Plasma alkalinization for tricyclic antidepressant toxicity: a systematic review

Common pitfalls in the use of hypertonic sodium bicarbonate for cardiac toxic drug poisonings

BACKGROUND

Hypertonic sodium bicarbonate is advocated for the treatment of sodium channel blocker poisoning, but its efficacy varies amongst different sodium channel blockers. This Commentary addresses common pitfalls and appropriate usage of hypertonic sodium bicarbonate therapy in cardiotoxic drug poisonings.

SODIUM BICARBONATE WORKS SYNERGISTICALLY WITH HYPERVENTILATION

Serum alkalinization is best achieved by the synergistic effect of hypertonic sodium bicarbonate and hyperventilation (PCO2 ∼ 30-35 mmHg [0.47-0.6 kPa]). This reduces the dose of sodium bicarbonate required to achieve serum alkalinization (pH ∼ 7.45-7.55) and avoids adverse effects from excessive doses of hypertonic sodium bicarbonate.

VARIABILITY IN RESPONSE TO SODIUM BICARBONATE TREATMENT

Tricyclic antidepressant poisoning responds well to sodium bicarbonate therapy, but many other sodium channel blockers may not. For instance, drugs that block the intercellular gap junctions, such as bupropion, do not respond well to alkalinization. For sodium channel blocker poisonings in which the expected response is unknown, a bolus of 1-2 mmol/kg sodium bicarbonate can be used to assess the response to alkalinization.

SODIUM BICARBONATE CAN EXACERBATE TOXICITY FROM DRUGS ACTING ON MULTIPLE CARDIAC CHANNELS

Hypertonic sodium bicarbonate can cause electrolyte abnormalities such as hypokalaemia and hypocalcaemia, leading to QT interval prolongation and torsade de pointes in poisonings with drugs that have mixed sodium and potassium cardiac channel properties, such as hydroxychloroquine and flecainide.

THE GOAL FOR HYPERTONIC SODIUM BICARBONATE IS TO ACHIEVE THE ALKALINIZATION TARGET (∼PH 7.5), NOT COMPLETE CORRECTION OF QRS COMPLEX PROLONGATION

Excessive doses of hypertonic sodium bicarbonate commonly occur if it is administered until the QRS complex duration is < 100 ms. A prolonged QRS complex duration is not specific for sodium channel blocker toxicity. Some sodium channel blockers do not respond, and even when there is a response, it takes a few hours for the QRS complex duration to return completely to normal. In addition, QRS complex prolongation can be due to a rate-dependent bundle branch block. So, no further doses should be given after achieving serum alkalinization (pH ∼ 7.45-7.55).

MAXIMAL DOSING FOR HYPERTONIC SODIUM BICARBONATE

A further strategy to avoid overdosing patients with hypertonic sodium bicarbonate is to set maximum doses. Exceeding 6 mmol/kg is likely to cause hypernatremia, fluid overload, metabolic alkalosis, and cerebral oedema in many patients and potentially be lethal.

RECOMMENDATION FOR THE USE OF HYPERTONIC SODIUM BICARBONATE IN SODIUM CHANNEL BLOCKER POISONING

We propose that hypertonic sodium bicarbonate therapy be used in patients with sodium channel blocker poisoning who have clinically significant toxicities such as seizures, shock (systolic blood pressure < 90 mmHg, mean arterial pressure <65 mmHg) or ventricular dysrhythmia. We recommend initial bolus dosing of hypertonic sodium bicarbonate of 1-2 mmol/kg, which can be repeated if the patient remains unstable, up to a maximum dose of 6 mmol/kg. This is recommended to be administered in conjunction with mechanical ventilation and hyperventilation to achieve serum alkalinization (PCO2∼30-35 mmHg [4-4.7 kPa]) and a pH of ∼7.45-7.55. With repeated bolus doses of hypertonic sodium bicarbonate, it is imperative to monitor and correct potassium and sodium abnormalities and observe changes in serum pH and on the electrocardiogram.

CONCLUSIONS

Hypertonic sodium bicarbonate is an effective antidote for certain sodium channel blocker poisonings, such as tricyclic antidepressants, and when used in appropriate dosing, it works synergistically with hyperventilation to achieve serum alkalinization and to reduce sodium channel blockade. However, there are many pitfalls that can lead to excessive sodium bicarbonate therapy and severe adverse effects.

2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

In this focused update, the American Heart Association provides updated guidance for resuscitation of patients with cardiac arrest, respiratory arrest, and refractory shock due to poisoning. Based on structured evidence reviews, guidelines are provided for the treatment of critical poisoning from benzodiazepines, β-adrenergic receptor antagonists (also known as β-blockers), L-type calcium channel antagonists (commonly called calcium channel blockers), cocaine, cyanide, digoxin and related cardiac glycosides, local anesthetics, methemoglobinemia, opioids, organophosphates and carbamates, sodium channel antagonists (also called sodium channel blockers), and sympathomimetics. Recommendations are also provided for the use of venoarterial extracorporeal membrane oxygenation. These guidelines discuss the role of atropine, benzodiazepines, calcium, digoxin-specific immune antibody fragments, electrical pacing, flumazenil, glucagon, hemodialysis, hydroxocobalamin, hyperbaric oxygen, insulin, intravenous lipid emulsion, lidocaine, methylene blue, naloxone, pralidoxime, sodium bicarbonate, sodium nitrite, sodium thiosulfate, vasodilators, and vasopressors for the management of specific critical poisonings.

Antidepressant Poisoning Trends in Pediatric Intensive Care: A Comparative Study of New- and Old-Generation Antidepressants

PURPOSE/BACKGROUND

This study aimed to compare the frequency, clinical findings, treatment practices, and outcomes of toxicity to old-generation (OG) and new-generation (NG) antidepressants in our pediatric intensive care unit (PICU) by year-to-year.

METHODS/PROCEDURES

The study included patients hospitalized for antidepressant poisoning during the 11-year period of January 2010 through December 2020. Antidepressants were classified as OG and NG. The groups were compared in terms of patient demographic characteristics, type of poisoning (accidental/suicidal), clinical findings, supportive and extracorporeal treatments received, and outcomes.

FINDINGS/RESULTS

The study included 58 patients (NG, n = 30; OG, n = 28). The median age of the patients was 178 months (range, 13.6-215 months) and 47 patients (81%) were female. Patients admitted for only antidepressant poisoning constituted 13.3% of all poisoning cases (58/436). Of these, 22 cases (37.9%) were accidental and 36 (62.3%) were suicidal. The most common cause of poisoning was amitriptyline (24/28) in the OG group and sertraline (13/30) in the NG group. Neurological symptoms were significantly more common in the OG group (76.2% vs 23.8%), while gastrointestinal involvement was more common in the NG group (82% vs 18%; P = 0.001 and P = 0.026, respectively). Old-generation antidepressant poisoning was associated with more frequent intubation (4 vs 0 patients, P = 0.048) and longer length of PICU stay (median, 1 day [range, 1-8] vs 1 day [range, 1-4], P = 0.019). Rates of therapeutic plasma exchange and intravenous lipid emulsion therapy did not differ ( P = 0.483 and P = 0.229, respectively).

IMPLICATIONS/CONCLUSIONS

In poisoned patients, proper evaluation and management of patients requiring PICU admission are vital for favorable patient outcomes.

Optimising alkalinisation and its effect on QRS narrowing in tricyclic antidepressant poisoning

AIMS

The objectives were to determine the effect of NaHCO₃ and/or mechanical ventilation on the biochemical profile and serum alkalinisation in tricyclic antidepressant (TCA) poisoning and investigate the impact of effective alkalinisation therapy on the QRS interval in TCA poisoning.

METHODS

This was a retrospective review of TCA poisonings from three Australian toxicology units and a poisons information centre (Jan 2013 to Jan 2019). We included patients with TCA toxicity who ingested>10 mg/kg or had clinically significant toxicities consistent with TCA poisoning, and analysed patients' clinical, electrocardiogram and biochemical data.

RESULTS

Of 210 patients, 84 received NaHCO₃ and ventilation (dual therapy), 12 NaHCO₃ , 46 ventilation and 68 supportive care treatment. When compared with single/supportive groups, patients who received dual therapy had taken a significantly higher median dose of TCA (1.5 g vs1.3 g, P < .001), a longer median maximum QRS interval (124 ms, interquartile ranges [IQR] 108-138 vs106 ms, IQR 98-115, P < .001) and were more likely to have seizures (14% vs3%, P = .006) and arrhythmias (17% vs1%, P < .001). The dual therapy group demonstrated greater increases in serum pH (median 0.11, IQR 0.04-0.17) compared to the single/supportive therapy group (median 0.03, IQR -0.01-0.09, p < .001). A greater proportion of patients reached the target pH 7.45-7.55 in the dual therapy group (59%) compared to the single/supportive therapy group (10%) (P < .001). For each 100 mmol bolus of NaHCO₃ given, the median increase in serum sodium was 2.5 mmol/L (IQR 1.5-4.0). QRS narrowing occurred twice as quickly in the dual therapy vs single/supportive therapy group.

CONCLUSIONS

A combination of NaHCO₃ and mechanical ventilation was most effective in achieving serum alkalinisation and was associated with a more rapid narrowing of the QRS interval. We advise that the maximal dose of NaHCO₃ should be <400 mmol (6 mmol/kg).

Antidotal Sodium Bicarbonate Therapy: Delayed QTc Prolongation and Cardiovascular Events

BACKGROUND

Sodium bicarbonate therapy (SBT) is currently indicated for the management of a variety of acute drug poisonings. However, SBT effects on serum potassium concentrations may lead to delayed QTc prolongation (DQTP), and subsequent risk of adverse cardiovascular events (ACVE), including death. Emergency department (ED)-based studies evaluating associations between SBT and ACVE are limited; thus, we aimed to investigate the association between antidotal SBT, ECG changes, and ACVE.

METHODS

This was a secondary data analysis of a consecutive cohort of ED patients with acute drug overdose over 3 years. Demographic and clinical data as well as SBT bolus dosage and infusion duration were collected, and outcomes were compared with an unmatched consecutive cohort of patients with potential indications for SBT but who did not receive SBT. The primary outcome was the occurrence of ACVE, and secondary outcomes were delayed QTc (Bazett) prolongation (DQTP), and death. Propensity score and multivariable adjusted analyses were conducted to evaluate associations between adverse outcomes and SBT administration. Planned subgroup analysis was performed for salicylates, wide QRS (> 100 ms), and acidosis (pH < 7.2).

RESULTS

Out of 2365 patients screened, 369 patients had potential indications for SBT, of whom 31 (8.4%) actually received SBT. In adjusted analyses, SBT was found to be a significant predictor of ACVE (aOR 9.35, CI 3.6-24.1), DQTP (aOR 126.7, CI 9.8-1646.2), and death (aOR 11.9, CI 2.4-58.9). Using a propensity score model, SBT administration was associated with ACVE (OR 5.07, CI 1.8-14.0). Associations between SBT and ACVE were maintained in subgroup analyses of specific indications for sodium channel blockade (OR 21.03, CI 7.16-61.77) and metabolic acidosis (OR: 6.42, 95% CI: 1.20, 34.19).

CONCLUSION

In ED patients with acute drug overdose and potential indications for SBT, administration of SBT as part of routine clinical care was an independent, dose-dependent, predictor of ACVE, DQTP, and death. This study was not designed to determine whether the SBT or acute overdose itself was causative of ACVE; however, these data suggest that poisoned patients receiving antidotal SBT require close cardiovascular monitoring.

Successful Outcome Following Intravenous Lipid Emulsion Rescue Therapy in a Patient with Cardiac Arrest Due to Amitriptyline Overdose

BACKGROUND The management of patients with tricyclic antidepressant drug overdose can be a challenge for the emergency department physician. Tricyclic antidepressants block alpha-adrenergic receptors and the anticholinergic effects may lead to cardiotoxicity, resulting in arrhythmias and hypotension that can lead to patient mortality. This report is of a case of a 28-year-old woman who presented with cardiac arrest due to amitriptyline overdose and who responded to intravenous lipid emulsion (ILE) therapy. CASE REPORT A 28-year-old woman was admitted to the emergency department with amitriptyline overdose. She suffered a cardiac arrest followed by cardiovascular and neurological complications. Hypotension and lack of a pulse did not respond to treatment with high-dose sodium, but she stabilized following treatment with ILE. The prompt response from the emergency team guaranteed rapid intervention that may have influenced the successful results. CONCLUSIONS Despite the frequency and severity of poisoning with tricyclic antidepressants, there is little consensus among physicians regarding patient management. This case showed the successful use of ILE as rescue therapy in a patient in cardiac arrest following amitriptyline overdose. However, the successful outcome obtained in this case is not a recommendation for the use of ILE as a first-line treatment for the management of patients with tricyclic antidepressant drug overdose. Controlled clinical studies are required to evaluate the safety and efficacy of ILE in the management of tricyclic antidepressant drug overdose.

A Case of Amitriptyline-induced Myocarditis

Amitriptyline is a widely prescribed tricyclic antidepressant (TCA) with a very concerning cardiotoxicity profile, but it is one that has not been discussed much in literature. Here, we present a case of amitriptyline toxicity presenting as myocarditis with pericardial involvement. A 21-year-old male with no previous cardiac history presented to the emergency department (ED) with a decreased level of consciousness after an amitriptyline overdose as a suicidal attempt. For concerns with airway protection, the patient was intubated and subsequently admitted to the intensive care unit (ICU). An electrocardiogram (EKG) showed sinus tachycardia, prolonged QRS complex, prolonged QTc interval, and nonspecific ST-T wave changes. Intravenous fluid resuscitation and sodium bicarbonate were administered with a target blood pH of 7.5 to 7.55. Two days later, the patient was taken off mechanical ventilation and improved clinically. However, troponin levels began to rise with a peak level of 4.08 µg/L. He then began having fevers, elevated white blood cell counts (WBCs), and elevated inflammatory markers. Transthoracic echo (TTE) revealed an ejection fraction (EF) of 45%-50%, no wall segment motion abnormalities, and a mild-to-moderate pericardial effusion. Cardiac magnetic resonance (CMR) was done, which revealed changes indicative of acute myocarditis, moderate pericardial effusion, a calculated EF of 45% with a moderate left ventricular dilation, and no coronary artery stenosis or anomalous coronary artery origin. Given the patient’s age, the absence of cardiac risk factors, and the presence of an amitriptyline overdose along with his EKG, TTE, and CMR findings, we hypothesize that this myocarditis with pericardial involvement is due to amitriptyline-induced direct toxicity.

Toxicologic Emergencies in Patients with Mental Illness: When Medications Are No Longer Your Friends

Patients with psychiatric disorders are at risk for toxicologic emergencies. Psychotropic medications have numerous effects on the neurologic, cardiac, and other organ systems and interact with other medications, potentially leading to further side effects. It is important to become familiar with accepted psychiatric practice guidelines, common toxidromes, medical sequelae associated with prescribed medications, and the specific workup and treatment of overdoses of frequently prescribed psychotropics.

The Role of Sodium Bicarbonate in the Management of Some Toxic Ingestions

Adverse reactions to commonly prescribed medications and to substances of abuse may result in severe toxicity associated with increased morbidity and mortality. According to the Center for Disease Control, in 2013, at least 2113 human fatalities attributed to poisonings occurred in the United States of America. In this article, we review the data regarding the impact of systemic sodium bicarbonate administration in the management of certain poisonings including sodium channel blocker toxicities, salicylate overdose, and ingestion of some toxic alcohols and in various pharmacological toxicities. Based on the available literature and empiric experience, the administration of sodium bicarbonate appears to be beneficial in the management of a patient with the above-mentioned toxidromes. However, most of the available evidence originates from case reports, case series, and expert consensus recommendations. The potential mechanisms of sodium bicarbonate include high sodium load and the development of metabolic alkalosis with resultant decreased tissue penetration of the toxic substance with subsequent increased urinary excretion. While receiving sodium bicarbonate, patients must be monitored for the development of associated side effects including electrolyte abnormalities, the progression of metabolic alkalosis, volume overload, worsening respiratory status, and/or worsening metabolic acidosis. Patients with oliguric/anuric renal failure and advanced decompensated heart failure should not receive sodium bicarbonate.

Amitriptyline-induced ventricular tachycardia: a case report

Background

In Bangladesh, each emergency physician faces amitriptyline overdose nearly a day. An acute cardiovascular complication, one of the worst complications is mainly responsible for the mortality in tricyclic overdose. Recently, we managed ventricular tachycardia in a young female presented with an impaired consciousness 10 h after intentionally ingesting 2500 mg amitriptyline. Here, we report it, discuss how the electrocardiography is vital to acknowledge and predict it and its’ complications and also the recent update of the management of it.

Case presentation

A young married Bangladeshi-Bengali girl, 25-year-old, having a history of disharmony with her husband, came with an impaired consciousness after intentionally ingesting 2500 mg amitriptyline about 10 h before arrival. There was blood pressure 140/80 mmHg, heart rate 140 beats-per-min, temperature 103 °F, Glasgow coma scale 10/15, wide complex tachycardia with QRS duration of 178 ms in electrocardiography, blood pH 7.36. Initially, treated with 100 ml 8.4% sodium bicarbonate. After that, QRS duration came to 100 ms in electrocardiography within 10 min of infusion. To maintain the pH 7.50–7.55 over the next 24 h, the infusion of 8.4% sodium bicarbonate consisting of 125 ml dissolved in 375 ml normal saline was started and titrated according to the arterial blood gas analysis. Hence, a total dose of 600 mmol sodium bicarbonate was given over next 24 h. In addition to this, gave a 500 ml intravenous lipid emulsion over 2 h after 24 h of admission as she did not regain her consciousness completely. Afterward, she became conscious, though, in electrocardiography, ST/T wave abnormality persisted. So that, we tapered sodium bicarbonate infusion slowly and stopped it later. At the time of discharge, she was by heart rate 124/min, QRS duration 90 ms in electrocardiogram along with other normal vital signs.

Conclusion

Diagnosis of amitriptyline-induced ventricular tachycardia is difficult when there is no history of an overdose obtained. Nevertheless, it should be performed in the clinical background and classic electrocardiographic changes and wise utilization of sodium bicarbonate, intravenous lipid emulsion, and anti-arrhythmic drugs may save a life.

Can empirical hypertonic saline or sodium bicarbonate treatment prevent the development of cardiotoxicity during serious amitriptyline poisoning? Experimental research

OBJECTIVE

The aim of this experimental study was to investigate whether hypertonic saline or sodium bicarbonate administration prevented the development of cardiotoxicity in rats that received toxic doses of amitriptyline.

METHOD

Thirty-six Sprague Dawley rats were used in the study. The animals were divided into six groups. Group 1 received toxic doses of i.p. amitriptyline. Groups 2 and 3 toxic doses of i.p. amitriptyline, plus i.v. sodium bicarbonate and i.v. hypertonic saline, respectively. Group 4 received only i.v. sodium bicarbonate, group 5 received only i.v. hypertonic saline, and group 6 was the control. Electrocardiography was recorded in all rats for a maximum of 60 minutes. Blood samples were obtained to measure the serum levels of sodium and ionised calcium.

RESULTS

The survival time was shorter in group 1. In this group, the animals' heart rates also decreased over time, and their QRS and QTc intervals were significantly prolonged. Groups 2 and 3 showed less severe changes in their ECGs and the rats survived for a longer period. The effects of sodium bicarbonate or hypertonic saline treatments on reducing the development of cardiotoxicity were similar. The serum sodium levels decreased in all the amitriptyline-applied groups. Reduction of serum sodium level was most pronounced in group 1.

CONCLUSION

Empirical treatment with sodium bicarbonate or hypertonic saline can reduce the development of cardiotoxicity during amitriptyline intoxication. As hypertonic saline has no adverse effects on drug elimination, it should be considered as an alternative to sodium bicarbonate therapy.

Sodium acetate as a replacement for sodium bicarbonate in medical toxicology: a review

Sodium bicarbonate is central to the treatment of many poisonings. When it was placed on the FDA drug shortage list in 2012, alternative treatment strategies to specific poisonings were considered. Many hospital pharmacies, poison centers, and medical toxicologists proposed sodium acetate as an adequate alternative, despite a paucity of data to support its use in medical toxicology. The intention of this review is to educate the clinician on the use of sodium acetate and to advise them on the potential adverse events when given in excess. We conducted a literature search focused on the pharmacology of sodium acetate, its use as a buffer in pathologic acidemia and dialysis baths, and potential adverse events associated with excess sodium acetate infusion. It appears safe to replace sodium bicarbonate infusion with sodium acetate on an equimolar basis. The metabolism of acetate, however, is more complex than bicarbonate. Future prospective studies will be needed to confirm the efficacy of sodium acetate in the treatment of the poisoned patient.

Extracorporeal treatment for tricyclic antidepressant poisoning: recommendations from the EXTRIP Workgroup

The Extracorporeal Treatments In Poisoning (EXTRIP) workgroup was formed to provide recommendations on the use of extracorporeal treatments (ECTR) in poisoning. Here, the workgroup presents its results for tricyclic antidepressants (TCAs). After an extensive literature search, using a predefined methodology, the subgroup responsible for this poison reviewed the articles, extracted the data, summarized findings, and proposed structured voting statements following a predetermined format. A two-round modified Delphi method was chosen to reach a consensus on voting statements and RAND/UCLA Appropriateness Method to quantify disagreement. Blinded votes were compiled, returned, and discussed in person at a meeting. A second vote determined the final recommendations. Seventy-seven articles met inclusion criteria. Only case reports, case series, and one poor-quality observational study were identified yielding a very low quality of evidence for all recommendations. Data on 108 patients, including 12 fatalities, were abstracted. The workgroup concluded that TCAs are not dialyzable and made the following recommendation: ECTR is not recommended in severe TCA poisoning (1D). The workgroup considers that poisoned patients with TCAs are not likely to have a clinical benefit from extracorporeal removal and recommends it NOT to be used in TCA poisoning.

Utility of the electrocardiogram in drug overdose and poisoning: theoretical considerations and clinical implications

The ECG is a rapidly available clinical tool that can help clinicians manage poisoned patients. Specific myocardial effects of cardiotoxic drugs have well-described electrocardiographic manifestations. In the practice of clinical toxicology, classic ECG changes may hint at blockade of ion channels, alterations of adrenergic tone, or dysfunctional metabolic activity of the myocardium. This review will offer a structured approach to ECG interpretation in poisoned patients with a focus on clinical implications and ECG-based management recommendations in the initial evaluation of patients with acute cardiotoxicity.

Review article: hypertonic saline use in the emergency department

Hypertonic saline (HS) is being increasingly used for the management of a variety of conditions, most notably raised intracranial pressure. This article reviews the available evidence on HS solutions as they relate to emergency medicine, and develops a set of recommendations for its use. To conclude, HS is recommended as an alternative to mannitol for treating raised intracranial pressure in traumatic brain injury. HS is also recommended for treating severe and symptomatic hyponatremia, and is worth considering for both recalcitrant tricyclic antidepressant toxicity and for cerebral oedema complicating paediatric diabetic ketoacidosis. HS is not recommended for hypovolaemic resuscitation.

Reversal of Citalopram-Induced Junctional Bradycardia with Intravenous Sodium Bicarbonate

The cardiotoxicity of tricyclic antidepressants is a well-described phenomenon requiring serious consideration in patients who have taken an overdose. In patients who are at high risk for suicide attempts, selective serotonin reuptake inhibitors (SSRIs) were thought to constitute a safe alternative. However, evidence is accumulating that they, too, possess proarrhythmic properties, which must be reconciled in the setting of an overdose. An 82-year-old woman intentionally ingested citalopram 1.6 g. Several hours after presentation, she developed sinus arrest and junctional bradycardia that resolved after infusion of intravenous sodium bicarbonate solution. Thereafter, she demonstrated no further electrocardiographic abnormalities and was safely transferred to the psychiatry service without the need for a temporary transvenous pacemaker. The dramatic effect of the sodium bicarbonate on the arrhythmia represents a probable event according to the Naranjo probability scale. Intravenous sodium bicarbonate may serve as an effective antidote to SSRI-induced bradyarrhythmias.

Management of the Cardiovascular Complications of Tricyclic Antidepressant Poisoning

Experimental studies suggest that both alkalinisation and sodium loading are effective in reducing cardiotoxicity independently. Species and experimental differences may explain why sodium bicarbonate appears to work by sodium loading in some studies and by a pH change in others. In the only case series, the administration of intravenous sodium bicarbonate to achieve a systemic pH of 7.5-7.55 reduced QRS prolongation, reversed hypotension (although colloid was also given) and improved mental status in patients with moderate to severe tricyclic antidepressant poisoning. This clinical study supports the use of sodium bicarbonate in the management of the cardiovascular complications of tricyclic antidepressant poisoning. However, the clinical indications and dosing recommendations remain to be clarified. Hypotension should be managed initially by administration of colloid or crystalloid solutions, guided by central venous pressure monitoring. Based on experimental and clinical studies, sodium bicarbonate should then be administered. If hypotension persists despite adequate filling pressure and sodium bicarbonate administration, inotropic support should be initiated. In a non-randomised controlled trial in rats, epinephrine resulted in a higher survival rate and was superior to norepinephrine both when the drugs were used alone or when epinephrine was used in combination with sodium bicarbonate. Sodium bicarbonate alone resulted in a modest increase in survival rate but this increased markedly when sodium bicarbonate was used with epinephrine or norepinephrine. Clinical studies suggest benefit from norepinephrine and dopamine; in an uncontrolled study the former appeared more effective. Glucagon has also been of benefit. Experimental studies suggest extracorporeal circulation membrane oxygenation is also of potential value. The immediate treatment of arrhythmias involves correcting hypoxia, electrolyte abnormalities, hypotension and acidosis. Administration of sodium bicarbonate may resolve arrhythmias even in the absence of acidosis and, only if this therapy fails, should conventional antiarrhythmic drugs be used. The class 1b agent phenytoin may reverse conduction defects and may be used for resistant ventricular tachycardia. There is also limited evidence for benefit from magnesium infusion. However, class 1a and 1c antiarrhythmic drugs should be avoided since they worsen sodium channel blockade, further slow conduction velocity and depress contractility. Class II agents (beta-blockers) may also precipitate hypotension and cardiac arrest.

[Hypotensive cardio-circulatory failure and metabolic acidosis after suicidal intoxication with trimipramine and quetiapine. Case report and background]

The case of a 44-year-old female patient is reported, who ingested trimipramine and quetiapine in a suicide attempt. Initially sinus tachycardia and hypotension were seen, which resulted in a hypotensive cardio-circulatory failure despite fluid therapy and administration of catecholamines. Because of the life-threatening situation and the fact that the ingestion was 2 h prior to admission, a rapid transport to the next hospital was preferred to treatment with active charcoal. Intoxication with tricyclic antidepressants are very common in Europe and have a mortality of up to 15% in severe cases. The specific therapy consists of airway management, hemodynamic stabilization and primary elimination of the poison. Secondary detoxication is less important. The administration of the antidote physostigmine is controversial but carbo medicinalis should be given orally or via a gastric tube.