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Biomedical subjects

K M Dubowski

Publications and source records attributed to K M Dubowski.

At least 19 recordsLinked to original sources
PubMed1999

Measurement of low breath-alcohol concentrations: laboratory studies and field experience.

Recent federal rules and traffic law changes impose breath-alcohol thresholds of 0.02 and 0.04 g/210 L upon some classes of motor vehicle operators, such as juveniles and commercial vehicle operators. In federally regulated alcohol testing in the workplace, removal of covered workers from safety-sensitive duties, and other adverse actions, also occur at breath-alcohol concentrations (BrACs) of 0.02 and 0.04 g/210 L. We therefore studied performance of vapor-alcohol and breath-alcohol measurement at low alcohol concentrations in the laboratory and in the field, with current-generation evidential analyzers. We report here chiefly our field experience with evidential breath-alcohol testing of drinking drivers on paired breath samples using 62 Intoxilyzer 5000-D analyzers, for BrACs of 0-0.059 g/210 L. The data from 62 law enforcement breath-alcohol testing sites were collected and pooled, with BrACs recorded to three decimal places, and otherwise carried out under the standard Oklahoma evidential breath-alcohol testing protocol. For 2105 pooled simulator control tests at 0.06-0.13 g/210 L the mean +/- SD of the differences between target and result were -0.001 +/- 0.0035 g/210 L and 0.003 +/- 0.0023 g/210 L for signed and absolute differences, respectively (spans -0.016-0.010, 0.000-0.016). For 2078 paired duplicate breath-alcohol measurements with the Intoxilyzer 5000-D, the mean +/- SD difference (BrAC1-BrAC2) were 0.002 +/- 0.0026 (span 0-0.020 g/210 L). Variability of breath-alcohol measurements was related inversely to the alcohol concentration. Ninety-nine percent prediction limits for paired BrAC measurements correspond to a 0.020 g/210 L maximum absolute difference, meeting the NSC/CAOD recommendation that paired breath-alcohol analysis results within 0.02 g/210 L shall be deemed to be in acceptable agreement. We conclude that the field system for breath-alcohol analysis studied by us can and does perform reliably and accurately at low BrACs.

Breath Tests↗
PubMed1997

The stability of ethanol in human whole blood controls: an interlaboratory evaluation.

Sterile whole human blood control materials were commercially prepared in batches containing anticoagulants and preservatives and approximately 90, 150, and 230 mg/dL ethanol with and without 0.3% (w/v) sodium azide. Aliquots in sealed vials were stored by the manufacturer at 2-8 degrees C until shipped monthly to three academic toxicology laboratories that analyzed them in duplicate by gas chromatographic headspace methods at monthly intervals for one year. The resulting data were pooled, and grand mean values were statistically analyzed to determine the respective alcohol stability in these azide-free and azide-containing blood samples. Azide-containing blood samples showed no alcohol losses during the 1-year period. Azide-free blood containing 1.0% (w/v) sodium fluoride and anticoagulants had small alcohol decreases over time, the total losses after one year being less than 5% of the original alcohol concentrations. The initial alcohol concentration of approximately 40 mg/dL also did not change during storage of additional samples of azide-free blood for one month at 4 degrees C. We concluded that addition of sodium azide to performance-test and control blood specimens for alcohol analysis is unnecessary and unwarranted and that alcohol losses in such blood samples can be minimized by simple appropriate treatments and conditions.

Anticoagulants↗
PubMed1996

Vapor-alcohol control tests with compressed ethanol-gas mixtures: scientific basis and actual performance.

Commercial compressed vapor-alcohol mixtures ("dry gas") were evaluated to ascertain their suitability for control tests in breath-alcohol analysis. Dry gas control tests were conducted at nominal vapor-alcohol concentrations (VACs) of 0.045, 0.085, and 0.105 g/210 L (n = 50 at each VAC) with Alcotest 7110 MK III and Intoxilyzer 1400 evidential breath-alcohol testers. The measurement results were analyzed by standard statistical methods, and their correlation with certified dry gas VAC target values was examined. Also measured and examined statistically were the VACs of National Institute of Standards and Technology-traceable Research Gas mixtures (dry gas) ethanol standards at 97.8 and 198 ppm (n = 30-50 at each VAC). With the Alcotest 7110 MK III programmed to report VACs normalized to standard atmospheric pressure at 760 torr and the intoxilyzer 1400 programmed to report VACs at ambient atmospheric pressure, the predicted effects of ambient atmospheric pressure were confirmed experimentally. We developed and validated the following conversion factor for VAC units at 34 degrees C and 760 torr: ppm/2605 = g/210 L and g/210 L x 2605 = ppm. We found that the dry gas vapor-alcohol control samples conformed to established formal specifications and concluded that they compared favorably with simulator effluents for control tests of breath-alcohol analyzers, which are capable of adjusting VAC results for ambient atmospheric pressure.

Atmospheric Pressure↗
PubMed1994

Quality assurance in breath-alcohol analysis.

Evidential breath-alcohol testing requires an adequate quality assurance (QA) program to safeguard the testing process and validate its results. A comprehensive QA program covers (a) test subject preparation and participation; (b) the analysis process; (c) test result reporting and records; (d) proficiency testing, inspections, and evaluations; and (e) facilities and personnel aspects. Particularly important are the following necessary scientific safeguards as components of quality control: (a) a pretest deprivation-observation period of at least 15 minutes; (b) blank tests immediately preceding each breath-collection step; (c) analysis of at least duplicate breath specimens; and (d) a control test accompanying every subject test. These safeguards have withstood adversarial challenges in the judicial system for more than 30 years.

Alcohol Drinking↗
PubMed1985

Absorption, distribution and elimination of alcohol: highway safety aspects.

Key aspects of the pharmacokinetics of alcohol are highly relevant to highway safety. Of particular pertinence are the partition of alcohol between various body tissues and fluids and the resulting alcohol concentration ratios for blood: breath and other body fluids, as well as the irregularity and short-term fluctuations of the blood and breath alcohol curves. Most alcohol pharmacokinetics parameters are subject to wide intersubject variability, as exemplified by peak blood alcohol concentrations reached on ingestion of identical weight-adjusted doses, time to peak after end of drinking and the rate of alcohol elimination from the blood. This great biological intersubject variability, when combined with sex-, age- and time-related differences, makes the blood alcohol information in widely distributed alcohol consumption nomograms and tables based on mean data inappropriate as a guide for the drinking behavior of individuals. Although there is good statistical correlation between the alcohol concentration of different body tissues and fluids in the fully postabsorptive state, wide individual variations from the population mean alcohol partition values exist. It is often impossible to determine whether the postabsorptive state has been reached at any given time. Those factors make it impossible or infeasible to convert the alcohol concentration of breath or urine to the simultaneous blood alcohol concentration with forensically acceptable certainty, especially under per se or absolute alcohol concentration laws. Inclusion of breath alcohol concentrations in drinking-driving statutes, as definitions or per se offense elements, makes unnecessary the conversion of breath alcohol analysis results into equivalent blood alcohol concentrations. Urine alcohol concentrations are inadequately correlated with blood alcohol concentrations or with driver impairment, and analysis of bladder urine is, therefore, inappropriate in traffic law enforcement. Significantly large sex-related differences in pharmacokinetic parameters have been demonstrated (e.g., in peak blood alcohol concentrations for weight-adjusted doses). The effects of age and time of day have been less extensively studies and are less clear. Breath and blood alcohol time curves are subject to short-term fluctuations from the trend line and other irregularities, and often do not follow the typical Widmark pattern. From the existing information on pharmacokinetics of alcohol and the characteristics and variability of blood and breath alcohol versus time curves, the following conclusions can be reached.(ABSTRACT TRUNCATED AT 400 WORDS)

Accident Prevention↗
PubMed1980

Alcohol determination in the clinical laboratory.

Four methods for blood-alcohol analysis--gas chromatography, enzymatic oxidation with alcohol dehydrogenase, chemical oxidation with acid dichromate, and osmometry--are briefly reviewed from the point of view of the clinical laboratory. Advantages and limitations of these methods are discussed, and their key features are tabulated. The correlation of the results of blood-alcohol analyses with stages of alcoholic influence and their corresponding signs and symptoms is presented in tabular form.

Blood Chemical Analysis↗
PubMed1977

Dose-related heart-rate, perceptual, and decisional changes in man following marihuana smoking.

Information processing was tested in 12 male subjects after smoking marihuana containing 0, 10, or 20 mg. of delta-9-tetrahydrocannabinol (THC) in three consecutive experimental sessions according to a Latin square protocol. Successful dose control was indicated both by the dose-related linear increase observed in heart rate and by preliminary assays of THC metabolites excreted in the urine. During tachistoscopic presentation of varying numbers of circles, statistically significant decrements in information processing occurred as a function of THC dosage. However, adding irrelevant information (triangles) to the display of circles eliminated effects of marihuana on accuracy of counting. Complex reaction times for oddity discrimination increased significantly only after the high dose. Nonetheless, both the social and high doses inappropriately inhibited the general tendency to respond to changing stimuli during oddity discrimination. Marihuana had no effect on field-dependence as measured by the Rod-and-frame test.

Adult↗
PubMed1976

Method for alcohol determination in biological liquids by sensing with a solid-state detector.

I describe a new method for quantitative alcohol determination in equilibrated headspace gas of biological liquids by means of a solid-state metal-oxide semiconductor (MOS) detector. After equilibration of the NaCl-saturated specimen at 40 degrees C or other convenient temperature in a closed vessel, a Taguchi MOS sensor is momentarily exposed to the headspace vapor. The resulting dc voltage change from the baseline conditions accurately reflects the alcohol concentration of the liquid specimen, and can be read in direct alcohol-concentration units. Calibration is linear to 3.00 g/liter (300 mg/dl). Values for analytical recovery ranged from 98 to 102%. Correlation of results for blood alcohol concentration by this method (yi) and an automated gas-chromatographic reference method (xi) was y, g/liter = 0.991x + 0.014, with r = 0.997 for 103 blood specimens having concentrations ranging from 0 to 2.89 g/liter (0-289 mg/dl), with a mean difference (xi - yi) - -6 mg/liter (0.6 mg/dl). The method is sensitive to 0.01 g/liter (1 mg/dl) and can be readily automated. An internal standard is not required.

Chromatography, Gas↗
PubMed1976

Breath-alcohol analysis: uses, methods, and some forensic problems--review and opinion.

Breath analysis for ethanol, especially in respect to the forensic aspects, has been reviewed. Included are matters dealing with instrumentation, physiological factors involved in the elimination of ethanol via the breath, and, especially, the uncertainties in the calculation of a whole blood concentration of ethanol from the quantity found in breath. We believe that the conversion of a breath quantity to a blood concentration of ethanol, for forensic purposes, should be abandoned and that the offense of driving while under the influence of alcohol should be statutorily defined in terms of the concentration of ethanol found in the breath in jurisdictions employing breath analysis. The breath sample should be obtained and analyzed only with instruments having capabilities which would require some extension of present federal standards for evidential breath-testing devices. Events in early 1975 indicate that implementation of some of these proposals may soon be undertaken.

Accidents, Traffic↗
PubMed1975

Studies in breath-alcohol analysis: biological factors.

Various biological factors affecting breath-alcohol analysis were studied experimentally. End-expiratory temperatures in 55 healthy subjects were found to range from 32.41 to 35.69 degrees C with a mean of 34.53 degrees C. Forced vital capacity in the same subjects ranged from 1825 to 6550 ml with a mean of 4038 ml, and maximum exhalation after normal inhalation ranged from 1180 to 4550 ml with a mean of 2730 ml. It was found that 65-70% of available breath must be discarded before the alveolar plateau is reached during expiration. End-expiratory (alveolar) carbon dioxide in 155 healthy subjects was 3.5-8.3% by volume (mean = 6.52). After oral alcohol intake, retained mouth-alcohol in 8 subjects had disappeared after 11 minutes without subsequent water-rinsing of the mouth, and after 8 minutes with rinsing. Water condensation in plastic mouthpieces/saliva traps during breath sampling yielded mean weight gains of 13.0, 8.6, and 4.6 mg., respectively, at initial mouthpiece temperatures of 3 degrees C, 22.5 degrees C, and 34.7 degrees C, respectively.

Air↗