Clinician Risk Tolerance and Rates of Admission From the Emergency Department

Importance

Much remains unknown about the extent of and factors that influence clinician-level variation in rates of admission from the emergency department (ED). In particular, emergency clinician risk tolerance is a potentially important attribute, but it is not well defined in terms of its association with the decision to admit.

Objective

To further characterize this variation in rates of admission from the ED and to determine whether clinician risk attitudes are associated with the propensity to admit.

Design, Setting, and Participants

In this observational cohort study, data were analyzed from the Massachusetts All Payer Claims Database to identify all ED visits from October 2015 through December 2017 with any form of commercial insurance or Medicaid. ED visits were then linked to treating clinicians and their risk tolerance scores obtained in a separate statewide survey to examine the association between risk tolerance and the decision to admit. Statistical analysis was performed from 2022 to 2023.

Main Outcomes and Measures

The ratio between observed and projected admission rates was computed, controlling for hospital, and then plotted against the projected admission rates to find the extent of variation. Pearson correlation coefficients were then used to examine the association between the mean projected rate of admission and the difference between actual and projected rates of admission. The consistency of clinician admission practices across a range of the most common conditions resulting in admission were then assessed to understand whether admission decisions were consistent across different conditions. Finally, an assessment was made as to whether the extent of deviation from the expected admission rates at an individual level was associated with clinician risk tolerance.

Results

The study sample included 392 676 ED visits seen by 691 emergency clinicians. Among patients seen for ED visits, 221 077 (56.3%) were female, and 236 783 (60.3%) were 45 years of age or older; 178 890 visits (46.5%) were for patients insured by Medicaid, 96 947 (25.2%) were for those with commercial insurance, 71 171 (18.5%) were Medicare Part B or Medicare Advantage, and the remaining 37 702 (9.8%) were other insurance category. Of the 691 clinicians, 429 (62.6%) were male; mean (SD) age was 46.5 (9.8) years; and 72 (10.4%) were Asian, 13 (1.9%) were Black, 577 (83.5%) were White, and 29 (4.2%) were other race. Admission rates across the clinicians included ranged from 36.3% at the 25th percentile to 48.0% at the 75th percentile (median, 42.1%). Overall, there was substantial variation in admission rates across clinicians; physicians were just as likely to overadmit or underadmit across the range of projected rates of admission (Pearson correlation coefficient, 0.046 [P = .23]). There also was weak consistency in admission rates across the most common clinical conditions, with intraclass correlations ranging from 0.09 (95% CI, 0.02-0.17) for genitourinary/syncope to 0.48 (95% CI, 0.42-0.53) for cardiac/syncope. Greater clinician risk tolerance (as measured by the Risk Tolerance Scale) was associated with a statistically significant tendency to admit less than the projected admission rate (coefficient, -0.09 [P = .04]). The other scales studied revealed no significant associations.

Conclusions and Relevance

In this cohort study of ED visits from Massachusetts, there was statistically significant variation between ED clinicians in admission rates and little consistency in admission tendencies across different conditions. Admission tendencies were minimally associated with clinician innate risk tolerance as assessed by this study's measures; further research relying on a broad range of measures of risk tolerance is needed to better understand the role of clinician attitudes toward risk in explaining practice patterns and to identify additional factors that may be associated with variation at the clinician level.

Association of Functional Status, Cognition, Social Support, and Geriatric Syndrome With Admission From the Emergency Department

Importance

The role of patient-level factors that are unrelated to the specific clinical condition leading to an emergency department (ED) visit, such as functional status, cognitive status, social supports, and geriatric syndromes, in admission decisions is not well understood, partly because these data are not available in administrative databases.

Objective

To determine the extent to which patient-level factors are associated with rates of hospital admission from the ED.

Design, Setting, and Participants

This cohort study analyzed survey data collected from participants (or their proxies, such as family members) enrolled in the Health and Retirement Study (HRS) from January 1, 2000, to December 31, 2018. These HRS data were linked to Medicare fee-for-service claims data from January 1, 1999, to December 31, 2018. Information on functional status, cognitive status, social supports, and geriatric syndromes was obtained from the HRS data, whereas ED visits, subsequent hospital admission or ED discharge, and other claims-derived comorbidities and sociodemographic characteristics were obtained from Medicare data. Data were analyzed from September 2021 to April 2023.

Main Outcomes and Measures

The primary outcome measure was hospital admission after an ED visit. A baseline logistic regression model was estimated, with a binary indicator of admission as the dependent variable of interest. For each primary variable of interest derived from the HRS data, the model was reestimated, including the HRS variable of interest as an independent variable. For each of these models, the odds ratio (OR) and average marginal effect (AME) of changing the value of the variable of interest were calculated.

Results

A total of 42 392 ED visits by 11 783 unique patients were included. At the time of the ED visit, patients had a mean (SD) age of 77.4 (9.6) years, and visits were predominantly for female (25 719 visits [60.7%]) and White (32 148 visits [75.8%]) individuals. The overall percentage of patients admitted was 42.5%. After controlling for ED diagnosis and demographic characteristics, functional status, cognition status, and social supports all were associated with the likelihood of admission. For instance, difficulty performing 5 activities of daily living was associated with an 8.5-percentage point (OR, 1.47; 95% CI, 1.29-1.66) AME increase in the likelihood of admission. Having dementia was associated with an AME increase in the likelihood of admission of 4.6 percentage points (OR, 1.23; 95% CI, 1.14-1.33). Living with a spouse was associated with an AME decrease in the likelihood of admission of 3.9 percentage points (OR, 0.84; 95% CI, 0.79-0.89), and having children living within 10 miles was associated with an AME decrease in the likelihood of admission of 5.0 percentage points (OR, 0.80; 95% CI, 0.71-0.89). Other common geriatric syndromes, including trouble falling asleep, waking early, trouble with vision, glaucoma or cataract, use of hearing aids or trouble with hearing, falls in past 2 years, incontinence, depression, and polypharmacy, were not meaningfully associated with the likelihood of admission.

Conclusion and Relevance

Results of this cohort study suggest that the key patient-level characteristics, including social supports, cognitive status, and functional status, were associated with the decision to admit older patients to the hospital from the ED. These factors are critical to consider when devising strategies to reduce low-value admissions among older adult patients from the ED.

Perspectives of Emergency Clinicians About Medical Errors Resulting in Patient Harm or Malpractice Litigation

This cross-sectional study analyzes responses to a survey about medical error outcomes completed by emergency department attending physicians and advanced practice clinicians.

Weak correlations in health services research: Weak relationships or common error?

OBJECTIVE

To examine whether the correlation between a provider's effect on one population of patients and the same provider's effect on another population is underestimated if the effects for each population are estimated separately as opposed to being jointly modeled as random effects, and to characterize how the impact of the estimation procedure varies with sample size.

DATA SOURCES

Medicare claims and enrollment data on emergency department (ED) visits, including patient characteristics, the patient's hospitalization status, and identification of the doctor responsible for the decision to hospitalize the patient.

STUDY DESIGN

We used a three-pronged investigation consisting of analytical derivation, simulation experiments, and analysis of administrative data to demonstrate the fallibility of stratified estimation. Under each investigation method, results are compared between the joint modeling approach to those based on stratified analyses.

DATA COLLECTION/EXTRACTION METHODS

We used data on ED visits from administrative claims from traditional (fee-for-service) Medicare from January 2012 through September 2015.

PRINCIPAL FINDINGS

The simulation analysis demonstrates that the joint modeling approach is generally close to unbiased, whereas the stratified approach can be severely biased in small samples, a consequence of joint modeling benefitting from bivariate shrinkage and the stratified approach being compromised by measurement error. In the administrative data analyses, the estimated correlation of doctor admission tendencies between female and male patients was estimated to be 0.98 under the joint model but only 0.38 using stratified estimation. The analogous correlations for White and non-White patients are 0.99 and 0.28 and for Medicaid dual-eligible and non-dual-eligible patients are 0.99 and 0.31, respectively. These results are consistent with the analytical derivations.

CONCLUSIONS

Joint modeling targets the parameter of primary interest. In the case of population correlations, it yields estimates that are substantially less biased and higher in magnitude than naive estimators that post-process the estimates obtained from stratified models.

Attitudes toward risk among emergency physicians and advanced practice clinicians in Massachusetts

OBJECTIVE

Risk aversion is a personality trait influential to decision making in medicine. Little is known about how emergency department (ED) clinicians differ in their attitudes toward risk taking.

METHODS

We conducted a cross-sectional survey of practicing ED clinicians (physicians and advanced practice clinicians [APCs]) in Massachusetts using the following 4 existing validated scales: the Risk-Taking Scale (RTS), Stress from Uncertainty Scale (SUS), the Fear of Malpractice Scale (FMS), and the Need for (Cognitive) Closure Scale (NCC). We used Cronbach's α to assess the reliability of each scale and performed multivariable linear regressions to analyze the association between the score for each scale and clinician characteristics.

RESULTS

Of 1458 ED clinicians recruited for participation, 1116 (76.5%) responded from 93% of acute care hospitals in Massachusetts. Each of the 4 scales demonstrated high internal consistency reliability with Cronbach's αs ranging from 0.76 to 0.92. The 4 scales also were moderately correlated with one another (0.08 to 0.54; all P < 0.05). The multivariable results demonstrated differences between physicians and APCs, with physicians showing a greater tolerance for risk or uncertainty (NCC difference, -3.58 [95% confidence interval, CI, -5.26 to -1.90]; SUS difference, -3.14 [95% CI: -4.99 to -1.29]) and a higher concern about malpractice (FMS difference, 1.14 [95% CI, 0.11-2.17]). Differences were also observed based on clinician age (a proxy for years of experience), with greater age associated with greater tolerance of risk or uncertainty (age older than 50 years compared with age 35 years and younger; NCC difference, -2.84 [95% CI, -4.69 to -1.00]; SUS difference, -4.71 [95% CI, -6,74 to -2.68]) and less concern about malpractice (FMS difference, -3.19 [95% CI, -4.31 to -2.06]). There were no appreciable differences based on sex, and there were no consistent associations between scale scores and the practice and payment characteristics assessed.

CONCLUSION

We found that risk attitudes of ED clinicians were associated with type of training (physician vs APC) and age (experience). These differences suggest one possible explanation for the observed differences in decision making.

National Trends In ED Visits, Hospital Admissions, And Mortality For Medicare Patients During The COVID-19 Pandemic

Concerns about avoidance or delays in seeking emergency care during the COVID-19 pandemic are widespread, but national data on emergency department (ED) visits and subsequent rates of hospitalization and outcomes are lacking. Using data on all traditional Medicare beneficiaries in the US from October 1, 2018, to September 30, 2020, we examined trends in ED visits and rates of hospitalization and thirty-day mortality conditional on an ED visit for non-COVID-19 conditions during several stages of the pandemic and for areas that were considered COVID-19 hot spots versus those that were not. We found reductions in ED visits that were largest by the first week of April 2020 (52 percent relative decrease), with volume recovering somewhat by mid-June (25 percent relative decrease). These reductions were of similar magnitude in counties that were and were not designated as COVID-19 hot spots. There was an early increase in hospitalizations and in the relative risk for thirty-day mortality, starting with the first surge of the pandemic, peaking at just over a 2-percentage-point increase. These results suggest that patients were presenting with more serious illness, perhaps related to delays in seeking care.

Analysis of Consistency in Emergency Department Physician Variation in Propensity for Admission Across Patient Sociodemographic Groups

IMPORTANCE

Sociodemographic disparities in health care and variation in physician practice patterns have been well documented; however, the contribution of variation in individual physician care practices to health disparities is challenging to quantify. Emergency department (ED) physicians vary in their propensity to admit patients. The consistency of this variation across sociodemographic groups may help determine whether physician-specific factors are associated with care differences between patient groups.

OBJECTIVE

To estimate the consistency of ED physician admission propensities across categories of patient sex, race and ethnicity, and Medicaid enrollment.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study analyzed Medicare fee-for-service claims for ED visits from January 1, 2016, to December 31, 2019, in a 10% random sample of hospitals. The allocation of patients to ED physicians in the acute care setting was used to isolate physician-level variation in admission rates that reflects variation in physician decision-making. Multi-level models with physician random effects and hospital fixed effects were used to estimate the within-hospital physician variation in admission propensity for different patient sociodemographic subgroups and the covariation in these propensities between subgroups (consistency), adjusting for primary diagnosis and comorbidities.

MAIN OUTCOMES AND MEASURES

Admission from the ED.

RESULTS

The analysis included 4 567 760 ED visits involving 2 334 361 beneficiaries and 15 767 physicians in 396 EDs. The mean (SD) age of the beneficiaries was 78 (8.2) years, 2 700 661 visits (59.1%) were by women, and most patients (3 839 055 [84.1%]) were not eligible for Medicaid. Of 4 473 978 race and ethnicity reports on enrollment, 103 699 patients (2.3%) were Asian/Pacific Islander, 421 588 (9.4%) were Black, 257 422 (5.8%) were Hispanic, and 3 691 269 (82.5%) were non-Hispanic White. Within hospitals, adjusted rates of admission were higher for men (36.8%; 95% CI, 36.8%-36.9%) than for women (33.7%; 95% CI, 33.7%-33.8%); higher for non-Hispanic White (36.0%; 95% CI, 35.9%-36.0%) than for Asian/Pacific Islander (33.6%; 95% CI, 33.3%-33.9%), Black (30.2%; 95% CI, 30.0%-30.3%), or Hispanic (31.1%; 95% CI, 30.9%-31.2%) beneficiaries; and higher for beneficiaries dually enrolled in Medicaid (36.3%; 95% CI, 36.2%-36.5%) than for those who were not (34.7%; 95% CI, 34.7%-34.8%). Within hospitals, physicians varied in the percentage of patients admitted, ranging from 22.4% for physicians at the 10th percentile to 47.6% for physicians at the 90th percentile of the estimated distribution. Physician admission propensities were correlated between men and women (r = 0.99), Black and non-Hispanic White patients (r = 0.98), and patients who were dually enrolled and not dually enrolled in Medicaid (r = 0.98).

CONCLUSIONS AND RELEVANCE

This cross-sectional study indicated that, although overall rates of admission differ systematically by patient sociodemographic factors, an individual physician's propensity to admit relative to other physicians appears to be applied consistently across sociodemographic groups of patients.

Variation in Rates of Hospital Admission from the Emergency Department Among Medicare Patients at the Regional, Hospital, and Physician Levels

STUDY OBJECTIVE

Rates of admission from the emergency department (ED) vary widely across regions of the country, hospitals within regions, and physicians within hospitals. Our objective was to determine the extent to which variation in admission decisions was described by differences in admission rates at these 3 levels. This understanding will serve to better target interventions to modify rates of admission where appropriate.

METHODS

In this cross-sectional observational cohort study, we analyzed Medicare fee-for-service claims for ED visits from 2012 to 2015 in a 20% random sample of beneficiaries. We first estimated the total regional-, hospital-, and physician-level variations in rates of admission and their proportions of the total variation after adjusting for patient and each level's covariates. We then estimated the extent to which each level's characteristics accounted for variation at that respective level.

RESULTS

Our study sample included 5,778,218 visits with 45,491 physicians at 3,480 EDs across 306 hospital referral regions. The mean rate of admission was 38.9% and ranged from 21.4% to 53.0% for physicians at the 10^th and 90^th percentile of the distribution, respectively. The residual (unexplained) variations at the regional, hospital, and physician levels were 13.3% (95% confidence interval [CI], 11.2 to 15.5%), 60.1% (57.1 to 62.9%), and 26.7% (26.4 to 26.9%), respectively. Regional, hospital, and physician characteristics accounted for 9.1% (95% CI, -5.6 to 23.8%), 51.1% (48.8 to 53.5%), and 2.7% (1.3 to 4.1%), respectively, of the explained variation at their respective levels.

CONCLUSION

Within-area variation, both across hospitals within a region and across physicians within a hospital, is a more substantial component of observed variation in admission rates from the ED than regional level variation. These findings suggest that variation in admission rates is at least in part related to institutional norms and cultures as well as heterogeneity of physician decisionmaking within hospitals, both of which could be targets of interventions to modify rates of admission.

Emergency Department Care for Patients with Limited English Proficiency: a Retrospective Cohort Study

BACKGROUND

Limited English proficiency (LEP) patients may be particularly vulnerable in the high acuity and fast-paced setting of the emergency department (ED).

OBJECTIVE

To compare the care processes of LEP patients in the ED.

DESIGN

Retrospective cohort study.

SETTING

ED in a large tertiary care academic medical center.

PATIENTS

Adult LEP and English Proficient (EP) patients during their index presentation to the ED from September 1, 2013, to August 31, 2015. LEP patients were identified as those who selected a preferred language other than English when registering for care.

MAIN MEASURES

Rates of diagnostic studies, admission, and return visits for those originally discharged from the ED.

KEY RESULTS

We studied 57,435 visits of which 5241 (9.1%) were for patients with LEP. In adjusted analyses, LEP patients were more likely to receive an X-ray/ultrasound (OR 1.11, CI 1.03-1.19) and be admitted to the hospital (OR 1.09, CI 1.01-1.19). There was no difference in 72-h return visits (OR 0.98, CI 0.73-1.33). LEP patients presenting with complaints related to the cardiovascular system were more likely to receive a stress test (OR 1.51, CI 1.22-1.86), and those with gastrointestinal diagnoses were more likely to have an X-ray/ultrasound (OR 1.31, CI 1.02-1.68). In stratified analyses, Spanish speakers were less likely to be admitted (OR 0.8, CI 0.70-0.91), but those preferring "other" languages, which were all languages with < 500 patients, had a statistically significant higher adjusted rate of admission (OR 1.35, CI 1.17-1.57).

CONCLUSIONS

ED patients with LEP experienced both increased rates of diagnostic testing and of hospital admission. Research is needed to examine why these differences occurred and if they represent inefficiencies in care.

Physician Variability in Management of Emergency Department Patients with Chest Pain

Introduction

Chest pain is a common emergency department (ED) presentation accounting for 8–10 million visits per year in the United States. Physician-level factors such as risk tolerance are predictive of admission rates. The recent advent of accelerated diagnostic pathways and ED observation units may have an impact in reducing variation in admission rates on the individual physician level.

Methods

We conducted a single-institution retrospective observational study of ED patients with a diagnosis of chest pain as determined by diagnostic code from our hospital administrative database. We included ED visits from 2012 and 2013. Patients with an elevated troponin or an electrocardiogram (ECG) demonstrating an ST elevation myocardial infarction were excluded. Patients were divided into two groups: “admission” (this included observation and inpatients) and “discharged.” We stratified physicians by age, gender, residency location, and years since medical school. We controlled for patient- and hospital-related factors including age, gender, race, insurance status, daily ED volume, and lab values.

Results

Of 4,577 patients with documented dispositions, 3,252 (70.9%) were either admitted to the hospital or into observation (in an ED observation unit or in the hospital), while 1,333 (29.1%) were discharged. Median number of patients per physician was 132 (interquartile range 89–172). Average admission rate was 73.7±9.5% ranging from 54% to 96%. Of the 3,252 admissions, 2,638 (81.1%) were to observation. There was significant variation in the admission rate at the individual physician level with adjusted odds ratio ranging from 0.42 to 5.8 as compared to the average admission. Among physicians’ characteristics, years elapsed since finishing medical school demonstrated a trend towards association with a higher admission probability.

Conclusion

There is substantial variation among physicians in the management of patients presenting with chest pain, with physician experience playing a role.

Variation in opioid prescribing patterns between ED providers

Abuse of opioid prescription drugs has become an epidemic across the developed world. Despite the fact that emergency physicians overall account for a small proportion of total opioids prescribed, the number of prescriptions has risen dramatically in the past decade and, to some degree, contributes to the available supply of opioids in the community, some of which are diverted for non-medical use. Since successfully reducing opioid prescribing on the individual level first requires knowledge of current prescribing patterns, we sought to determine to what extent variation exists in opioid prescribing patterns at our institution. This was a single-institution observational study at a community hospital with an annual ED volume of 47,000 visits. We determined the number of prescriptions written by each provider, both total number and accounting for the number of patients seen. Our primary outcome measure was the level of variation at the physician level for number of prescriptions written per patient. We also identified the mean number of pills written per prescription. We analyzed data from November 13, 2014 through July 31, 2015 for 21 full-time providers. There were a total of 2211 prescriptions for opioids written over this time period for a total of 17,382 patients seen. On a per-patient basis, the rate of opioid prescriptions written per patient during this period was 127 per 1000 visits (95 % CI 122-132). There was a variation on the individual provider level, with rates ranging from 33 per to 332 per 1000 visits. There was also substantial variation by provider in the number of pills written per prescription with coefficient of variation (standard deviation divided by mean) averaged over different opioids ranging from 16 to 40 %. There was significant variation in opioid prescribing patterns at the individual physician level, even when accounting for the number of patients seen.

Disclosure, apology, and offer programs: stakeholders' views of barriers to and strategies for broad implementation

CONTEXT

The Disclosure, Apology, and Offer (DA&O) model, a response to patient injuries caused by medical care, is an innovative approach receiving national attention for its early success as an alternative to the existing inherently adversarial, inefficient, and inequitable medical liability system. Examples of DA&O programs, however, are few.

METHODS

Through key informant interviews, we investigated the potential for more widespread implementation of this model by provider organizations and liability insurers, defining barriers to implementation and strategies for overcoming them. Our study focused on Massachusetts, but we also explored themes that are broadly generalizable to other states.

FINDINGS

We found strong support for the DA&O model among key stakeholders, who cited its benefits for both the liability system and patient safety. The respondents did not perceive any insurmountable barriers to broad implementation, and they identified strategies that could be pursued relatively quickly. Such solutions would permit a range of organizations to implement the model without legislative hurdles.

CONCLUSIONS

Although more data are needed about the outcomes of DA&O programs, the model holds considerable promise for transforming the current approach to medical liability and patient safety.

A novel approach to identifying targets for cost reduction in the emergency department

This article introduces a novel framework that classifies emergency department (ED) visits according to broad categories of severity, identifying those categories of visits that present the most potential for reducing costs associated with the ED. Although cost savings directly attributable to the ED are apt to be an important emphasis of organizations operating under reformed payment systems, our framework suggests that a focus on diverting low-acuity visits away from the ED would result in far less savings compared with strategies aimed at reducing admissions and to a lesser extent improving the efficiency of ED care for intermediate or complex conditions. We conclude that targeting these categories, rather than minor injuries/illnesses, should be the primary focus of cost-reduction strategies from the ED. Given this understanding, we then discuss the implications of these findings on the financing of an emergency care system that needs to account for the required fixed costs of "stand-by capacity" of the ED and explore ways in which the ED can be better integrated into a patient-centered health care system.

Emergency department utilization after the implementation of Massachusetts health reform

STUDY OBJECTIVE

Health care reform in Massachusetts improved access to health insurance, but the extent to which reform affected utilization of the emergency department (ED) for conditions potentially amenable to primary care is unclear. Our objective is to determine the relationship between health reform and ED use for low-severity conditions.

METHODS

We studied ED visits, using a convenience sample of 11 Massachusetts hospitals for identical 9-month periods before and after health care reform legislation was implemented in 2006. Individuals most affected by the health reform law (the uninsured and low-income populations covered by the publicly subsidized insurance products) were compared with individuals unlikely to be affected by the legislation (those with Medicare or private insurance). Our main outcome measure was the rate of overall and low-severity ED visits for the study population and the comparison population during the period before and after health reform implementation.

RESULTS

Total visits increased from 424,878 in 2006 to 442,102 in 2008. Low-severity visits among publicly subsidized or uninsured patients decreased from 43.8% to 41.2% of total visits for that group (difference=2.6%; 95% confidence interval [CI] 2.25% to 2.85%), whereas low-severity visits for privately insured and Medicare patients decreased from 35.7% to 34.9% of total visits for that group (difference=0.8%; 95% CI 0.62% to 0.98%), for a difference in differences of 1.8% (95% CI 1.7% to 1.9%).

CONCLUSION

Although overall ED volume continues to increase, Massachusetts health reform was associated with a small but statistically significant decrease in the rate of low-severity visits for those populations most affected by health reform compared with a comparison population of individuals less likely to be affected by the reform. Our findings suggest that access to health insurance is only one of a multitude of factors affecting utilization of the ED.

Myasthenia gravis: lessons for the emergency physician

We describe three patients with myasthenia gravis who presented to the emergency department - one with a previously established diagnosis and two others who were newly diagnosed as a result of workup initiated in the emergency department. Differential diagnosis of conditions causing neuromuscular weakness is broad; however, a key aspect of myasthenia gravis is fluctuating muscle weakness that increases with repeated use and improves with rest. Both newly diagnosed patients presented with ocular complaints, a common finding in myasthenia gravis. The third patient presented with a potentially life-threatening myasthenic crisis. Key points of discussion include: bedside tests to diagnose myasthenia gravis; distinction between cholinergic versus myasthenic crisis; and emergency department considerations when intubating a myasthenia gravis patient becomes necessary.

Ex vivo cardiac allograft preservation by continuous perfusion techniques

The current technique of cardiac preservation for clinical transplantation by infusion of cold cardioplegia and immersion of the heart in an isotonic saline bath at 4 degrees C limits safe tissue preservation time to 4 to 6 hours. The myriad of benefits to be gained by extending cardiac preservation time has prompted the search for alternatives to hypothermic immersion of the heart, the most promising of which involves techniques of coronary artery perfusion. Countless studies have shown the benefits of long-term storage of donor hearts by perfusion rather than the immersion technique. Continuous perfusion preservation has three basic advantages over simple immersion. Perfusion preservation with oxygen carrying solutions has the advantage of preventing ischemia, anaerobic metabolism, and reperfusion injury. Second, nutritional supplementation and provision of substrate can be more effectively delivered to myocardial cells. Third, continuous perfusion preservation effects the clearance of metabolic waste products from the coronary circulation. The composition of the ideal perfusion solution and optimal preservation conditions remain incompletely defined.