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At least 415 records · Page 23Linked to original sources

PubMed2003

LC-MS/MS determination of Synercid injections.

Synercid is a combination of two semisynthetic pristinamycin derivatives, quinupristin and dalfopristin in 30:70 (w/w) ratio. A rapid and specific high-performance liquid chromatography-mass spectrometry was developed for the determination of quinupristin and dalfopristin using positive electrospray tandem mass spectrometry (+ESI-MS/MS). Multiple reaction monitoring transitions at 1023.05>134.34 and 691.87>166.26 were selected for the quantitation of quinupristin and dalfopristin, respectively. The assay run cycle-time was approximately 2.0 min injection-to-injection. The assay was linear up to concentration of 4000 ng x ml(-1) quinupristin and 1920 ng x ml(-1) dalfopristin. The lowest limits of quantitation of quinupristin and dalfopristin were found to be 1000 and 480 ng x ml(-1), respectively. Quantitation was based on peak area measurement of quinupristin and dalfopristin using weighed linear regression. Linear relationships with correlation coefficients (r>0.99) were automatically computed for both constituents by MASSLYNX quantify program. The ratio of the slopes of the calibration curves of quinupristin and dalfopristin was found to be 0.425, which matches the nominal ratio composition of the antimicrobial compounds in Synercid. The %RSD ranges were 2.3-4.0% for dalfopristin and 1.3-4.2% for quinupristin, whereas the %DEV ranges were (-7.5+3.7) and (-1.2+9.1%), respectively, indicating appropriate precision and accuracy. Recoveries of 99.5-103.8% and 97.8-99.0% of quinupristin and dalfopristin, respectively, were computed from Synercid injection. The described method is recommended for rapid determination of the contents and for tracking the stability and compatibility of quinupristin and dalfopristin in Synercid injection.

Calibration↗

PubMed2003

Alpha-adducin gene polymorphism is associated with essential hypertension in Chinese: a case-control and family-based study.

OBJECTIVE: A polymorphism at position 460(G <-- W) of the alpha-adducin gene was found to be associated with essential hypertension in some but not all studies. The aim of the present study was to further investigate the association of the alpha-adducin 460W allele with essential hypertension in Chinese population. METHODS: Individuals from a population-based sample (n = 748) and 95 nuclear families and 47 discordant sibships were studied by questionnaire as well as by physical examination and biochemical analyses. The alpha-adducin gene G460W polymorphism was determined by polymerase chain reaction and restriction enzyme digestion. Chi-square test, one-way analysis of variance, logistic regression, linear regression, haplotype-based haplotype relative risk and transmission/disequilibrium test analyses were used to determine the association between the alpha-adducin G460W polymorphism and essential hypertension. RESULTS: In the case-control study, the prevalence of hypertension was higher in individuals with the WW genotype (40.0%) as compared with those with the GW and GG genotype (31.7%) (chi2 = 4.768, P = 0.029, odds ratio = 1.43). Adjusted for the conventional risk factors of hypertension, alpha-adducin polymorphism still plays an independent role on systolic blood pressure. We confirmed the results of our case-control study by observing a significant preferential transmission of the 460W allele of the alpha-adducin to the affected subjects in another northern Chinese population (for haplotype-based haplotype relative risk, chi2 = 6.24, P = 0.01; and for the transmission/disequilibrium test, chi2 = 4.69, P = 0.03). CONCLUSIONS: The present findings show a positive association between the alpha-adducin G460W polymorphism and essential hypertension in a northern Chinese population. This evidence indicates that the alpha-adducin gene may be a susceptible gene to essential hypertension.

Adult↗

PubMed2001

[Volumetric pumps for blood transfusions. Viability in pediatrics].

UNLABELLED: The authors determine whether or not nurses should use perfusion pumps for concentrated hematin transfusions, measuring the degree of hemolysis which occurs in two distinct models. METHODOLOGY STUDY SAMPLE: Concentrated hematin transfusions by means of an infusion pump on children in a Pediatrics Intensive Care Unit at the Maternity-Pediatrics Ward in Granada. Dependent Variable: Degree of Hemolysis, measured by means of: free hemoglobin, potassium, LDH. INDEPENDENT VARIABLES: Pump; dated/used blood; hematocrit; catheter caliber; type of procedure; pump working pressure; other perfusion rhythms; infusion rhythm. Sample size. One year study group, 95% confidence rate, 0.50 prevalence of awaited hemolysis, +/- 0.05 precision (relative precision 10%). Data Obtained: Two samples are taken per transfusion: removal of blood bag, extreme distal removal system. Investigative Method: Prospective descriptive study. STATISTICAL ANALYSIS: Descriptive statistics, by means of frequency distributions. Variable analysis, multiple variable analysis. RESULTS: 55 observations were carried, of these, 50.9% corresponded to pump number one. Simple regression linear analysis showed differences in the degree of hemolysis in terms of free hemoglobin and hematocrit. Dated/used blood registered a higher hemolysis level above 75 percentile. The greater hemolysis in terms of potassium difference was associated with the type of procedure, having an average of 0.44 mEq/l, in presence of other perfusions, greater rhythm (p = 0.118), dated/used blood (p = 0.008), hematocrit (p = 0.063). The greatest difference in LDH occurred with smaller caliber catheters, other perfusions, more dated blood (p = 0.117). In multiple linear regression, results were equal to those predicted: an average difference in hemoglobin of 3.87 mg/l (p = 0.661); in potassium, 0.39 mEq/l (p = 0.138); in LDH, 53.6 (p = 0.568). This documents with verify this study have been consulted by the ROL Editorial Board and may be requested from the authors.

Blood Transfusion↗

PubMed2006

Head rotation during vertical impact predicted using initial head angle and anthropometry.

INTRODUCTION: Dynamic inertial loading to the head and neck complex, similar to what is experienced during the rocket boost phase of pilot ejection, results in diverse kinematic responses when observed in live human volunteers. The purpose of this study was to develop a predictive model of head rotation during the compressive phase of pilot ejection. METHODS: Post hoc analyses were conducted on data from two previous experimental studies. This analysis included observing 138 tests involving 27 human volunteers (both men and women) where the various kinematic responses were categorized into five modes based on the location of primary rotation and the direction of head rotation. Several statistical methods (logistic regression, linear regression, and Fisher's Exact test) were employed to evaluate the influence of independent variables, body anthropometry, and initial head angle on dependent variables head acceleration and direction of head rotation. RESULTS: Statistical results of this data indicated that initial head position and body anthropometry are significant factors with respect to head response during the compressive phase of an ejection. Two statistical tools were developed; one to assist in predicting the location of primary head rotation, and the other to predict the direction of head rotation. DISCUSSION: By using the two statistical tools together, a simplified method was developed for predicting the modes of head response to vertical impact based on initial position and anthropometry. The results of this study show the importance of initial position prior to an ejection and may assist in identifying individuals at greater risk of injury during an ejection.

Anthropometry↗

PubMedDate not supplied

[Systematic bias in measuring of the utilization of ambulatory medical services].

The results of utilization studies on ambulatory medical care are usually disappointing. Since these studies have used the regression linear model with cross-sectional data, they have rarely considered the utilization of medical services as a dynamic process unfolding over a certain period of time. The utilization of medical services was observed during three consecutive two-week periods with the help of a sample, drawn from the files of the RAMQ, of 41,811 individuals living in Laval and in the Metropolitan region of Quebec. Transition rates towards user or non-user status between each period are predicted, rather than volumes of utilization. Results show that the variables which predict the volume of utilization are not those which predict the transition towards non-user status, though volume of utilization arises from the cumulation over time periods of the using status. Differences appear between the utilization processes of persons aged 65 and over and other adults. Consequently, studies on the utilization of medical services should no longer use multiple linear regression. Thus, the conclusions which these studies draw about the impact of policies of accessibility to health care are also biased.

Adult↗

PubMedDate not supplied

Steady state enzyme kinetics: experimental design and data analysis by microcomputer.

One of the most time-consuming, yet essential, operations involved in the steady state kinetic study of enzymes is the design and optimization of experimental conditions. A computer program was developed for the Sinclair ZX-81 (or TS-1000, 1500) microcomputer which will optimize substrate concentration for preliminary and subsequently more refined kinetic analysis of one, two or three substrate systems. This program also analyzes the data collected from these studies by linear regression, weighted linear regression or weighted non-linear regression. In addition to the above program several of the enzyme kinetic statistical analysis programs of Cleland (1979) have been translated from FORTRAN into BASIC and implemented on the ZX-81 and the TRS-80 model II. Inexpensive commercially available software was used to overcome the inability of the ZX-81 to read data files from magnetic tape making the data analysis programs easier to use.

Computers↗

PubMed1994

Development and application of a calibration regression routine in conjunction with linear and non-linear chromatographic detector responses.

Linear regression is widely used in the calibration of chromatographic assays even in conjunction with some chromatographic detectors which show significant non-linearity in their response characteristics. A calibration routine, based upon the curve y = axlnx+bx+c is presented which describes the non-linear behaviour of some chromatographic systems, including electron capture, nitrogen-phosphorus and UV photometric detectors, and gives comparable results to weighted linear regression with assays showing linear concentration versus response relationships. The ratio of the coefficients a and b in the equation allows quantification of the deviation from linearity and provides a more sensitive indicator of linearity than the correlation coefficient often quoted with linear regression.

Blood Chemical Analysis↗

PubMed2000

[Single-blood-sample method for the determination of glomerular filtration rate using 99mTc-DTPA in Japanese].

The study was aimed to evaluate glomerular filtration rate with 99mTc-DTPA by means of a single-plasma-sample method in Japanese. Three were 50 patients (29 males and 21 females, age range being 25 to 91 years) with diabetes mellitus of various degree of the renal function. 99mTc-DTPA of 300 MBq/2 ml that was prepared in our hospital was injected. Dynamic renal scintigraphy was carried out and 10 blood samples were taken after the injection. Blood clearance (true GFR) of 99mTc-DTPA was determined from plasma concentration which was fitted to the biexponential curve by a non-linear least squares method. Plasma concentration (ml/min/1.73 m2) after 75 min-post injection showed very higher linear regression and linear correlation with true GFR than 0.900. The best linear regression and linear correlation was observed with 180 min-sample (r = 0.989). As general, the following equation was obtained; Y = A + Bln(X), A = 436.1217 - 3.45817t + 0.01205t2 - 0.000015t3, B = -212.601 + 1.42518t - 0.04834t2 + 0.0000062t3, X = plasma concentration at sampling time t (%ID/L/1.73 m2), t = sampling time from 75 to 300 min (r > 0.900). This is the new equation of single-plasma-sample method for the determination of GFR using 99mTc-DTPA for Japanese. The clinical feasibility should be accessed in a field of a nuclear medicine practice.

Adult↗

PubMed1995

[Studies on health effects of cadmium exposure in the general environment].

Effects of exposure to cadmium (Cd) in the general environment on health have been studied in several Cd-polluted areas in Japan. In this paper, results of investigations in the Kakehashi River basin, Ishikawa, a Cd-polluted area, are mainly reviewed as follows. 1. In an epidemiological study, prevalences of beta 2-microglobulinuria (beta 2-MG-uria) were 14. 3 and 18.7% in Cd-exposed men and women over 50 years of age, respectively, when a cutoff level of beta 2-MG of 1000 micrograms/g.cr. was used. These values are significantly high compared with those of nonexposed subjects. 2. Using several urinary indicators of renal function, such as alpha 1-microglobulin, N-acetyl-beta-D-glucosaminidase, human intestinal alkaline phosphatase, mucoprotein and albumin, levels of all indicators were significantly higher in Cd-exposed subjects than in nonexposed subjects. Furthermore, in a 5-year follow-up study, irreversibility of Cd-induced renal damage was shown after the level of beta 2-MG rose above 1000 micrograms/g.cr. 3. Exposure to Cd caused marked osteopenia, in particular in women, as assessed by microdensitometry, and this osteopenia was significantly associated with Cd-induced renal dysfunction. Serum 1 alpha, 25 dihydroxy-vitamin D levels were lower and serum parathyroid hormone (PTH) levels were higher in Cd-exposed subjects with renal damage than in nonexposed subjects. We assume that disturbances in vitamin D and PTH metabolism may be one of the causative factors for Cd-induced bone damage. 4. The dose-response relationships between Cd exposure and renal dysfunction were assessed using several statistical methods such as simple linear regression, probit linear regression, logistic regression analysis and general linear models. The prevalences of beta 2-MG-uria or metallothioneinuria were employed as indices of health effects, while urinary Cd and total Cd intake was used as indicators of Cd exposure. As the biological threshold, urinary Cd concentrations were calculated to be 3.8-4.2 micrograms/g.cr. in men and 3.8-4.8 micrograms/g.cr. in women, and a maximum allowable intake of about 2 g Cd is considered to be a reasonable estimate for preventing Cd-induced renal dysfunction. 5. A significant association was found between urinary beta 2-MG and mortality in a 9-year follow-up study of 3178 Cd-exposed inhabitants, using Cox's proportional hazards model. Moreover, mortality rates increased in proportion to increases in the amount of urinary beta 2-MG excreted. These results suggest that the prognosis for Cd-exposed subjects with renal tubular dysfunction is unfavorable.

Aged↗

PubMedDate not supplied

Prediction of spectacle-corrected visual acuity using videokeratography.

PURPOSE: Our aim was to improve prediction of spectacle-corrected visual acuity (SCVA) using indices derived from the EyeSys System 2000 data (version 3.1). METHODS: We studied corneal topography in 182 eyes from 8 groups of patients. Holladay Diagnostic Summary indices were recorded. Nine statistical indices calculated with the first 8-ring data and refractive power symmetry index were also studied. Correlation with SCVA (LogMAR units) was studied by means of Pearson's regression. Multiple linear regression was used to obtain linear equations combining several indices. RESULTS: At a univariate level, total astigmatism cylinder showed the strongest correlation with SCVA (r = .63, P = .0001). At a multivariate level, the predicted visual acuity obtained by linear equation combining the asphericity coefficient, the predicted corneal acuity, the mean of the means, and the total astigmatism cylinder was closely associated with SCVA (r = .72, P = .0001). It was identical to SCVA in 58.2% of the cases, within one line in 75.8%, and within two lines in 91.2%. CONCLUSION: Multiple linear regression resulted in the best prediction of spectacle-corrected visual acuity, giving notable improvement in prediction of spectacle-corrected visual acuity as compared to the predicted corneal acuity available in the EyeSys System 2000.

Astigmatism↗

PubMed2003

Measuring explained variation in linear mixed effects models.

We generalize the well-known R(2) measure for linear regression to linear mixed effects models. Our work was motivated by a cluster-randomized study conducted by the Eastern Cooperative Oncology Group, to compare two different versions of informed consent document. We quantify the variation in the response that is explained by the covariates under the linear mixed model, and study three types of measures to estimate such quantities. The first type of measures make direct use of the estimated variances; the second type of measures use residual sums of squares in analogy to the linear regression; the third type of measures are based on the Kullback-Leibler information gain. All the measures can be easily obtained from software programs that fit linear mixed models. We study the performance of the measures through Monte Carlo simulations, and illustrate the usefulness of the measures on data sets.

Antipsychotic Agents↗

PubMed2002

Outcome analysis of 286 severely burned patients: retrospective study.

OBJECTIVE: To evaluate the outcomes of severely burned patients treated at a regional burns unit and to develop a predictive model for survival and length of hospital stay for major burn patients in Hong Kong. DESIGN: Retrospective study. SETTING: Burns unit of a regional public hospital, Hong Kong. PATIENTS: Two hundred and eighty-six severely burned patients treated from March 1993 to February 2000. MAIN OUTCOME MEASURES: Details of demographics, mechanism of burn, extent of burn, incidence of inhalation injury, length of hospital stay, and mortality rate were recorded and entered into a database. Stepwise logistic regression and linear regression were applied to develop a predictive model for mortality and morbidity, respectively. RESULTS: Of 286 major burn patients treated in this 7-year period, 25 patients died from their injuries, yielding a mortality rate of 8.7%. Stepwise logistic regression was applied to develop a predictive model for mortality. We found that inhalation injury, age, and total body surface area involvement were independent significant predictors of death. Accuracy of this predictive model reached 93%. Similarly, stepwise linear regression was used to develop a predictive model for length of hospital stay. Sex, inhalation injury, total body surface area of burn, and total body surface area(2) of burn were significant predictors of length of hospital stay (R(2)=0.2). Only three patients' duration of hospital stay was more than three standard deviations from the predicted length of hospital stay. CONCLUSION: A predictive model for mortality and length of hospital stay has been developed for major burn patients in Hong Kong. This model may help clinicians to counsel patients and relatives at an early stage of care, to provide a basis from which new treatment plans can be compared, and to facilitate efficient allocation of valuable medical resources.

Adolescent↗

PubMed1997

Factors determining pubertal growth and final height in growth hormone treatment of idiopathic growth hormone deficiency. Analysis of 195 Patients of the Kabi Pharmacia International Growth Study.

A total of 195 children (117 males and 78 females) with idiopathic growth hormone deficiency (IGHD) treated with growth hormone (GH) for at least 1 year before puberty onset and who had completed treatment to adult height, were selected from the KIGS database for study of growth during puberty. Spontaneous and induced puberty started at 13.8 and 14.9 years in boys and at 12.9 and 13.7 years in girls, respectively. Duration of GH treatment and height gained prepubertally were greater when puberty was induced; prepubertal catch up growth (expressed as a percentage of the difference between target height and height at start of GH) was greater when puberty was induced in boys (59% induced vs. 45% spontaneous, p < 0.001), and in girls (72% induced vs. 53.9% spontaneous, p < 0.01). Final height was attained at 17.8 and 19.2 years in boys and at 16.0 and 17.0 years in girls following spontaneous and induced puberty, respectively. Final heights were greater after induced puberty compared with spontaneous puberty in boys (171.3 vs. 166.0 cm, p < 0.001) and in girls (157.0 vs. 155.0 cm, n.s.). Target height was also significantly greater in boys with spontaneous puberty (172.2 cm vs. induced = 174.2 cm) as compared to girls (spontaneous = 158 cm vs. induced = 160 cm). Duration of pubertal growth was longer in boys compared to girls (3.6 vs. 3.0 years, p < 0.001) and was negatively correlated with age, height, and distance from target height at onset of puberty, but was not correlated with the dose of GH. Catch-up growth during puberty (expressed as a percentage of the difference between target height and height at puberty onset) after induced and spontaneous puberty was 87.9% and 80.5% (not significant) in boys and 66.4% and 75.5% (not significant in girls. Total pubertal growth (TPG) (cm) was inversely correlated with prepubertal growth by simple linear regression. Multiple linear regression analysis indicated 5 independent predictors of TPG accounting for 78% of the variability, namely sex (boys grew more), distance of target height from height at onset of puberty (+), dose of GH at onset of puberty (+), age at onset of puberty (-), and age at end of growth (+).

Adolescent↗

PubMed2004

Statistical estimation of resin composite polymerization sufficiency using microhardness.

With respect to determining sub-surface resin polymerization sufficiency, this study compared a traditional method of applying linear regression to bottom- to top-surface Knoop hardness ratios to an alternative method based on nonlinear regression. Inverse linear regression on ratios was used to estimate the exposure duration required for 80% bottom-surface hardness with respect to the top, in six light-by-material groups. Alternatively, a one-phase, two-parameter, exponential association of the form Y=Y(max)(1-e(-kt)) (where Y(max) is maximum hardness, k is a rate constant, and t is exposure duration), was used to model hardness. Inverse nonlinear regression estimated, for each condition, the exposure duration required for the bottom surface to achieve 80% of corresponding condition (light and material) top-surface Y(max). Mathematically, analysis of ratios was demonstrated to yield potentially less precise and biased estimates. Nonlinear regression yielded better statistical fit and provided easily accessible tests for differences in k across light-system groups. Another recently proposed nonlinear model for polymerization, Y=Y(max)kt(n)/(1+kt(n)), was also considered. While this new model has substantially greater phenomenological and mechanistic justification, we found that the model-fitting process was more sensitive to initial parameter values and sometimes yielded untenable results when applied to our data. However, we believe that these problems would not occur if sample points are well distributed across a wide range of exposure durations, and that the model, Y=Y(max)kt(n)/(1+kt(n)), should be considered for such data sets.

Analysis of Variance↗

PubMed2004

Creep functions of dental ceramics measured in a beam-bending viscometer.

OBJECTIVE: To characterize the high temperature viscoelastic properties of several dental ceramics by the determination of creep functions based on mid-span deflections measured in a beam-bending viscometer (BBV). METHODS: Six groups of beam specimens (58 x 5.5 x 2.5 mm) were made from the following materials: (1) IPS Empress2 body--a glass veneer ceramic (E2V); (2) an experimental glass veneer (EXV); (3) Vita VMK 68 feldspathic body porcelain--a low-expansion body porcelain (VB); (4) Will-Ceram feldspathic body porcelain--a high-expansion body porcelain (WCB); (5) Vita feldspathic opaque porcelain--a medium-expansion opaque porcelain (VO); and (6) Will-Ceram feldspathic opaque porcelain--a high-expansion opaque porcelain (WCO). Midpoint deflections for each specimen were measured in a BBV under isothermal conditions at furnace temperatures ranging from 450 to 675 degrees C. Non-linear regression and linear regression analyses were used to determine creep functions and shear viscosities, respectively, for each material at each temperature. RESULTS: The shear viscosities of each group of dental ceramics exhibited bilinear Arrhenius behavior with the slope ratios (x) ranging from 0.19 for WCB to 0.71 for EXV. At the higher temperature ranges, activation energies ranged from 363 kJ/mol for VO to 386 kJ/mol for E2V. SIGNIFICANCE: The viscoelastic properties of dental ceramics at high temperatures are important factors in understanding how residual stresses develop in all-ceramic and metal-ceramic dental restorations.

Dental Porcelain↗

PubMed1987

Contrast echo washout curves from the left ventricle: application of basic principles of indicator-dilution theory and calculation of ejection fraction.

Time-intensity curves can be obtained from contrast echocardiography of the left ventricle. The purposes of this study were: 1) to verify whether these curves conform to the basic principles of indicator-dilution theory; and 2) to derive indexes of left ventricular ejection fraction from curve analysis. In seven closed chest dogs, 31 doses of the polysaccharide agent SHU-454 were injected into the left ventricular cavity during apical four chamber two-dimensional echocardiography. Data were obtained at different levels of ejection fraction, which were induced by changes in preload, afterload and contractility, and measured by single plane Simpson's rule analysis of digital subtraction left ventriculograms. In a subset of two dogs, eight incremental doses (from 1 to 8 ml) of SHU were injected in the basal state. Contrast echocardiograms were digitized off-line, the mean gray level/pixel of a region of interest inside the left ventricular cavity was measured, and the average value for three systolic frames of each beat was used to obtain time-intensity curves. A good correlation was observed between the peak of the time-intensity curve and the quantity of contrast injected (correlation coefficient r = 0.91 by a logarithmic fit). The echo intensities observed in each animal were subsequently transformed in quantity of contrast according to these functions and their natural logarithm was calculated both with and without background subtraction. All curves relating time and the natural logarithm of the corrected intensity exhibited a descending rectilinear portion (washout) in which the correlation was very good (r = 0.97 +/- 0.02 = mean +/- SD) and which was not significantly affected by background subtraction. The validity of this fit was also unaffected by heart rate (55 to 158 beats/min) and angiographic ejection fraction (22 to 74%), and only minimally influenced by duration of contrast washout (3.3 to 14.6 seconds). Ejection fraction was calculated by an algorithm derived from indicator-dilution theory: ejection fraction = [1 - e(-bd)] X 100, where b = slope of the curve and d = cardiac cycle duration. Linear regression analysis between values of ejection fraction derived by angiography and contrast echo yielded r = 0.73. A second index, based on b and d, was derived by multiple regression analysis. Linear regression analysis of this index and angiographic ejection fraction yielded a correlation of r = 0.87.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2002

A field comparison of the IOM inhalable aerosol sampler and a modified 37-mm cassette.

This research focused on comparing a modified 37-mm (Mod37) sampling cassette with an IOM inhalable dust sampler. Paired IOM and Mod37 breathing-zone air samples were collected for workers engaged in corrosion control maintenance operations on several types of aircraft at several U.S. Air Force bases in the United States. Sampled operations included hand and power sanding, blow-down and wipe-down to remove dust, and spray finishing. The cassettes' interior surfaces were swabbed and the swabs combined with the filters for chromium analysis by NIOSH Method 7300. This approach utilized total chromium as a sensitive surrogate indicator of total aspirated mass. The influences of work location, work type, sample duration, and sampler type on measured concentration were evaluated using analysis of variance techniques. Only work type (process) was found to be a statistically significant predictor of measured concentration. The relationship between IOM- and Mod37-measured values for paired samples was evaluated by work type using linear regression techniques. Linear regressions showed that the modified 37-mm cassette over-samples aerosol by 35 percent compared to the IOM when a wide range of aerosol concentrations and compositions for divergent work tasks in multiple field locations are sampled. Interpretation of these results in light of previous results involving filter-only Mod37 analyses suggests that while the Mod37 has a higher aspiration efficiency than the IOM, substantial Mod37 wall losses result in underestimation of exposure when only the 37-mm filter is analyzed rather than filters plus wall swabs.

Aerosols↗

PubMed1997

Estimation of condensed pulmonary parenchyma from gas exchange parameters in patients with multiple trauma and blunt chest trauma.

Pulmonary gas exchange in correlation with condensed lung volume was prospectively studied in 10 patients with multiple injuries and blunt chest trauma. The purpose was to find nomograms that allow the estimation of the extent of pulmonary density from gas exchange parameters. The condensed lung volume was determined planimetrically from serial transverse sections of chest computed tomographic scans. There was no correlation between condensed lung volume and mean pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, or cardiac index and a week negative correlation to the oxygenation index (PaO2/FIO2) (r2 = 0.46) and to the total static lung compliance (r2 = 0.29). A strong correlation between pulmonary density and intrapulmonary shunt fraction (Qs/Qt) (r2 = 0.95) as well as alveoloarterial PO2 difference (P[A-a]O2) (r2 = 0.86) was evident. By using linear regression equations (linear regression line with 95% confidence interval), nomograms were calculated. The extent of pulmonary density can easily be obtained from these nomograms by measuring Qs/Qt or P(A-a)O2. The presented nomograms may be helpful in monitoring the effect of treatment in patients with blunt chest trauma.

Adolescent↗