Jeffrey N. Love

Acute Beta Blocker Overdose: Factors Associated with the Development of Cardiovascular Morbidity

Objective: To identify factors in exposures to beta blockers (beta-adrenergic receptor antagonists) that are associated with the development of cardiovascular morbidity and contribute to disposition decisions from the emergency department. Methods: Prospective cohort of 280 beta blocker exposures reported to 2 regional poison centers. Multiple logistic regression was used to determine association of various clinical factors and outcome. Results: In this series of beta blocker exposures, 41 (15%) developed cardiovascular morbidity and 4 (1.4%) died. A history of cardioactive coingestant was the only factor significantly associated with the development of cardiovascular morbidity (p <. 05). When cases reporting cardioactive coingestants were excluded, a history of ingesting a beta blocker with membrane stabilizing activity was significantly associated with the development of cardiovascular morbidity (p <. 05). All those in whom the timing of symptoms could be determined, developed symptoms within 6 hours of ingestion. Conclusions: The single most important factor associated with the development of cardiovascular morbidity in beta blocker ingestion is a history of a cardioactive coingestant, primarily calcium channel blockers, cyclic antidepressants, and neuroleptics. In the absence of such co-ingestion, exposure to a beta blocker with membrane stabilizing activity is associated with an increased risk of cardiovascular morbidity. Beta blocker ingestion is unlikely to result in symptoms if the patient remains asymptomatic for 6 hours after the time of ingestion.

Characterization of Fatal Beta Blocker Ingestion: A Review of the American Association of Poison Control Centers Data from 1985 to 1995

OBJECTIVE To characterize beta blocker-related deaths. METHODS This is a retrospective review of beta blocker-related exposure data and fatality case abstracts reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System during the 11 year period, 1985 to 1995. Historical and laboratory data were used to determine those fatalities which resulted primarily from beta blocker intoxication. RESULTS Of 52,156 reported beta blocker exposures, 164 were fatal. In 38 cases, beta blockers were implicated as the primary cause of death. Propranolol was responsible for the greatest number of exposures (44%) and implicated as the cause of death in a disproportionately high percentage of fatalities (71%). Patients were generally young women; 63% were female and 92% were less than 50 years old. The dysrhythmias most often noted in fatal cases were bradycardia and asystole. Cardiopulmonary arrest did not develop until patients were in the care of health care personnel in 59% of cases. Though glucagon was initiated more often than any other intervention in fatal intoxications (83%), optimal dosing and maintenance infusions appear to have been underutilized. CONCLUSIONS The predominance of fatalities associated with propranolol compared to other beta blockers reflects both its greater frequency of use over the time period studied and its greater toxicity. Since 59% developed. cardiac arrest after reaching health care personnel, further study should focus on identifying medical intervention that can reduce mortality in this group.

A comparison of amrinone and glucagon therapy for cardiovascular depression associated with propranolol toxicity in a canine model.

This studys objective is to evaluate the ability of glucagon and amrinone to reverse propranolol induced cardiovascular depression in a canine model, compared to a control of normal saline. The study design included 18 animals which received intravenous propranolol (10 mg/kg) resulting in significant depression in heart rate, cardiac output, mean arterial pressure, maximal ventricular dP/dt and stroke volume. Each canine was randomly assigned to one of three treatment groups; controls (normal saline only), glucagon (20 micrograms/kg bolus) and amrinone (4 mg/kg bolus). Cardiovascular parameters were monitored at 1, 6, 11, 21 and 31 min after treatment was rendered. Multiple comparison procedures at each time period controlled the overall alpha-level at .05. Compared to control animals, both amrinone and glucagon were effective in reversing propranolol-induced depression of dP/dtmax at 6 and 11 min for glucagon and 11 min for amrinone and cardiac output at 1, 6 and 11 min for glucagon and 1 min for amrinone. Amrinone and glucagon significantly increased stroke volume over control values at 1 min and tended to do so at the remaining time periods. The two days caused a similar degree of arteriolar vasodilation which was significantly greater than that seen in control animals at 1 and 6 min. Beta blocker induced bradycardia did not respond significantly to amrinone while glucagon induced a tachycardia which is unique to canines. It is concluded that in this canine model, amrinone appears to be an effective therapeutic alternative to glucagon for reversing depressed dP/dtmax, cardiac output and stoke volume induced by propranolol toxicity. Unlike glucagon, amrinone appears to lack positive chronotropic activity which may limit its clinical utility in the treatment of beta blocker overdose.

Hemodynamic Effects of Calcium Chloride in a Canine Model of Acute Propranolol Intoxication

STUDY OBJECTIVE To evaluate the hemodynamic effects of calcium chloride in a canine model of acute propranolol toxicity. METHODS Two minutes after the completion of a propranolol infusion (10 mg/kg), a bolus of .125 mL/kg 10% CaCl solution followed by an infusion of .375 mL/kg over the next 30 minutes or a bolus and subsequent infusion of an equivalent volume of normal saline solution was administered to each dog. RESULTS CaCl yielded significant improvements in propranolol-induced decreases in cardiac index and stroke volume compared with saline solution-treated control animals (overall alpha = .05). Furthermore, CaCl administration resulted in earlier improvement in propranolol-induced alterations in mean arterial pressure, maximal left ventricular pressure change over time, and peripheral vascular resistance compared with saline solution (overall alpha = .05). We observed no difference between treatment groups in response to propranolol-induced bradycardia or QRS-interval prolongation. CONCLUSION In this model of acute propranolol toxicity, CaCl therapy improved depressed hemodynamic status, mainly by a positive inotropic action.

Factors That Influence Medical Student Selection of an Emergency Medicine Residency Program: Implications for Training Programs

OBJECTIVES An understanding of student decision-making when selecting an emergency medicine (EM) training program is essential for program directors as they enter interview season. To build upon preexisting knowledge, a survey was created to identify and prioritize the factors influencing candidate decision-making of U.S. medical graduates. METHODS This was a cross-sectional, multi-institutional study that anonymously surveyed U.S. allopathic applicants to EM training programs. It took place in the 3-week period between the 2011 National Residency Matching Program (NRMP) rank list submission deadline and the announcement of match results. RESULTS Of 1,525 invitations to participate, 870 candidates (57%) completed the survey. Overall, 96% of respondents stated that both geographic location and individual program characteristics were important to decision-making, with approximately equal numbers favoring location when compared to those who favored program characteristics. The most important factors in this regard were preference for a particular geographic location (74.9%, 95% confidence interval [CI] = 72% to 78%) and to be close to spouse, significant other, or family (59.7%, 95% CI = 56% to 63%). Factors pertaining to geographic location tend to be out of the control of the program leadership. The most important program factors include the interview experience (48.9%, 95% CI = 46% to 52%), personal experience with the residents (48.5%, 95% CI = 45% to 52%), and academic reputation (44.9%, 95% CI = 42% to 48%). Unlike location, individual program factors are often either directly or somewhat under the control of the program leadership. Several other factors were ranked as the most important factor a disproportionate number of times, including a rotation in that emergency department (ED), orientation (academic vs. community), and duration of training (3-year vs. 4-year programs). For a subset of applicants, these factors had particular importance in overall decision-making. CONCLUSIONS The vast majority of applicants to EM residency programs employed a balance of geographic location factors with individual program factors in selecting a residency program. Specific program characteristics represent the greatest opportunity to maximize the success of the immediate interview experience/season, while others provide potential for strategic planning over time. A working knowledge of these results empowers program directors to make informed decisions while providing an appreciation for the limitations in attracting applicants.

Urinary retention resulting from incarceration of a retroverted, gravid uterus.

Urinary retention resulting from urethral obstruction by a retroverted, gravid uterus is an uncommon disorder that is reported only once in the Emergency Medicine literature. Yet these patients may present in extreme distress and precipitate considerable confusion regarding the cause of and solution to this problem. No study evaluating outcome, risk of complications, or therapy exists. We present two cases that clarify diagnostic and therapeutic controversies and provide a better understanding of what is known about the pathophysiology and treatment alternatives.

Acebutolol overdose resulting in fatalities

Two fatal cases of Acebutolol intoxication are presented that demonstrate its clinical characteristics and potential lethality. A review of the literature suggests that acebutolol is one of the most toxic beta blockers when taken as an overdose. In addition to demonstrating characteristics of membrane-stabilizing activity, both fatal cases demonstrate significant QTc prolongation and ventricular tachycardia. The latter findings suggest an impact on ventricular repolarization not seen with Propranolol intoxication. Clarification of these findings has important implications regarding identification and treatment of this potentially fatal intoxication.

Lack of toxicity from pediatric beta-blocker exposures

The risk of toxicity in a child who is unintentionally exposed to a beta-blocking drug remains uncertain. The current study further defines this risk, particularly in the common scenario of ingestion of one or two tablets. A prospective cohort of 208 pediatric patients, 6 months to 6 years of age, reported to two regional poison centers serves as the study population. Data were collected with a standardized instrument during the care of each patient and for a minimum of 24 hours after exposure. No instances of serious toxicity typical of beta-blocker intoxication, such as ‘shock-like’ states, arrhythmias or seizures were observed in this series. Furthermore, there were no reported episodes of hypoglycemia, symptomatic bradycardia or bronchospasm. Nine instances of altered mental status or behavioral changes were reported. All appeared to be minor in nature. The most serious outcome was charcoal aspiration during gastrointestinal decontamination. This study adds to a growing body of evidence suggesting that exposure to one or two beta-blocker tablets places children at very little, if any, risk of toxicity.

β-Blocker toxicity: A clinical diagnosis

An overdose of the beta-blocking agent metoprolol is presented in which the patient remained asymptomatic despite blood levels that were more than 25 times that reported to be the upper limit of therapeutic. This case emphasizes the need to diagnose beta-blocker toxicity on clinical grounds, not on blood levels that correlate poorly with the severity of symptoms. Furthermore, the question is raised as to whether patients are at any subsequent risk for morbidity, if they have not demonstrated signs or symptoms within 4 hours of ingestion.

Emphysematous cholecystitis in an elderly woman: Case report and review of the literature

Cholecystitis, a frequent diagnosis in emergency departments, has been discussed extensively in the medical literature. We report a case of emphysematous cholecystitis, an unusual form of this disease process, including the classic radiographic findings. We also offer a review of the literature, emphasizing the proposed pathophysiology and the life-threatening nature of this surgical condition. Early recognition and surgical consultation are vital in these patients.