Acetaminophen concentrations prior to 4 hours of ingestion: Impact on diagnostic decision-making and treatment

Introduction of an electrochemical point-of-care assay for quantitative determination of paracetamol in finger-prick capillary whole blood samples

AIMS

Measuring venous plasma paracetamol concentrations is time- and resource-consuming. We aimed to validate a novel electrochemical point-of-care (POC) assay for rapid paracetamol concentration determinations.

METHODS

Twelve healthy volunteers received 1 g oral paracetamol, and its concentrations were analysed 10 times over 12 h for capillary whole blood (POC), venous plasma (high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS)), and dried capillary blood (HPLC-MS/MS).

RESULTS

At concentrations >30 μM, POC showed upward biases of 20% (95% limits of agreement [LOA] -22 to 62) and 7% (95% LOA -23 to 38) compared with venous plasma and capillary blood HPLC-MS/MS, respectively. There were no significant differences between mean concentrations for the paracetamol elimination phase.

CONCLUSIONS

Upward biases in POC compared with venous plasma HPLC-MS/MS were likely due to higher paracetamol concentrations in capillary blood than in venous plasma and to faulty individual sensors. The novel POC method is a promising tool for paracetamol concentration analysis.

Failure of Risk Assessment After Paracetamol Overdose-A Short Communication

BACKGROUND

The accepted treatment for patients with acetaminophen/paracetamol overdose includes risk assessment based on the Rumack-Matthew (R-M) nomogram. An inaccurate use of the nomogram may result in improper treatment. Clinicians were surveyed to determine their understanding and proper use of this risk assessment tool in practice.

METHODS

Differences between visual risk assessment using the same depiction of the R-M nomogram and calculated risk assessment were determined using an online calculator developed based on the Rumack equation. An online survey was administered in French between August 25, 2021, and November 25, 2021, as a Google Form with 14 questions (the paracetamol concentration and time postingestion were stated). A total of 147 respondents with an average age of 32 years (range 23-61 years) performed risk assessment (low/possible/probable/not assessable). The mean assessment accuracy was 66.2 ± 26.7% (12.3-99.3). The sensitivity, specificity, positive predictive value, and negative predictive value were 93%, 55%, 71%, and 89%, respectively. A subcohort of n = 31 senior clinicians showed the same trends (91%, 52%, 69%, and 84%).

RESULTS

Approximately 7% of patients who are at risk of hepatotoxicity based on the R-M nomogram would not be treated. By contrast, N-acetylcysteine was not recommended by the R-M nomogram but would be administered to approximately 50% of patients. A concern for the latter group is that anaphylactoid reactions occur in up to 25% of patients with low paracetamol concentrations.

CONCLUSIONS

Some patients may be undertreated, resulting in possible hepatotoxicity, and many patients may be overtreated, resulting in a high percentage of anaphylaxis. Rather than relying on visual risk assessment, physicians should use an online calculator ( www.hopitox.com/?lang=en ) or consult with a toxicologist or poison center to substantially improve patient care after acetaminophen/paracetamol overdose.

Acute Liver Failure: An Update

Pediatric acute liver failure (PALF) is a dynamic, life-threatening condition of disparate etiology. Management of PALF is dependent on intensive collaborative clinical care and support. Proper recognition and treatment of common complications of liver failure are critical to optimizing outcomes. In parallel, investigations to identify underlying cause and the implementation of timely, appropriate treatment can be life-saving. Predicting patient outcome in the era of liver transplantation has been unfulfilling and better predictive models must be developed for proper stewardship of the limited resource of organ availability.

Salicylate toxicity after undetectable serum salicylate concentration: a retrospective cohort study

BACKGROUND

Salicylates are usually rapidly absorbed and quickly measurable in serum. An undetectable serum salicylate concentration ([ASA]) may occur early after ingestion and may be interpreted as evidence of non-exposure and not repeated. Although cases of delayed salicylate detection are reported rarely, the risk factors associated with this phenomenon are not known.

RESEARCH QUESTION

What factors are associated with an early undetectable [ASA] in salicylate poisoning?

METHODS

Records from a single regional poison center were searched from 2002 to 2016 for cases of salicylate toxicity treated with bicarbonate and [ASA] > 30 mg/dL. Cases were excluded if initial [ASA] was obtained >4 h after presentation. Case information, serial [ASA], and outcomes were recorded and compared between groups.

RESULTS

A total of 313 records met all criteria with 11 initially undetectable [ASA] (3.5%) and 302 detectable [ASA] (96.5%). Time of first [ASA] occurred sooner in the undetectable [ASA] group (89 vs. 137 min, p = 0.011) while time to peak [ASA] was longer (640 vs. 321 min, p < .001). The longest interval between ingestion and undetectable [ASA] was 225 min. Peak [ASA] and reported mean ingested dose were similar in both groups (45 vs. 50 mg/dL, p = NS; 19.7 g vs. 32.9 g, p = NS). Coingestion of agents that delay gastric emptying were similar in both groups (18% [2/11] vs. 25% [76/302], p = NS, chi-square). Hemodialysis was performed in 9% (1/11) of undetectable [ASA] patients and 5.6% (17/302) of detectable [ASA] patients (p = NS, chi-square). A single death occurred in the entire cohort in a patient with an initially detectable [ASA].

DISCUSSION

In this series, a small but significant proportion (3.5%) of patients who developed [ASA] > 30 mg/dL had an initially undetectable [ASA]. Those with an undetectable [ASA] were measured earlier after ingestion with a longer time to peak [ASA]. However, neither coingestion of agents prolonging gastric emptying nor reported dose ingested was different between groups. Formulation was infrequently recorded but one undetectable [ASA] did ingest a non-enteric coated product. Limitations include the small number of patients with undetectable [ASA], use of single poison center data and partial data on co-ingestants and aspirin formulation.

CONCLUSIONS

[ASA] may be undetectable early after an overdose and need for serial [ASA] in the evaluation of salicylate ingestion should be further explored. Additional research is needed to determine any causative factors and the optimal timing of [ASA] measurements.