Young Woman With Seizures

Efficacy of lipid emulsion therapy in treating cardiotoxicity from diphenhydramine ingestion: a review and analysis of case reports

INTRODUCTION

Lipid emulsion therapy (LET) has been most thoroughly studied to reverse local anesthetic systemic toxicity (LAST). Case reports suggest that LET can successfully rescue cardiovascular collapse from bupropion, amitriptyline, and propranolol. The efficacy of LET against refractory hypotension and dysrhythmias from diphenhydramine, a commonly ingested lipophilic cardiotoxic agent, is less well described.

OBJECTIVE

Summarize the evidence that LET rescues cardiac ion channel blockade (QRS, QTc widening) or hypotension attributable to diphenhydramine overdose.

METHODS

We searched MEDLINE, EMBASE, and Google Scholar for English-language full-length case reports of diphenhydramine (DPH) intoxication in patients 17 years of age or older. We extracted data with a PRISMA-compliant protocol, dividing the case reports into two groups, one that received LET and one that did not. We performed a pooled analysis to compare the change in mean arterial pressure (MAP), QRS duration, and QTc duration between the two groups.

RESULTS

We identified 23 reports (25 patients). Lipid emulsion therapy (LET) was used in 6 cases because the patient suffered from hypotension refractory to traditional resuscitation. Those who received LET and those who did not were comparable in age, gender, amount ingested, and frequency of seizures. The mean arterial pressure (MAP) decreased by 4.5 ± 11.5 mm Hg in those who did not receive LET compared to an increase in MAP 37 ± 17.5 mm Hg in those who did receive LET. The QRS narrowed by 29 ± 33.9 ms (no LET group) vs 68 ± 49.5 ms (LET group) and QTc by 168.5 ± 126.75 ms (no LET group) vs 134 ± 88 ms (LET group). All values are expressed as median ± interquartile range. One out of the 6 patients who received LET died after withdrawal of care. In the group that did not receive LET 4 out of 19 died and 3 had no outcome reported.

DISCUSSION

LET may improve MAP in patients with hypotension refractory to vasopressors due to diphenhydramine toxicity. We found no significant effect of LET on QRS or QTc duration. These results are limited by a small sample size, reporting bias of case reports, incomplete data, and heterogeneity.

CONCLUSION

An analysis of pooled case reports suggests that LET may rescue hypotension when other methods have failed in patients with hypotension attributable to diphenhydramine overdose.

IV Lipid Emulsion Infusion in the Treatment of Severe Diphenhydramine Overdose

BACKGROUND Diphenhydramine is a commonly available over-the-counter antihistamine; however, there are few documented cases of treatment when ingested in toxic quantities, where it can cause a sodium channel blockade leading to wide-complex tachycardia, seizures, and death. Conventional treatment includes sodium bicarbonate infusion, but few cases have documented the addition of lipid emulsion therapy. CASE REPORT A 24-year-old African American female ingested 18 g (360 pills of 50 mg) over-the-counter diphenhydramine. She presented comatose, with hemodynamic instability and hypotension, intubated with pupil dilation to 6 to 7 mm, and initial electrocardiography findings showing a type 1 AV block with a QT/QTc of 360/402 ms which progressed into sinus tachycardia with widened QRS intervals of 134 ms and prolonged QT/QTc intervals of up to 638/759 ms. Treatment using sodium bicarbonate and magnesium was initiated; however, the intraventricular conduction delay persisted. Infusion of 20% intravenous lipid emulsion was administered; following this, the patient developed narrow complex QRS with sinus rhythm and shortened the QT/QTc interval to 448/516 ms. She recovered quickly and was transferred to inpatient psychiatric unit for further evaluation, and discharged 1 month later. CONCLUSIONS Lipid emulsion therapy has been utilized in treatment of various medication overdoses, but there are few documented cases in the treatment of diphenhydramine overdose. With the amount of diphenhydramine ingested by the patient in this case report, the use of combined conventional and lipid emulsion therapy was utilized in the stabilization and management of the patient, and should be considered in scenarios where conventional treatments have not improved the clinical outcome.

When good times go bad: managing 'legal high' complications in the emergency department

Patients can use numerous drugs that exist outside of existing regulatory statutes in order to get "legal highs." Legal psychoactive substances represent a challenge to the emergency medicine physician due to the sheer number of available agents, their multiple toxidromes and presentations, their escaping traditional methods of analysis, and the reluctance of patients to divulge their use of these agents. This paper endeavors to cover a wide variety of "legal highs," or uncontrolled psychoactive substances that may have abuse potential and may result in serious toxicity. These agents include not only some novel psychoactive substances aka "designer drugs," but also a wide variety of over-the-counter medications, herbal supplements, and even a household culinary spice. The care of patients in the emergency department who have used "legal high" substances is challenging. Patients may misunderstand the substance they have been exposed to, there are rarely any readily available laboratory confirmatory tests for these substances, and the exact substances being abused may change on a near-daily basis. This review will attempt to group legal agents into expected toxidromes and discuss associated common clinical manifestations and management. A focus on aggressive symptom-based supportive care as well as management of end-organ dysfunction is the mainstay of treatment for these patients in the emergency department.