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PubMed2007

Analysis of prognostic indexes and other parameters to predict the length of hospitalization in thermally burned patients.

BACKGROUND: In a retrospective study the influence of several clinical data and prognostic indexes on the length of hospital stay in burned patients was investigated. METHODS: We recorded all admitted patients from January 2004 to December 2005 except for electrical and chemical injuries or patients that died during recovery. Age, gender, weight, height, body surface area, fluid, caloric and protein delivery, Total Burn Surface Area, full thickness burn surface area, Roi index, Baux score, Unit Burn Standard index, Abbreviated Burn Severity Index and the length of hospitalization were registered. A univariate and multivariate analysis was performed to look for correlations between these parameters and the length of hospitalization. RESULTS: We recorded eligible 233 patients. The univariate analysis showed that age, protein and caloric delivery, Roi index and ABSI were significantly related with the length of hospitalization while, at the multivariate analysis, only Roi index was related (p<0.05). However, Roi index was able to predict only 5.5-6% of cases. CONCLUSIONS: A correlation exists between the length of hospital stays and the Roi index in burned patients but does not explain the bulk of evidence. Further studies are required to investigate this relation, to screen other parameters and to correlate them with measures of outcome, i.e. functional (the range of motion of articulations) or aesthetic (patient's self assessment of his body image).

Adult↗
PubMed2006

Psychometric properties of brief indexes designed to measure social-cognitive predictors of smoking initiation.

BACKGROUND: Constructing indexes which measure factors that may predict smoking initiation is essential for planning prevention programs. Our aim was to examine the criterion-related construct validity of brief psychological indexes of attitude, social influence and self-efficacy to be used in future studies for predicting smoking initiation in adolescents. METHODS: Five indexes were evaluated using cross-sectional data on 4819 adolescents age 13 in a random sample of schools in six Danish counties. Item analyses were performed with the graphical log-linear Rasch model, a modification of the Rasch model that allows for differential item functioning and positive local dependence. RESULTS: The three indexes social influence-norms, social influence-pressure and attitude showed acceptable deviations from the Rasch model, while the two indexes self-efficacy and social influence-behavior were invalidated by negative local dependence. CONCLUSION: Of the five tested indexes, three (social influence-norms, social influence-pressure and attitude) showed acceptable criterion-related construct validity and may be considered unbiased representations of the theory-based factors if statistical analyses are appropriately adjusted. The results of this population-based study show that the graphical log-linear Rasch model is useful for evaluating health-related behavior indexes and identifying problems, which can be dealt with when using the indexes in future studies.

Adolescent↗
PubMed2005

Noninvasive prediction of complications with anteroseptal acute myocardial infarction by left ventricular Tei index.

BACKGROUND: Tei index has been proposed as a noninvasive and simple index that enables the evaluation of global left ventricular (LV) function and prediction of patient prognosis. However, its use to predict complications with acute myocardial infarction (AMI) is not fully investigated. Therefore, the purpose of this study was to investigate whether or not LV Tei index allows noninvasive prediction of complications with AMI. METHODS: In all, 80 consecutive patients with anteroseptal AMI were enrolled. LV Tei index was measured at the time of admission as (a - b)/ b , where a is the interval between cessation and onset of mitral filling flow and interval b is the aortic flow ejection time. Subsequent complications including cardiac death, shock, congestive heart failure, ventricular tachycardia/fibrillation, paroxysmal atrial fibrillation/flutter, advanced atrioventricular block requiring pacing, pericardial effusion, and LV aneurysm during the 30 days after the onset of AMI were prospectively evaluated and compared with the initial Tei index at admission. RESULTS: Complications developed in 31 of 80 (39%) patients with AMI. The Tei index was significantly increased for patients with complications compared with those without them (0.69 +/- 0.16 vs 0.50 +/- 0.11, P < .0001). When Tei index > or = 0.59 was used for the criteria, the sensitivity, specificity, and overall accuracy to predict subsequent complications were 77%, 86%, and 85%, respectively. CONCLUSION: In patients with anteroseptal AMI, LV Tei index at arrival to the hospital in the acute phase allows noninvasive prediction of subsequent complications.

Adult↗
PubMed2005

Comparison of the Tei index with invasive measurements of right ventricular function.

The Doppler-derived Tei index has been reported to be clinically useful in assessing global right ventricular function. It could increase in response to combinations of increased pulmonary artery pressure and/or ventricular dysfunction. We compared the Tei index with invasive measurements of right ventricular function during acute pulmonary hypertension. Right and left ventricular pressures, pulmonary and aortic pressures, pulmonary flow and right ventricular volume by sonomicrometry were measured in six anaesthetized sheep. Graded pulmonary arterial hypertension was induced by a mechanical occlusion maneuver. Pressure-volume loops were generated during preload reduction through caval occlusion. Epicardial echocardiograms were also performed. Invasive indexes including preload recruitable stroke work, ventricular diastolic time constant and stiffness constant, and cardiac output were assessed, as were noninvasive echocardiographic indexes including Tei index and E/A ratio. The right ventricular pressure-volume loop became rectangular, with well-defined isovolumic phases. The slope of preload recruitable stroke work was increased significantly during pulmonary pressure of 30 mm Hg. The ventricular time constant showed a significant increase with no change of chamber stiffness during pulmonary pressure of 35 mm Hg. Concomitantly, the Tei index increased significantly from 0.06+/-0.03 to 0.31+/-0.06, together with the shortening of the ejection time and a decrease of the E/A ratio (P<0.05). Thus, the right ventricular Tei index was noted to be affected by acute graded afterload increase. The alteration in invasive measurements of systolic and diastolic function makes the Tei index a sensitive indicator of right ventricular dysfunction in the settings of acute pulmonary hypertension.

Acute Disease↗
PubMed2006

White blood cell count adds prognostic information to the thrombolysis in myocardial infarction risk index in patients following primary percutaneous coronary intervention (ANIN Myocardial Infarction Registry).

AIMS: To determine the relationship between baseline white blood cell (WBC) count, Thrombolysis in Myocardial Infarction (TIMI) risk index, and 30-day mortality in unselected patients with ST-elevation myocardial infarction (STEMI) treated with primary mechanical reperfusion (PCI). METHODS AND RESULTS: 903 patients from prospective registry admitted for primary PCI to a tertiary cardiological center. Both baseline WBC count and TIMI risk index data were dichotomized about the respective medians. Overall 30-day mortality was 4.3%. Higher WBC count was associated with adverse clinical outcome (6.3% vs. 2.4%; Kaplan-Meier p=0.004) as were higher TIMI risk index values (7.2% vs. 1.4%; Kaplan-Meier p<0.00001). In addition, median WBC count stratified patients within TIMI risk index strata into very low risk (0%), intermediate risk (3.3%) and high risk (11%) (Kaplan-Meier p=0.023 and p=0.005 for comparison of lower and higher WBC count within TIMI risk index stratas). In multivariate analysis WBC count provided independent and additional to TIMI risk index predictive information (Hosmer-Lemeshow p=0.57 and p=0.88 respectively for predictive value of TIMI risk index alone and combined with WBC count). Other independent predictors of death were current smoking (RR 0.33; 95% CI: 0.13-0.87) and previous MI (RR 3.13; 95% CI: 1.28-7.69). CONCLUSIONS: WBC count may be a simple and useful tool for risk stratification in STEMI patients, providing additional to established risk index prognostic information. Our findings stress the strong correlation of inflammation and poor outcome in STEMI patients, which may indicate directions of development of new therapies.

Aged↗
PubMed2005

Quantification the relationship between FITA scores and EMG skill indexes in archery.

Forearm electromyographic (EMG) data are assumed to be an effective method in estimating performance level in archery. The aim of the current study was to establish archery skill indexes based on EMG data. Elite (n=7, FITA score=1303.4+/-26.2), beginner (n=6, FITA score=1152+/-9.0) and non-archers (n=10, assumed FITA score=250+/-0), were involved in the study. EMG activity of Muscle flexor digitorum superficialis and Muscle extensor digitorum were quantified. Two-second periods--1 s before and 1 s after the fall of the clicker--were used to obtain averaged and rectified EMG data. The averaged and rectified EMG data were filtered by averaging finite impulse response filter with 40 ms time window and then normalized with respect to maximum voluntary contraction. To estimate FITA scores from EMG data, the following skill indexes that based on mean area under some parts of processed EMG waveforms was offered for archery. These were the pre-clicker archery skill index (PreCASI), post-clicker archery skill index (PostCASI), archery skill index (ASI) and post-clicker archery skill index 2 (PostCASI2). The correlations between rank of FITA scores and natural logarithms of archery skill indexes were significant for log(PreCASI): r=-0.66, p<0.0008; for log(PostCASI): r=-0.70, p<0.0003; for log(ASI): r=-0.74, p<0.0001; log(PostCASI2): r=-0.63, p<0.002. It is concluded that EMG skill indexes may be useful for: (a) assessing shooting techniques, (b) evaluation of archers' progress and (c) selection of talented archers.

Area Under Curve↗
PubMed2006

The effect of time of day on apnoea index in the sleeping rat.

This study tested the hypothesis that apnoea index would be greater during daytime sleep than nighttime sleep in the rat. Electroencephalogram and electromyogram were monitored via biotelemetry implant and respiration was measured using whole body plethysmography in six male rats in two separate 34h recording sessions per animal. Apnoeas were classified as "spontaneous" or "post-sigh". Daily average spontaneous apnoea index was 35 times greater (p<0.0001) during rapid eye movement (REM) sleep than in non-REM (NREM) sleep. In contrast, daily average post-sigh apnoea index was not significantly greater in REM sleep than in non-REM (NREM) sleep (p=0.39). There was a greater post-sigh apnoea index during daytime REM than during nighttime REM (p=0.043) but REM-related spontaneous apnoea index was unaffected by time of day. There was no day to night difference in spontaneous apnoea index or post-sigh apnoea index during NREM sleep. Respiratory variability (coefficient of variation for breath duration and tidal volume) was not affected by time of day in REM or NREM sleep. We conclude that the circadian timing system has no effect on apnoea index during NREM sleep in the rat, but it may influence the propensity for post-sigh apnoea during REM sleep.

Animals↗
PubMed2005

NZiDep: a New Zealand index of socioeconomic deprivation for individuals.

The aim of this research was to identify a small set of indicators of an individual's deprivation that is appropriate for all ethnic groups and can be combined into a single and simple index of individual socioeconomic deprivation in New Zealand. The NZiDep index of socioeconomic deprivation was derived using the same theoretical basis as the national census-based small-area indices of relative socioeconomic deprivation. The index has been created and validated from the analysis of representative sample survey data obtained from approximately 300 Maori, 300 Pacific, and 300 non-Maori, non-Pacific adults. Twenty-eight deprivation-related characteristics, derived from New Zealand and overseas surveys, were analysed by standard statistical techniques (factor analysis, Cronbach's coefficient alpha, item-total correlations, principal component analysis). The index was validated using information on tobacco smoking, which is known to be strongly related to deprivation. The NZiDep index is based on eight simple questions which take 2-3 min to administer. The index is a significant new (non-occupational) tool for measuring socioeconomic position for individuals. We argue that the index has advantages over existing measures, including a specific focus on deficits, applicability to all adults (not just the economically active), and usefulness for all ethnic groups. Its strengths include focus, simplicity, utility, acceptability across ethnic groups, construct validity, statistical validity, criterion validity (measured with reference to tobacco smoking), and relevance to the current New Zealand context. The index is indicative of deprivation in general, and is designed for use as a variable in research, and for elucidating the relationships between socioeconomic position and health/social outcomes.

Age Factors↗
PubMed2005

Consistent indexing of a (set of) single crystal SAED pattern(s) with the ProcessDiffraction program.

A computer program called "ProcessDiffraction" helps indexing a set of single crystal selected area electron diffraction (SAED) patterns by determining which of the presumed structures can fit all the measured patterns simultaneously. Distances and angles are measured in the digitalized patterns with a graphical tool by clicking on the two shortest non-collinear vectors (spots), using user-supplied calibration data. Centers of the spots and center of the pattern are optionally refined by the program. Suggested individual indexing solutions (consistent with an assumed unit cell) are listed by the program for each pattern. Simulated patterns are also consulted to check if the shortest calculated distances coincide with measured ones. Common solutions for the set are selected by checking the angles between the suggested zone axes against the angles between the experimental goniometer settings. The indexing process is manually controlled by selecting the candidate structures (one-by-one) for indexing and by specifying the tolerances for d-values, plane angles and zone angles. Patterns of any crystal system can be indexed successfully. Although error bars are larger in electron diffraction than in X-ray diffraction (XRD), frequently, many unrelated indexings are possible for any one electron diffraction pattern (irrespective of the indexing method), a set of SAED patterns can generally be indexed unambiguously, i.e. the three-dimensional reciprocal space can be identified correctly. Two other tools also help planning tilting experiments: zones along a plane can be listed (with their angles extended from a pre-selected zone in that plane) and zones lying at a given angle (specified with a tolerance) from a zone can also be identified (as they are situated between two cones). Another tool searches the XRD database directly either for advice on possible structures for a composition or to help calibration.

Journal Article↗
PubMed2004

Validation of a sensitivity performance index test protocol and evaluation of colour Doppler sensitivity for a range of ultrasound scanners.

The ability to detect flow is the most crucial aspect of an ultrasound (US) system because, if flow cannot be detected, no other aspect of performance matters. The objectives of this study were to validate a Doppler "sensitivity performance index," a figure of merit, and to determine if it could be used to differentiate colour Doppler sensitivity performance in scanners of varying complexity. The sensitivity performance index was developed to give a combined measure of related aspects of sensitivity, such as the lowest detectable velocity, the vessel size and the penetration depth. The colour Doppler sensitivity was evaluated objectively as the lowest detectable velocity signal from the deepest achievable point within the Doppler sensitivity phantom free from extraneous noise in a small diameter vessel (3.2 mm inner diameter). The effect of vessel size and mean velocity on the sensitivity performance index were investigated and it was found that the index was not proportional to vessel size, but this may be accounted for by considering the effect of the acoustic properties of the vessel material, the clutter filter and beam shape. The results obtained using flow phantoms with vessel sizes different from those used in this study are, therefore, not directly comparable to the results found in this study; however, a similar trend should be found in the results for the effect of control settings and a similar range of US scanners. It was found that the Doppler sensitivity performance index was a robust challenging test because none of the US scanners evaluated was capable of achieving the highest sensitivity performance index score, which would be limited by the lowest pump velocity and the deepest point of the vessel within the flow phantom. Therefore, this suggests that this method of determining Doppler sensitivity performance is valuable in the absence of other suitable methods, despite the fact that the relationship between the sensitivity performance index and vessel size is not proportional. Furthermore, use of the Doppler sensitivity performance index for the evaluation of a range of scanners demonstrated that curvilinear transducers have higher sensitivity performance indices than higher-frequency linear transducers, due to the higher achievable penetration depth. The effect of instrument settings was assessed for two transducers, the 4C3 curvilinear general-purpose transducer (Aspen) and the PVM375AT curvilinear general-purpose transducer (Nemio). The colour Doppler sensitivity performance was found to be significantly dependent on the clutter filter setting and the output power setting for both transducers tested. Users need to be aware of the effect of these settings on the colour Doppler sensitivity performance of their US scanner when interpreting the clinical significance of the colour Doppler information.

Blood Flow Velocity↗
PubMed2005

A fuzzy index model for trophic status evaluation of reservoir waters.

An index model for quality evaluation based on the formula of similarity membership functions in the fuzzy c-means (FCM) clustering algorithm is proposed. Summing up the weighted similarity degrees between an observation and designed specific quality-ordered levels develops an alternative overall index. Stretching the values of the controlling parameters in the formula of the similarity membership functions causes diverse patterns of overall index models. Applying this proposed fuzzy index model to the trophic evaluation of reservoir waters is studied to demonstrate the practical application of this index. Every measurement of the variables is standardized by the membership function of quality evaluation on the interval [0,1], referring to the trophic status clarified in the Carlson Trophic State Index. The sensitivity analyses are studied both in the proposed index system and the Carlson Trophic State Index. Besides, a case study of the trophic status evaluation of the Feitsui Reservoir from 1987 to 2003 is presented to demonstrate the feasibility of applying the proposed evaluation model.

Chlorophyll↗
PubMed1977

Left ventricular contractile function in aortic stenosis evaluated by isovolumic and ejection phase indexes.

This study is to reappraise the usefulness of isovolumic as compared to ejection phase indexes for detecting abnormal left ventricular contractile function patients with a common hemodynamic abnormality, namely, chronic left ventricular pressure overload. In 41 subjects with pure or predominant aortic stenosis left ventricular pressure measurements were performed by micromanometry. Single-plane left ventricular cineangiograms were carried out in the right anterior oblique (RAO) and the A-P position. The isovolumic contractile indexes we used in this study were peak measured velocity of shortening of the contractile elements (Vpm) and Vmax obtained from linear extrapolation of total pressure-velocity curves. The end-diastolic and end-systolic RAO cineventriculograms served for the calculation of the ejection phase parameters mean velocity of circumferential fiber shortening (VCF) and mean normalized systolic ejection rate (MNSER). Of the 41 patients, Vpm was depressed in 16 (39 per cent), Vmax in 17 (42 per cent), VCF in 12 (29 per cent), and MNSER in 14 (34 per cent). When the isovolumic and the ejection phase parameters were combined, 24 patients (59 per cent) were found to have at least one of the four contractile indexes below normal. In 26 of the 41 patients the isovolumic and the ejection phase indexes provided the same conclusions as to normality of left ventricular function. In contrast, 15 patients showed discordant isovolumic and ejection phase indexes. An increased left ventricular end-diastolic pressure was only inconsistently related to an abnormal left ventricular function because in 7 of 28 patients with an end-diastolic pressure above 14 mm. Hg all contractile indexes were normal. Furthermore, a normal end-diastolic pressure was present in three of 24 patients with depressed myocardial function. It is concluded that in chronic left ventricular pressure overload from aortic stenosis neither the isovolumic nor the ejection phase indexes are superior in sensitivity for assessing contractile function. In this clinical setting the combination of both types of indexes appears to be the most reliable way for identifying patients with depressed contractile function of theleft ventricle in the basal state.

Adolescent↗
PubMed1996

Increase in the delta ST/delta heart rate (HR) index: a new predictor of restenosis after successful percutaneous transluminal coronary angioplasty.

With the goal of improving the prediction of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we evaluated the usefulness of the delta ST/delta heart rate (HR) index derived from serial exercise treadmill tests. Exercise treadmill tests were performed by 125 patients with single-vessel coronary artery disease before and several days after PTCA, and just before follow-up angiography 3 to 12 months later. Simple HR-adjusted indexes of ST-segment depression during exercise (delta ST/delta HR index) were derived. We compared the usefulness of the increase in delta ST/delta HR index at follow-up over the value obtained several days after PTCA for prediction of restenosis with that of a positive exercise treadmill test and a positive thallium scintigram at follow-up. At follow-up, 47 of the 125 patients showed restenosis. The delta ST/delta HR index increased in 43 of 47 patients in the restenosis group and in 18 of 78 patients without restenosis (p < 0.0001). Separate analysis of each criterion revealed the following respective values for sensitivity, specificity, and positive and negative predictive values for prediction of restenosis; increased delta ST/delta HR index of follow-up: 91%, 77%, 70%, and 94%; positive exercise treadmill test: 83%, 65%, 59%, and 86%; and positive thallium scintigram: 79%, 78%, 69%, and 86%. The increased delta ST/delta HR index had a significantly (p < 0.05) higher sensitivity than the positive thallium scintigram and a significantly (p < 0.01) higher specificity than the positive exercise treadmill test. An increased delta ST/delta HR index at follow-up identifies subgroups of patients who are at high risk for restenosis after PTCA.

Aged↗
PubMed1998

A new criterion combining ST/HR slope and deltaST/deltaHR index for detection of coronary artery disease in patients on digoxin therapy.

We evaluated the clinical value of a new index combining deltaST/delta heart rate (HR) index and ST/HR slope for diagnosing coronary artery disease (CAD) in patients on digoxin therapy. Exercise treadmill tests were performed by 72 patients on digoxin therapy. Simple HR-adjusted indexes of ST-segment depression during exercise (deltaST/deltaHR index) and the decline calculated from the final 12 data points relating ST-segment depression to HR (ST/HR slope) were determined. A new index was obtained by subtracting the deltaST/deltaHR index from the ST/HR slope. On thallium scintigraphy, 37 of the 72 patients showed reversible perfusion defects related to the diseased coronary artery. The new index derived from this ST-HR relation was 4.1 +/- 3.6 microV/beats/min in the ischemic group and 1.3 +/- 1.0 microV/beats/min in the group of patients without ischemia (p <0.0001). An ST-HR relation > or = 1.5 was found in 33 of the 37 patients in the ischemic group, and in 7 of the 35 patients without ischemia (p <0.0001). The sensitivity of this criterion for prediction of myocardial ischemia was 89%, the specificity was 80%, and the predictive accuracy was 85%. Thus, this new ST-HR index is useful for detecting CAD in patients on digoxin therapy.

Aged↗
PubMed1998

Prospective evaluation of an index for predicting the risk of major bleeding in outpatients treated with warfarin.

PURPOSE: To evaluate the accuracy and clinical utility of the Outpatient Bleeding Risk Index for estimating the probability of major bleeding in outpatients treated with warfarin. The index was previously derived in a retrospective cohort of 556 patients from a different hospital (derivation cohort). SUBJECTS AND METHODS: We enrolled 264 outpatients starting warfarin (validation cohort) to validate the index prospectively. All patients were identified upon hospital discharge, and physician estimates of the probability of major bleeding were obtained before discharge in the validation cohort. RESULTS: Major bleeding occurred in 87 of 820 outpatients (6.5%/yr). The index included four independent risk factors for major bleeding: age 65 years or greater; history of gastrointestinal bleeding; history of stroke; and one or more of four specific comorbid conditions. In the validation cohort, the index predicted major bleeding: the cumulative incidence at 48 months was 3% in 80 low-risk patients, 12% in 166 intermediate-risk patients, and 53% in 18 high-risk patients (c index, 0.78). The index performed better than physicians, who estimated the probability of major bleeding no better than expected by chance. Of the 18 episodes of major bleeding that occurred in high-risk patients, 17 were potentially preventable. CONCLUSIONS: The Outpatient Bleeding Risk Index prospectively classified patients according to risk of major bleeding and performed better than physicians. Major bleeding may be preventable in many high-risk patients by avoidance of over-anticoagulation and nonsteroidal anti-inflammatory agents.

Aged↗
PubMed1996

Systemic vascular resistance index determined by thoracic electrical bioimpedance predicts the risk for maternal hypotension during regional anesthesia for cesarean delivery.

OBJECTIVE: Our purpose was to evaluate the predictive value of the baseline systemic vascular resistance index for the development of maternal hypotension during regional anesthesia for cesarean delivery. STUDY DESIGN: Patients receiving a standardized spinal or epidural anesthetic for nonemergency cesarean delivery were studied prospectively. Hemodynamic data were obtained noninvasively with an NCCOM-3 cardiac output monitor (Bomed Medical Manufacturing, Irvine, Calif.), which uses thoracic electrical bioimpedance to estimate stroke volume and cardiac output. Measurements obtained were indexed to body surface area. The systemic vascular resistance index was calculated from mean arterial pressure and thoracic electrical bioimpedance-derived cardiac index. Hemodynamic data obtained were analyzed to identify statistically significant predictors of maternal hypotension. RESULTS: Maternal hypotension occurred in 24 of 42 (57%) patients studied. The incidence of hypotension did not differ between the types of anesthesia: spinal 17 of 274 (62%) versus epidural 7 of 15 (47%, p=0.48). The mean interval to the onset of hypotension was 12.2 minutes (SD 2.2 minutes, range 2 to 24 minutes). Mean (SD) baseline maternal systolic blood pressure was higher in patients who had hypotension (145 torr [4]) than those who did not (129 torr [4], p=0.01). The mean (SD) baseline systemic vascular resistance index was higher in patients who had hypotension (633 [SD 36] dyne . cm . sec-5/m2) than those who did not (454 [SD 29] dyne . cm . sec-5/m2; p =0.001). With receiver-operator characteristic curves, a baseline systemic vascular resistance index of 500 had a sensitivity of 83%, a specificity of 78%, a positive predictive value of 83%, and a negative predictive value of 78% for maternal hypotension (odds ratio 17.5, 95% confidence interval 3.1 to 109.4). A baseline systolic blood pressure of 140 torr had a sensitivity and specificity of 42% and 72%, respectively (odds ratio 1.9, 95% confidence interval 0.4 to 8.8). CONCLUSIONS: Baseline systemic vascular resistance index obtained by noninvasive cardiac output monitoring with thoracic electrical bioimpedance and systolic blood pressure are useful to predict the risk for maternal hypotension with regional anesthesia. Patients with increased baseline systemic vascular resistance index or systolic blood pressure are at increased risk for hypotension.

Adult↗
PubMed2003

Changes in the refractive index of lens fibre membranes during maturation--impact on lens transparency.

PURPOSE: Local variations in refractive index are the physical cause of light scattering in a material or tissue and also induce phase changes of propagating light waves. The goal of this study was to analyse local differences in refractive index by phase contrast microscopy of sections of human lenses. METHODS: Refractive index was estimated by immersion refractometry. Cryo-sections of quick-frozen human donor lenses were embedded in a graded series of bovine serum albumin solutions, and in immersion oil, ranging in refractive index from 1.34 to 1.52. RESULTS: Fibre membranes in the lens cortex prove to have a refractive index considerably above that of fibre cytoplasm at the same location. Fibre membranes in the lens nucleus have a refractive index approximately the same as that of fibre cytoplasm at the same location. CONCLUSION: In the lens cortex, transparency is obtained by a high spatial order of the lens fibre lattice to compensate for the light scattering caused by differences in refractive index between fibre membranes and cytoplasm. In the lens nucleus, high spatial order is less important, because the minor differences in the refractive index between fibre membranes and fibre cytoplasm lead only to minimal scattering.

Cryopreservation↗
PubMed2000

Temporal evolution of traditional versus transformed ECG-based indexes in patients with induced myocardial ischemia.

The time course of changes in the electrocardiogram as a result of myocardial ischemia induced during prolonged coronary angioplasty has been studied. We have analyzed the electrocardiogram evolution during the occlusion in terms of the Ischemic Changes Sensor, which is a parameter that describes the capacity of different indexes to detect induced changes. Traditional indexes at specific time locations (ST level, T wave amplitude and position, and durations of QT interval and QRS complex) and global indexes (based on the Karhunen-Loève transform as applied to the QRS complex, ST-T complex, ST segment and T wave) have been considered. The global indexes better detected ischemic changes than the traditional indexes. The most sensitive were the index for the ST-T complex (89%) in the Karhunen-Loève transform-derived group and for the ST level (61%) in the traditional group. Changes in the ventricular repolarization period usually appeared earlier (77% of patients) than changes in the depolarization period (23% of patients). A similar percentage of patients exhibited the earliest ischemic changes in the T wave (41%) and in the ST segment (36%). The evolution of the Ischemic Changes Sensor parameters showed that the majority (60%) of the total changes occurred during the first minute of occlusion. The results suggest that the use of global electrocardiogram indexes better reflect ischemic changes than do traditional indexes, such as the ST segment deviation.

Angioplasty, Balloon, Coronary↗