Vomiting in paracetamol overdose

Abstract

A short cut review was carried out to establish whether there was any evidence to decide between oral or intravenous antidote in paracetamol (acetaminophen) poisoning. Altogether 330 papers were found using the reported search, of which two presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated. Clinical scenarioA 23 year old woman attends an emergency department having taken sixty 500 mg paracetamol tablets. Her four hour paracetamol levels are above the treatment line. She does not want to be treated with intravenous therapy. You wonder whether oral antidote is as effective. Search outcomeAltogether 330 papers were identified, of which two were directly relevant to the question (table 1). Comment(s)Perry's study used historical controls although the demographic characteristics of the two groups were remarkably similar. It was not included in Buckley's meta-analysis because the patients were not recruited sequentially and it was unclear whether the patients were treated solely at the study centre (possible variations in other treatment modalities could act as confounding factors).There have been no RCTs in this area. A meta-analysis of observational studies has failed to show a difference in efficacy between the oral and intravenous routes. However, these studies do not address other factors that may influence the choice of route, which include: activated charcoal adsorbs antidote and therefore precludes its use; the IV regimen is shorter than the oral (24 hours and 52 hours respectively); the IV route is safer with patients with altered levels of consciousness (for example due to coingestants) who may subsequently lose their airway protective reflexes.c CLINICAL BOTTOM LINE The IV route is the treatment of choice for paracetamol poisoning, but the oral route has a similar efficacy and is a suitable alternative if IV access is difficult (for example IV drug abusers) or refused by the patient. Best evidence topic reports (BETs) summarise the evidence pertaining to particular clinical questions. They are not systematic reviews, but rather contain the best (highest level) evidence that can be practically obtained by busy practising clinicians. The search strategies used to find the best evidence are reported in detail in order to allow clinicians to update searches whenever necessary. The BETs published below were first reported at the Critical Appraisal Journal Club at the Manchester Royal Infirmary. 1 Each BET has been constructed in the four stages that have been described elsewhere.2 The BETs shown here together with those published previously and those currently under construction can be seen at http://www.bestbets.org.3 Six BETs are included in this issue of the journal.

Assessing the Impact of Vomiting Episodes on Outcome after Acetaminophen Poisoning

“…Vomiting associated with certain poisons can be detrimental to the treatment of the patient. Although vomiting is observed among patients with acetaminophen poisoning [1–3], there are no data concerning the prevalence of, and the relationship between, vomiting and outcome in patients presenting to hospital with acetaminophen poisoning [4]. Early markers of poor outcome are important both for acute physicians and liver units.…”

Paracetamol poisoning: Which nomogram should we use?

“…The treating physician now takes responsibility for plotting the paracetamol level on the nomogram. Of note, the incidence of vomiting after paracetamol overdose is relatively low and does not necessarily imply toxicity 7 …”

“…Of note, the incidence of vomiting after paracetamol overdose is relatively low and does not necessarily imply toxicity. 7 To further investigate these issues we decided to review treatment practices at other Australasian institutions, and review the literature on the treatment of paracetamol overdose.…”