Search PubMed⌕ Search

Biomedical subjects

R M Gardner

Publications and source records attributed to R M Gardner.

At least 37 records · Page 2Linked to original sources
PubMed1997

Computerized ventilator data selection: artifact rejection and data reduction.

OBJECTIVE: To determine acceptable strategies for automated data acquisition and artifact rejection from computerized ventilators using the Medical Information Bus. DESIGN: Medical practitioners were surveyed to establish 'clinically important' ventilator events. A prospective study involving frequent data collection from ventilators was also conducted. SUBJECTS: Data from 10 adult patients were collected every 10 seconds from a Puritan Bennett 7200A ventilator for a total of 617.1 hours. INTERVENTIONS: Twelve different computerized data selection and artifact algorithms were tested and evaluated. MEASUREMENTS AND MAIN RESULTS: Data derived from 12 data selection algorithms were compared with each other and with data manually charted by respiratory therapists into a computerized charting system. Ventilator setting data collected by the algorithms, such as FIO2, reduced the amount of data collected to about 25% compared to manually charted data. The amount of data collected for measured parameters, such as tidal volume, from the ventilator had large variability and many artifacts. Automated data capture and selection generally increased the amount of data collected compared to manual charting, for example for the 3 minute median the increase was a modest 1.2 times. CONCLUSION: Computerized methods for collecting ventilator setting data were relatively straightforward and more-efficient than manual methods. However, the method for automated selection and presentation of observed measured parameters is much more difficult. Based on the findings and analysis presented here, the authors recommend recording ventilator setting data after they have existed for three minutes and measured parameters using a three minute median data selection strategy. Such an algorithm rejected most artifacts, required minimal computational time, had minimal time-delay, and provided clinically acceptable data acquisition. The results presented here are but a starting point in developing automated ventilator data selection strategies.

Adult↗
PubMed1997

A preliminary assessment of intra-oral lubricating systems for dry mouth patients.

OBJECTIVE: To provide extended intra-oral delivery of a saliva substitute. INTERVENTION: Three different types of prostheses containing saliva substitute were designed and assessed: a two-part device resembling a mandibular complete denture sealed by cobalt-samerium magnets, a one-part clear resin device for the edentate patients and a flexible mouth guard type of appliance containing a lubricant releasing bubble for the dentate patients. SETTING: A teaching hospital Oral Medicine and Rheumatology Clinic. SUBJECTS: 8 edentate and 3 dentate Sjogren Syndrome sufferers. OUTCOME MEASURES: Subjective dryness after a week of wearing the lubricating appliance. RESULTS: The majority of the subjects wore the appliances for 6-12 hours during each 24 hours. The initial dryness severity diminished after wearing the lubricating prosthesis. The patients preferred to wear the appliance at night. CONCLUSION: All criteria were fulfilled on designing a saliva substitute lubricating appliance and some of the subjects have worn this prosthesis successfully for up to 3 years. Particular benefit was obtained by night-time wear.

Aged↗
PubMed1997

Misconceptions about classical psychophysics and the measurement of response bias.

Misconceptions exist about the ability of classical psychophysical techniques to measure separately the sensory and nonsensory (response bias) factors in a discrimination task. The views of the early researchers in psychophysics are reviewed. The manner in which the method of constant stimuli gives separate measures of sensory sensitivity and response bias is illustrated. Modern derivatives of classical psychophysical techniques which estimates sensory and nonsensory components are described. Finally, data indicating a correspondence between sensory and nonsensory factors obtained with various psychological techniques are reviewed.

Humans↗
PubMed1996

The role of sensory and nonsensory factors in body size estimations of eating disorder subjects.

Body size distortion of anorectic and bulimic subjects was compared to controls via a video-distortion technique. Subjects judged the whole body, chest, hips and stomach regions. A adaptive probit estimation (APE) methodology examined separately the sensory and nonsensory components of body image distortion. Eating disorder subjects overestimated body size more than control subjects. There were no significant differences between eating disorder groups, although there was more variability in eating disorder subjects. Subjects overestimated more on whole body as compared to body regions. There were no differences in sensory sensitivity to detecting size differences between groups. Results indicate that differences in body size distortion between eating disorder and control subjects are due exclusively to affective, nonsensory factors.

Adolescent↗
PubMed1996

Equivalence of fast flush and square wave testing of blood pressure monitoring systems.

BACKGROUND: The accurate recording of intraarterial pressure depends upon an appropriate dynamic response of the monitoring system. Generation of a square wave (SW) at the catheter tip is the engineering and in vitro laboratory gold standard. Fast flush (FF) testing is the clinical test of choice. Results from these two test methods have been assumed equal but have not been empirically confirmed. METHODS: We studied three different 5.1 cm catheter sizes (16 G, 18 G, 20 G Becton Dickinson, Sandy, UT) attached to three different lengths of arterial pressure tubing (36 in, 91.4 cm; 72 in, 182.9 cm; 108 in, 274.3 cm). An arterial recording system was assembled in the standard fashion by attaching a catheter to arterial pressure tubing, which was attached to a transducer (TXX-R, Ohmeda, formerly Viggo-Spectramed, Oxnard, CA) whose signal was recorded by a strip chart recorder (Gould 2400, Rolling Meadows, IL). The system was attached to a pressurized saline flush. The catheter tip was inserted into one port of a pressure generator. With the other port of the pressure generator open to atmosphere, FF tests were performed by activating the flush device of the transducer. Subsequent step response signals from the FF tests were then recorded from which natural frequency (fn) and damping coefficient (zeta) were calculated. Next, square waves were generated by closing the port that was open to atmosphere and attaching a signal generator to a pressure generator. Square waves so generated were recorded as described above and natural frequency and damping coefficients calculated. These procedures were repeated after 0.05 cc of air was introduced in the transducer and repeated again in a system containing a damping device (R.O.S.E., Resonant OverShoot Eliminator, Viggo-Spectramed, Oxnard, CA). RESULTS: There was no significant difference between fn and zeta as calculated from the step response generated from the FF test versus fn and zeta as calculated from the square wave (SW) test in systems without air. However, in systems containing air, fn by FF testing was always less than fn by SW testing for all catheter sizes and extension tubing lengths (p < 0.05). Damping was also always greater by FF testing than by SW testing in systems with air for all catheter sizes and extension tubing lengths (p < 0.05). The R.O.S.E device created marked qualitative differences, although exact fn and zeta could not be quantified. CONCLUSIONS: For the characterization of dynamic response of invasive blood pressure monitoring systems, the FF test and SW test yield identical results. However, under certain conditions-air, R.O.S.E device-dynamic response as measured by FF testing was not equivalent to dynamic response as measured by the gold standard-the SW test. Specifically, small amounts of air in fluid-filled invasive blood pressure monitoring systems cause a slightly worse dynamic response as measured by FF testing versus the laboratory gold standard-the SW test.

Blood Pressure Monitors↗
PubMed1996

Current status of mechanical ventilation decision support systems: a review.

Objectives of computerized decision support systems for mechanical ventilation are discussed. Questions considered are: Why is computerized decision support for mechanical ventilation important? What parameter(s) should be optimized? What are the differences between a single attribute and a multiattribute value function used for optimization? How is it possible to achieve optimization in clinical practice with existing ventilators? How does one solve the problem of acquiring measurement of data needed for closed loop control? The possibilities and limitations of three existing decision support systems are discussed. 1) Computerized protocols from LDS Hospital in Salt Lake City, Utah, USA. 2) Optimization Program (OPTPROG) developed jointly at the Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland and Medical Intensive Care Unit, Department of Medicine at Karolinska Institute, South Hospital, Stockholm, Department of Medical Informatics Linkoping University, Sweden. 3) Ventilator Therapy Planner (VENT-PLAN) from the Section on Medical Informatics at Stanford University, Palo Alto, California, USA. Strategies leading to an optimal computerized decision support system are proposed. These strategies include development of better measurement methods for blood gases and cardiac output, improvement of man-machine and machine-machine interaction and the selection of optimization criteria. Finally, research directed towards building quantitative, dynamic patient models based on computerized databases of mechanically ventilated patients are discussed.

Algorithms↗
PubMed1996

Accuracy and reliability of disposable pressure transducers coupled with modern pressure monitors.

OBJECTIVE: To determine the bedside accuracy of direct patient pressure monitoring when used with new and clinically used disposable blood pressure (BP) transducers. DESIGN: Prospective study. SETTING: Laboratory bench and critical care units in an adult and children's hospital. SUBJECTS: Seventy-five bedside patient monitors (25 Marquette Electronics, 25 Spacelab Medical, and 25 Hewlett-Packard), and 100 disposable transducers (50 from Utah Medical Products and 50 from Abbott Critical Care Systems [25 new, 25 clinically used of each manufacturer]) were tested. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A +/- 2% accuracy requirement for bedside monitors and the +/- 3% American National Standards Institute accuracy standard for disposable BP transducers were used. To test the accuracy of the bedside monitors, a certified transducer simulator was used to apply 100 mm Hg to each bedside monitor. To test the accuracy of the disposable BP transducers, a very accurate (+/- 0.05%) pneumatic dead weight tester was used to apply pressures to the transducer. A digital power supply and a 6 1/2 digit voltmeter were used. The average output of the bedside monitors when 100 mm Hg was applied was 99.90 +/- 0.83 mm Hg, with the worst cases being 98 and 103 mm Hg. For all 100 disposable pressure transducers, the average output was 100.03 +/- 0.55 mm Hg, with the worst cases being 98.53 and 101.36 when 100 mm Hg was applied. There was no important difference in the accuracy of the transducers obtained from the two vendors nor whether the transducers had been used clinically. CONCLUSIONS: All disposable BP transducers tested were much more accurate than the American National Standards Institute standard for accuracy. Even the worst case transducers were twice as accurate as required by the American National Standards Institute standard. Only one bedside monitor was outside the +/- 2% accuracy range (103 mm Hg). Based on these findings, this author recommends that fixed calibration disposable transducers and fixed calibration bedside pressure monitoring systems be used. The clinical risks of air embolism and infection from the calibrating mercury manometer and the complexity of the calibration task are the overriding factors for making these recommendations.

Adult↗
PubMed1996

Methodological issues in assessment of the perceptual component of body image disturbance.

An individual's body image consists of both a perceptual and an attitudinal (subjective) component. Methodological issues relative to the measurement of the perceptual component of body image are discussed. Traditionally, research in body image has employed psychophysical techniques and analyses which confound these two components. Psychophysical techniques which allow for a separate measurement of these two components are discussed, including method of constant stimuli, signal detection theory and adaptive probit estimation. The results of research utilizing these techniques are described and the importance of separately measuring perceptual and attitudinal components is discussed.

Adult↗
PubMed1995

Integrating computerized anesthesia charting into a hospital information system.

BACKGROUND: Systems for computerization of anesthesia records have typically been 'stand-alone' computers many times connected to monitoring devices in the operating theater. A system was developed and tested at LDS Hospital in Salt Lake City, Utah, USA that was an integral part of the Health Evaluation through Logical Processing (HELP) hospital information system. METHODS: The system was evaluated using time and motion studies to assess impact of the system on the anesthesiologists use of time, an assessment for completeness of the anesthesia record was conducted, and a questionnaire was used to assess anesthesiologists attitudes. Timing studies were performed on 44 surgical cases before computerization and 41 surgical cases after computerization. For both before and after computerization, about 80% of procedures were D&C, vaginal hysterectomy, laparoscopy, tubal ligation, or A&P repair. RESULTS: The study showed a major reduction in time required for charting from 20.4% to 13.4% which was statistically significant (p = 0.0001). Other significant factors were a reduction in the time spent scanning the entire area which dropped from 10.5% to 5.6% (p = 0.001), patient preparation time increased from 10.1% to 13.1% (p = 0.02), the time spent arranging equipment increased from 6.4% to 8.1%, and the average time spent on non-anesthesia activities increased from 6.3% to 11.3%. The computerized anesthesia record was more legible, and complete than the manual record. The overall assessment of computer charting by anesthesiologists questionnaire was positive. The computerized anesthesia charting was preferred by the anesthesiologists, who, after one or two training sessions, used the system on their own. CONCLUSIONS: It appears that having a computerized anesthesia charting system that is an integral part of a hospital information system not only saves anesthesiologists charting time, but also improves the quality of the record and was well accepted by busy private practice anesthesiologists.

Anesthesia Department, Hospital↗
PubMed1995

Comparison of three psychophysical techniques for estimating body-size perception.

Perception of body size was recorded for 63 university students (M age = 25.3 yr., 41 women) who estimated their own body size using three methods. Using the method of adjustment, subjects over- or underestimated their body size. A signal-detection analysis indicated that subjects were sensitive to detecting a 4% distortion in body size and that there was no systematic bias for reporting distortion as present or absent. Scores on the adaptive probit estimation task were significantly correlated with values for point of subjective equality and the size judgements with the method of adjustment. Over-all, this experiment demonstrated adaptive probit estimation as a reliable indicator of perceived body size, sensitivity in detecting size distortion, and response bias in making body-size judgements.

Adolescent↗
PubMed1995

Computers in critical care.

This article reviews the current state-of-the-art and future applications of computers in critical care, with particular attention to ventilator and drug-delivery applications. Automated charting, alerts and alarms, and tools for decision support (such as expert systems and closed-loop control) are discussed also.

Computers↗
PubMed1995

Nurses, pagers, and patient-specific criteria: three keys to improved critical value reporting.

At LDS Hospital, we have developed and evaluated a computerized critical value reporting system based on digital pagers. Criteria used to identify critical values are patient-specific. An evaluation of the system was conducted from October 23, 1993 to January 21, 1994. Results showed that 100% of all critical values (497 values in the form of 335 alerts) were reported to clinicians within an average of 38.6 minutes, and that 51% of all alerts were received within 12 minutes. Data also showed that 92% of the alerts were considered valid, that 76% were communicated directly to the primary care nurse, and that 67% of the time nurses were previously unaware of the critical value(s).

Artificial Intelligence↗
PubMed1995

Factors impacting the success of computerized preadmission screening.

Many approaches to controlling costs under managed care rely on the ability to prospectively identify the type or level of service a patient requires at the time of presentation. Although computers may effectively predict these factors, the impact of such a computer system is greatly dependent on its integration into the admission process. Three factors that influence the effectiveness of predictive screening using a computer were identified. They are detection, intervention and compliance. The effect of these factors was then measured in a prospective randomized trial evaluating the effectiveness of computerized preadmission screening for predicting the appropriateness of inpatient care. This paper examines the three factors and their impact on the effectiveness of the system. A mathematical model that relates the factors to the overall effectiveness of computerized preadmission screening is proposed and considered in a more general context.

Diagnostic Tests, Routine↗
PubMed1994

Decision support in medicine: examples from the HELP system.

Computerized health information systems can contribute to the care received by patients in a number of ways. Not the least of these is through interactions with health care providers to modify diagnostic and therapeutic decisions. Since its beginning, developers have used the HELP hospital information system to explore computerized interventions into the medical decision making process. By their nature these interventions imply a computer-directed interaction with the physicians, nurses, and therapists involved in delivering care. In this paper we describe four different approaches to this intervention. These include: (1) processes that respond to the appearance of certain types of clinical data by issuing an alert informing caregivers of these data's presence and import, (2) programs that critique new orders and propose changes in those orders when appropriate, (3) programs that suggest new orders and procedures in response to patient data suggesting their need, and (4) applications that function by summarizing patient care data and that attempt to retrospectively assess the average or typical quality of medical decisions and therapeutic interventions made by health care providers. These approaches are illustrated with experience from the HELP system.

Adult↗
PubMed1994

Representative charting of vital signs in an intensive care unit.

An automatic vital signs charting system had been operational in the intensive care units of our hospital for over 10 years, but the system was susceptible to non-representative transients in the data. A median selection rule was implemented to make the system less susceptible to transients. After implementation of the median rule, we examined (1) the agreement of the resulting medians and the values that would have been reported using the previous "real-time" system and (2) the frequency of occurrence of "out-of-range" values for each system. The median value system was found to improve the representativeness of the recorded data. Improved representativeness will enhance the usefulness of reports, but more importantly will enable us to use the resulting data as inputs to computerized practice protocols and other computerized decision support applications.

Blood Pressure↗
PubMed1994

Computerized detection of nosocomial infections in newborns.

Hospital-acquired infections are responsible for an increase in patient mortality and costs. Their detection is essential to permit better infection control. We developed an expert system specifically to detect infections in pediatric patients. The expert system is implemented at LDS Hospital that has a level three newborn intensive care unit and well baby units. We describe how the knowledge base of the expert system was developed, implemented, and validated in a retrospective study. The results of the system were compared to manual reviewer results. The expert system had a sensitivity of 84.5% and specificity of 92.8% in detecting hospital-acquired infections when compared to a physician reviewer. The Cohen's kappa between the expert system and the physician reviewer was 0.62 (p < .001).

Artificial Intelligence↗