Organophosphate acetylcholine esterase inhibitor poisoning from a home-made shampoo.

Organophosphate acetylcholine esterase inhibitor poisoning is a major health problem in children. We report an unusual cause of organophosphate acetylcholine esterase inhibitor poisoning. Two children were admitted to the pediatric intensive care unit due to organophosphate acetylcholine esterase inhibitor poisoning after exposure from a home-made shampoo that was used for the treatment of head lice. Owing to no obvious source of poisoning, the diagnosis of organophosphate acetylcholine esterase inhibitor poisoning in one of these patients was delayed. Both patients had an uneventful recovery. Organophosphate acetylcholine esterase inhibitor poisoning from home-made shampoo is possible. In cases where the mode of poisoning is unclear, direct questioning about the use of home-made shampoo is warranted, in these cases the skin and particularly the scalp should be rinsed thoroughly as soon as possible.

INTRODUCTION

Acetylcholine esterase inhibitor poisoning, from organophosphates (OP) or carbamate is a common cause of life threatening poisoning in children worldwide. However, in some of the children with OP acetylcholine esterase inhibitor poisoning, the diagnosis is delayed because an obvious source of exposure is not identified at the onset of clinical symptoms and the diagnosis is eventually established using clinical signs and pseudo-cholinesterase level.[1] In southern Israel, OP acetylcholine esterase inhibitor poisoning is relatively common.[2] We report two children with OP poisoning from a home remedy for lice that was misused as a shampoo.

CASE REPORTS

Case 1

A previously healthy 8-year-old Bedouin female presented to the pediatric emergency department (ED) with apathy, recurrent vomiting, and diarrhea that began a few hours prior to admission. In the primary care clinic, the initial presumptive diagnosis was gastroenteritis. The child was treated with a bolus of 0.9% saline and metoclopramide; however, she did not improve and was transferred to the ED. The patient's condition further deteriorated and she was admitted to the Intensive Care Unit (ICU). The patient's mother could not confirm any form of poisoning, use of medications, or presence of agricultural pesticides. On admission to the ICU the patient's heart rate was 67 beats per minute, blood pressure was 119/61, and oxygen saturation was 98%. The patient was lethargic, with pin-point pupils and fasciculation of the facial muscles. The rest of the physical examination was unremarkable. Blood count showed a hemoglobin concentration of 11 gr/dL, WBC 30,700/ul, (granulocytes 85%), and a thrombocyte count of 438,000/ul. Blood chemistry showed elevated blood glucose (322 mg/dl) and hypokalemia (3 mEq/L). Other electrolytes, renal and liver functions and blood gas tests were within normal limits. Clinical signs suggestive of OP poisoning incited a pseudo-cholinesterase evaluation, which revealed a pseudo-cholinesterase activity of 84 U/L (normal: 6400-12000 U/L). The extremely low pseudo-cholinesterase level prompted a careful review of possible environmental exposures for a potential source of the poisoning. The parents recalled the use of a common folk remedy in the form of shampoo for treatment of pediculosis capitis. Four hours prior to admission, the patient was treated with the above-mentioned shampoo, which was thoroughly applied but not rinsed from her hair. The parents were able to provide the substance for testing. After chemical analysis by gas chromatography-mass spectrometry, the substance was identified as Fenamiphos – (ethyl-4-methyltjio-m-toyl isopropyl phosphoramidate). The patient was thoroughly washed including the hair. Therapy was initiated with IV fluids, atropine 0.05 mg/kg and obidoxime chloride (toxogonin) 6 mg/kg, three doses, for 5 days, until a significant clinical and laboratory improvement was achieved. The patient had an uneventful recovery.

Case 2

A 14-year-old previously healthy female was admitted to our hospital 4 days after suspected OP acetylcholine esterase inhibitor poisoning. She was initially hospitalized at another hospital with vomiting and respiratory distress. Pinpoint pupils and bradycardia were noted. Less than 24 hours prior to admission the patient applied a home-made shampoo against lice with unknown ingredients which was not rinsed. Extremely low pseudocholine esterase activity was found; however, the initial laboratory evaluation is unavailable. A diagnosis of OP acetylcholine esterase inhibitor poisoning was made and the patient was intubated and ventilated. Therapy with obidoxime chloride (toxogonin) 6 mg/kg and atropine 0.05 mg/kg was administered. A day following admission she was extubated, however, a short tonic clonic seizure was noted and on the fourth day, the patient was admitted to our hospital. At that time, the patient's pseudocholine esterase level was 1762 U/L (6400-12000). During the next 2 days her condition deteriorated due to pneumonia, complete atelectasis of the LLL and pneomothorax. A chest drain was inserted, she was reintubated, and antimicrobial treatment (Piperacilin 90 mg/kg and Amikacin 15 mg/kg) was administered. Five days post admission to our hospital, the activity of pseudocholine esterase was 4089 U/L. She was extubated successfully 12 days postadmission and pseudocholine activity continued to gradually improve.

DISCUSSION

OPs and carbamates are agricultural insecticides used in large quantities around the world.[3] Toxic exposure to these chemicals is a serious global public health problem, with more than three million poisonings and 200,000 deaths reported per year.[3] Organophosphate acetylcholine esterase inhibitor poisoning in children is usually due to unintentional ingestion.[1] However, the mode of exposure to OP acetylcholine esterase inhibitor is not obvious in the initial evaluation in some patients, which may lead to a delay in diagnosis and subsequent fatality.[1] Organophosphate acetylcholine esterase inhibitor poisoning from exposure through shampoo has been reported previously; Halle and Sloas reported a patient with OP poisoning from exposure through the skin during treatment of pubic lice.[4] Paget et al. reported 2 children, and Levy-Khademi et al. reported 5/31 (16.1%) cases of unintentional OP poisoning in children from Israel, that were attributed to the use of shampoo.[15] The present report reiterates this unusual route of OP acetylcholine esterase inhibitor poisoning. The use of shampoo containing OP acetylcholine esterase inhibitor may be the source of intoxication in some of the patients in whom the exact mode of exposure is not obvious at presentation. The patient described in the first case was initially erroneously diagnosed as having gastroenteritis. Only after bradycardia and pinpoint pupils were noticed then the correct diagnosis of OP poisoning was made. This emphasizes the fact that the diagnosis of OP poisoning is not always obvious and a high level of suspicion is warranted.

We propose that acetylcholine esterase inhibitor poisoning from home-made shampoo containing OPs or carbamates may be common in other agricultural societies where these insecticides are used in large quantities. The use of such a shampoo may lead to absorption from the relatively large surface area of the scalp which allows for significant systemic toxicity.

CONCLUSIONS

We conclude that the importance of taking a diligent history including possible modes of exposure to OP acetylcholine esterase inhibitors is imperative in cases where the mode of intoxication is not obvious. In cases where the mode of intoxication is unclear, direct questioning about the use of home made shampoo is warranted. Whenever history of exposure is not clear, skin and particularly the scalp should be rinsed in every child with suspected OP acetylcholine esterase inhibitor intoxication.