High serum acetaminophen concentrations were associated with fewer anaphylactoid reactions, suggesting that these might in some way be protective. The biological basis needs further exploration so as to allow a better understanding of the mechanisms responsible for adverse reactions to NAC treatment.

Objectives: Little is known about the clinical significance of acute ethanol coingestion around the time of acetaminophen (paracetamol) overdose. This study prospectively examined the effect of acute ethanol coingestion on risk of hepatotoxicity among patients admitted to hospital for N-acetylcysteine (NAC) therapy after deliberate acetaminophen overdose.Methods: This was a prospective observational study and included sequential patients who presented within 24 hours of acute acetaminophen ingestion and required NAC therapy. Significant hepatotoxicity was defined by alanine transaminase > 1,000 U ⁄ L or the international normalized ratio > 1.3 after a standardized intravenous administration of 300 mg ⁄ kg NAC.Results: There were 362 patients, including 178 (49.2%) who coingested ethanol acutely. The prevalence of hepatotoxicity was 5.1% (95% CI = 2.6% to 9.5%) in those who ingested ethanol, compared to 15.2% (95% CI = 10.7% to 21.2%) in those who did not (p = 0.0027 by chi-square proportional test). Acute ethanol intake conferred a lower risk of hepatotoxicity in patients who had acetaminophen concentrations above or below the ''200-line'' and was independent of the interval between ingestion and assessment.Conclusions: Acute ethanol intake is associated with a lower risk of hepatotoxicity after acetaminophen overdose. This apparent protective effect cannot be explained solely by lower exposure to acetaminophen in this group, nor differences in the interval between ingestion and initiation of treatment. Further work is required to establish mechanisms by which ethanol might confer protection against hepatotoxicity, so as to identify novel strategies for reducing risk after acute acetaminophen ingestion.ACADEMIC EMERGENCY MEDICINE 2008; 15:54-58 ª

Therefore, ingestion of >12 g predicted higher paracetamol exposure and increased risk of hepatotoxicity and supports the validity of patient history in this context.

Low serum urea concentration is not an independent risk factor for hepatotoxicity after paracetamol overdose.

SummaryUse of a bougie is not without risk, and insertion too far may cause airway injury. We designed a new bougie with a 'traffic light' system to indicate depth of insertion. Forty anaesthetists were randomly assigned to insert either a conventional single-coloured bougie or a novel traffic light bougie. Depth of insertion was measured before and after railroading a tracheal tube. Participants were not informed as to the purpose of the colouring system. The median (IQR [range]) insertion depth of the traffic light bougie was 22 (21-24 [19-27]) cm and for the conventional bougie was 28 (21-32 [20-35]) cm (p = 0.011). Median (IQR [range]) insertion depth after railroading for the traffic light bougie was 25 (25-28 [21-34]) cm and for the conventional bougie was 30.5 (27-35 [23-40]) cm (p = 0.003). This simple colouring system appears to allow intuitive use and significantly reduced the depth of bougie insertion. This system could be also used with other airway exchange devices to improve safety.