Clinical Implication of Acetylcholinesterase in Acute Organophosphate Poisoning

ABSTRACT

Purpose: Acute organophosphate (OP) poisoning may be monitored by measuring the acetylcholinesterase (AChE). It is important to assess severity and establish prognostic tests in the early stage of OP poisoning. The aim of this study was to look at the relationship between various clinical aspects of the OP poisoning, prognostic indicators of OP poisoning including Simplified Acute Physiology Score (SAPS) 3, and the associated changes in AChE levels. Methods: Clinical data and initial AChE levels from thirty-seven patients with OP poisoning were prospectively reviewed from 12 teaching hospitals in South Korea from August 2005 to July 2006. Clinical manifestations at the time of arrival such as miosis, respiratory abnormality, salivation, urinary incontinence, GCS score, AVPU scale, need for intubation, and mechanical ventilation requirements were recorded. SAPS 3 was calculated using clinical data and laboratory results. Results: The median level of AChE was 9.8 (1.3-53.6) U/gHb. There was no significant difference in AChE levels between the groups with and without cholinergic symptoms. The median level of AChE of the patients who required intubation and those who did not were 3.5 U/gHb and it 19.7 U/gHb respectively (Mann-Whitney test; p<0.001). The AChE levels were also significantly different (p=0.007) in patients who needed mechanical ventilation compared to those who did not with AChE levels found to be 3.1 U/gHb and it was 14.8 U/gHb, respectively. Level of consciousness assessed using the AVPU scale was correlated with AChE levels (Kruskal-Wallis test; p=0.013). GCS score were correlated with AChE levels (p=0.007, Spearman's rho = 0.454). In addition, the lower the level of initial AChE, the longer the ICU stay (p=0.029, Spearman's rho=-0.380). SAPS 3 was inversely correlated with the initial AChE (p<0.001, Spearman's rho=-0.633). Conclusion: In the acute OP poisoning, low AChE levels appear to help indicate the severity of poisoning. The initial AChE level may be a useful prognostic parameter for acute OP poisoning.