapeutic and prognostic implications. However, it is questionable whether stroke thresholds are applicable to TBI. Therefore, the aim of this study was to determine physiological thresholds for the development of irreversible tissue damage in contusional and pericontusional regions in TBI, and to determine the ability of such thresholds to accurately differentiate irreversibly damaged tissue. This study involved 14 patients with structural abnormalities on late-stage MRI, all of whom had been studied with (15)O PET within 72 h of TBI. Lesion regions of interest (ROI) and non-lesion ROIs were constructed on late-stage MRIs and applied to co-registered PET maps of CBF, CMRO(2) and oxygen extraction fraction (OEF). From the entire population of voxels in non-lesion ROIs, we determined thresholds for the development of irreversible tissue damage as the lower limit of the 95% confidence interval for CBF, CMRO(2) and OEF. To test the ability of a physiological variable to differentiate lesion and non-lesion tissue, we constructed probability curves, demonstrating the ability of a physiological variable to predict lesion and non-lesion outcomes. The lower limits of the 95% confidence interval for CBF, CMRO(2) and OEF in non-lesion tissue were 15.0 ml/100 ml/min, 36.7 mumol/100 ml/min and 25.9% respectively. Voxels below these values were significantly more frequent in lesion tissue (all P < 0.005, Mann-Whitney U-test). However, a significant proportion of lesion voxels had values above these thresholds, so that definition of the full extent of irreversible tissue damage would not be possible based upon single physiological thresholds. We conclude that, in TBI, the threshold of CBF below which irreversible tissue damage consistently occurs differs from the classical CBF threshold for stroke (where similar methodology is used to define such thresholds). The CMRO(2) threshold is comparable to that reported in the stroke literature. At a voxel-based level, however (and in common with ischaemic stroke), the extent of irreversible tissue damage cannot be accurately predicted by early abnormalities of any single physiological variable.

Adolescent↗

PubMed2003

Body size as a latent variable in a structural equation model: thermal acclimation and energetics of the leaf-eared mouse.

Body size is one of the most important determinants of energy metabolism in mammals. However, the usual physiological variables measured to characterize energy metabolism and heat dissipation in endotherms are strongly affected by thermal acclimation, and are also correlated among themselves. In addition to choosing the appropriate measurement of body size, these problems create additional complications when analyzing the relationships among physiological variables such as basal metabolism, non-shivering thermogenesis, thermoregulatory maximum metabolic rate and minimum thermal conductance, body size dependence, and the effect of thermal acclimation on them. We measured these variables in Phyllotis darwini, a murid rodent from central Chile, under conditions of warm and cold acclimation. In addition to standard statistical analyses to determine the effect of thermal acclimation on each variable and the body-mass-controlled correlation among them, we performed a Structural Equation Modeling analysis to evaluate the effects of three different measurements of body size (body mass, m(b); body length, L(b) and foot length, L(f)) on energy metabolism and thermal conductance. We found that thermal acclimation changed the correlation among physiological variables. Only cold-acclimated animals supported our a priori path models, and m(b) appeared to be the best descriptor of body size (compared with L(b) and L(f)) when dealing with energy metabolism and thermal conductance. However, while m(b) appeared to be the strongest determinant of energy metabolism, there was an important and significant contribution of L(b) (but not L(f)) to thermal conductance. This study demonstrates how additional information can be drawn from physiological ecology and general organismal studies by applying Structural Equation Modeling when multiple variables are measured in the same individuals.

Acclimatization↗

PubMed1986

Behavioral and physiological effects associated with changes in muscarinic receptors following administration of an irreversible cholinergic agonist (BM 123).

Previous work in our laboratory has shown that the aziridinium ion of BM 123 (N-[4(2-chloroethylmethylamino)-2-butynyl]-2 pyrrolidone) is a potent and selective muscarinic agonist and binds irreversibly to muscarinic receptors (mAChR). The present series of experiments was designed to study the effects of BM 123 on behavioral and physiological variables known to be sensitive to manipulations of the cholinergic neurotransmitter system. BM 123 was injected into the tail vein of Sprague-Dawley rats, reducing mAChR to approximately 10% of normal as judged by [3H](-)QNB binding. Oxotremorine was injected IV for purposes of comparison. Behavioral and physiological variables were measured daily for 26 days. Physiological variables (e.g., tremor, chromodacryorrhea, salivation, and temperature) showed effects in less than 5 min after injection and returned to their pretreatment baselines within minutes. Nociceptive thresholds, dependent on sensory-perceptual processes, showed peak changes of approximately +230% and returned to normal within hours. Motoric responses, i.e., drinking and general activity, recovered in 3-4 days. Learned responses and those requiring temporal discrimination took 8-11 days to recover and were the only responses paralleling the return of the mAChRs to their normal levels. Changes elicited by oxotremorine recovered more rapidly than those elicited by BM 123. The results suggest that the different variables measured are dependent on different densities of functional receptors. Implications for a theoretical model are discussed.

Animals↗

PubMed1997

Therapy of patients with head injuries: key parameters for management.

BACKGROUND: Secondary brain injury, presumed secondary to ischemia, increases the mortality and morbidity of traumatic brain injury. Although many mechanisms appear to be involved, many potential ischemic insults results from changes in readily observable physiologic variables. METHODS: A focused search of scientific articles published in English to determine what data are available to suggest parameters within which key physiologic variables should be maintained. RESULTS: Few data demonstrate that maintenance of variables within specific ranges alters outcome; however, considerable evidence establishes association with poor outcome and hypotension, intracranial hypertension, and cerebral venous saturation. Key parameters vary somewhat based upon the phase of treatment after injury. Other variables, such as systemic oxygen delivery and brain saturation measured by near-infrared spectroscopy, are less well linked to outcome. CONCLUSIONS: Further research is necessary to establish that manipulation of physiologic variables to maintain them within preset ranges improves outcome.

Brain Injuries↗

PubMedDate not supplied

Neuroprotection as initial therapy in acute stroke. Third Report of an Ad Hoc Consensus Group Meeting. The European Ad Hoc Consensus Group.

Although a considerable body of scientific data is now available on neuroprotection in acute ischaemic stroke, this field is not yet established in clinical practice. At its third meeting, the European Ad Hoc Consensus Group considered the potential for neuroprotection in acute stroke and the practical problems attendant on the existence of a very limited therapeutic window before irreversible brain damage occurs, and came to the following conclusions. NEUROPROTECTANTS IN CLINICAL DEVELOPMENT: Convincing clinical evidence for an efficacious neuroprotective treatment in acute stroke is still required. Caution should be exercised in interpreting and extrapolating experimental results to stroke patients, who are a very heterogeneous group. The limitations of the time windows and the outcome measures chosen in trials of acute stroke therapy have an important influence on the results. The overall distribution of functional outcomes provides more statistical information than the proportion above a threshold outcome value. Neurological outcome should also be assessed. Neuroprotectants should not be tested clinically in phase II or phase III trials in a time window that exceeds those determined in experimental studies. The harmful effects of a drug in humans may override its neuroprotective potential determined in animals. Agents that act at several different levels in the ischaemic cascade may be more effective than those with a single mechanism of action. CURRENT IN-HOSPITAL MANAGEMENT OF ACUTE STROKE: The four major physiological variables that must be monitored and managed are blood pressure, arterial blood gas levels, body temperature, and glycaemia. The effects of controlling these physiological variables have not been studied in prospective trials, though they may all contribute to the outcome of acute ischaemic stroke and affect the duration of the therapeutic window. Optimal physiological parameters are inherently neuroprotective. Trials of new agents for the treatment of acute stroke should aim to maintain these physiological variables as close to normal as possible, and certainly within strictly defined limits. THE PLACE OF NEUROPROTECTANTS IN ACUTE STROKE MANAGEMENT: Stroke patients are a very heterogeneous group with respect to stroke mechanisms and severity, general condition, age and co-morbidities. At the present time, the only firm guideline than can be proposed for patient selection is the need for early admission to enable neuroprotectant and/or thrombolytic treatment to be started as soon as possible within the therapeutic window. The severity of potential side-effects will largely determine who should assess a patient with suspected stroke and initiate treatment. There is little information on which to base the duration of neuroprotectant therapy, and more experimental data are needed. Even if prehospital treatment proves to be feasible, it should not replace comprehensive stroke management in a specialist hospital unit. Clinical trials of neuroprotectants should only be performed in stroke units. The combined approach of restoring blood flow and providing neuroprotection may be the most productive in human stroke, but current clinical trial design will have to change in order to test combination therapy. Important side-effects are those that interfere with any possible benefit or increase mortality. PHARMACO-ECONOMIC ASPECTS OF NEUROPROTECTANTS: The early increase in hospital cost associated with neuroprotectant therapy may be balanced by the shorter length of hospital stay and lesser degree of disability of the surviving patients. The overall direct financial cost is highly dependent on the number of patients eligible for neuroprotectant therapy, which is itself dependent on the length of the therapeutic window and the severity of potential side-effects. A treatment that achieves a good functional outcome is the most cost-effective approach.

Acute Disease↗

PubMed1993

Physiological predictors of short-course triathlon performance.

The purpose of this study was to investigate if selected physiological variables were related to triathlon performance. Eighteen male and seven female triathletes competed in a short-course triathlon (1-km swim, 30-km cycle, 9-km run) and underwent physiological testing within 14 d. VO2max and ventilatory threshold (VT) were measured on a cycle ergometer, treadmill, and tethered swim apparatus. Leg flexion and extension strength were measured on a Cybex II isokinetic dynamometer. Multiple linear regression did not improve the prediction of triathlon performance over that provided by simple correlations. Swim performance was related to relative swim VO2max in both males (r = -0.48) and females (r = -0.93) as well as the resistance pulled at swim VT (r = -0.81) and absolute leg flexion strength (r = -0.77) in females. No physiological variables were significantly related to cycling time in either gender. Running time was related to relative VO2max (r = -0.88) in females and velocity at run VT in both females (r = -0.88) and males (r = -0.73). Relative swim VO2max (r = -0.98), velocity at run VT (r = -0.89), and absolute leg flexion strength (r = -0.80) were related to overall performance in female triathletes. The only significant predictor of overall triathlon time for males was velocity at run VT (r = -0.78). It therefore appears that in short-course triathletes physiological variables in swimming and running are important to overall performance. Differences in sample size, group variability, and level of performance between males and females may account for the reported differences in the physiological predictors of performance between genders.

Adult↗

PubMed1992

Cerebral cardiovascular and respiratory variables after an experimental brain missile wound.

Brain missile wounding (BMW) affects brainstem and medullary cadiorespiratory functions leading to immediate systemic hypertension, bradycardia, and apnea. Secondary complications may also occur because of subsequent changes in systemic and intracranial physiological variables. To delineate the immediate and secondary effects of BMW, we monitored changes in several cerebral and cardiorespiratory parameters in pentobarbital-anesthetized spontaneously breathing cats before wounding and up to 90 min afterward. Total and regional cerebral blood flow (rCBF) and cardiac output (CO) were measured (microsphere technique) and arterial blood was sampled for pH, PO2 and PCO2 once before BMW and one to four times afterward. Mean arterial blood pressure (MABP), intracranial pressure (ICP), cerebral perfusion pressure (CPP = MABP - ICP), electrocardiogram (ECG), heart rate (HR), and electroencephalogram (EEG) were continuously recorded. Respiratory frequency (f), tidal volume (Vt), and ventilation (V) were recorded during each flow measurement and periodically throughout the experiment. Four unwounded cats served as controls and 15 cats were wounded at 1.4 J fronto-occipitally through an intact cranium. Unwounded cats showed no significant changes in any physiological variable measured during a 100 min experimentation period. Four wounded cats survived a 90 min post-BMW period and had only a transient brainstem effect including a 50% increase in MABP concurrently with 50% reductions in the f and HR. Nonsurvivors (11 of 15) lived from 1 to 41 min after wounding. These cats initially demonstrated similar changes in MABP, f, and HR to survivors, but these variables remained unstable, possibly indicating a persisting brainstem damage. Apnea accounted for death in 10 of 11 nonsurvivors. Although the primary brainstem effect might have existed in all nonsurvivors, it appears that only one cat died from reduced respiration alone. Others had one or several postwounding secondary complications: abruptly increased ICP producing a negative CPP, extreme reductions in CO or CBF and ventilation. Cardiac arrest occurred once. Thus, post-BMW mortality cannot be consistently ascribed to the impairment of a single physiological variable.

Analysis of Variance↗

PubMed1986

Relationship of fat patterning to coronary artery disease risk in obese adolescents.

Fatness and fat patterning of 27 male and 33 female obese adolescents were identified by principal-components analysis of five skinfolds (triceps, subscapular, iliac, abdominal, and thigh). Correlations were computed between the component scores, based on the eigen vectors, and anthropometric and physiological variables. Overall fatness, component I, was highly correlated with all anthropometric and body composition variables. Also, component I significantly correlated with fasting insulin and VO2 max for both sexes and with basal metabolism and HDL-cholesterol for females and males, respectively. Extremity fat patterning, component II, was poorly correlated with all the anthropometric and physiological variables except diastolic blood pressure for the females. Upper-lower body fat patterning, component III, was correlated with the fewest physiological variables.

Adipose Tissue↗

PubMed2005

The dynamics of single-substrate continuous cultures: the role of ribosomes.

When a chemostat is perturbed from its steady state, it displays complex dynamics. For instance, if the identity of the growth-limiting substrate is switched abruptly, the substrate concentration and cell density undergo a pronounced excursion from the steady state that can last several days. These dynamics occur because certain physiological variables respond slowly. In the literature, several physiological variables have been postulated as potential sources of the slow response. These include transport enzymes, biosynthetic enzymes, and ribosomes. We have been addressing this problem by systematically exploring the role of these variables. In previous work Shoemaker et al. (J. Theor. Biol., 222 (2003) 307-322), we studied the role of transport enzymes, and we showed that transients starting from low transport enzyme levels could be quantitatively captured by a model taking due account of transport enzyme synthesis. However, there is some experimental data indicating that slow responses occur even if the initial enzyme levels are high. Here, we analyse this data to show that in these cases, the sluggish response is most probably due to slow adjustment of the ribosome levels. To test this hypothesis, we extend our previous model by accounting for the evolution of both the transport enzyme and the ribosomes. Based on a kinetic analysis of the data in the literature, we assume that the specific protein synthesis rate is proportional to the ribosome level, and the specific ribosome synthesis rate is autocatalytic. Simulations of the model show remarkable agreement with experimentally observed steady states and the transients. Specifically, the model predictions are in good agreement with (1) the steady-state profiles of the cell density, substrate concentration, RNA, proteins, and transport enzymes, (2) the instantaneous specific substrate uptake, growth, and respiration rates in response to a continuous-to-batch shift, and (3) the transient profiles of the cell density, substrate concentration, and RNA in response to feed switches and dilution rate shifts. Time-scale analysis of the model reveals that every transient response is a combination of two fundamental (and simpler) dynamics, namely, substrate-sufficient batch dynamics and cell-sufficient fed-batch dynamics. We obtain further insight into the transient response by analysing the equations describing these fundamental dynamics. The analysis reveals that in feed switches or dilution rate shift-ups, the transport enzyme reaches a maximum before RNA achieves its maximum, and in dilution rate shift-downs the cell density reaches a maximum before RNA achieves a minimum.

Bacterial Physiological Phenomena↗

PubMed1995

Does Acute Physiologic and Chronic Health Evaluation (APACHE II) scoring predict need for prolonged support after coronary revascularization?

Significant intensive care unit (ICU) resources are allocated to patients recovering from coronary artery bypass graft (CABG) procedures, suggesting that a system to identify patients at risk for prolonged ICU therapy would help to enhance the use of this resource. To test the hypothesis that post-CABG patients likely to require prolonged ICU stay could be identified at the time of admission using the Acute Physiologic and Chronic Health Evaluation (APACHE II) system for scoring the severity of illness, we retrospectively reviewed the length of ICU stay for all patients recovering from CABG procedures over 1 yr, comparing the APACHE II scores assigned to patients requiring the longest stay with scores for patients with the briefest stay to determine whether a difference in score corresponded with the difference in length of stay. All medical records were reviewed and the physiologic variables (n = 12) used to assess acute physiologic status were recorded. Perioperative therapeutic interventions having significant impact on the physiologic variables used to derive the APACHE II score also were recorded. The study group was defined as patients requiring ICU care lasting between 14 and 84 days (n = 20); a control group of 23 patients was randomly selected from 124 patients having an ICU stay of 48 h or less. The overall APACHE II scores, and the component scores used to derive the overall scores, were calculated for both groups and were compared. The mean APACHE II score for the study group was 23.5 compared with 13.2 (P < 0.001) for the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

APACHE↗

PubMed1991

Discharge variability and physiological properties of human masseter motor units.

Intramuscular electrodes were used to study discharge variability in motor units of human masseter whose physiological properties were determined using spike-triggered averaging. Subjects voluntarily controlled the mean firing rate of a selected motor unit at 10 Hz for 15 min of continuous activation. Discharge variability was assessed at the beginning and end of this period. In 81% of units, the discharge variability at a mean interspike interval (ISI) of 100 ms increased after 15 min of continuous activity. There was a wide range of discharge variability within the population of masseter units studied, but no significant correlations were found between initial discharge variability and recruitment threshold, twitch tension or time-to-peak tension (TTP). There was, however, a significant correlation between motor unit fatigability and its initial discharge variability. This represents a link between the motoneuron and the functional properties of the muscle fibers in innervates.

Adolescent↗

PubMed2001

Intraspecific differences in behaviour and physiology: effects of captive breeding on patterns of torpor in feathertail gliders.

Studies on the physiology of mammals and birds are often conducted using captive-bred individuals and it is commonly assumed that the resulting data are representative of individuals living in the field. To investigate whether these assumptions are justified, we quantified morphological, behavioural, and physiological variables of the small marsupial feathertail glider (Acrobates pygmaeus). We compared three populations: (i) individuals from a cool-temperate, montane area, (ii) individuals form a subtropical, coastal area, and (iii) captive-bred individuals. Captive-bred gliders differed from the montane field gliders in morphology (longer tails and snouts), behaviour (longer activity periods) and physiology (less frequent torpor, shorter torpor, shallower torpor, higher metabolic rates during rest and torpor, and slower rates of rewarming). Most of these differences were also apparent between the captive-bred and the coastal field gliders. Unlike both field populations, captive-bred gliders often became hypothermic and were unable to rewarm. In contrast to the other physiological variables, the minimum body temperatures defended during torpor and the corresponding air temperatures differed between the montane and coastal field gliders, but were similar in coastal field and captive-bred gliders. Our study shows that morphology, behaviour and physiology can be strongly affected by breeding in or acclimation to captivity. The poor expression of torpor and thermal performance of the captive-bred gliders raises the question of whether they possess the physiological capability for survival in the wild. Even though captive breeding appears to have only minor effects on some physiological variables, data from captive-bred individuals should only be extrapolated to the field with caution.

Adaptation, Physiological↗

PubMed2003

Physiological correlates with endurance running performance in trained adolescents.

PURPOSE: To examine the relationship between competitive 800-m and 1500-m performance times and a number of physiological variables in a group of endurance-trained, adolescent runners. METHODS: Twenty-three boys and 17 girls volunteered to participate in the study. Track-based, running performance times were available for 18 boys and 14 girls for the 800 m, and 16 boys and 13 girls for the 1500 m. The relationships between these times and the following physiological variables were determined: peak VO(2) running economy (RE), estimated running speed at peak vV0(2peak), peak and mean anaerobic power, and fixed [BLa ] at 2.0, 2.5, and 4.0 mmol.L. RESULTS: RE and vV0(2peak) were significant independent variables for the boys' 800 m (r = 0.62 and -0.62, < 0.01). For the girls, once chronological age was partialled out, none of the measured variables were significantly related to 800-m performance. For the 1500-m event, peak V0(2), vV0(2peak), and the running speed at 2.5 mmol.L (v2.5) were significant independent variables in the boys (r = -0.43, -0.39, and -0.53, < 0.05) and girls (r = -0.50, -0.61, and -0.54, < 0.05). In addition, the V0(2) at 2.5 mmol.L V0(2) (2.5) was related to the 1500-m time in the girls (r = -0.54, < 0.05). CONCLUSION: The physiological variables that were most strongly correlated with middle-distance running performance were v2.5 and the vV0(2peak). To a lesser extent peak V02 may also play a role although it is understood that its contribution may be accounted by vV0(2 peak).

Adolescent↗

PubMed1991

Age-related alterations of Doppler left ventricular filling indexes in normal subjects are independent of left ventricular mass, heart rate, contractility and loading conditions.

The purpose of this study was to determine whether age-related alterations in Doppler diastolic filling indexes occur independent of cardiovascular disease and confounding physiologic variables. Ten old (62 to 73 years) and 10 young (21 to 32 years) healthy male volunteers were rigorously screened for cardiovascular disease and underwent comprehensive Doppler echocardiography, radionuclide ventriculography and invasive measurements of right heart and left atrial pressures. There were no differences between the two groups in the physiologic variables of left ventricular mass, volumes, ejection fraction, end-systolic wall stress, left atrial size, heart rate and right atrial, pulmonary artery, pulmonary capillary wedge and systemic arterial pressures. However, there were marked differences in Doppler left ventricular filling indexes. Compared with the young group, the old group had reduced peak early diastolic flow velocity (56 +/- 13 vs. 82 +/- 12 cm/s, p = 0.0002) and increased atrial diastolic flow velocity (59 +/- 14 vs. 43 +/- 10 cm/s, p = 0.009) and had a peak atrial/early flow velocity (A/E) ratio twice that of the young group (1.09 +/- 0.29 vs. 0.54 +/- 0.15, p less than 0.0001). Similar results were obtained for the time-velocity integrals of the peaks. Subjects in the old group also had a markedly reduced peak filling rate (274 +/- 62 vs. 448 +/- 152 ml/s, p = 0.004). In univariate and multivariate regression analyses, peak early and atrial flow velocities were not related to any of the physiologic variables measured once age was accounted for, although peak filling rate, a volumetric measure flow, was related to body surface area as well as age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2001

Fast, nondestructive measurement of frost hardiness in conifer seedlings by VIS+NIR spectroscopy.

Frost hardiness development from mid-August to mid-November was evaluated in seedlings of three provenances of Norway spruce (Picea abies (L.) Karst.) and three provenances of Scots pine (Pinus sylvestris L.) raised at nurseries in north, central and south Sweden. Measurements of the visible + near infrared (VIS+NIR) spectra of shoots were made simultaneously with estimates of frost hardiness based on electrolyte leakage following artificial freezing. Nine physiological variables known to influence frost hardiness were measured throughout the experiment. Multivariate analysis showed that VIS+NIR spectra explained 69% and 72% of the variation in frost hardiness in Scots pine and Norway spruce, respectively. Stem lignification, dry weight fraction, and starch, glucose, fructose, galactose, sucrose, raffinose and stachyose concentrations together explained 80% and 85% of the variation in frost hardiness in Scots pine and Norway spruce, respectively when used as independent X variables in a partial least squares model. These physiological variables could be related to varying degrees with variation in the VIS+NIR spectra. We conclude that VIS+NIR spectroscopy provides a rapid nondestructive technique for measuring frost hardiness in conifer seedlings based on causal relationships between the spectra and the physiology of seedling frost hardiness.

Freezing↗

PubMed1997

Comparison of the APACHE III, APACHE II and Glasgow Coma Scale in acute head injury for prediction of mortality and functional outcome.

OBJECTIVES: This study examines the efficacy of the predicting power for hospital mortality and functional outcome of three different scoring systems for head injury in a neurosurgical intensive care unit (NICU). DESIGN: On the day of admission, data were collected from each patient to compute the Acute Physiology, Age, and Chronic Health Evaluation (APACHE) II and III, and Glasgow Coma Scale (GCS) scores. Hospital mortality was defined as the deaths of patients before discharge from hospital. Early mortality was defined as death before the 14th day after admission. Late mortality was defined as death after the 15th day from admission. Functional outcome was evaluated by Index of Independence in Activities of Daily Living (Index of ADL). SETTING: An 8-bed NICU in a 1270-bed medical center in Taichung Veterans General Hospital. PATIENTS AND PARTICIPANTS: Two hundred non-selected patients with acute head injury were included in our study in a consecutive period of 2 years. Patients less than 14 years old were not included. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Sensitivity, specificity and correct prediction outcome were measured by the chi-square method in three scoring systems. The Youden index was also obtained. The best cut-off point in each scoring system was determined by the Youden index. The difference in Youden index was calculated by Z score. A difference was also considered if the probability value was less than 0.05. The area under Receiver Operating Characteristic (ROC) curve was computed. Then the area under ROC of each scoring system was compared by Z score. There was statistical significance if p was less than 0.05. For prediction of hospital mortality, the best cut-off points are 55 for APACHE III, 17 for APACHE II and 5 for GCS. The correct prediction outcome is 82.4% in APACHE III, 78.4% in APACHE II and 81.9% in the GCS. The Youden index has best cut-off points at 0.68 for APACHE III 0.59 for APACHE II, and 0.56 for GCS. The area under Receiver Operating Characteristic (ROC) curve is 0.90 in the APACHE III, 0.84 in the APACHE II and 0.86 in the GVS. There are no statistical differences among APACHE III and II, and GCS in terms of correct prediction outcome, Youden Index and the area under the ROC curve. Other physiological variables excluding GCS in APACHE III and II (AP III-GCS, AP II-GCS) have less statistical value in the determination of mortality for acute head injury. For the prediction of late mortality, APACHE III and II yield significantly better results in the area under the ROC curve, correct prediction and Youden index than those of GCS. Other physiological variables (AP III-GCS and AP II-GCS) play an important role in the prediction of late mortality in APACHE scores. For prediction of the functional outcome of surviving patients with acute head injury, the APACHE III yields the best results of correct prediction outcome, Youden index and the area under the ROC curve. CONCLUSION: The APACHE III and II may not replace the role of GCS in cases of acute head injury for hospital or early mortality assessment. But for prediction of the late mortality, the APACHE III and II have better accuracy than GCS. Other physiological variables excluding GCS in the APACHE system play a crucial contribution for late mortality. GCS is simple, less time-consuming and economical for patients with acute head injury for the prediction of hospital and early mortality. The APACHE III provides better prediction for severe morbidity than GCS and APACHE II. Therefore, the APACHE III provides a good assessment not only for hospital and late mortality, but also for functional outcome.

APACHE↗

PubMed2003

Physiologic correlates of comfort in healthy children.

Pain assessment is particularly challenging when children are unable or unwilling to provide a self-report. Although clinicians frequently use vital signs as an adjunct to pain assessment, little evidence exists to support this practice. The purpose of this study was to explore the ability of selected physiologic variables (peripheral skin temperature, heart rate, skin conductance activity [SCA], respiratory rate, electromyogram [EMG] of the frontalis and right forearm muscles, and systolic and diastolic blood pressure [BP]) to detect changes in children's autonomic arousal from baseline. A one-group, repeated measures, randomized crossover design guided the study. Chosen from a convenience sample, 100 healthy children (ages 8-17 years) served as their own controls while undergoing two levels of intervention: cold pressor pain and guided imagery. Although most physiologic responses showed changes in the expected direction, EMG, SCA, and heart rate decreased slightly during cold pressor. Few significant intercorrelations were demonstrated among the physiologic variables. SCA, forehead EMG, respiratory rate, systolic and diastolic BP detected significant changes in arousal across measures. Notably, heart rate failed to detect changes for any of the measures. Results emphasize the need for caution in interpreting heart rate as an index of comfort. Further research is needed to examine the effects of clinical pain on physiologic indices and to further examine age and sex influences. To be relevant for assessment of acute established pain, physiologic variables must also be tested for their sensitivity beyond the immediate period of autonomic arousal.

Adolescent↗