Correlation of paired toxic plasma and saliva paracetamol concentrations following deliberate self-poisoning with paracetamol

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Paracetamol is commonly used in deliberate self poisoning (DSP) and this requires blood sampling to refine risk assessment. If saliva concentrations agreed with plasma concentrations, then this could support the development of non-invasive testing. Our pilot work supports this hypothesis, but was largely confined to nontoxic concentrations.

WHAT THIS STUDY ADDS

• We found agreement between the indications for treatment of paracetamol DSP based on plasma and saliva paracetamol concentrations. Saliva may hold promise as a non-invasive method to risk stratify paracetamol poisoning.

AIMS

Paracetamol is commonly used in deliberate self poisoning (DSP) and requires blood sampling to refine risk assessment. We aimed to test the agreement between plasma and saliva paracetamol concentrations in the toxic range in DSP.

METHODS

Contemporaneous paired plasma and saliva paracetamol concentrations were measured. Saliva was collected using a Sarstedt Salivette® device and the concentration was measured using a colorimetric method.

RESULTS

Fifty-six patients (44, 78% female) median age 26 years (IQR 20-41) were enrolled. The median reported paracetamol ingestion was 10 g (IQR 6-14). Specimens were collected at a median of 4 h (IQR 4-5.3) post ingestion. The median plasma and saliva paracetamol concentrations were 29 mg l(-1) (IQR 8-110) and 38 mg l(-1) (IQR 10-105) respectively [mean difference 8 mg l(-1) , 95% confidence interval (CI) 2, 14]. Lin's concordance correlation was 0.97 (95% CI 0.96, 0.98). There were 15 patients who were treated with N-acetylcysteine. Their median reported paracetamol ingestion was 14 g (IQR 10-23) and samples were collected at a median of 4 h post ingestion. The median plasma and saliva paracetamol concentrations were 167 mg l(-1) (IQR 110-200) and 170 mg l(-1) (IQR 103-210) respectively (mean difference 15 mg l(-1) , 95% CI -4, 35). Lin's concordance correlation was 0.94 (95% CI 0.88, 0.99). No patient needing treatment would have been missed using saliva concentrations only.

CONCLUSIONS

The agreement between the indications for treatment of paracetamol DSP based on plasma and saliva paracetamol concentrations extends into the toxic range, but with slightly lower agreement. Saliva may hold promise as a non-invasive method to risk stratify paracetamol poisoning.

Patient perceptions of the potential lethality associated with deliberate self-poisoning

INTRODUCTION

Little is known about patient perceptions of the lethality of their overdose. Our aim was to compare patient perceptions with the risk assessment of clinical toxicologists.

METHODS

A prospective observational study of overdose patients presenting to a tertiary hospital. Eligible patients were surveyed once they were medically fit for psychiatric evaluation. Descriptive data were collected, including the Pierce Suicide Intent Scale (SIS). In response to 'how dangerous did you think this overdose was when you took the tablets?' patients marked a 10 cm VAS, with 0 = would be harmless, 10 = certain to cause death. A panel of clinical toxicologists independently made a risk assessment on a 10 cm VAS, with 0 = non-toxic ingestion and 10 = uniform lethality even with full medical intervention.

RESULTS

Of 202 patients enrolled, 118 (58.4%, 95% CI 51-65) were female; median age 33 years (interquartile range [IQR] 24-42). One hundred and three (51%, 95% CI 44-58) stated it was their intention to kill themselves and 44 (21.8%, 95% CI 16-28) wrote a suicide note. They most commonly used their own prescription medications (141, 69.8%, 95% CI 63-76). The median patient visual analog scale (VAS) was 5.8 (IQR 2.3-8.3) and median toxicology VAS was 1.4 (IQR 0.6-2.8); this difference was statistically significant (P < 0.0001). The correlation between the patient visual analog scale (VAS) and Pierce SIS (median 8.5/25 [IQR 4-12]) was strong (r= 0.73, P < 0.0001).

CONCLUSIONS

Patient perceptions of the lethality of their overdose are correlated with their suicidal intent as measured on the Pierce SIS, with a significant mismatch between patient perceptions and the toxicological risk assessment.

Brain abnormalities detected on magnetic resonance imaging of amphetamine users presenting to an emergency department: a pilot study

OBJECTIVES

To determine the prevalence of occult brain abnormalities in magnetic resonance imaging of active amphetamine users.

DESIGN, SETTING AND PARTICIPANTS

Prospective convenience study in a tertiary hospital emergency department (ED). Patients presenting to the ED for an amphetamine-related reason were eligible for inclusion. We collected demographic data, drug use data, and performed a mini-mental state examination (MMSE).

MAIN OUTCOME MEASURES

The proportion of patients with an abnormality on their MRI scan.

RESULTS

Of 38 patients enrolled, 30 had MRI scans. Nineteen were male and their mean age was 26.7 +/- 5.4 years (range 19-41 years). The mean age of first amphetamine use was 18 years (range 13-26 years). Sixteen patients used crystal methamphetamine (mean amount 2.5 g/week), nine used amphetamine ("speed") (mean amount 2.9 g/week), and 23 used ecstasy (mean amount 2.3 tablets/week). Marijuana was smoked by 26 (mean amount 5.9 g/week), and 28 drank alcohol (mean amount 207 g/week). The median MMSE score was 27/30 (interquartile range, 26-29). Abnormalities on brain MRI scans were identified in six patients, most commonly an unidentified bright object (n = 4).

CONCLUSION

In this pilot study of brain MRI of young people attending the ED with an amphetamine-related presentation, one in five had an occult brain lesion. While the significance of this is uncertain, it is congruent with evidence that amphetamines cause brain injury.

Amphetamine-related presentations to an inner-city tertiary emergency department: a prospective evaluation

OBJECTIVE

To describe the prevalence, characteristics and outcomes of amphetamine-related presentations to a tertiary hospital emergency department (ED).

DESIGN, SETTING AND PARTICIPANTS

Prospective observational study of amphetamine-related presentations to the ED of the Royal Perth Hospital (RPH), an adult, inner-city, tertiary referral hospital, between 3 August and 2 November 2005. For all patients presenting to the ED, the treating doctors were automatically prompted by the computerised data entry system to consider amphetamine use.

MAIN OUTCOME MEASURES

Proportion of ED presentations related to amphetamine use; demographic features and usage practices of amphetamine users; characteristics of presentations and admissions; associated psychiatric illnesses and use of other drugs.

RESULTS

Over the study period, there were 13 125 presentations, of which 156 (1.2%) were judged to be causally related to amphetamine use. Of those 156 patients, over half were habitual drug users (89 [57.1%] used amphetamines at least weekly), and the majority were men (111 [71.2%]). The mean age was 28 years (range, 16-55 years). Presentations were of high acuity: 104 patients [66.7%] were rated 1, 2 or 3 on the Australasian Triage Scale; 50 (32.1%) arrived by ambulance; and 25 (16.0%) arrived with police. The mean time spent in the ED was 6 h (range, 0.5-24 h). Fifty patients (32.1%) required sedation, and the likelihood of requiring sedation increased almost threefold if the heart rate was over 100 beats/min on presentation. Sixty-two patients (39.7%) were admitted and 58 (37.2%) required psychiatric evaluation. Repeat attendance was common, with 71 patients (45.5%) having previous amphetamine-related presentations to the RPH ED.

CONCLUSIONS

Amphetamine-related presentations comprise 1.2% of all ED attendances and have a major impact on hospital EDs. Patients are often agitated and aggressive, require extensive resources, and frequently re-attend. The burden of amphetamine-related illnesses on EDs is likely to increase in the future.

Neutralization of Latrodectus mactans and L. hesperus venom by redback spider (L. hasseltii) antivenom

OBJECTIVE

To test the effectiveness of L. hasseltii (redback spider) antivenom in neutralizing the lethal effects of L. hesperus and L. mactans (North American black widow) venoms.

METHODS

LD50 values for the L. hesperus and L. mactans venom preparations were determined. A prospective, randomized, double-blind antivenom efficacy experiment was then performed for each venom using a mouse envenomation model. The following treatments were premixed and incubated at 25 degrees C for 1 hour prior to intraperitoneal injection: 1) saline control + protein control, 2) saline control + L. hasseltii antivenom, 3) L. hesperus or L. mactans venom + protein control, and 4) L. hesperus or L. mactans venom + L. hasseltii antivenom. The study endpoints were time elapsed until death and survival at 24 hours.

RESULTS

The mouse LD50 values for L. hesperus and L. mactans venoms were 0.64 mg/kg and 0.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both experiments, all mice in group 4 (L. hesperus or L. mactans venom + antivenom) survived (p < 0.0001).

CONCLUSION

This is the first study to derive mouse LD50 values for L. hesperus and L. mactans venom obtained by electrical stimulation of live adult spiders. Redback spider antivenom is effective in neutralizing the lethal effects of L. hesperus and L. mactans venoms in a mouse envenomation model. While this study is limited by the optimized premixing of antigen with antibody, it generates the hypothesis that redback antivenom would be effective in the treatment of latrodectism in humans caused by the two clinically relevant species of North American widow spiders.

Acute myocardial infarction associated with amphetamine use

Myocardial infarction is a rarely reported complication of amphetamine use. We report the case of a healthy 31-year-old man who presented to our emergency department with no clinical evidence of an acute coronary event after intravenous injection of amphetamines. However, he subsequently experienced a non-Q-wave anterior wall myocardial infarction associated with the use of amphetamines.

The Medical Emergency Team (MET): a model for the district general hospital

BACKGROUND

Most hospitals have a Cardiac Arrest Team, activated after cardiopulmonary arrest. The Medical Emergency Team (MET) is a newer concept, encompassing a proactive response to a wide range of emergencies with the aim of preventing irreversible organ failure and cardiopulmonary arrest.

AIM

To describe the application of the MET model to the district general hospital, the spectrum of clinical conditions encountered, outcomes and administrative problems.

METHOD

Data regarding each MET activation was collected prospectively.

RESULTS

The MET responded to 68 calls to 63 patients in 12 months. The mean age was 60.4 years (range: neonatal to 94 years). The most common conditions leading to MET activation were chest pain (19.1%), cardiopulmonary arrest (14.7%), seizures (14.7%) and respiratory distress (13.2%).

CONCLUSION

This paper demonstrates that the application of the MET model to the district general hospital improves the process of patient care. We are unable to conclude whether the MET alters morbidity or mortality for hospital inpatients.