Cardiac Arrest With Residual Blindness After Overdose of Tessalon® (Benzonatate) Perles

Background: The extent to which benzonatate (Tessalon®), a structurally similar agent to other local anesthetics including tetracaine and procaine, poses a risk to the public is not fully appreciated as it is still one of the most widely prescribed antitussives available. Objectives: To report a case of cardiac arrest with residual blindness after Tessalon® overdose, review its clinical manifestations, toxicology and management considerations, and describe the need for rational prescribing. Case Report: A 17-year-old woman with no previous medical history presented to the Emergency Department (ED) status post cardiac arrest. One to two hours prior, the patient had ingested at least 10 200-mg Tessalon® capsules as part of a suicide attempt. The patient was sedated, intubated, and given magnesium as prophylaxis against recurrent dysrhythmias. Emergent gastric lavage was performed and well tolerated. A 24-h hypothermia protocol with 6-h cooling period was initiated. Toxicological studies, chest radiograph, and a computed tomography scan of the head were all unremarkable. The patient was admitted to the Pediatric Intensive Care Unit for further work-up and supportive care. The patient was extubated and able to follow some commands 1 week post-admission. The patient developed blindness and experienced generalized confabulations, which did not resolve. Conclusion: Ingestion of Tessalon®, a seemingly innocuous and widely prescribed antitussive, may pose a risk to patients due to its potential for the rapid development of life-threatening adverse events and limited treatment options in the overdose setting. Rational prescribing and patient education is needed.     

Cardiac Arrhythmias and ECG Abnormalities in Tricyclic Antidepressant Overdose

Background. Ethanol used as an antidote is said to have various adverse effects, particularly in children. The rate of these adverse effects is not known.

Methods. Twenty-one-year retrospective chart review (1980–2000) from suspected methanol poisoning patients treated with ethanol in two large pediatric tertiary care centers.

Results. A total of 60 children (median age of 24 months) received ethanol for suspected methanol poisoning: 39 orally and 21 intravenously. Median initial methanol level was 4.16 mmol/L (13.3 mg/dL) (range 0 to 87.5 mmol/L or 0 to 280 mg/dL). Median duration of ethanol treatment was 16 hours (range 1.5 to 72 hours). None [0% (95% CI 0–5%)] of the 60 patients developed symptomatic hypoglycemia. Of the 50 patients that had a glucose level measured, none [(0% [95% CI 0–6%)] had a serum glucose concentration <2.78 mmol/L (<50 mg/dL). Eight patients [16% (95% CI 8–30%)] had at least one serum glucose concentration between 2.78–3.61 mmol/L (50–65 mg/dL), but none of those had symptoms compatible with hypoglycemia. A total of 42 patients [84% (95% CI 70–92%)] had all their serum glucose concentrations >3.61 mmol/L (>65 mg/dL). There was no identifiable difference in the glucose intake between the serum glucose concentration groups. Six out of the 60 patients [10% (95% CI 4–21%)] were described as more drowsy after ethanol but none was comatose or needed intubation. No child showed signs of hypothermia [0/40 (95% CI 0–8%)] (rectal temperature <35°C), hepatotoxicity (0/12) (AST or ALT>100 U/L) or even thrombophlebitis (0/21). None of the 22 patients with toxic levels of methanol (≥6.2 mmol/L–≥20 mg/dL) died or had ethanol-induced morbidity despite wide variation in ethanol levels.

Conclusion. The rate of clinically important adverse effects related to ethanol used as an antidote to treat methanol poisoning in children was either absent or low in a tertiary care pediatric hospital setting. There was no morbidity or mortality associated with ethanol when it was used despite wide variation in ethanol levels. These results suggest that with appropriate monitoring and intravenous glucose intake in a controlled environment such as a pediatric intensive care unit, ethanol therapy does not carry as many risks as currently believed.     

Occurrence and Significance of Arrhythmias Associated with Atrial-Triggered Ventricular Pacing

A review of electrocardiograms from 85 patients with atrial-triggered ventricular pacing (VAT, VDD, DDD) showed that various disturbances of rhythm were relatively common, and that the effects of an arrhythmia could be aggravated by this type of pacing. In certain circumstances even potentially dangerous ventricular extrasystoles were induced by the pacemaker. Abnormal triggering, sometimes with regular sinus rhythm, could also induce tachycardia. Our observations provided indications for a pacemaker design that would avoid such disturbing effects. The best available pacer for atrial-triggered ventricular pacing is the programmable DDD type.     

Cardiotoxicity Associated With Intentional Ziprasidone And Bupropion Overdose

Background: Ziprasidone (Geodon^®) and bupropion (Wellbutrin^®) are medications prescribed for mood and behavior disorders. They have apparently safe cardiac safety profiles in both therapeutic and supra-therapeutic doses. Case Report:?A 17-year-old male developed a widened QRS and a prolonged QTc interval following an overdose of ziprasidone and bupropion. He required hospital admission for aggressive cardiac monitoring and anti-dysrhythmic therapy, stabilizing to baseline by 80 hours post-ingestion. Conclusions:?We present a case that underscores the potential cardiotoxicities of these medications. Ziprasidone and bupropion ingestion can be associated with cardiotoxicities that may require several days of aggressive cardiac monitoring and treatment.     

Skin Burns Associated with Radiofrequency Catheter Ablation of Cardiac Arrhythmias

Skin burns are a rare complication associated with radiofrequency catheter ablation of cardiac arrhythmias. Burns related to the indifferent electrode patch may be severe and result in significant comorbidity. We describe our experience of skin burns and discuss potential predisposing and possible causative factors.     

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.     

Ventricular Arrhythmias and Mortality Associated with Isoflurane and Sevoflurane in a Porcine Model of Myocardial Infarction

Ischemia of the myocardium can lead to reversible or irreversible injury depending on the severity and duration of the preceding ischemia. Here we compared sevoflurane and isoflurane with particular reference to their hemodynamic effects and ability to modify the effects of acute severe myocardial ischemia and reperfusion on ventricular arrhythmias and mortality in a porcine model of myocardial infarction. Female Large White pigs were premedicated with ketamine, midazolam, and atropine. Propofol was given intravenously for the anesthetic induction, and anesthesia was maintained with isoflurane or sevoflurane. Endovascular, fluoroscopy-guided, coronary procedures were performed to occlude the midleft anterior descending artery by using a coronary angioplasty balloon. After 75 min, the balloon catheter system was withdrawn and the presence of adequate reperfusion flow was verified. The pigs were followed for 2 mo, and overall mortality rate was calculated. The isoflurane group showed lower arterial pressure throughout the procedure, with the difference reaching statistical significance after induction of myocardial ischemia. The ventricular fibrillation rate was higher in isoflurane group (81.3%) than the sevoflurane group (51.7%; relative risk, 1.57 [1.03 to 2.4]). Overall survival was lower in the isoflurane group (75%) than the sevoflurane group (96.4%). In conclusion, in this porcine model of myocardial ischemia and reperfusion, sevoflurane was associated with higher hemodynamic stability and fewer ventricular arrhythmias and mortality than was isoflurane.Ischemia and the subsequent reperfusion of the myocardium can lead to reversible or irreversible injury, depending on the severity and duration on the preceding ischemia. This damage has different clinical manifestations, including the development of ventricular arrhythmias with high incidence of ventricular fibrillation.^34,42,51Many factors can influence the incidence and severity of the arrhythmias associated with myocardial ischemia, from isolated premature ventricular beats to ventricular fibrillation: location and distribution of the occluded coronary artery, extension of myocardial infarction, duration of the coronary occlusion, anesthetic protocol, and heart rate.^4,13The porcine model of myocardial infarction has been used in experimental cardiology for many decades because of its proved reproducibility and similarity with key human anatomic characteristics and pathophysiologic events known to occur in patients with myocardial infarction.^{1,16,52,55,60,67} One of the undisputed complications of this model is its high incidence of ventricular arrhythmias and fibrillation, which complicates anesthetic protocols and postoperative managment.^{29,32,34,42,58,66}Myocardial ischemia–reperfusion injury can lead to severe complications; measures to minimize myocardial damage have been an important target of research. Because anesthetics may provide protection against this damage,^36,53 improved understanding of the role of anesthetics in the prevention of myocardial injury may provide anesthesiologists with strategies to improve outcome. The use of particular anesthetics for the induction and maintenance of general anesthesia is one such approach proposed to protect against the adverse effects of ischemia.^18,17Experimental evidence suggests that volatile anesthetic agents have direct protective properties against ischemic myocardial damage.^33,35,41 These cardioprotective effects of inhalant anesthetics can be attributed to several properties exhibited by these agents: preservation of myocardial energy stores (ATP concentrations),^45,53 free radical scavenging,^19,61,62 and negative inotropic and chronotropic actions.¹⁰ Decreases in heart rate, systolic pressure, and, therefore, the rate–pressure product would lower myocardial energy demand and oxygen consumption, thereby reducing myocardial metabolic requirements.⁵³ In addition, halogenated anesthetics reduce the incidence of ventricular arrhythmia, as compared with intravenous agents.^18,19,45 Some authors³³ have suggested that halogenated anesthetics have an antiarrhythmic effect similar to that of verapamil. The ability of these agents to alter Ca²⁺ homeostasis in myocardium could explain this effect.^28,31,41In the present study, we compared sevoflurane with isoflurane with special reference to their hemodynamic effects and ability to modify the effects of acute severe myocardial ischemia and reperfusion on ventricular arrhythmias and mortality. Therefore, this study had as its main objective the development of a suitable and safe anesthetic protocol in swine as an animal model to study acute myocardial infarction after induction of acute myocardial ischemia. Improving survival rates in animal models not only increases the efficiency of these models but also the ethical acceptability of the procedures. Using the most appropriate anesthetic protocol ensures animal welfare, reduces morbidity, optimizes performance, and increases the quality of research.     

Acute Felbamate Overdose with Crystalluria

A 3-year-old child developed vomiting, ataxia, and crystalluria after ingestion of approximately 232 mg/kg of felbamate elixir. High-powered polarization microscopy of the urine revealed sharp, needle-like crystals. The analysis of the urine crystals showed unchanged felbamate (80.9%), monocarbamate felbamate (18.8%), and trace amounts of mercapturic acid conjugates of the metabolite 2-phenylpropenal (0.1%). The serum felbamate level 15 h after ingestion was 138 mg/L. Crystalluria and hematuria resolved with intravenous fluid therapy, and the child recovered within 24 h.     

Overdose with sustained-release lithium preparations

Two cases of overdose with sustained-release lithium preparations are presented. Initial serum lithium levels were in the therapeutic or subtherapeutic range. Subsequent levels were in the toxic range. These cases illustrate the potential danger of delayed toxicity with ingestion of these agents.     

Sertraline Overdose

Objective: To determine the clinical presenting signs and symptoms in presumed overdoses of sertraline, a recently approved antidepressant. Methods: A prospective study involving five western regional poison control centers was performed to evaluate the clinical manifestations of presumed sertraline ingestions (overdoses). Information about calls pertaining to sertraline ingestions was recorded on a standard data collection form. Data including subject age, sex, amount ingested, coingestants, time interval to evaluation, vital signs, presenting signs and symptoms, ECG abnormalities, treatment given, disposition, and length of stay in the ED were collected over a nine–month period. Results: Of 42 ingestions reported, two were adverse reactions to normal doses and 40 were overdoses. Stated amounts of sertraline ingested ranged from 50 to 8, 000 mg (mean 1, 579 mg). Mean patient age was 35. 3 years (range 1 to 69 years). Mean interval to presentation was 3. 0 hours. Seventeen of the 40 patients ingested sertraline alone. Of this subgroup, ten had no sign or symptom. The most common abnormalties reported in isolated sertraline overdose were tremor, lethargy, and nausea. Less common findings included agitation, confusion, and vomiting. There was no significant morbidity in this subgroup of presumed isolated sertraline ingestion. Of the 23 patients who ingested other medications along with sertraline, four were asymptomatic. Benzodiazepines and alcohol were the most frequently coingested substances. Lethargy, nausea, dry mouth, and mydriasis were the most common features reported in this group. Treatment included lavage, activated charcoal, and observation. Twelve patients were admitted for 24–hour observation, none had an adverse outcome. Of the patients released from the ED, the mean length of stay was 3. 9 hours. Conclusion: Sertraline is commonly taken in overdose with other medications or alcohol. The signs and symptoms that develop in association with an overdose of sertraline appear to be minor and of short duration.     

Severe Atenolol and Diltiazem Overdose

Case Report: A case of combined, massive overdose of both atenolol and diltiazem in an adult male is reported. Cardiac arrest ensued which was responsive to cardiopulmonary resuscitation. Bradycardia, hypotension, and oliguria followed which were resistant to intravenous pacing and multiple pharmacologic interventions, including intravenous fluids, calcium, dopamine, dobutamine, epinephrine, prenalterol, and glucagon. Adequate mean arterial pressure and urine output were restored only after addition of phenylephrine to therapy with multiple agents and transvenous pacing. The patient survived until discharge after a hospital course complicated by nontransmural myocardial infarct on hospital day 4 and pneumonia. Laboratory testing subsequently revealed high serum levels of both atenolol and diltiazem. The atenolol level of 35 μg/mL in this patient is the highest reported associated with survival. Conclusion: This case illustrates severe cardiovascular toxicity after overdose of both atenolol and diltiazem. Oliguria, which has previously been reported in severe atenolol overdose, was successfully treated without hemodialysis by the addition of phenylephrine to aggressive therapy with pacing, inotropic, and pressor support.     

Seizures associated with quetiapine treatment

OBJECTIVE: To report a case of seizures in a patient with Alzheimer disease, who was receiving quetiapine for psychoses. CASE SUMMARY: A 75-year-old white man with Alzheimer disease was observed to have seizures while receiving quetiapine 500 mg/d and carbamazepine 200 mg/d. He had been taking quetiapine for 18 months prior to the event. No other toxic, metabolic, or anatomic abnormalities were identified to explain the seizures. After cessation of quetiapine treatment, the patient remained seizure free. An objective causality assessment revealed that the adverse drug reaction was possible. DISCUSSION: The patient was taking a relatively high dose of quetiapine. An increased risk of seizures has been associated with Alzheimer disease. Using a relatively high dose of quetiapine may have resulted in seizures in our patient with Alzheimer disease. CONCLUSIONS: As with other antipsychotics, quetiapine should be used cautiously in elderly patients with conditions that can lower the seizure threshold, and special monitoring should be performed for this serious adverse effect.