Biomedical subjects
Publications and source records attributed to R M Gardner.
A new interference test requires subjects to read a list of 10 pairs of words with affective responses inappropriate to the terms listed. 80 adults were given the task with significant interference occurring which decreased speed and accuracy of performance. Significantly increased variability was also noted under the condition of interference. The source of interference is discussed and possible uses of this new task are described.
Alterations in rat myometrial ultrastructure and in vivo uterine contractile responses to oxytocin were examined in estradiol-treated (40 micrograms/kg) euglycemic and streptozotocin-induced (85 mg/kg) diabetic rats. Myometrial morphology was examined 18, 24, and 36 hr after estradiol administration. At the time points examined, nuclei of myometrial cells from euglycemic and diabetic rats were pleomorphic and contained large areas of heterochromatin dispersed throughout the nuclei. Mitochondria were round to oval in shape and contained a dense matrix with cristae that extended across the mitochondria. Myofilaments were found in both euglycemic and diabetic cells but the relative number of myofilaments in diabetic cells appeared to be less than the number found in myometrial cells removed from euglycemic animals. The number of free cytoplasmic ribosomes in diabetic cells also appeared to be less than those found in euglycemic cells. In order to determine if apparent differences in the number of myofilament found in diabetic myometrial cells could be correlated with changes in uterine contractile responses to hormones, oxytocin dose-response curves (10(-8) to 10(-5) M) were examined in isolated uteri removed from saline-injected and estradiol-injected (24-hr pretreatments) euglycemic and diabetic rats. The maximal contractile responses (milligrams tension developed per milligrams tissue) in saline-injected euglycemic and diabetic rats were 49 +/- 5 and 36 +/- 4, respectively, while maximal contractile responses in estradiol-injected euglycemic and diabetic rats were 68 +/- 7 and 45 +/- 5, respectively. Maximal contractile responses induced by oxytocin in estradiol-treated diabetic uteri were significantly smaller than the contractile responses measured in euglycemic estradiol-treated uteri. This study demonstrates that estradiol-induced changes in both myometrial cell morphology and in vitro uterine contractile responses to oxytocin are altered in diabetic rats.
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A respiratory care computer-charting system was developed and implemented as an addition to our hospital's computerized information system. Medical personnel charted and reviewed respiratory care procedures at nursing station computer terminals instead of using the patient's traditional paper chart. The computer automatically performed billing and provided management as well as clinical information. In an attempt to isolate specific benefits or shortcomings, we evaluated charting systems both before and after computer implementation. Four assessments were made: (1) a survey of therapists' attitudes, (2) an observation of work patterns, (3) an audit of the content of charting, and (4) an analysis of productivity statistics. Computer charting was well accepted by therapists. Charge capture was reduced from a four-step manual process to a single-step computer documentation of the procedure. Computer charting was more complete and informative. Productivity increased 18%, although it remains unclear to what degree the computer was responsible. Computer charting streamlined the process of documentation and allowed more beneficial use of clinical information.
40 obese and 40 normal weight individuals were given a series of reaction time (RT) tasks in the presence or absence of a distracting 75-dB static noise under varying levels of task complexity. Both RT and movement time (MT) from a "home" button to a response button were recorded. There were no significant differences in RT between obese and normal subjects although a significant interaction between task complexity and subjects' weight showed that obese subjects had a faster mean RT on the 1-light task but slower RTs on the choice-discrimination tasks with 2, 4, or 8 lights. Obese subjects had a significantly faster mean MT at all levels of task complexity. The distracting stimulus had no differential effect on over-all RTs although an interaction of distraction X task complexity was obtained. The distractor significantly decreased MT for all subjects with no differential for the groups. The results are not in accordance with previous RT studies which supported the internality/externality hypothesis about obesity but rather support the view that obese subjects approach the experimental task with a differential level of motivation or response set.
New instrumentation, techniques and computers have made such large amounts of information rapidly available to ICU clinicians that there is now a danger of information overload. To help with this problem at LDS Hospital, a computerized system was implemented in the Shock-Trauma ICU. This ICU is almost totally computerized with each patient's physiologic, laboratory, drug, demographic, fluid input/output and nutritional data integrated into the patient's computer record. In the ICU, physician decision-making takes place in two situations: during rounds and on-site. For this study, data usage in decision-making was evaluated in both of these environments. The items of data used in decision-making were tabulated into six categories: bedside monitor, laboratory, drugs, input/output and IV, blood gas laboratory, observations and other. Comparisons were made between the portion of the computerized database occupied by a category and its use in decision-making. Combined laboratory data (clinical, microbiology and blood gas) made up 38 to 41% of total patient data reviewed and occupied 16.3% of the database. Observations made up 21-22% of the data reviewed and occupied 6.8% of the database. Drugs, input/output and IV data usage ranged from 13% to 23%, but occupied 36% of the database. Bedside monitor data usage was 12.5% to 22% and occupied 32.5% of the database. The 'other' category, used 2.5% to 5% of the time, made up 8.4% of the database. These results indicate that patient data collection and storage must be evaluated and optimized. This evaluation, along with implementation of the computerized ICU Rounds Report developed for optimal data presentation, will help physicians to evaluate patient status and should facilitate effective decisions.
A microprocessor-controlled data gathering system for telemetry and analysis of spirometry waveforms was implemented using a completely digital design. Spirometry waveforms were obtained from an optical shaft encoder attached to a rolling seal spirometer. Time intervals between 10-ml volume changes (volume sampling) were stored. The digital design eliminated problems of analog signal sampling. The system measured flows up to 12 liters/sec with 5% accuracy and volumes up to 10 liters with 1% accuracy. Transmission of 10 waveforms took about 3 min. Error detection assured that no data were lost or distorted during transmission. A pulmonary physician at the central hospital reviewed the volume-time and flow-volume waveforms and interpretations generated by the central computer before forwarding the results and consulting with the rural physician. This system is suitable for use in a major hospital, rural hospital, or small clinic because of the system's simplicity and small size.
A total of 2711 pulmonary artery wedge pressure (WP) measurement attempts were made prospectively from WP recordings in 44 (30 men) critically ill patients, using 77 flow-directed catheters. Of these, 322 (12%) failed to yield a WP measurement, and 521 (18%) were associated with technical problems. One half of these technical problems were due to poor dynamic response or damped pressure tracings; other problems included balloon overinflation, partial WP, and inability to aspirate blood from the pulmonary artery (PA) port. Only 50% of wedge blood sampled at the time of initial PA catheterization yielded capillary blood (PO2 greater than or equal to 10 torr higher than PaO2). In 12 stable patients in whom paired measurements were available, there were clinically important differences (-13 to +22 torr) between paired WP measurements made before and after rapid correction of technical problems. Technical problems are common and may be associated with clinically important errors. Those due to poor dynamic response are easily and rapidly detected at the bedside.
To determine if a culture of blood obtained through an arterial catheter reflects culture of the catheter's tip, we studied 68 arterial catheters removed from 65 patients with and without suspected catheter infections. Cultures of blood obtained before catheter removal were compared to catheter-tip cultures. The arterial catheter blood culture was neither sensitive nor highly predictive of positive catheter-tip cultures. Suspicion of catheter infection was not associated with a significantly higher rate of positive catheter-tip or blood cultures.
Although the Fleisch pneumotachograph has many advantages, its flow-conductance characteristics are nonlinear and sensitive to changes in gas composition. The purpose of this study was to assess the effect of different O2, N2, and CO2 compositions on the nonlinearity of the Fleisch pneumotachograph flow-conductance characteristics, by use of a recently developed computerized calibration method. Hospital-grade O2 was mixed with room air to obtain seven gas mixtures (containing O2 percentages of 20.9, 28.3, 38.7, 52.8, 66.7, 78.7, and 99.6%). Within the accuracy of the applied method, the measured flow-conductance curves of the pneumotachograph had the same shape. Relative flow resistance of gas mixtures to room air was directly proportional to their O2 composition. Two O2-N2-CO2 mixtures were also tested. Their relative flow resistance compared with room air was proportional to the viscosity ratios. We concluded that the change in O2, N2, and CO2 composition does not affect the nonlinearity of the Fleisch pneumotachograph flow-conductance characteristics. However, the relative flow resistance compared with room air does change in a predictable way.
A comparison was made of automated versus manual measurement of pulmonary artery (PA) and wedge (WP) pressures. The manual pressure measurements were taken at end-expiration whereas the automated measurements were taken using existing monitor and computer algorithms. A total of 40 critical care patients were divided into groups according to the ventilatory mode used (spontaneous, intermittent mandatory ventilation [IMV], or assist/control). In patients who were breathing spontaneously, the automated method underestimated mean PA pressure (MPAP) (p less than 0.01), WP (p less than 0.001), and PA diastolic (p less than 0.001) pressure but not PA systolic pressure. In patients on IMV, the automated method underestimated MPAP (p less than 0.05), WP (p less than 0.001), and PA diastolic (p less than 0.001) pressure and overestimated PA systolic pressure (p less than 0.05). In patients on assist/control, the automated method overestimated WP (p less than 0.001) and PA systolic (p less than 0.005) pressure pressure, underestimated PA diastolic (p less than 0.001) pressure and did not affect MPAP. The error was not affected by respiratory rate, thoracic compliance, or level of PEEP. The errors in automated pressure measurements believed to be clinically important varied with the ventilatory mode used. Patients breathing spontaneously had the largest measurement error, with 42% of these patients having a clinically important error in WP and 99% having a clinically important error in PA diastolic pressure. Patients on assist/control had the fewest errors in automated pressure measurements. In all ventilatory modes used, automated measurement of PA diastolic pressure had the largest amount of error.
To evaluate risk factors for infections associated with indwelling arterial catheters, 186 catheters were randomly allocated for either femoral or radial insertion in 155 critically ill patients. Femoral catheters were easier to insert and it was easier to obtain blood specimens from them. Rates of local infection at the insertion sites and rates of positive catheter-tip cultures were similar for femoral and radial catheters. Evidence of local infection was not predictive of a positive catheter-tip culture. Percutaneously inserted femoral and radial artery catheters had a similarly low incidence of catheter-associated infections. There was only one catheter-related infection, and no cultured catheter was judged the cause of bacteremia. Routine prophylactic replacement of arterial catheter systems may be unnecessary in critical care units where rates of arterial catheter-associated infections are low.
Despite the popularity of the concept of "anaerobic threshold" (AT), the noninvasive detection criteria remain subjective, and invasive validations of AT have been based on lactate data of arterial, mixed venous, venous, and capillary blood samples without any concern for the possible lactate differences from these sources. Eight normal subjects underwent two exercise tests on a bicycle ergometer. The protocol consisted of 3 min of rest, 3 min of 0 work load, and a 20 W/min ramp (1 W/3 s) until exhaustion. Simultaneous arterial and venous blood samples were drawn during the second test. Noninvasive gas response data were measured using a computerized breath-by-breath stress test system. Threshold phenomenon of the lactate accumulation was not found. The arterial lactate levels increased continuously after the start of the exercise ramp. The rise in venous lactate lagged behind the rise of the arterial lactate by about 1.5 min, and therefore venous lactate was not considered suitable for AT detection. Four independent exercise physiologists determined AT from the gas response data. The reviewer variability (avg range 16%) of AT for a given subject was representative of AT values reported for untrained and trained individuals (40-70% maximum O2 consumption). We concluded that 1) AT is not detectable using invasive methods (arterial and venous lactates); and 2) the noninvasive gas response determination has such a large range of reviewer variability that it is unsuitable for clinical use.
Controversy still exists regarding the paper speed necessary for accurate measurements from records of maneuvers for forced vital capacity. Twenty-four spirometric wave forms of known characteristics were plotted by a computer at 1, 2, and 3 cm/sec and were measured in random order by 12 experienced readers. We found that all readers made a surprisingly large number of major errors. The speed of the paper was found to be an important determinant for accurately measuring the forced expiratory volume in one second and the mean forced expiratory flow during the middle half of the forced vital capacity. A minimum paper speed of at least 3 cm/sec is important if spirograms are to be accurately measured by hand. Human errors in measurement may be minimized by obtaining results from at least three acceptable curves, by making duplicate reading of curves, and by making use of validated computerized measurement systems.
9 obese and 9 normal subjects performed a psychophysical task in which food- or non-food-related stimuli were briefly flashed tachistoscopically at a speed and intensity near the visual threshold. A signal was presented on one-half the trials and noise only on the other one-half of the trials. Using signal detection theory methodology, separate measures of sensory sensitivity (d') and response bias (beta) were calculated. No differences were noted between obese and normal subjects on measures of sensory sensitivity but significant differences on response bias. Obese subjects had consistently lower response criteria than normal ones. Analysis for subjects categorized by whether they were restrained or unrestrained eaters gave findings identical to those for obese and normal. The importance of using a methodology that separates sensory and non-sensory factors in research on obesity is discussed.