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Biomedical subjects

M B Weinger

Publications and source records attributed to M B Weinger.

At least 19 recordsLinked to original sources
PubMed2004

Video capture of clinical care to enhance patient safety.

Experience from other domains suggests that videotaping and analyzing actual clinical care can provide valuable insights for enhancing patient safety through improvements in the process of care. Methods are described for the videotaping and analysis of clinical care using a high quality portable multi-angle digital video system that enables simultaneous capture of vital signs and time code synchronization of all data streams. An observer can conduct clinician performance assessment (such as workload measurements or behavioral task analysis) either in real time (during videotaping) or while viewing previously recorded videotapes. Supplemental data are synchronized with the video record and stored electronically in a hierarchical database. The video records are transferred to DVD, resulting in a small, cheap, and accessible archive. A number of technical and logistical issues are discussed, including consent of patients and clinicians, maintaining subject privacy and confidentiality, and data security. Using anesthesiology as a test environment, over 270 clinical cases (872 hours) have been successfully videotaped and processed using the system.

Humans↗
PubMed2001

Ventilatory response to 2-h sustained hypoxia in humans.

We used two protocols to determine if hypoxic ventilatory decline (HVD) involves changes in slope and/or intercept of the isocapnic HVR (hypoxic ventilatory response, expressed as the increase in VI per percentage decrease in SaO2). Isocapnia was defined as 1.5 mmHg above hyperoxic PET(CO2). HVD was recorded in protocol I during two sequential 25 min exposures to isocapnic hypoxia (85 and 75% SaO2, n=7) and in protocol II during 14 min of isocapnic hypoxia (90% SaO2, FIO2=0.13, n=15), extended to 2 h of hypoxia with CO2-uncontrolled in eight subjects. HVR was measured by the step reduction to sequentially lower levels of SaO2 in protocol I and by 3 min steps to 80% SaO2 at 8, 14 and 120 min in protocol II. The intercept of the HVR (VI predicted at SaO2=100%) decreased after 14 and 25 min in both protocols (P<0.05). Changes in slope were observed only in protocol I at SaO2=75%, suggesting that the slope of the HVR is more sensitive to depth than duration of hypoxic exposure. After 2 h of hypoxia the HVR intercept returned toward control value (P<0.05) with still no significant changes in the HVR slope. We conclude that HVD in humans involves a decrease in hyperoxic ventilatory drive that can occur without significant change in slope of the HVR. The partial reversal of the HVD after 2 h of hypoxia may reflect some components of ventilatory acclimatization to hypoxia.

Adult↗
PubMed2001

Variation in practice patterns of anesthesiologists in California for prophylaxis of postoperative nausea and vomiting.

STUDY OBJECTIVE: To assess the responses to a survey asking anesthesiologists to report their clinical practice patterns for postoperative nausea and vomiting (PONV) prophylaxis. These practice patterns data may be useful for understanding how to optimize the decision to provide PONV prophylaxis. DESIGN: A written questionnaire with three detailed clinical scenarios with differing levels of a priori risk of PONV (a low-risk patient, a medium-risk patient, and a high-risk patient) was mailed to 454 anesthesiologists. SETTING: Survey was completed by anesthesiologists (n = 240) in 3 university and 3 community practices in California. MEASUREMENTS: Type and number of pharmacological and nonpharmacological interventions for PONV prophylaxis were recorded. To assess the variability in the responses (by the a priori risk of patient), we counted the number of different regimens that would be necessary to account for 80% of the responses. MAIN RESULTS: For the 240 respondents, we found that 1, 9, and 11 different pharmacological prophylaxis regimens were required to account for 80% of the variability in practice patterns for the low-, medium-, and high-risk patients, respectively. For the low-risk patient, 19% of practitioners would use pharmacological prophylaxis, and 37% would use nonpharmacological prophylaxis. For the medium-risk patient, 61% would use nonpharmacological prophylaxis and 67% of practitioners would use multidrug prophylaxis: 45% of patients would receive a 5HT(3) antagonist, 35% would receive metoclopramide, and 16% would receive droperidol. For the high-risk patient, 94% of practitioners would administer a 5HT(3) antagonist, whereas 84% would use multi-drug prophylaxis. CONCLUSIONS: We found a wide range of PONV prophylaxis management patterns. This variation in clinical practice may reflect uncertainty about the efficacy of available interventions, or differences in practitioners' clinical judgment and beliefs about how to treat PONV. Some therapies with proven benefit for PONV may be underused. Our results may be useful for designing studies aimed at determining the impact on PONV rates when physicians develop and implement guidelines for PONV prophylaxis.

Adult↗
PubMed2001

Drug wastage contributes significantly to the cost of routine anesthesia care.

STUDY OBJECTIVE: To complement previous studies that employed indirect methods of measuring anesthesia drug waste. DESIGN: Prospective, blinded observational study. SETTING: Operating rooms of a single university hospital. SUBJECTS: Anesthesia providers practicing in this setting who were completely unaware of the conduct of the study. MEASUREMENTS: All opened and unused or unusable intravenous (IV) anesthesia drugs left over at the end of each workday were collected over a randomly selected typical 2-week period. MAIN RESULTS: 166 weekday cases were performed. Thirty different drugs were represented in the 157 syringes and 139 ampoules collected. Opioid waste as well as opened vials that became outdated were counted in the tally. Based on actual hospital drug acquisition costs, $1,802 of drugs were wasted during this 2-week period ($300/OR), amounting to an average cost per case of $10.86. On a cost basis, six drugs accounted for three quarters of the total wastage: phenylephrine (20.8%), propofol (14.5%), vecuronium (12.2%), midazolam (11.4%), labetalol (9.1%), and ephedrine (8.6%). Because incompletely used syringes or vials that were discarded in the trash were not measured in this analysis, the results may underestimate the total cost of drug wastage at this institution by up to 40%. CONCLUSIONS: The results of this study are similar to those of previous studies that employed electronic record keeping techniques to calculate drug waste. Intravenous drugs that are prepared but unused may be a significant cost of intraoperative anesthesia care. Methods to reduce the amount of drug wasted are proposed.

Anesthesiology↗
PubMed2001

The use of a computer-based decision support system facilitates primary care physicians' management of chronic pain.

We tested whether computer-based decision support (CBDS) could enhance the ability of primary care physicians (PCPs) to manage chronic pain. Structured summaries were generated for 50 chronic pain patients referred by PCPs to a pain clinic. A pain specialist used a decision support system to determine appropriate pain therapy and sent letters to the referring physicians outlining these recommendations. Separately, five board-certified PCPs used a CBDS system to "treat" the 50 cases. A successful outcome was defined as one in which new or adjusted therapies recommended by the software were acceptable to the PCPs (i.e., they would have prescribed it to the patient in actual practice). Two pain specialists reviewed the PCPs' outcomes and assigned medical appropriateness scores (0 = totally inappropriate to 10 = totally appropriate). One year later, the hospital database provided information on how the actual patients' pain was managed and the number of patients re-referred by their PCP to the pain clinic. On the basis of CBDS recommendations, the PCP subjects "prescribed" additional pain therapy in 213 of 250 evaluations (85%), with a medical appropriateness score of 5.5 +/- 0.1. Only 25% of these chronic pain patients were subsequently re-referred to the pain clinic within 1 yr. The use of a CBDS system may improve the ability of PCPs to manage chronic pain and may also facilitate screening of consults to optimize specialist utilization.

Adult↗
PubMed2001

Human factors research in anesthesia patient safety.

Patient safety has become a major public concern. Human factors research in other high-risk fields has demonstrated how rigorous study of factors that affect job performance can lead to improved outcome and reduced errors after evidence-based redesign of tasks or systems. These techniques have increasingly been applied to the anesthesia work environment. This paper describes data obtained recently using task analysis and workload assessment during actual patient care and the use of cognitive task analysis to study clinical decision making. A novel concept of "non-routine events" is introduced and pilot data are presented. The results support the assertion that human factors research can make important contributions to patient safety. Information technologies play a key role in these efforts.

Anesthesiology↗
PubMed2000

Quantitative description of the workload associated with airway management procedures.

STUDY OBJECTIVES: To measure the workload associated with specific airway management tasks. SETTING AND INTERVENTION: Written survey instrument. PATIENTS: 166 Stanford University and 75 University of California, San Diego, anesthesia providers. MEASUREMENTS AND MAIN RESULTS: Subjects were asked to use a seven-point Likert-type scale to rate the level of perceived workload associated with different airway management tasks with respect to the physical effort, mental effort, and psychological stress they require to perform in the typical clinical setting. The 126 subjects completing questionnaires (overall 52% response rate) consisted of 43% faculty, 26% residents, 23% community practitioners, and 8% certified registered nurse-anesthetists (CRNAs). Faculty physicians generally scored lower workload measures than residents, whereas community practitioners had the highest workload scores. Overall, workload ratings were lowest for laryngeal mask airway (LMA) insertion and highest for awake fiberoptic intubation. Airway procedures performed on sleeping patients received lower workload ratings than comparable procedures performed on awake patients. Direct visualization procedures received lower workload ratings than fiberoptically guided procedures. CONCLUSIONS: These kinds of data may permit more objective consideration of the nonmonetary costs of technical anesthesia procedures. The potential clinical benefits of the use of more complex airway management techniques may be partially offset by the impact of increased workload on other clinical demands.

Adult↗
PubMed1998

The respiratory effects of the cytokine regulating agent HP 228 alone and in combination with morphine in human volunteers.

HP 228 is a synthetic heptapeptide analog of alpha-MSH that attenuates the production and release of inflammatory cytokines. The purpose of this study was to define HP 228's effects, alone and in combination with morphine, on resting ventilation and the ventilatory response to hypoxia and hypercarbia. Six healthy nonsmoking young adult males completed the four-session experiment. Subjects first underwent an initial training session. During subsequent sessions, each subject was tested for the respiratory effects of intravenous HP 228 (30 microg/kg), morphine (0.15 mg/kg), or HP 228 (30 microg/kg) plus morphine (0.15 mg/kg) in a double-blind placebo-controlled randomized balanced within-subjects experimental design. Sessions began with baseline measurement of resting ventilation, oxygen consumption, the isocapnic hypoxic ventilatory response (HVR), and normoxic hypercapnic ventilatory response (HCVR). A second set of respiratory measurements were obtained 10 min after completion of HP 228 or placebo infusion. Morphine or placebo was then administered and ventilatory responses were determined 15 and 40 min postinfusion. HP 228 produced cutaneous flushing, but had no significant effect on respiration or hemodynamics. Morphine significantly decreased metabolism, resting ventilation, and hypoxic and hypercarbic ventilatory responsiveness, independent of prior HP 228 administration. A seventh subject experienced a significant cardiac arrhythmia upon exposure to hypoxia after receiving both HP 228 and morphine and was withdrawn from further study. In conclusion, in this early Phase I clinical trial, HP 228 was found to neither depress ventilation nor augment morphine-induced respiratory depression in healthy young males.

Adult↗
PubMed1997

The effect of electronic record keeping and transesophageal echocardiography on task distribution, workload, and vigilance during cardiac anesthesia.

BACKGROUND: Electronic anesthesia record keeping (EARK) systems increasingly are used in the operating room, but studies have only recently begun to investigate their effect on anesthesia task performance. Teak analysis, workload assessment, and vigilance assessment techniques were used to study senior residents providing anesthesia for coronary artery bypass graft (CABG) procedures. The impact on anesthesia residents' workload of the routine use of transesophageal echocardiography (TEE) also was examined. METHODS: Before each case, the record keeping system was randomly selected as either electronic (Distek ARKIVE; EARK) or traditional manual recording (MAN). Twenty CABG procedures (10 EARK and 10 MAN) were examined, with observation commencing with anesthetic induction and terminating on initiation of cardiopulmonary bypass. The activities of each resident, divided into 32 task categories (e.g., "laryngoscopy," "observe monitors," etc.), were recorded by a trained observer using a computer. The response latency to a randomly activated alarm light was used as a measure of vigilance ("vigilance latency"). Workload was rated by subject and observer at random 10- to 15-min intervals throughout the case. Data analysis included calculation of workload density (number of tasks/min multiplied by task-specific workload values) and task-links (relationship between sequential tasks). RESULTS: The two groups had a similar distribution of tasks before intubation. In only 4 of the 20 cases studied did any manual record keeping occur before intubation. After intubation, the EARK group spent less time record keeping and using the TEE but more time observing the monitors and conversing with the attending physician than the MAN group did. All subjects reported significantly higher workload scores before intubation compared with after intubation. Similarly, vigilance latency was greater before intubation compared with after intubation (57 vs. 31 s; P < 0.001). There were no significant differences between the two record keeping groups in subjective workload scores, workload density, or vigilance latency. During TEE use, vigilance latency was significantly longer, and workload density was greater than during other monitoring or recording tasks. CONCLUSIONS: This study provides an objective description of the task distribution and workload during the administration of anesthesia for cardiac surgery. Under the conditions of this study. EARK use modestly decreased the time spent record keeping during the postintubation prebypass period. However, there was no effect of EARK either on vigilance or several measures of workload. TEE use was associated with increased workload and possibly decreased vigilance.

Anesthesiology↗
PubMed1996

Role of central mu, delta-1, and kappa-1 opioid receptors in opioid-induced muscle rigidity in the rat.

BACKGROUND: Opioids appear to produce their physiologic effects by binding to at least three types of opioid receptors, the mu (mu), delta (delta), and kappa (kappa) receptors. Muscle rigidity occurs after administration of supra-analgesic doses of potent mu-preferring agonists like alfentanil. The role of different supraspinal opioid receptors in this rigidity has been addressed only recently. To elucidate the contribution of central mu, delta, and kappa receptors to muscle rigidity, the effects of intracerebroventricularly administered opioid receptor-selective agonists and antagonists on alfentanil-induced muscle rigidity were examined in rats. METHODS: Rats in which chronic intracerebroventricular cannulae had been implanted received an intracerebroventricular infusion of either saline or a mu (D-Ala2,N-Me-Phe4-Gly5-olenkephalin; DAMGO), delta(1) (D-Pen2,D-Pen5-enkephalin; DPDPE), or kappa(1) (trans-(+/-)-3,4-dichloro-N-methyl-N-(2-(1-pyrrolidinyl)- cyclohexyl)-benzene-acetamide methane sulfonate; U50,488H) opioid agonist. Ten minutes later, they received either saline or the mu-agonist alfentanil subcutaneously. Muscle rigidity was assessed using hindlimb electromyographic activity. Different groups of animals were pretreated with an intracerebroventricular infusion of either saline or a mu (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2; CTAP), delta (naltrindole), or kappa(1) (norbinaltorphimine) opioid antagonist before administration of either saline or a selective intracerebroventricular agonist. RESULTS: The mu agonist DAMGO alone dose-dependently induced muscle rigidity. This effect was antagonized by pretreatment with the mu-selective antagonist CTAP. Neither DPDPE nor U50,488H, when administered alone, affected muscle tone. However, both the delta(1) and kappa(1) agonists dose-dependently attenuated alfentanil-induced rigidity. This antagonism of alfentanil rigidity was abolished after pretreatment with the delta (naltrindole) and kappa(1) (nor-binaltorphimine) antagonists, respectively. CONCLUSIONS: The present data demonstrate that whereas systemic opiate-induced muscle rigidity is primarily due to the activation of central mu receptors, supraspinal delta(1) and kappa(1) receptors may attenuate this effect. This finding is consistent with previous demonstrations of functional interactions between different central opioid receptor populations in other opiate effects, and could have important pharmacotherapeutic implications.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1996

The impact of health care reform on anesthesiologists and their patients in the United States: an ergonomic perspective.

The current status of health care reform in the United States is discussed with a special emphasis on its impact on anesthesiology. The author then takes an ergonomic perspective to explore the premise that health care reform of any type may subtly or not so subtly affect the ability of clinical care providers to do their job. It is asserted that alterations in the structure of the health care delivery system, provider incentives, work schedules, production pressures, and other factors can adversely impact anesthesiologist performance. If this is the case then the cost of care actually may increase due to unanticipated inefficiencies or a higher incidence of either patient or provider morbidity. The potential role of human, environmental, equipment, and task factors on anesthesiologist performance are reviewed. The author concludes with a discussion of technology assessment and the role of new anesthesia drugs and devices in a cost-sensitive health care marketplace.

Anesthesiology↗
PubMed1995

A role for CNS alpha-2 adrenergic receptors in opiate-induced muscle rigidity in the rat.

A number of potential neurochemical mediators of opiate-induced muscle rigidity have been proposed based on the results of systemic drug studies and on knowledge of the brain sites implicated in opiate rigidity. The effects of i.c.v. pretreatment with selected opioidergic, alpha adrenergic and serotonergic drugs on muscle rigidity induced with systemic injection of the potent opiate agonist alfentanil (ALF) were investigated in spontaneously ventilating rats. The opiate antagonist methylnaloxonium (MN; 0.2-14 nmol), alpha-2 adrenergic agonists dexmedetomidine (DEX; 0.4-42 nmol) or 2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride (ST91; 4-400 nmol), alpha-1 adrenergic antagonist prazosin (PRZ; 7-70 nmol) or serotonergic antagonist ketanserin (KET; 18-550 nmol) were injected i.c.v. (10 microliters) and ALF (500 micrograms/kg s.c.) was administered 10 min later. S.c. electrodes were used to record gastrocnemius electromyographic activity. Both MN and DEX dose-dependently and potently antagonized ALF-induced rigidity. ST91 produced shorter-lived, less profound, antagonism of ALF rigidity. PRZ, at the highest dose tested, produced a delayed and modest reduction in ALF rigidity. A large, non-selective, dose of KET incompletely attenuated ALF rigidity. These results lend support to the hypothesis that central opioid and alpha-2 adrenergic receptors mediate opiate-induced muscle rigidity in the rat.

Adrenergic alpha-Agonists↗