Richard A. Harrigan

Poisoning from “Spanish fly” (cantharidin)

Cantharidin, known popularly as Spanish fly, has been used for millennia as a sexual stimulant. The chemical is derived from blister beetles and is notable for its vesicant properties. While most commonly available preparations of Spanish fly contain cantharidin in negligible amounts, if at all, the chemical is available illicitly in concentrations capable of causing severe toxicity. Symptoms of cantharidin poisoning include burning of the mouth, dysphagia, nausea, hematemesis, gross hematuria, and dysuria. Mucosal erosion and hemorrhage is seen in the upper gastrointestinal (GI) tract. Renal dysfunction is common and related to acute tubular necrosis and glomerular destruction. Priapism, seizures, and cardiac abnormalities are less commonly seen. We report four cases of cantharidin poisoning presenting to our emergency department with complaints of dysuria and dark urine. Three patients had abdominal pain, one had flank pain, and the one woman had vaginal bleeding. Three had hematuria and two had occult rectal bleeding. Low-grade disseminated intravascular coagulation, not previously associated with cantharidin poisoning, was noted in two patients. Management of cantharidin poisoning is supportive. Given the widespread availability of Spanish fly, its reputation as an aphrodisiac, and the fact that ingestion is frequently unwitting, cantharidin poisoning may be a more common cause of morbidity than is generally recognized. Cantharidin poisoning should be suspected in any patient presenting with unexplained hematuria or with GI hemorrhage associated with diffuse injury of the upper GI tract.

Tuberculous psoas abscess

Although its historical significance is well established, Mycobacterium tuberculosis today is considered an extremely rare cause of psoas abscess. Nontuberculous bacterial infection, most commonly secondary to an intraabdominal process but at times appearing without an identifiable source, is responsible for the vast majority of psoas abscesses. The recent resurgence of tuberculosis may portend another change in the etiologic trend of psoas abscess. It is essential that the emergency physician not only recognize the potentially subtle presentation of psoas abscess, but also include tuberculosis in the differential diagnosis of infectious causes of this entity. A case of tuberculous psoas abscess in an HIV-negative man is presented. A review of the anatomy, pathophysiology, clinical presentation, epidemiology, and treatment follows, highlighting the similarities and differences between tuberculous and nontuberculous psoas infection.

Electrocardiographic Electrode Misplacement, Misconnection, and Artifact

BACKGROUND Electrocardiograms (ECGs) are performed by humans, and thus are subject to human error. An underappreciated source of electrocardiographic abnormality is electrode misconnection, both limb and precordial, and improper placement, which is principally an issue with the precordial electrodes due to anatomic variation. Patterns of abnormality exist; recognition allows the emergency physician to avoid mistaking the resulting electrocardiographic findings for true pathology. OBJECTIVES The purpose of this clinical review is to describe the patterns of electrocardiographic electrode reversal, misplacement, and artifact and thus make them recognizable to the Emergency Physician. DISCUSSION Common limb electrode reversals feature distinctive patterns manifesting as unexpected morphologic and frontal plane axis changes in the QRS complexes in the limb and augmented leads. Precordial electrode misplacement (improper positioning of the electrodes on the chest) is common and may mimic a pseudoinfarction pattern, or ST-segment/T-wave changes, which must be recognized as the result of the misplacement rather than true cardiac ischemia. Precordial electrode reversal should be suspected when the normal R/S wave amplitude transition is violated. Electrocardiographic artifact must be distinguished from dysrhythmia to avoid a potentially hazardous progression to unnecessary diagnostics and therapeutics. CONCLUSIONS The hallmarks of electrode misconnection, misplacement, and electrocardiographic artifact can be easily mastered by the Emergency Physician; recognition of these findings can positively impact patient care by avoiding unnecessary intervention secondary to misattribution of findings on the 12-lead ECG to cardiac pathology.

DIAGNOSIS AND MANAGEMENT OF BRADYCARDIA AND ATRIOVENTRICULAR BLOCK ASSOCIATED WITH ACUTE CORONARY ISCHEMIA

Bradyarrhythmias arising in the setting of myocardial infarction occur in a significant minority of patients with AMI. In the majority of cases, these abnormalities are owing to myocardial ischemia or infarction with necrosis of the cardiac pacemaker sites and/or conduction system. Other factors responsible for these bradyarrhythmias include altered autonomic influence, systemic hypoxia, electrolyte disturbances, acid-based disorders, and complications of various medical therapies. This article will focus on not only the diagnosis and management of these rhythm disturbances, but also on the pathophysiology of the arrhythmias.

EVALUATION AND MANAGEMENT OF BRADYARRHYTHMIAS IN THE EMERGENCY DEPARTMENT

Bradyarrhythmias may be due to varied causes, although acute myocardial infarction, hypoxia, sepsis, and hypothermia should be considered. Emergency department therapy consists of treatment of the underlying cause, pharmacologic interventions, and temporary pacing. This article provides a detailed discussion of the causes and treatment of bradyarrhythmias in the emergency department.

Postexposure rabies prophylaxis in an urban emergency department.

The purpose of this retrospective study was to identify those patients presenting to an urban emergency department with animal-related wounds, define source animal demographics, and assess adequacy of wound care, rabies immunoprophylaxis, and follow-up. Sixty-three patients comprised the study population; dogs (76%) and cats (16%) were the principal source animals. Postexposure rabies prophylaxis was indicated in ten patients (16%) due to wounds inflicted by stray dogs and cats. Animal behavior and vaccination history were inconsistently addressed, but were documented significantly more often in patients who received prophylaxis. Inclusion of soap in wound care was not significantly more common in the treated group. Human rabies immune globulin was administered incorrectly at least one-third of the time. Appropriate follow-up was arranged in only 31% of cases; this occurred significantly more often with treated patients. An awareness of both regional epidemiological trends in animal rabies and local health department treatment recommendations will encourage optimal delivery of postexposure treatment in cases of potential rabies exposure.

EVALUATION AND TREATMENT OF ACUTE URINARY RETENTION

Acute urinary retention is a common presentation to the Emergency Department and is often simply treated with placement of a Foley catheter. However, various cases will arise when this will not remedy the retention and more aggressive measures will be needed, particularly if emergent urological consultation is not available. This article will review the causes of urinary obstruction and systematically review emergent techniques and procedures used to treat this condition.

Electrocardiographic manifestations: bundle branch blocks and fascicular blocks.

Intraventricular conduction block is the general name given to a varied group of electrocardiographic entities. All share a common finding of some degree of delay in ventricular activation; recognition of these blocks hinges upon analysis of the QRS complex, as well as the ST-T changes associated with them. Bundle branch block (right or left), and fascicular block (left anterior or left posterior) are all examples of intraventricular conduction block. Causation of intraventricular conduction block may be cardiac or noncardiac; early recognition of the etiology may be of clinical importance. This article reviews the basic anatomy and physiology related to intraventricular conduction blocks, and then examines each in terms of electrocardiographic definition and clinical correlation.

Electrocardiographic manifestations: ventricular tachycardia

Ventricular tachycardia is a serious rhythm disturbance that originates from any part of the myocardium or conduction system below the atrioventricular node. Ventricular tachycardia (VT) presents with a wide QRS complex and a rate greater than 120 beats/min. Ventricular tachycardia is frequently encountered as a complication of coronary artery disease or cardiomyopathy; furthermore, VT is also seen in patients with medication adverse effect or electrolyte disturbance. Ventricular tachycardia presents electrocardiographically in several forms, including monomorphic and polymorphic VT. As is true in most Emergency Department presentations, the Emergency Physician must approach the dysrhythmic patient from an undifferentiated perspective, in this instance, the wide complex tachycardia (WCT) scenario. The electrocardiographic differential diagnosis of WCT classically includes VT and supraventricular tachycardia with aberrant intra-ventricular conduction. This article will review the electrocardiographic presentations encountered in patients with ventricular tachycardia.

GENERAL PHARMACOLOGIC TREATMENT OF ACUTE MYOCARDIAL INFARCTION

The general pharmacotherapeutic issues surrounding AMI are complex and expanding, especially with regard to treatment aimed at the [table: see text] culprit, coronary atherosclerotic thrombus. Basic, well-established therapy includes the routine administration of oxygen, nitroglycerin, aspirin, and at times morphine, with selected cases invoking caution with respect to these agents (e.g., nitroglycerin and the risk of hypotension in right ventricular infarction; contraindication to nitrolycerin in patients on sildenafil). Cardioprotective agents, especially beta-adrenergic antagonists, should be considered early in light of their demonstrated benefit; others, such as ACE inhibitors, need not be administered in the ED. Heparin, both UFH and the newer LMWHs, have well-established roles in acute coronary syndromes. The GP IIb/IIIa inhibitors are the most recent addition to the pharmacologic armamentarium; their role is evolving rapidly as research on this frontier continues. Table 2 reviews recommended dosing of selected agents in acute coronary syndromes.