Clinical evaluation of patients diagnosed with methanol poisoning in the emergency department and retrospective analysis of poisoning-related sequelae

Aim: Methanol poisoning is a severe clinical condition that can manifest with serious metabolic acidosis, shock, and acute multiple organ failure. Methanol poisoning can lead to significant sequelae such as permanent blindness, resulting in high morbidity and mortality rates. The aim of this study is to provide valuable data on the diagnosis, treatment, sequelae rates, and outcomes of patients with methanol poisoning through retrospective analysis. Materials and Methods: After obtaining approval from the Çukurova University Faculty of Medicine Non-Interventional Clinical Research Ethics Committee, patients diagnosed with toxic alcohol poisoning in the emergency department between January 1, 2015, and June 1, 2023, were retrospectively screened using the hospital's information management system and archive files. Patients for whom complete data could not be obtained were excluded from the study. Patient characteristics, presenting complaints, mode of presentation, diagnosis, treatment, antidote administration rates, hemodialysis access, laboratory and imaging results, duration of hospitalization, types of outcomes, and sequelae rates were recorded and statistically analyzed. Results: A total of 116 patients with accessible data were evaluated in this study. The mean age of the patients was 48.3±13.5 years, with 94.8% (110 patients) being male. Ambulance transportation was the most common mode of arrival for patients (18 from the scene/home, 72 referred from another institution). It was observed that patients with fatal outcomes were more frequently transported by ambulance (p<0.05). The most common presenting complaints in patients with methanol poisoning were blurred vision and altered consciousness. While ocular symptoms were most frequently observed in surviving patients, altered consciousness was the most common presenting complaint in deceased patients (p<0.05). Evaluation of vital signs at presentation revealed that patients with fatal outcomes had significantly lower blood pressure and oxygen saturation values, while pulse rate and respiratory rate were significantly higher (p<0.05). When laboratory results of patients with fatal outcomes were evaluated, several parameters including White blood cell (WBC), glucose, blood urea nitrogen (BUN), creatinine, direct bilirubin, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), sodium, potassium, amylase, and C-reactive protein (CRP) levels were found to be significantly higher, while chloride levels were significantly lower compared to surviving patients (p<0.05). The pH and HCO3 values measured in the blood gas of patients with fatal outcomes were significantly lower, while base deficit, anion gap, and lactate levels were significantly higher compared to surviving patients (p<0.05). There was no statistically significant difference in terms of methanol and ethanol levels on mortality (p>0.05). The frequency of brain edema and intracranial hemorrhage on Brain CT was found to be significantly higher in patients with fatal outcomes (p<0.05), while the frequency of brain edema on Brain MRI was significantly higher (p<0.05). There was no statistically significant difference in the optic nerve sheath diameter between surviving and deceased patients (p>0.05). 33.7% of our patients were discharged with visual sequelae and 6.2% with neurological sequelae. Conclusion: In a patient presenting to the emergency department with sudden visual impairment (blindness, blurred vision, double vision, etc.) following the consumption of any alcoholic beverage, especially if accompanied by hyperventilation, altered consciousness, increased anion gap, and base-deficit metabolic acidosis, methanol poisoning should be considered until proven otherwise. Many laboratory parameters and imaging findings, especially arterial blood gas, are predictive of mortality. Unfortunately, although early-presenting patients can be effectively treated, the rates of visual sequelae leading to disability and mortality remain quite high. Keywords: Methanol poisoning, emergency medicine, mortality