ABSTRACT
Background:
Carbon monoxide (CO) a silent killer is recognized as a major health threat in clinical toxicology that can result in neurological sequelae or even death. Among survivors of CO poisoning, 15–40% may experience long-term neurological and neuropsychiatric effects leading to brain damage. The neutrophil-to-lymphocyte ratio (NLR) is an inflammatory indicator generated from peripheral blood, indicating the equilibrium between systemic inflammation as well as immunological response.

Objectives:
This work aims to study the hematological parameters as outcome predictors in patients who were acutely poisoned by CO and admitted to Tanta University Poison Control Center (TUPCC), Egypt.
Methodology:
The data of the patients of this study were collected from the medical files including demographic Information, symptoms at the time of admission, Electrocardiogram (ECG) and laboratory tests complete blood count (CBC) with differential, renal and liver function tests, random blood glucose and arterial blood gases). Carboxyhemoglobin levels were measured using oximetry. Utilizing hyperbaric oxygen (HBO2) therapy, ICU admission, total length of hospitalization and follow-up findings were studied.
Results:
Poor outcomes of acutely CO-intoxicated patients were statistically significantly associated with sinus tachycardia, ICU admission, longer hospital stay, low GCS, lower O2 saturation and higher COHb level (P value< 0.005). Regarding CBC, a significantly increased white blood cell (WBC) count, mean neutrophil count and neutrophil-lymphocyte ratio (NLR) were linked to poor outcomes. Conversely, significantly lower lymphocyte count and platelet volumes were detected. Based on the ROC curves, NLR showed the most significant studied indicator of poor outcome (100.0% sensitivity, 100.0% specificity, and 1.00 area under the curve), while lymphocyte count displayed the weakest diagnostic capability (80.0% sensitivity, 68.9% specificity and 0.790 area under the curve).
Conclusion:
CBC Differential is a simple and cost-effective laboratory test that is routinely performed in most laboratories. Combining CBC data with clinical findings enhances the ability to predict outcomes in acute CO poisoning and identify patients requiring ICU admission and HBO2 therapy. NLR was a significant predictor of poor clinical outcomes of CO Poisoning.