Case 12-2018: A 30-Year-Old Woman with Cardiac Arrest

Prediction of drug capturing by lipid emulsions in vivo for the treatment of a drug overdose

Despite the successful treatment of drug intoxications, little information is available to quantitively predict the effect of lipid emulsions on pharmacokinetic features of overdosed drug molecules. We defined two new parameters, drug accommodation capacity and drug capture kinetics, to characterize the drug capture capability of lipid emulsions. By precisely characterizing their drug capture capability, the effect of lipid emulsions on pharmacokinetic features of overdosed drug molecules was quantitively described. This quantitative description enabled an accurate prediction of the reducing extent on the half-life and area under drug concentration-time curve, which was verified by the successful treatment of overdosed propafenone. Moreover, the capture effect prediction using drug capture capability was more accurate than that of directly using logP. Overall, the developed capture capability accurately described the effect of lipid emulsions on drug pharmacokinetic features, which can guide the clinical application of lipid emulsions for the treatment of drug overdose.

Differential diagnosis of wide QRS tachycardia: A review

Differential diagnosis of wide QRS tachycardia (WQRST) on the electrocardiogram remains a challenging exercise. Correct diagnosis is important for prescribing appropriate therapy and determining prognosis. Differential diagnosis of wide QRS tachycardia revolves around differentiation between supraventricular tachycardia with aberrant conduction and ventricular tachycardia. Observations such as clinical history, findings of physical examination during tachycardia, AV dissociation, QRS morphology in lead V1 and lead V6, precordial concordance, RS complexes in precordial leads, contralateral bundle branch block during wide QRS tachycardia, R wave morphologies in lead aVR, and ventricular initial/terminal velocity of conduction ratio can help arrive at the correct diagnosis with reasonable accuracy. The observations described here can help arrive at the correct diagnosis of WQRST with both reasonable accuracy and confidence.

Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review

RATIONALE

Cardiotoxicity is a common cause of death in tricyclic antidepressant (TCA) intoxication. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is effective in critically ill poisoned patients who do not respond to conventional therapies, and targeted temperature management (TTM) is associated with improved neurological outcomes and mortality in comatose out-of-hospital cardiac arrest survivors. However, few reports have documented cases of TCA intoxication that required intensive care, including VA-ECMO or TTM.

PATIENT CONCERNS

A 19-year-old Japanese man with a history of depression was brought to our hospital because he was in a comatose state with a generalized seizure. Before admission, he had taken an unknown amount of amitriptyline.

DIAGNOSIS

After intubation, the electrocardiogram (ECG) displayed a wide QRS complex tachycardia, and the patient suffered from cardiovascular instability despite intravenous bolus of sodium bicarbonate. At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest.

INTERVENTIONS

We initiated VA-ECMO 240 minutes after ingestion. The hemodynamic status stabilized, and the ECG abnormality improved gradually. In addition, we initiated targeted temperature management (TTM) with a target temperature of 34°C.

OUTCOMES

Twenty seven hours after starting the pump, the patient was weaned off the VA-ECMO. After completing the TTM, his mental status improved, and he was extubated on day 5. He was discharged on day 15 without neurological impairment, and the post-discharge course was uneventful.

LESSONS

First, VA-ECMO is effective in patients with TCA-induced cardiac arrest. Second, routine ECG screening during VA-ECMO support is useful for assessing the timing to wean off the VA-ECMO, as well as the degree of cardiotoxicity. Third, TTM is safe in comatose survivors of cardiac arrest caused by severe TCA intoxication.

Heterogeneity and bias in animal models of lipid emulsion therapy: a systematic review and meta-analysis

INTRODUCTION

Clinicians utilize lipid emulsion to treat local anesthetic toxicity and non-local anesthetic toxicities, a practice supported by animal experimentation and clinical experience. Prior meta-analysis confirmed a mortality benefit of lipid emulsion in animal models of local anesthetic toxicity but the benefit of lipid emulsion in models of non-local anesthetic toxicity remains unanswered. Further, swine suffer an anaphylactoid reaction from lipid emulsions calling into question their role as a model system to study lipid, so we examined swine and non-swine dependent outcomes in models of intravenous lipid emulsion.

METHODS

We conducted a systematic review and meta-analysis examining the use of lipid emulsion therapy in animal models of cardiac toxicity. We quantified mortality using a random-effects odds-ratio method. Secondary outcomes included survival in the following subgroups: local-anesthetic systemic toxicity, non-local anesthetic toxicity, swine-based models, and non-swine models (e.g., rat, rabbit and dog). We assessed for heterogeneity with Cochran's Q and I². We examined bias with Egger's test & funnel plot analysis.

RESULTS

Of 2784 references screened, 58 met criteria for inclusion. Treatment with lipid emulsion reduced chance of death in all models of toxicity with an odds ratio of death of 0.26 (95% CI 0.16-0.44, Z-5.21, p < 0.00001, Cohen's-d = 0.72, n = 60). Secondary outcomes confirmed a reduced chance of death in models of local anesthetic toxicity (OR 0.16 {95% CI 0.1-0.33}) and non-local anesthetic toxicity (OR 0.43 {95% CI 0.22-0.83}). Heterogeneity (Cochran's Q 132 {df = 59, p < 0.01}, I ² = 0.55) arose primarily from animal-model and disappeared (I ² < = 0.12) when we analyzed swine and non-swine subgroups independently. Swine only benefited in models of local anesthetic toxicity (OR 0.28 {95% CI 0.11-0.7}, p = 0.0033) whereas non-swine models experienced a homogeneous benefit across all toxins (OR 0.1 {95% CI 0.06-0.16}, p < 0.00001). Egger's test identified risk of bias with outliers on funnel plot analysis.

DISCUSSION

Lipid emulsion therapy reduces mortality in animal models of toxicity. Heterogeneity arises from the animal-model used. Swine only benefit in models of local anesthetic toxicity, potentially due to lipid dose, experimental design or swine's anaphylactoid reaction to lipid. Outlier analysis reinforced the need for appropriate dosing of lipid emulsion along with airway management and chest compressions in the setting of cardiac arrest.