Biomedical subjects
Publications and source records attributed to Matthew B Weinger.
We present a case of oxygen analyzer malfunction diagnosed by the failure of the patient to adequately breathe oxygen as measured by end-tidal oxygen concentration. A warning icon, compliant with international standards, was not noticed at the time by those involved in the patient's care. The role of effective medical device user interface design is discussed.
UNLABELLED: In this study, we sought to examine several measures of anesthesia provider workload during different phases of anesthesia care and during teaching and nonteaching cases. Clinical work was assessed in real-time during 24 general anesthetics performed by consenting anesthesia providers. Workload was measured using physiological (provider heart rate), psychological (self-assessment and observer rating), and procedural (response latency to an alarm light and workload density) techniques. Clinicians' heart rates, observer and self-reported workload scores, and nonteaching workload density were consistently increased during anesthetic induction and emergence compared with maintenance. In nonteaching cases, workload density correlated with heart rate and with psychological workload. Workload density during teaching cases did not decrease during the induction and was significantly greater than during nonteaching cases. Alarm-light response latency (a measure of clinical vigilance) was significantly prolonged during the teaching compared with nonteaching cases. These results suggest that intraoperative teaching increases the workload of the clinician instructor and may reduce vigilance during anesthesia care. Additionally, multiple workload measures may provide a more comprehensive profile of the work demands of clinical cases. IMPLICATIONS: Psychological, physiological, and procedural workload measures during routine general anesthesia cases documented the increased work demands of induction and emergence. Intraoperative teaching increased workload and decreased vigilance, suggesting the need for caution when educating during patient care.
OBJECTIVE: Data representations on today's medical monitors need to be improved to advance clinical awareness and prevent data vigilance errors. Simply building graphical displays does not ensure an improvement in clinical performance because displays have to be consistent with the user's clinical processes and mental models. In this report, the development of an original pulmonary graphical display for anesthesia is used as an example to show an iterative design process with built-in usability testing. DESIGN: The process reported here is rapid, inexpensive, and requires a minimal number of subjects per development cycle. Three paper-based tests evaluated the anatomic, variable mapping, and graphical diagnostic meaning of the pulmonary display. MEASUREMENTS: A confusion matrix compared the designer's intended answer with the subject's chosen answer. Considering deviations off the diagonal of the confusion matrix as design weaknesses, the pulmonary display was modified and retested. The iterative cycle continued until the anatomic and variable mapping cumulative test scores for a chosen design scored above 90% and the graphical diagnostic meaning test scored above 75%. RESULTS: The iterative development test resulted in five design iterations. The final graphical pulmonary display improved the overall intuitiveness by 18%. The display was tested in three categories: anatomic features, variable mapping, and diagnostic accuracy. The anatomic intuitiveness increased by 25%, variable mapping intuitiveness increased by 34%, and diagnostic accuracy decreased slightly by 4%. CONCLUSION: With this rapid iterative development process, an intuitive graphical display can be developed inexpensively prior to formal testing in an experimental setting.
BACKGROUND: Sleep deprivation causes physiologic and subjective sleepiness. Studies of fatigue effects on anesthesiologist performance have given equivocal results. The authors used a realistic simulation environment to study the effects of sleep deprivation on psychomotor and clinical performance, subjective and objective sleepiness, and mood. METHODS: Twelve anesthesia residents performed a 4-h anesthetic on a simulated patient the morning after two conditions of prior sleep: sleep-extended (EXT), in which subjects were allowed to arrive at work at 10:00 AM for 4 consecutive days, thus allowing an increase in nocturnal sleep time, and total sleep deprivation (DEP), in which subjects were awake at least 25 h. Psychomotor testing was performed at specified periods throughout the night in the DEP condition and at matched times during the simulation session in both conditions. Three types of vigilance probes were presented to subjects at random intervals as well as two clinical events. Task analysis and scoring of alertness were performed retrospectively from videotape. RESULTS: In the EXT condition, subjects increased their sleep by more than 2 h from baseline (P = 0.0001). Psychomotor tests revealed progressive impairment of alertness, mood, and performance in the DEP condition over the course of the night and when compared with EXT during the experimental day. DEP subjects showed longer response latency to vigilance probes, although this was statistically significant for only one probe type. Task analysis showed no difference between conditions except that subjects "slept" more in the DEP condition. There was no significant difference in the cases' clinical management between sleep conditions. Subjects in the DEP condition had lower alertness scores (P = 0.02), and subjects in the EXT condition showed little video evidence of sleepiness. CONCLUSIONS: Psychomotor performance and mood were impaired while subjective sleepiness and sleepy behaviors increased during simulated patient care in the DEP condition. Clinical performance between conditions was similar.
UNLABELLED: OBJECTIVE To determine the percentage of time that intensive care unit (ICU) nurses spend on documentation and other nursing activities before and after installation of a third-generation ICU information system. DESIGN: Prospective data collection using real-time time-motion analysis, before and after installation of the ICU information system. SETTING: A ten-bed surgical ICU at a Veterans Affairs medical center. SUBJECTS: ICU nurses. INTERVENTIONS: Installation of a third-generation ICU information system. MEASUREMENTS AND MAIN RESULTS: Ten ICU nurses were studied before and after installation of the ICU information system. Each ICU nurse's activities and tasks, during 4-hr observation periods, were categorized in real-time by a nurse observer and recorded in a laptop computer. Each recorded task was automatically time-stamped and logged into a data file. The percentage of time spent on documentation decreased from 35.1 +/- 8.3% to 24.2 +/- 7.6% (p =.025) after the ICU information system was installed. The percentage of time providing direct patient care increased from 31.3 +/- 9.2% to 40.1 +/- 11.7% (p =.085). The percentage of time doing patient assessment, a direct patient care task, increased from 4.0 +/- 4.7% to 9.4 +/- 4.4% (p =.001). CONCLUSIONS: Installation of a third-generation ICU information system decreased the percentage of time ICU nurses spent on documentation by >30%. Almost half of the time saved on documentation was spent on patient assessment, a direct patient care task.
UNLABELLED: "Human error" in anesthesia can be attributed to misleading information from patient monitors or to the physician's failure to recognize a pattern. A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. We designed a graphic display to show hemodynamic variables. Twenty anesthesiologists were asked to assume care of a simulated patient. Half the participants used the graphic cardiovascular display; the other half used a Datex As/3 monitor. One scenario was a total hip replacement with a transfusion reaction to mismatched blood. The second scenario was a radical prostatectomy with 1.5 L of blood loss and myocardial ischemia. Subjects who used the graphic display detected myocardial ischemia 2 min sooner than those who did not use the display. Treatment was initiated sooner (2.5 versus 4.9 min). There were no significant differences between groups in the hip replacement scenario. Systolic blood pressure deviated less from baseline, central venous pressure was closer to its baseline, and arterial oxygen saturation was higher at the end of the case when the graphic display was used. The study lends some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnose, manage, and treat critical cardiovascular events in a simulated environment. IMPLICATIONS: A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. A user-centered design process led to a novel object-oriented graphic display of hemodynamic variables containing emergent features and functional relationships. In a simulated environment, this display appeared to support clinicians' ability to diagnose, manage, and treat a critical cardiovascular event in a simulated environment. We designed a graphic display to show hemodynamic variables. The study provides some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnosis, mange, and treat critical cardiovascular events in a simulated environment.
Many medical procedures require fine motor skills, and these skills are developed over years of practice and through performing hundreds to thousands of procedures. However medical training that is based upon gaining this expertise by performing procedures on patients results in unnecessary risk to the patient. In this project expert medical skill is quantified, so that advanced medical simulators can be created to provide a realistic training environment. This approach is applied to airway intubation with a rigid laryngoscope; a procedure that is performed prior to general anesthesia and during emergency situations. A laryngoscope has been instrumented with a 3 dimensional force/torque sensor, and magnetic position sensors have been placed on the laryngoscope and the patient. Measurements are made in the operating room of both experts and novices as they perform laryngoscopy on consenting patients undergoing general anesthesia. The skill of the laryngoscopist is represented by the motion and force trajectories applied to the laryngoscope during the procedure. Preliminary results show that novices often err in the placement of the tip of the laryngoscope blade. However, when two experts perform laryngoscopy on the same patient, both experts perform key elements of the task consistently. The measured consistency among experts indicates that it will be possible to apply algorithms developed for Human Skill Acquisition, and thereby define regions of expert motion relative to patient anatomy. This is the first step in developing advanced training simulators that will simulate the procedure accurately, provide guidance to the trainee, and can be used for assessment of medical skill.
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BACKGROUND: Usable real-time displays of intravenous anesthetic concentrations and effects could significantly enhance intraoperative clinical decision-making. Pharmacokinetic models are available to estimate past, present, and future drug effect-site concentrations, and pharmacodynamic models are available to predict the drug's associated physiologic effects. METHODS: An interdisciplinary research team (bioengineering, architecture, anesthesiology, computer engineering, and cognitive psychology) developed a graphic display that presents the real-time effect-site concentrations, normalized to the drugs' EC(95), of intravenous drugs. Graphical metaphors were created to show the drugs' pharmacodynamics. To evaluate the effect of the display on the management of total intravenous anesthesia, 15 anesthesiologists participated in a computer-based simulation study. The participants cared for patients during two experimental conditions: with and without the drug display. RESULTS: With the drug display, clinicians administered more bolus doses of remifentanil during anesthesia maintenance. There was a significantly lower variation in the predicted effect-site concentrations for remifentanil and propofol, and effect-site concentrations were maintained closer to the drugs' EC(95). There was no significant difference in the simulated patient heart rate and blood pressure with respect to experimental condition. The perceived performance for the participants was increased with the drug display, whereas mental demand, effort, and frustration level were reduced. In a post-simulation questionnaire, participants rated the display to be a useful addition to anesthesia monitoring. CONCLUSIONS: The drug display altered simulated clinical practice. These results, which will inform the next iteration of designs and evaluations, suggest promise for this approach to drug data visualization.
BACKGROUND: Task analysis may be useful for assessing how anesthesiologists alter their behavior in response to different clinical situations. In this study, the authors examined the intraobserver and interobserver reliability of an established task analysis methodology. METHODS: During 20 routine anesthetic procedures, a trained observer sat in the operating room and categorized in real-time the anesthetist's activities into 38 task categories. Two weeks later, the same observer performed task analysis from videotapes obtained intraoperatively. A different observer performed task analysis from the videotapes on two separate occasions. Data were analyzed for percent of time spent on each task category, average task duration, and number of task occurrences. Rater reliability and agreement were assessed using intraclass correlation coefficients. RESULTS: Intrarater reliability was generally good for categorization of percent time on task and task occurrence (mean intraclass correlation coefficients of 0.84-0.97). There was a comparably high concordance between real-time and video analyses. Interrater reliability was generally good for percent time and task occurrence measurements. However, the interrater reliability of the task duration metric was unsatisfactory, primarily because of the technique used to capture multitasking. CONCLUSIONS: A task analysis technique used in anesthesia research for several decades showed good intrarater reliability. Off-line analysis of videotapes is a viable alternative to real-time data collection. Acceptable interrater reliability requires the use of strict task definitions, sophisticated software, and rigorous observer training. New techniques must be developed to more accurately capture multitasking. Substantial effort is required to conduct task analyses that will have sufficient reliability for purposes of research or clinical evaluation.
BACKGROUND: A reengineering approach to intravenous drug and fluid administration processes could improve anesthesia care. In this initial study, current intravenous administration tasks were examined to identify opportunities for improved design. METHODS: After institutional review board approval was obtained, an observer sat in the operating room and categorized, in real time, anesthesia providers' activities during 35 cases ( approximately 90 h) into 66 task categories focused on drug/fluid tasks. Both initial room set-up at the beginning of a typical workday and cardiac and noncardiac general anesthesia cases were studied. User errors and inefficiencies were noted. The time required to prepare de novo a syringe containing a mock emergency drug was measured using a standard protocol. RESULTS: Drug/fluid tasks consumed almost 50 and 75%, respectively, of the set-up time for noncardiac and cardiac cases. In 8 cardiac anesthetics, drug/fluid tasks comprised 27 +/- 6% (mean +/- SD) of all prebypass clinical activities. During 20 noncardiac cases, drug/fluid tasks comprised 20 +/- 8% of induction and 15 +/- 7% of maintenance. Drug preparation far outweighed drug administration tasks. Inefficient or error prone tasks were observed during drug/fluid preparation (e.g., supply acquisition, waste disposal, syringe labeling), administration (infusion device failure, leaking stopcock), and organization (workspace organization and navigation, untangling of intravenous lines). Anesthesia providers (n = 21) required 35 +/- 5 s to prepare a mock emergency drug. CONCLUSIONS: Intravenous drug and fluid administration tasks account for a significant proportion of anesthesia care, especially in complex cases. Current processes are inefficient and may predispose to medical error. There appears to be substantial opportunity to improve quality and cost of care through the reengineering of anesthesia intravenous drug and fluid administration processes. General design requirements are proposed.
To enhance patient safety, data about actual clinical events must be collected and scrutinized. This paper has two purposes. First, it provides an overview of some of the methods available to collect and analyze retrospective data about medical errors, near misses, and other relevant patient safety events. Second, it introduces a methodological approach that focuses on non-routine events (NRE), defined as all events that deviate from optimal clinical care. In intermittent in-person surveys of anesthesia providers, 75 of 277 (27%) recently completed anesthetic cases contained a non-routine event (98 total NRE). Forty-six of the cases (17%) had patient impact while only 20 (7%) led to patient injury. In contrast, in the same hospitals over a two-year period, we collected event data on 135 cases identified with traditional quality improvement processes (event incidence of 0.7-2.7%). In these quality improvement cases, 120 (89%) had patient impact and 74 (55%) led to patient injury. Preliminary analyses not only illustrate some of the analytical methods applicable to safety data but also provide insight into the potential value of the non-routine event approach for the early detection of risks to patient safety before serious patient harm occurs.