Criteria for admitting patients with tricyclic antidepressant overdose

Lethal Tricyclic Antidepressant Overdose

Tricyclic antidepressant remains widely prescribed despite its dangerous cardiovascular and neurological effects in overdosed patients. We present a case of lethal dothiepin overdose and discuss the major complications and its management strategies.

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.

Incidence of tricyclic antidepressant-like complications after cyclobenzaprine overdose

BACKGROUND

The cyclobenzaprine structure is similar to amitriptyline; however, tricyclic antidepressant (TCA)-like wide complex dysrhythmia has not been reported. Our objective was to determine the incidence of TCA-like effects in cyclobenzaprine overdoses as reported to 6 poison centers for 2 years. We compared the incidence of these effects to amitriptyline overdoses collected during the same period.

METHODS

We performed a retrospective review of 2 years of cases as reported to the Texas Poison Center Network. We identified sole ingestions of cyclobenzaprine and of amitriptyline. Cases had a recorded clinical outcome and clinical effect. A trained reviewer used a standard data collection sheet within a secured electronic database. One investigator audited a random sample of charts.

RESULTS

We identified 3974 cases of cyclobenzaprine calls. Of these, we collected 209 cases of acute overdoses without coingestions. There were no deaths. No cases of cyclobenzaprine ingestions were reported to have died or have a wide QRS or ventricular dysrhythmia. Seizures were reported in 2 cases; however, both were unrelated to cyclobenzaprine. Hypotension was reported in 1.4% (3/209) of cases, and a vasopressor was used in one case (0.5%). Patients with an amitriptyline overdose were more likely to have seizure, coma, tachycardia, a wide QRS or ventricular dysrhythmia, and have received sodium bicarbonate or be intubated.

CONCLUSIONS

Cyclobenzaprine overdoses were not reported to cause widened QRS, ventricular dysrhythmias, or seizures, and hypotension was rarely reported. Tricyclic antidepressant-related effects occurred more often in our comparison group of amitriptyline overdoses.

Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management

A review of U.S. poison center data for 2004 showed over 12,000 exposures to tricyclic antidepressants (TCAs). A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce healthcare costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate prehospital triage and management of patients with suspected ingestions of TCAs by 1) describing the manner in which an ingestion of a TCA might be managed, 2) identifying the key decision elements in managing cases of TCA ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of TCAs alone. Co-ingestion of additional substances could require different referral and management recommendations depending on their combined toxicities. This guideline is based on the assessment of current scientific and clinical information. The panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) Patients with suspected self-harm or who are the victims of malicious administration of a TCA should be referred to an emergency department immediately (Grade D). 2) Patients with acute TCA ingestions who are less than 6 years of age and other patients without evidence of self-harm should have further evaluation including standard history taking and determination of the presence of co-ingestants (especially other psychopharmaceutical agents) and underlying exacerbating conditions, such as convulsions or cardiac arrhythmias. Ingestion of a TCA in combination with other drugs might warrant referral to an emergency department. The ingestion of a TCA by a patient with significant underlying cardiovascular or neurological disease should cause referral to an emergency department at a lower dose than for other individuals. Because of the potential severity of TCA poisoning, transportation by EMS, with close monitoring of clinical status and vital signs en route, should be considered (Grade D). 3) Patients who are symptomatic (e.g., weak, drowsy, dizzy, tremulous, palpitations) after a TCA ingestion should be referred to an emergency department (Grade B). 4) Ingestion of either of the following amounts (whichever is lower) would warrant consideration of referral to an emergency department: an amount that exceeds the usual maximum single therapeutic dose or an amount equal to or greater than the lowest reported toxic dose. For all TCAs except desipramine, nortriptyline, trimipramine, and protriptyline, this dose is >5 mg/kg. For despiramine it is >2.5 mg/kg; for nortriptyline it is >2.5 mg/kg; for trimipramine it is >2.5 mg/kg; and for protriptyline it is >1 mg/kg. This recommendation applies to both patients who are naïve to the specific TCA and to patients currently taking cyclic antidepressants who take extra doses, in which case the extra doses should be added to the daily dose taken and then compared to the threshold dose for referral to an emergency department (Grades B/C). 5) Do not induce emesis (Grade D). 6) The risk-to-benefit ratio of prehospital activated charcoal for gastrointestinal decontamination in TCA poisoning is unknown. Prehospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activated charcoal (Grades B/D). 7) For unintentional poisonings, asymptomatic patients are unlikely to develop symptoms if the interval between the ingestion and the initial call to a poison center is greater than 6 hours. These patients do not need referral to an emergency department facility (Grade C). 8) Follow-up calls to determine the outcome for a TCA ingestions ideally should be made within 4 hours of the initial call to a poison center and then at appropriate intervals thereafter based on the clinical judgment of the poison center staff (Grade D). 9) An ECG or rhythm strip, if available, should be checked during the prehospital assessment of a TCA overdose patient. A wide-complex arrhythmia with a QRS duration longer than 100 msec is an indicator that the patient should be immediately stabilized, given sodium bicarbonate if there is a protocol for its use, and transported to an emergency department (Grade B). 10) Symptomatic patients with TCA poisoning might require prehospital interventions, such as intravenous fluids, cardiovascular agents, and respiratory support, in accordance with standard ACLS guidelines (Grade D). 11) Administration of sodium bicarbonate might be beneficial for patients with severe or life-threatening TCA toxicity if there is a prehospital protocol for its use (Grades B/D). 12) For TCA-associated convulsions, benzodiazepines are recommended (Grade D). 13) Flumazenil is not recommended for patients with TCA poisoning (Grade D).

Are one or two dangerous? Tricyclic antidepressant exposure in toddlers

Tricyclic antidepressants (TCA), increasingly prescribed for multiple indications in children and adults, are responsible for many pediatric poisonings. Though the majority of TCA exposures in this age group remain asymptomatic, several reports in the English language literature reveal significant morbidity as well as fatalities in toddlers, primarily from imipramine and desipramine. These few cases indicate that doses of 10-20 mg/kg (one to two pills) have the potential for toxicity and fatalities. More recent studies have focused on the relative safety of small exposures suggesting that with doses less than 5 mg/kg the patient may be safely observed at home. Though further studies are necessary to determine the exact dosing that places the child at risk, the authors recommend a 6-h Emergency Department observation period for children who ingest more than 5 mg/kg of most TCAs, as clinical toxicity becomes evident within this time frame.

A Meta‐Analysis of Prognostic Indicators to Predict Seizures, Arrhythmias or Death After Tricyclic Antidepressant Overdose

OBJECTIVES

To systematically review and summarize studies on the accuracy of ECG and tricyclic antidepressant (TCA) concentration as prognostic indicators of the risk of seizures, ventricular arrhythmia (VA) or death in patients with TCA overdose.

METHODS

Articles were identified with MedLine and Cochrane register of controlled clinical trials searches and review of medical toxicology textbooks. Quality of the included studies was assessed. Pooled estimates of sensitivity, specificity, likelihood ratios and Summary Receiver Operating Characteristics (SROC) curves were generated.

RESULTS

A total of 18 studies were included in the analysis. The pooled sensitivity (Se) and specificity (Sp) of the QRS for predicting seizures were 0.69 [95% CI 0.57-0.78] and 0.69 [95% CI 0.58-0.78] as compared to 0.75 [95% CI 0.61-0.85] and 0.72 [95% CI 0.61-0.81] for the TCA concentration. The Se and Sp of the QRS to predict VA were 0.79 [95% CI 0.58-0.91] and 0.46 [95% CI 0.35-0.59] compared to 0.78 [95% CI 0.56-0.90] and 0.57 [95% CI 0.46-0.67] for the TCA concentration. The Se and Sp of the QRS to predict death were 0.81 [95% CI 0.54-0.94] and 0.62 [95% CI 0.55-0.68] compared to 0.76 [95% CI 0.49-0.91] and 0.60 [95% CI 0.47-0.72] for the TCA concentration. Very few studies evaluated the accuracy of QTc, T 40 ms axis and the R/S ratio.

CONCLUSIONS

Overall, the studies suggested that the ECG and TCA concentration have similar but relatively poor performance for predicting complications, such as seizures, VA or death, associated with TCA overdose.

Poisonings and overdoses in the intensive care unit: General and specific management issues

OBJECTIVE

To provide current information on general and specific interventions for overdoses likely to require intensive care.

DESIGN

Review of literature relevant to selected interventions for general management of overdoses and specific poisons.

RESULTS

The benefit of interventions to decrease absorption or enhance elimination of toxins is limited to a relatively small number of specific agents. Antidotes and certain interventions may be helpful in preventing or treating toxicity in specific poisonings when used appropriately. Intensive supportive care is also necessary to achieve good outcomes.

CONCLUSION

Knowledge of the indications and limitations of current interventions for poisonings and overdoses is important for care of the critically ill poisoned patient.

Toxicology in the critically ill patient

Intoxications present in many forms including: known drug overdose or toxic exposure, illicit drug use, suicide attempt, accidental exposure, and chemical or biological terrorism. A high index of suspicion and familiarity with toxidromes can lead to early diagnosis and intervention in critically ill, poisoned patients. Despite a paucity of evidence-based information on the management of intoxicated patients, a rational and systematic approach can be life saving.

Tricyclic antidepressant overdose: a review

Overdoses of tricyclic antidepressants are among the commonest causes of drug poisoning seen in accident and emergency departments. This review discusses the pharmacokinetics, clinical presentation and treatment of tricyclic overdose.

Emergency department observation for toxicologic exposures

Most toxicologic exposures resolve within 24 hours, yet catastrophic outcomes may occur if patients are directly discharged from the emergency department (ED). These cases are, perhaps, the ideal candidates for observation unit (OU) management. This article reviews the criteria for admission and discharge as well as clinical management strategies in the OU for the most common toxicologic exposures. Special attention is given to the multidisciplinary interactions among the ED physician, the medical toxicologist, the physiatrist, and the specialty laboratory.

Delayed toxidromes

Some toxins do not result in clinical manifestations until several hours after exposure. This article reviews those agents that may cause delayed-onset toxicity. They are organized into four classes: specific pharmaceuticals, biologicals, pharmaceutical dosage forms, and chemicals. There are five basic mechanisms for delayed toxicity: delayed absorption, distribution factors, metabolic factors, cellular and organ capacity effects, and unknown. Scientific evidence for delayed-onset of effects varies considerably among the individual toxins.

ECG abnormalities in tricyclic antidepressant ingestion

The tricyclic antidepressant (TCA) agents are recognized for their potentially lethal cardiovascular and neurological effects in poisoned patients. The 12-lead electrocardiogram (ECG) has emerged as a popular bedside tool in the evaluation of TCA toxicity. Although the history and physical examination play a key role in the assessment of the patient with potential TCA poisoning, the presence or absence of features of the TCA toxidrome are not sufficient to detect or exclude toxicity from this class of drugs. A variety of ECG findings occur with TCA toxicity. Aside from the sinus tachycardia due principally to anticholinergic effects, TCA-toxic changes seen on the ECG are attributable primarily to the sodium channel blockade caused by these agents. The majority of patients at significant risk for developing cardiac or neurological toxicity will have a QRS complex greater than 0.10 seconds or a rightward shift of the terminal 40 ms of the frontal plane QRS complex vector. The majority of these patients will also display these changes early in their emergency department stay. However, the appearance of these findings, either alone or in combination, does not mean the patient will develop significant cardiac or neurological toxicity. The ECG can neither unequivocally rule in nor rule out impending toxicity; recognizing these limitations, the emergency physician can use this bedside tool in combination with other clinical data during the assessment of the poisoned patient.

Identifying toxicity risk early after antidepressant overdose

Despite the risk of life-threatening toxicities, care of most patients after antidepressant overdose (ADO) does not require the use of critical care resources. The use of emergency department (ED) clinical findings to identify ADO patients who subsequently manifested toxicity was evaluated prospectively. ADO risk assessment (ADORA) criteria included development of QRS interval > 0.10 seconds, arrhythmias, altered mental status, seizures, respiratory depression, or hypotension. Sixty-seven ADO patients were identified on presentation to a single ED and classified as low risk (LR, absence of criteria) or high risk (HR, presence of one or more criteria) based on development of criteria within 6 hours of ingestion (or ED presentation if ingestion time was not established). This system demonstrated 100% sensitivity in identifying study patients who developed significant toxicity problems. None of the 28 LR patients and 13 of 39 HR patients had subsequent complications (P < .01). No single clinical finding permitted risk classification. ADORA should identify patients who do not require further monitoring or other aggressive medical management for ADO.

Comparison of three methods of gut decontamination in tricyclic antidepressant overdose

The purpose of this study was to prospectively compare the effectiveness of three different gut decontamination methods in 51 patients presenting to an emergency department with tricyclic antidepressant overdose. Patients were randomized to three treatments; Group 1 received activated charcoal, Group 2 received saline lavage followed by activated charcoal, and Group 3 received activated charcoal followed by saline lavage followed by activated charcoal. Baseline characteristics of the three groups did not differ, including Glasgow Coma Scores, age, and mean tricyclic antidepressant levels. Average length of stay in admitted patients was 93.3 hours in Group 1, 107.2 hours in Group 2, and 66.7 hours in Group 3. Of those admitted to an ICU, average ICU time was 66.9 hours in Group 1, 54.1 hours in Group 2, and 34.4 hours in Group 3. Average duration of sinus tachycardia was 20.8 hours in Group 1, 30.8 hours in Group 2, and 32.2 hours in Group 3. Of those requiring mechanical ventilation, average ventilator time was 43.4 hours in Group 1, 24.1 hours in Group 2, and 17.8 hours in Group 3. No statistically significant difference could be shown with respect to the clinical endpoints noted. There were no deaths in any of the groups. All three methods of gut decontamination had similar clinical outcomes.

Cyclic antidepressant overdose: a review of current management strategies

Cyclic antidepressant (CA) overdose can produce life-threatening seizures, hypotension, and dysrhythmias. It accounts for up to half of all overdose-related adult intensive care unit admissions and is the leading cause of death from drug overdose in patients arriving at the emergency department alive. Several factors contribute to the significant morbidity and mortality associated with CA overdose. First, CAs are widely prescribed and are dispensed to patients at increased risk for attempting suicide. Second, drugs of this class generally have a low therapeutic toxic ratio. Third, in the majority of fatal cases, the patient dies before reaching a hospital. Finally, and of greatest significance for the clinician, the presenting signs and symptoms of CA overdose may be missed by the physician, even in cases of severe toxicity. Therefore, CAs must be considered early in any case of suspected overdose, and all such cases should be managed as potentially fatal ones. The following case demonstrates the current approach to the patient with significant CA toxicity.

Response of depression to very high plasma levels of imipramine plus desipramine

Forty-five depressed patients were treated with imipramine for 6 weeks. Seven of 7 patients (100%) who had plasma levels of imipramine plus desipramine greater than 500 ng/ml showed a 50% or greater improvement in Hamilton depression scores compared with 23 of 38 patients (60%) with plasma levels less than 500 ng/ml (p less than 0.057).

Tricyclic antidepressant poisoning

OBJECTIVE

To review poisoning with tricyclic antidepressants.

DATA SOURCE

English language literature search using Australian Medlars Service (1977-1989), manual search of journals and review of bibliographies in identified articles.

STUDY SELECTION

Approximately 250 articles, abstracts and book chapters were selected for analysis.

DATA EXTRACTION

The literature was reviewed and 93 articles were selected as representative of important advances.

DATA SYNTHESIS

The major features of overdose are neurological, cardiac, respiratory and anticholinergic. Life-threatening complications develop within six hours of overdose or not at all. All patients seen within six hours of overdose should have their stomachs emptied. All patients should receive activated charcoal. Coma, convulsions, respiratory depression and hypotension are treated with standard resuscitation techniques and drugs. Treat patients with significant cardiotoxicity or cardiac arrest with alkalinisation by sodium bicarbonate or hyperventilation, aiming for an arterial pH of 7.45-7.55. Lignocaine is used for ventricular arrhythmias. Other antiarrhythmic drugs are contraindicated (Class 1A, Class 1C), potentially lethal (Class II), of no benefit (phenytoin) or of unproven efficacy (Class III and Class IV). Physostigmine has no role at all. Haemodialysis and haemoperfusion are of no benefit.

CONCLUSION

The death rate of those who reach hospital is 2%-3%. Most of these deaths are cardiac in origin, and are caused by direct depression of myocardial function rather than cardiac arrhythmias.

The electrocardiographic manifestations of cyclic antidepressant therapy and overdose: a review

Cyclic antidepressants may cause changes in the electrocardiogram at therapeutic or toxic serum levels. The most serious complications of cyclic antidepressant toxicity are dysrhythmias, hypotension, and seizures. It is predominantly the cardiotoxic effects that cause mortality. Once cardiotoxicity is evident, the treatment of choice is serum alkalinization, preferably by sodium bicarbonate therapy. In order to predict which overdose patients are at high risk for complications, electrocardiographic criteria have been identified as reliable screens. For "first generation" tricyclic antidepressants, QRS prolongation (particularly greater than 100 msec) and a terminal 40-ms frontal plane axis greater than 120 degrees are the most sensitive. This article reviews antidepressant pharmacology, electrocardiographic manifestations of antidepressant cardiotoxicity, and approaches to treatment of antidepressant-induced conduction disturbances and dysrhythmias.

Tricyclic antidepressant overdose: conservative management in a community hospital with cost-saving implications

Reports of late-onset cardiovascular complications following tricyclic antidepressant (TCA) overdose have led to a very conservative approach to these patients. Many patients have been hospitalized for continuous cardiac monitoring, regardless of the clinical presentation. Management algorithms based on clinical predictors of outcome have recently been proposed. We used the algorithm developed by Tokarski and Young to retrospectively evaluate the care of 33 TCA overdose patients admitted to our hospital over a 3-year period. We then identified 11 patients who could have been treated on an outpatient basis had the algorithm been employed. Ten were admitted to a monitored unit and spent a mean of 31.6 +/- 15.64 hours on the unit. None of the 11 patients developed complications during their hospital stay. Use of the algorithm would have resulted in an estimated cost savings of 13 hospital days and $14,000.