HCA Florida Aventura Hospital
Emergency Medicine | Medicine and Health Sciences
Introduction: Carbamates are a class of insecticides structurally and mechanistically similar to organophosphate (OP) insecticides. Carbamates are N-methyl carbamates derived from a carbamic acid and cause carbamylation of acetylcholinesterase at neuronal synapses and neuromuscular junctions. While they possess a similar mechanism of action to the irreversible phosphorylation of acetylcholinesterase by organophosphates, carbamates bind to acetylcholinesterase reversibly. Subsequently, carbamates typically have a similar toxicological presentation to OP poisonings with a duration of toxicity that is typically less than 24 hours.
Case Presentation: We present a case of a 51-year-old male who was complaining of diarrhea, lacrimation, salivation, headache, photophobia, diaphoresis, and chest tightness that had progressively gotten worse over the course of 2 weeks. Two weeks prior to coming into the emergency department (ED), the patient and his wife were cleaning their home with an insecticide spray. Both the patient and his wife had symptoms that started within 24 hours of using the insecticide spray, however, the wife’s symptoms subsided after 2 days of supportive care and symptomatic treatment at the hospital. The patient’s symptoms, however, progressively worsened over the course of 2 weeks since the exposure. In the ED the patient presented bradycardic and hypotensive. His physical exam was remarkable for miosis, photophobia, diaphoresis and abdominal pain and he was in moderate distress. He was given Atropine sulfate for his bradycardia per poison control’s recommendation, ketorolac for pain, ondansetron for nausea, famotidine for reflux as well as some gastrointestinal discomfort, and sodium lactate for fluid resuscitation. His initial labs were significant for leukocytosis, elevated creatinine, lactic acidosis and hypercalcemia. Once stabilized in the ED, the patient was admitted to the intensive care unit (ICU) for close observation on telemetry and symptom control. On reevaluation before sending the patient to the ICU the patient’s status was improving from the atropine, fluids and symptom control. Once transferred to the ICU the patient was given Loperamide for his diarrhea and Atropine boluses as needed for bradycardia. Pralidoxime would have also been considered if there were any signs of muscle weakness or symptoms related to nicotinic receptor activation. Frequent neuro checks and echocardiograms were done on a scheduled basis. With supportive care and time, the patient’s clinical condition started to improve over the course of 3 days. On day 3, the patient was discharged and stayed at a friend’s home as the patient’s home needed professional cleaning.
Discussion: This case illustrates the importance of persistent signs and symptoms of a carbamate toxicity which classically subside within 96 hours after exposure. However, carbamate toxicity cannot be ruled out in someone who presents with all the classic signs and symptoms, which can persist and even progressively worsen over the course of days to weeks.
Mahmood, Kashan; Marra, Erin; Craig, Taylor; and Patel, Gaurav, "From Pest Control to Poison Control: A Novel Case Report of Delayed Carbamate Poisoning." (2023). East Florida Research Day 2023. 36.