Emerging epidemic of fatal human self-poisoning with a washing powder in Southern Sri Lanka: a prospective observational study

INTRODUCTION

Self-poisoning is a public health problem in Sri Lanka. A new laundry detergent consisting of a sachet each of 1.2 g of potassium permanganate and 12.5 g of oxalic acid has become a popular agent among the youth for self-poisoning.

METHOD

Prospective clinical data and major outcomes were recorded in all patients admitted to a referring and a referral hospital. Serial biochemistry was performed in 20 patients. Postmortem examinations were performed in some patients.

RESULTS

There were 115 patients. The majority developed symptoms of the gastrointestinal tract within the first 24 h. There were 18 deaths. Ingestion of oxalic acid was associated with a case fatality ratio of 25.4% (95% CI = 14-39), while ingestion of both potassium permanganate and oxalic acid was associated with a case fatality ratio of 9.8% (95% CI = 3.2-21). Ingestion of more than one sachet was associated with a significantly higher risk of death (risk ratio = 13.26, 95% CI = 3.2-54, p < 0.05). Majority of the deaths occurred within an hour since ingestion. Postmortem examinations revealed mucosal ulceration in the majority of deaths.

DISCUSSION

This case series brings to light an emerging epidemic of fatal self-poisoning in Sri Lanka from a compound that is not regulated. As deaths occur soon after ingestion, medical management of these patients is bound to be difficult.

CONCLUSION

This case series highlights a fatal mode of self-poisoning that could be controlled through regulation of the manufacture and sale of the product.

Acute human self-poisoning with imidacloprid compound: a neonicotinoid insecticide

Background

Deliberate self-poisoning with older pesticides such as organophosphorus compounds are commonly fatal and a serious public health problem in the developing world. The clinical consequences of self-poisoning with newer pesticides are not well described. Such information may help to improve clinical management and inform pesticide regulators of their relative toxicity. This study reports the clinical outcomes and toxicokinetics of the neonicotinoid insecticide imidacloprid following acute self-poisoning in humans.

Methodology/Principal Findings

Demographic and clinical data were prospectively recorded in patients with imidacloprid exposure in three hospitals in Sri Lanka. Blood samples were collected when possible for quantification of imidacloprid concentration. There were 68 patients (61 self-ingestions and 7 dermal exposures) with exposure to imidacloprid. Of the self-poisoning patients, the median time to presentation was 4 hours (IQR 2.3–6.0) and median amount ingested was 15 mL (IQR 10–50 mL). Most patients only developed mild symptoms such as nausea, vomiting, headache and diarrhoea. One patient developed respiratory failure needing mechanical ventilation while another was admitted to intensive care due to prolonged sedation. There were no deaths. Median admission imidacloprid concentration was 10.58 ng/L; IQR: 3.84–15.58 ng/L, Range: 0.02–51.25 ng/L. Changes in the concentration of imidacloprid in serial blood samples were consistent with prolonged absorption and/or saturable elimination.

Conclusions

Imidacloprid generally demonstrates low human lethality even in large ingestions. Respiratory failure and reduced level of consciousness were the most serious complications, but these were uncommon. Substitution of imidacloprid for organophosphorus compounds in areas where the incidence of self-poisoning is high may help reduce deaths from self-poisoning.

Clinical outcomes and kinetics of propanil following acute self-poisoning: a prospective case series

Background

Propanil is an important cause of death from acute pesticide poisoning, of which methaemoglobinaemia is an important manifestation. However, there is limited information about the clinical toxicity and kinetics. The objective of this study is to describe the clinical outcomes and kinetics of propanil following acute intentional self-poisoning.

Methods

431 patients with a history of propanil poisoning were admitted from 2002 until 2007 in a large, multi-centre prospective cohort study in rural hospitals in Sri Lanka. 40 of these patients ingested propanil with at least one other poison and were not considered further. The remaining 391 patients were classified using a simple grading system on the basis of clinical outcomes; methaemoglobinaemia could not be quantified due to limited resources. Blood samples were obtained on admission and a subset of patients provided multiple samples for kinetic analysis of propanil and the metabolite 3,4-dichloroaniline (DCA).

Results

There were 42 deaths (median time to death 1.5 days) giving a case fatality of 10.7%. Death occurred despite treatment in the context of cyanosis, sedation, hypotension and severe lactic acidosis consistent with methaemoglobinaemia. Treatment consisted primarily of methylene blue (1 mg/kg for one or two doses), exchange transfusion and supportive care when methaemoglobinaemia was diagnosed clinically. Admission plasma concentrations of propanil and DCA reflected the clinical outcome. The elimination half-life of propanil was 3.2 hours (95% confidence interval 2.6 to 4.1 hours) and the concentration of DCA was generally higher, more persistent and more variable than propanil.

Conclusion

Propanil is the most lethal herbicide in Sri Lanka after paraquat. Methylene blue was largely prescribed in low doses and administered as intermittent boluses which are expected to be suboptimal given the kinetics of methylene blue, propanil and the DCA metabolite. But in the absence of controlled studies the efficacy of these and other treatments is poorly defined. More research is required into the optimal management of acute propanil poisoning.

Comparison of two commonly practiced atropinization regimens in acute organophosphorus and carbamate poisoning, doubling doses vs. ad hoc: a prospective observational study

There is a wide variation and lack of evidence in current recommendations for atropine dosing schedules leading to subsequent variation in clinical practice. Therefore, we sought to examine the safety and effectiveness of a titrated vs. ad hoc atropine treatment regimen in a cohort of patients with acute cholinesterase inhibitor pesticide poisoning. A prospective cohort study was conducted in three district secondary referral hospitals in Sri Lanka using a structured data collection form that collected details of clinical symptoms and outcomes of cholinesterase inhibitor pesticide poisoning, atropine doses, and signs of atropinization. We compared two hospitals that used a titrated dosing protocol based on a structured monitoring sheet for atropine infusion with another hospital using an ad hoc regime. During the study, 272 symptomatic patients with anticholinesterase poisoning requiring atropine were admitted to the three hospitals. Outcomes of death and ventilation were analyzed for all patients, 226 patients were prospectively assessed for atropine toxicity. At baseline, patients in the titrated dose cohort had clinical signs consistent with greater toxicity. This in part may be due to ingestion of more toxic organophosphates. They received less pralidoxime and atropine, and were less likely to develop features of atropine toxicity, such as delirium (1% vs. 17%), hallucinations (1% vs. 35%), or either (1% vs. 35%) and need for patient restraint (3% vs. 48%) compared with the ad hoc dose regime. After adjusting for the pesticides ingested, there was no difference in mortality and ventilatory rates between protocols. Ad hoc high dose atropine regimens are associated with more frequent atropine toxicity without any obvious improvement in patient outcome compared with doses titrated to clinical effect. Atropine doses should be titrated against response and toxicity. Further education and the use of a structured monitoring sheet may assist in more appropriate atropine use in anticholinesterase pesticide poisoning.

Personal and professional challenges in the management of deliberate self-poisoning patients in rural Sri Lanka: a qualitative study of rural hospital doctors' experiences and perceptions

Background

Deliberate self-poisoning is a major public heath issue in developing countries. In rural Sri Lanka deliberate self-poisoning is one of the leading causes of hospital death. The majority of patients with poisoning present to rural hospitals for initial treatment that are staffed by non-specialist and often relatively junior doctors. The treatment of self-poisoning patients poses numerous clinical challenges and further difficulties are experienced if patients are uncooperative and aggressive, intoxicated with alcohol or suffering mental illness. Previous research in developed countries has examined self-poisoning patients and their treatment but little is know about self-poisoning patient care in the context of rural health provision in developing countries. This study provides the first focused exploration of the experiences and perceptions of primary care rural hospital doctors in Sri Lanka toward the treatment of self-poisoning patients.

Methods

Semi-structured in-depth interviews were conducted with fifteen doctors from rural hospitals in the North Central Province, Sri Lanka. All interviews were recorded and transcribed and subject to thematic analysis.

Results

Participating doctors did perceive that treating self-poisoning patients in a primary care rural hospital as potentially confidence-building. However, resource issues such as the lack of medication, equipment and staffing were seen as important challenges to treating self-poisoning patients. Other challenges identified included disparity with community and other staff members regarding expectations of care, a sense of professional isolation and a lack of continuing education programs.

Conclusion

Addressing professional isolation through educational and trainee programs for doctors and reducing the variance in expectations between professional groups and the community has the potential to improve delivery of care for self-poisoning patients.

Management of acute organophosphorus pesticide poisoning

Organophosphorus pesticide self-poisoning is an important clinical problem in rural regions of the developing world, and kills an estimated 200,000 people every year. Unintentional poisoning kills far fewer people but is a problem in places where highly toxic organophosphorus pesticides are available. Medical management is difficult, with case fatality generally more than 15%. We describe the limited evidence that can guide therapy and the factors that should be considered when designing further clinical studies. 50 years after first use, we still do not know how the core treatments--atropine, oximes, and diazepam--should best be given. Important constraints in the collection of useful data have included the late recognition of great variability in activity and action of the individual pesticides, and the care needed cholinesterase assays for results to be comparable between studies. However, consensus suggests that early resuscitation with atropine, oxygen, respiratory support, and fluids is needed to improve oxygen delivery to tissues. The role of oximes is not completely clear; they might benefit only patients poisoned by specific pesticides or patients with moderate poisoning. Small studies suggest benefit from new treatments such as magnesium sulphate, but much larger trials are needed. Gastric lavage could have a role but should only be undertaken once the patient is stable. Randomised controlled trials are underway in rural Asia to assess the effectiveness of these therapies. However, some organophosphorus pesticides might prove very difficult to treat with current therapies, such that bans on particular pesticides could be the only method to substantially reduce the case fatality after poisoning. Improved medical management of organophosphorus poisoning should result in a reduction in worldwide deaths from suicide.

Postcards from the EDge: 24-month outcomes of a randomised controlled trial for hospital-treated self-poisoning

BACKGROUND

Repetition of self-poisoning is common.

AIMS

To report the 24-month outcomes of a non-obligatory postcard intervention (plus treatment as usual) compared with treatment as usual.

METHOD

In a randomised-controlled trial (Zelen design) conducted in Newcastle, Australia, eight postcards were sent to participants over a 12-month period. The principal outcomes were the proportion of participants with one or more repeat episodes of self-poisoning and the number of repeat episodes per person.

RESULTS

No significant reduction was observed in the proportion of people repeating self-poisoning in the intervention group (21.2%, 95% CI 17.0-25.3) compared with the control group (22.8%, 95% CI 18.7-27.0; chi(2)=0.32, d.f.=1, P=0.57); the difference between groups was -1.7% (95% CI -7.5 to 4.2). There was a significant reduction in the rate of repetition, with an incidence risk ratio of 0.49 (95% CI 0.33-0.73).

CONCLUSIONS

A postcard intervention maintained the halving of the rate of repetition of hospital-treated self-poisoning events over a 2-year period, although it did not significantly reduce the proportion of individuals who repeated self-poisoning.

Safety and efficacy of intravenous N-acetylcysteine for acetaminophen overdose: analysis of the Hunter Area Toxicology Service (HATS) database

BACKGROUND

Acetaminophen (N-acetyl-p-aminophenyl; APAP) is the leading drug used in self-poisoning and frequently causes hepatotoxicity, including acute liver failure.

OBJECTIVE

To provide descriptive data on the safety and efficacy of intravenous N-acetylcysteine (IV-NAC) in the treatment of APAP toxicity, based on information in the Hunter Area Toxicology Service (HATS) database involving residents of the Greater Newcastle Area of New South Wales, Australia.

METHODS

This was a retrospective analysis of all APAP overdoses from January 1987 to January 2003. Data were collected prospectively according to a published protocol and included patient characteristics, exposures to APAP and other potential toxins, treatments, and outcomes. Primary safety/tolerability endpoints included the mortality rate and incidence of adverse drug reactions, while efficacy endpoints included alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels.

RESULTS

Of 1749 patients, 399 (22.8%) were treated with IV-NAC. Of these, 37 (9.3%) had an adverse drug reaction to IV-NAC, of which seven (1.8% of total) were anaphylactoid. There were five deaths in hospital (mortality rate = 0.3%), including two attributed to APAP (0.1%) and none to IV-NAC. Of 64 patients who were treated with IV-NAC within 8 hours after APAP ingestion and had available ALT/AST data, two (3.1%) developed hepatotoxicity (AST/ALT > 1000 IU/L) compared with 32 (25%) of 128 patients receiving IV-NAC > 8 hours after APAP ingestion (p = 0.0002). A total of 26 patients (15.6%) receiving IV-NAC treatment within 8 hours after APAP ingestion had hospitalization stays > 48 hours compared with 70 (33.3%) receiving IV-NAC > 8 hours after ingestion (p < 0.0001).

CONCLUSIONS

For patients with APAP overdose seen in the HATS database of New South Wales, Australia, in-hospital death was infrequent (< 1%) and hepatotoxicity was significantly less likely when IV-NAC was administered within 8 hours after APAP ingestion compared with longer intervals (p < 0.01). As a descriptive retrospective database analysis, this study could not exclude certain sources of bias, including temporal changes over the 16-year course of data collection in the use of IV-NAC and low ascertainment of mild, self-limiting reactions to IV-NAC.

Community uptake of safe storage boxes to reduce self-poisoning from pesticides in rural Sri Lanka

BACKGROUND

Acute poisoning by agricultural pesticides is a well established global public health problem. Keeping pesticides under safe storage is now promoted as a potential way to reduce the number of severe poisoning cases. However, there have been no published studies documenting the feasibility of such an approach. Therefore, the objective of the study presented here was to determine community perceptions and use of in-house safe storage boxes for pesticides in rural Sri Lanka.

METHODS

Boxes with a lock, to be used for the in-house safe storage of pesticides, were distributed to 200 randomly selected farming households in two agricultural communities. A baseline survey determined pesticide storage practices and household characteristics prior to distribution. The selected households were encouraged to make use of the box at community meetings and during a single visit to each household one month after distribution. No further encouragement was offered. A follow-up survey assessed storage practices seven months into the project.

RESULTS

Following the distribution of the boxes the community identified a number of benefits including the protection of pesticide containers against exposure from the rain and sun and a reduced risk of theft. Data were analysed for 172 households that reported agricultural use of pesticides at follow-up. Of these, 141 (82%) kept pesticides in the house under lock against 3 (2%) at baseline. As expected, the distribution of boxes significantly reduced the number of households storing pesticides in the field, from 79 (46%) at baseline to 4 (2%) at follow-up. There was a significant increase in the number of households keeping pesticides safe from children between baseline (64%) and seven months after the distribution of boxes (89%). The same was true for adults although less pronounced with 51% at baseline and 66% at follow-up.

CONCLUSION

The farming community appreciated the storage boxes and made storage of pesticides safer, especially for children. It seems that additional, intensive promotion is needed to ensure that pesticide boxes are locked. The introduction of in-house safe storage boxes resulted in a shift of storage into the farmer's home and away from the field and this may increase the domestic risk of impulsive self-poisoning episodes. This increased risk needs attention in future safe storage promotion projects.

Identification of strategies to prevent death after pesticide self-poisoning using a Haddon matrix

Despite pesticide self-poisoning causing around 300 000 deaths each year in the rural Asia Pacific region, no comprehensive public health response has yet been formulated. The authors have developed a Haddon matrix to identify factors that increase the risk of fatal rather than non-fatal pesticide self-poisoning in Sri Lanka. Many important host factors such as age, gender, and genetics are not alterable; factors that could be changed-alcohol use and mental health-have previously proved difficult to change. Interventions affecting agent or environmental factors may be easier to implement and more effective, in particular those limiting the human toxicity and accessibility of the pesticides, and the quality, affordability, and accessibility of health care in the community. Controlled studies are required to identify effective strategies for prevention and harm minimization and to garner political support for making the changes necessary to reduce this waste of life. Lessons learnt from Sri Lanka are likely to be highly relevant for much of rural Asia.

The need for translational research on antidotes for pesticide poisoning

1. Pesticide poisoning kills hundreds of thousands of people in the Asia-Pacific region each year. The majority of deaths are from deliberate self-poisoning with organophosphorus pesticides (OP), aluminium phosphide and paraquat. The current response from a public health, medical and research perspective is inadequate. 2. There are few proven or effective treatments; in addition, very little clinical research has been performed to transfer antidotes shown to work in animal studies into clinical practice. 3. The human toxicity of pesticides is poorly studied and better information may inform a more sustained and appropriate regulatory response. Further understanding may also lead to improvements in diagnosis and treatment. 4. The few effective treatments are not being recommended or delivered in an optimal and timely fashion to poisoned patients. A regional approach to facilitate appropriate pricing, packaging and delivery of antidotes is required.

Intentional self-poisoning with the chlorophenoxy herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA)

STUDY OBJECTIVE

Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka.

METHODS

Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively.

RESULTS

Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor.

CONCLUSION

Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.

Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study

BACKGROUND

Although more than 100 organophosphorus insecticides exist, organophosphorus poisoning is usually regarded as a single entity, distinguished only by the compound's lethal dose in animals. We aimed to determine whether the three most common organophosphorus insecticides used for self-poisoning in Sri Lanka differ in the clinical features and severity of poisoning they cause.

METHODS

We prospectively studied 802 patients with chlorpyrifos, dimethoate, or fenthion self-poisoning admitted to three hospitals. Blood cholinesterase activity and insecticide concentration were measured to determine the compound and the patients' response to insecticide and therapy. We recorded clinical outcomes for each patient.

FINDINGS

Compared with chlorpyrifos (35 of 439, 8.0%), the proportion dying was significantly higher with dimethoate (61 of 264, 23.1%, odds ratio [OR] 3.5, 95% CI 2.2-5.4) or fenthion (16 of 99, 16.2%, OR 2.2, 1.2-4.2), as was the proportion requiring endotracheal intubation (66 of 439 for chlorpyrifos, 15.0%; 93 of 264 for dimethoate, 35.2%, OR 3.1, 2.1-4.4; 31 of 99 for fenthion, 31.3%, 2.6, 1.6-4.2). Dimethoate-poisoned patients died sooner than those ingesting other pesticides and often from hypotensive shock. Fenthion poisoning initially caused few symptoms but many patients subsequently required intubation. Acetylcholinesterase inhibited by fenthion or dimethoate responded poorly to pralidoxime treatment compared with chlorpyrifos-inhibited acetylcholinesterase.

INTERPRETATION

Organophosphorus insecticide poisoning is not a single entity, with substantial variability in clinical course, response to oximes, and outcome. Animal toxicity does not predict human toxicity since, although chlorpyrifos is generally the most toxic in rats, it is least toxic in people. Each organophosphorus insecticide should be considered as an individual poison and, consequently, patients might benefit from management protocols developed for particular organophosphorus insecticides.

Postcards from the EDge project: randomised controlled trial of an intervention using postcards to reduce repetition of hospital treated deliberate self poisoning

OBJECTIVE

To determine whether an intervention using postcards (postcards from the EDge project) reduces repetitions of hospital treated deliberate self poisoning.

DESIGN

Randomised controlled trial.

SETTING

Regional referral service for general hospital treated deliberate self poisoning in Newcastle, Australia.

PARTICIPANTS

772 patients aged over 16 years with deliberate self poisoning.

INTERVENTION

Non-obligatory intervention using eight postcards over 12 months along with standard treatment compared with standard treatment alone.

MAIN OUTCOME MEASURES

Proportion of patients with one or more repeat episodes of deliberate self poisoning and the number of repeat episodes for deliberate self poisoning per person in 12 months.

RESULTS

The proportion of repeaters with deliberate self poisoning in the intervention group did not differ significantly from that in the control group (57/378, 15.1%, 95% confidence interval 11.5% to 18.7% v 68/394, 17.3%, 13.5% to 21.0%: difference between groups -2%, -7% to 3%). In unadjusted analysis the number of repetitions were significantly reduced (incidence risk ratio 0.55, 0.35 to 0.87).

CONCLUSION

A postcard intervention reduced repetitions of deliberate self poisoning, although it did not significantly reduce the proportion of individual repeaters.

Presumed Angel's trumpet (Brugmansia) poisoning: clinical effects and epidemiology

OBJECTIVE

To investigate the pattern and epidemiology of anticholinergic plant poisoning, and to characterize its time course and clinical features.

METHODS

We reviewed all anticholinergic plant poisonings using a prospective database of all poisonings admitted to a major toxicology unit in Australia. All patients that presented with anticholinergic plant poisoning between July 1990 and June 2000 were included. Patient demographics, details of poisoning, diagnostic clinical features, adverse effects (seizures, arrhythmias, hypotension, accidental injury), and treatments required were obtained. Important diagnostic features were analysed and compared to previous studies.

RESULTS

Thirty-three patients were presumed to have ingested Brugmansia spp. (Angel's trumpet) based on their description of the plant; median age 18 years (interquartile range 16-20); 82% males. Thirty-one ingested a brewed tea or parts of the plant (flower). Thirty-one used it recreationally. Common clinical features were: mydriasis (100%), mean duration 29 h (SD 13) and delirium (88%) with a mean duration of 18 h (SD 12). Tachycardia only occurred in 11 of the 33 patients (33%). In 24 patients where the time of ingestion was certain, 7 of 8 (88%) patients presenting within 5 h had tachycardia and only 5 out of 16 (31%) presenting after 5 h had tachycardia. There were no deaths, seizures or arrhythmias (excepting tachycardia). One patient had hypotension and two sustained accidental traumatic injuries. Nineteen patients required sedation, mainly with benzodiazepines. Physostigmine was used diagnostically in eight cases.

CONCLUSIONS

Anticholinergic plant abuse is sporadic in nature. Most cases were moderate in severity, requiring sedation only, and severe toxicity was rare. Mydriasis and delirium were the commonest features, the later having important implications for management.

Aspiration pneumonitis in an overdose population: frequency, predictors, and outcomes

OBJECTIVE

To characterize the frequency of aspiration pneumonitis in an unselected population of overdose patients and, further, to identify factors that predispose to aspiration pneumonitis and the outcomes of patients with aspiration pneumonitis compared with those without.

DESIGN

Retrospective cohort study.

SETTING

Toxicology unit of a tertiary referral hospital.

PATIENTS

All poisoning admissions.

MEASUREMENTS AND MAIN RESULTS

A total of 71 of 4,562 poisoning admissions to the Hunter Area Toxicology Service between January 1997 and October 2002 had definite aspiration pneumonitis (1.6%; 95% confidence interval, 1.2-2.0). Older age, Glasgow Coma Score of <15, spontaneous emesis, seizures, delayed presentation to hospital, and ingestion of tricyclic antidepressants were associated with an increased risk of aspiration pneumonitis. Paracetamol poisoning and female sex were associated with a decreased risk of aspiration pneumonitis with univariate analysis. Ingestion of alcohol, benzodiazepines, antipsychotics, and administration of activated charcoal were not associated with aspiration pneumonitis. A logistic regression model for predicting aspiration pneumonitis contained seven predictors: age, sex, Glasgow Coma Score of <15 (odds ratio, 3.14; 95% confidence interval, 1.87-5.27), emesis (odds ratio, 4.17; 95% confidence interval, 2.44-7.13), seizure, tricyclic antidepressant ingestion, and time from ingestion to presentation (delay of >24 hrs [odds ratio, 4.42; 95% confidence interval, 2.42-8.10]). The mortality for patients with aspiration pneumonitis was 8.5% compared with 0.4% for those without (odds ratio, 23; 95% confidence interval, 9-60; p <.0001), and they had a significantly higher intensive care unit admission rate. The median length of stay of patients with aspiration pneumonitis was 126 hrs (interquartile range, 62-210 hrs) compared with 14.7 hrs (interquartile range, 7-23 hrs) in patients without (p <.0001).

CONCLUSIONS

Our study has shown a number of risk factors in overdose patients that are associated with aspiration pneumonitis that may allow the early identification of these patients for appropriate observation and management. Patients with aspiration pneumonitis have a significantly increased mortality and length of stay in the hospital.

Moclobemide poisoning: toxicokinetics and occurrence of serotonin toxicity

AIMS

To investigate the spectrum of toxicity of moclobemide overdose, the occurrence of serotonin toxicity, and to estimate toxicokinetic parameters.

METHODS

All moclobemide overdoses presenting over a 10-year period to the Hunter Area Toxicology Service were reviewed. Clinical features, complications, length of stay (LOS) and intensive care (ICU) admission rate were extracted from a standardized, prospectively collected database. Comparisons were made between moclobemide alone and moclobemide with a serotonergic coingestant poisoning. Serotonin toxicity was defined by a combination of Sternbach's criteria and a clinical toxicologist's diagnosis. In five patients serial moclobemide concentrations were measured. Time to maximal plasma concentration (Tmax), peak plasma concentration (Cmax) and terminal elimination half-lives were estimated.

RESULTS

Of 106 included patients, 33 ingested moclobemide alone, 21 ingested moclobemide with another serotonergic agent (in some cases in therapeutic doses) and 52 ingested moclobemide with a nonserotonergic agent. Eleven (55%) of 21 patients coingesting a serotonergic drug developed serotonin toxicity, which was significantly more than one (3%) of 33 moclobemide-alone overdoses (odds ratio 35, 95% confidence interval 4, 307; P < 0.0001). In six of these 21 cases severe serotonin toxicity developed with temperature >38.5 degrees C and muscle rigidity requiring intubation and paralysis. The 21 patients had a significantly increased LOS (34 h) compared with moclobemide alone overdoses (12 h) (P < 0.0001) and a significantly increased ICU admission rate of 57% vs. 3% (P < 0.0001). Time to peak plasma concentration was delayed in two patients where prepeak samples were obtained. Cmax increased slightly with dose, but all three patients ingesting > or = 6 g vomited or had charcoal. The mean elimination half-life of moclobemide in the five patients in whom serial moclobemide concentrations were measured was 6.3 h and elimination was first order in all cases. There was no evidence of a dose-dependent increase in half-life.

CONCLUSIONS

The effects of moclobemide alone in overdose are minor, even with massive ingestions. However, moclobemide overdose in combination with a serotonergic agent (even in normal therapeutic doses) can cause severe serotonin toxicity. The elimination half-life is prolonged by two to four times in overdose, compared with that found in healthy volunteers given therapeutic doses. This may be a result of wide interindividual variation in overall elimination, also seen with therapeutic doses, but appears not to be due to saturation of normal elimination pathways.

The Hunter Serotonin Toxicity Criteria: simple and accurate diagnostic decision rules for serotonin toxicity

BACKGROUND

There are difficulties with the diagnosis of serotonin toxicity, particularly with the use of Sternbach's criteria.

AIM

To improve the criteria for diagnosing clinically significant serotonin toxicity.

DESIGN

Retrospective analysis of prospectively collected data

METHODS

We studied all patients admitted to the Hunter Area Toxicology Service (HATS) following an overdose of a serotonergic drug from January 1987 to November 2002 (n = 2222). Main outcomes were: diagnosis of serotonin toxicity by a clinical toxicologist, fulfillment of Sternbach's criteria and treatment with a serotonin receptor (5-HT(2A)) antagonist. A learning dataset of 473 selective serotonin reuptake inhibitor (SSRI)-alone overdoses was used to determine individual clinical features predictive of serotonin toxicity by univariate analysis. Decision rules using CART analysis were developed, and tested on the dataset of all serotonergic overdose admissions.

RESULTS

Numerous clinical features were associated with serotonin toxicity, but only clonus (inducible, spontaneous or ocular), agitation, diaphoresis, tremor and hyperreflexia were needed for accurate prediction of serotonin toxicity as diagnosed by a clinical toxicologist. Although the learning dataset did not include patients with life-threatening serotonin toxicity, hypertonicity and maximum temperature > 38 degrees C were universal in such patients; these features were therefore added. Using these seven clinical features, decision rules (the Hunter Serotonin Toxicity Criteria) were developed. These new criteria were simpler, more sensitive (84% vs. 75%) and more specific (97% vs. 96%) than Sternbach's criteria.

DISCUSSION

These redefined criteria for serotonin toxicity should be more sensitive to serotonin toxicity and less likely to yield false positives.

Feasibility of prehospital treatment with activated charcoal: Who could we treat, who should we treat?

OBJECTIVES

To investigate the feasibility and potential risk benefit of prehospital administration of activated charcoal.

METHODS

Review of deliberate self poisoning presentations to the emergency department (ED) of a toxicology unit by ambulance over six years. Data were extracted from a standardised prospective database of poisonings. Outcomes included: number of patients attended by ambulance and number arriving in emergency within one hour. Cases were stratified by ingestion type, based on toxicity and sedative activity.

RESULTS

2041 poisoning admissions were included. The median time to ambulance attendance was 1 h 23 min (IQR 37 min-3 h) and to hospital attendance was 2 h 15 min (IQR 1 h 25 min-4 h). In 774 cases (38%) ambulance attendance occurred within one hour, but in only 161 (8%) did ED attendance occur within one hour. Non-sedating, highly toxic substances were ingested in 55 cases, 24 (23 with GCS>14) with ambulance attendance, and five with ED attendance, within one hour. Conversely 439 patients ingested a less toxic, sedative agent, 160 with ambulance attendance, and 32 with ED attendance, within one hour. Limiting decontamination to patients ingesting highly toxic, non-sedating compounds (GCS<14) reduces the proportion requiring treatment to 23 of the 774 (3.0%), an additional 18 patients.

CONCLUSION

More patients could potentially be decontaminated if all patients attended by ambulance within one hour received charcoal. However, this would expose 128 patients with sedative, low risk poisonings to the risk of aspiration, and only treat 18 extra high risk poisonings. This small potential benefit of prehospital charcoal is unlikely to justify the expense in training and protocols required to implement it

Relative toxicity of venlafaxine and selective serotonin reuptake inhibitors in overdose compared to tricyclic antidepressants

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) and venlafaxine have been regarded as less toxic in overdose than tricyclic antidepressants (TCAs). Within the TCAs, dothiepin has greater toxicity. Venlafaxine may be more toxic than SSRIs.

AIM

To assess the toxicity in overdose of venlafaxine and SSRIs compared to TCAs, and of dothiepin compared to other TCAs.

DESIGN

Cohort study of prospectively collected data from the Hunter area, NSW, Australia.

METHODS

First admissions with antidepressant deliberate self-poisoning (DSP) (November 1994 to April 2000) were identified; the presence of seizures, life-threatening arrhythmias, coma, serotonin toxicity or ICU admission, and QRS duration were noted.

RESULTS

There were 538 admissions, with no deaths. The odds ratio (OR) for seizures with dothiepin vs. other TCAs was 3.4 (95%CI 1.2-9.9). Seizures occurred in 7/51 (14%) venlafaxine overdoses; all patients with seizures consumed > or =900 mg. The OR for seizures vs. TCAs was 4.4 (95%CI 1.4-13.8). Coma was less likely with venlafaxine and SSRIs. SSRIs, but not venlafaxine, were less likely to prolong the QRS to > or =100 ms. ICU admission was less likely for SSRIs. Serotonin toxicity was much more common with venlafaxine and SSRIs.

DISCUSSION

Venlafaxine and dothiepin are pro-convulsant in overdose. Venlafaxine is more likely to cause serotonin toxicity, but less likely to cause coma than TCAs. SSRIs are less likely to cause coma, require ICU admission, or prolong the QRS, but are more likely to cause serotonin toxicity. Antidepressants other than TCAs or venlafaxine should be considered in patients at risk of seizure or suicide.