In acute organophosphate poisoning, the efficacy of hemoperfusion on clinical status and mortality

Efficacy of fresh packed red blood transfusion in organophosphate poisoning

The mortality rate caused by organophosphate (OP) poisoning is still high, even the standard treatment such as atropine and oxime improves a lot. To search for alternative therapies, this study was aimed to investigate the effects of packed red blood cell (RBC) transfusion in acute OP poisoning, and compare the therapeutic effects of RBCs at different storage times.Patients diagnosed with OP poisoning were included in this prospective study. Fresh RBCs (packed RBCs stored less than 10 days) and longer-storage RBCs (stored more than 10 days but less than 35 days) were randomly transfused or not into OP poisoning patients. Cholinesterase (ChE) levels in blood, atropine usage and durations, pralidoxime durations were measured.We found that both fresh and longer-storage RBCs (200-400 mL) significantly increased blood ChE levels 6 hours after transfusion, shortened the duration for ChE recovery and length of hospital stay, and reduced the usage of atropine and pralidoxime. In addition, fresh RBCs demonstrated stronger therapeutic effects than longer-storage RBCs.Packed RBCs might be an alternative approach in patients with OP poisoning, especially during early stages.

Methamidophos, dichlorvos, O-methoate and diazinon pesticides used in Turkey make a covalent bond with butyrylcholinesterase detected by mass spectrometry

Organophosphorus pesticides used most commonly in Turkey include methamidophos, dichlorvos, O-methoate and diazinon. These toxic chemicals or their metabolites make a covalent bond with the active site serine of butyrylcholinesterase. Our goal was to identify the adducts that result from the reaction of human butyrylcholinesterase with these pesticides. Highly purified human butyrylcholinesterase was treated with a 20-fold molar excess of pesticide. The protein was denatured by boiling and digested with trypsin. MS and MSMS spectra of HPLC-purified peptides were acquired on a MALDI-TOF-TOF 4800 mass spectrometer. It was found that methamidophos added a mass of +93, consistent with addition of methoxy aminophosphate. A minor amount of adduct with an added mass of +109 was also found. Dichlorvos and O-methoate both made dimethoxyphosphate (+108) and monomethoxyphosphate adducts (+94). Diazinon gave a novel adduct with an added mass of +152 consistent with diethoxythiophosphate. Inhibition of enzyme activity in the presence of diazinon developed slowly (15 h), concomitant with isomerization of diazinon via a thiono-thiolo rearrangement. The isomer of diazinon yielded diethoxyphosphate and monoethoxyphosphate adducts with added masses of +136 and +108. MSMS spectra confirmed that each of the pesticides studied made a covalent bond with serine 198 of butyrylcholinesterase. These results can be used to identify the class of pesticides to which a patient was exposed.

Factors for determining survival in acute organophosphate poisoning

BACKGROUND/AIMS

Organophosphate poisoning has a high mortality rate. Recently, differences among organophosphorus insecticides in human self-poisoning were reported. This study investigated the prognostic risk factors and the mortality of different organophosphates following acute organophosphate poisoning.

METHODS

This retrospective study included 68 patients with acute organophosphate poisoning. We investigated patient survival according to initial parameters, including the initial Acute Physiology and Chronic Health Evaluation (APACHE) II score, serum cholinesterase level, and hemoperfusion and evaluated the mortality according to organophosphate types.

RESULTS

Thirteen of the 68 patients died. The agents responsible for mortality were different. The APACHE II score was a significant predictor of mortality (odds ratio [OR], 1.194; p<0.01; 95% confidence interval [CI], 1.089 to 1.309) and respiratory failure (OR, 1.273; p<0.01; 95% CI, 1.122 to 1.444). The mortality was 0% for dichlorvos, malathion, chlorpyrifos and profenofos. However, other organophosphates showed different mortality (16.7% for O-ethyl-O-4-nitrophenyl phenylphosphonothioate, 25% for phenthoate, 37.5% for phosphamidon, 50% for methidathion). The usefulness of hemoperfusion appears to be limited.

CONCLUSIONS

The initial APACHE II score is a useful prognostic indicator, and different organophosphates have different mortality.

Adjuncts and Alternatives to Oxime Therapy in Organophosphate Poisoning—is There Evidence of Benefit in Human Poisoning? A Review

Organophosphate poisoning is common in developing countries. The morbidity and mortality with organophosphate poisoning is relatively high despite the use of atropine as specific antidotal therapy and oximes to reactivate acetylcholinesterase. Several adjunct and alternative therapies have been explored in animal and human studies. We reviewed the literature to ascertain if there was evidence of benefit of such therapies. Adjunct and alternative therapies included treatments to reduce poison absorption by topical application of creams, enhance toxin elimination by haemoperfusion or bioremediation and neutralise the poison by scavenging free organophosphate with cholinesterase-rich human plasma. In addition, magnesium, clonidine, diazepam, N-acetyl cysteine and adenosine receptor agonists have also been used to counteract poison effects. Detailed assessment was limited by the paucity of trials on adjunct/alternative therapies. The limited evidence from the review process suggested potential benefit from the use of human plasma infusion, early initiation of haemoperfusion and intravenous magnesium, in addition to standard therapy with atropine and pralidoxime. There appeared to be no additional benefit with alkalinisation or use of glycopyrrolate instead of atropine in human trials. Diazepam administration has been advocated by military authorities if symptoms developed following exposure to organophosphate. Bioremediation, clonidine, N-acetyl cysteine and adenosine receptor agonists have been evaluated only in animal models. The impact of adjunct and alternate therapies on outcomes in human poisoning needs to be further explored before implementation as standard treatment.

Advances in the management of organophosphate poisoning

Organophosphate (OP) poisoning is commonly encountered in agricultural communities. The mainstay of therapy in OP poisoning is the use of atropine. However, several other therapies have been evaluated. Although oxime has been the most studied antidote, results in humans have been disappointing and limited by the lack of well-designed, prospective, randomised controlled trials. The key factor in determining outcomes in OP poisoning appears to be the timing of antidote administration. Other adjuvants, such as magnesium, fresh frozen plasma and haemoperfusion appear promising, and need to be explored further. A multi-faceted approach may be the answer to improving outcomes in OP poisoning. This review evaluates the advances in OP management over the last 20 years.