Correlation between Arterial Blood Gas Parameters (PH, PaO2, PaCO2, and HCO3) and the Severity of Bronchiolitis

Background: Bronchiolitis is a major cause of lower respiratory tract infections and hospitalizations in infants, particularly under two years of age.Accurate severity assessment is crucial for informing treatment decisions, optimizing resource utilization, and preventing complications.Although oxygen saturation is routinely monitored, the clinical relevance of arterial blood gas (ABG) parameters such as pH, PaO, PaCO, and HCO in assessing disease severity remains uncertain.This study aims to evaluate the correlation between arterial blood gas (ABG) parameters and the clinical severity of bronchiolitis in children. Methods:This cross-sectional observational study was conducted at the Pediatric Ward, Chattogram Maa-Shishu O General Hospital from January to July 2015.Fifty children aged 2 months to 2 years, diagnosed clinically with bronchiolitis, were included in this study.Participants were stratified into moderate and severe categories based on clinical signs and oxygen saturation levels.Demographic and clinical data, including pulse oximetry and arterial blood gas (ABG) results, were collected using a structured questionnaire.Statistical analysis was performed using SPSS version 19.0, with significance set at p<0.05. Results:The mean age of the participants was 5.21 1.90 months.Of the 50 children, 35 (70%) were male and 15 (30%) were female.Twenty-eight (56%) had moderate bronchiolitis, while 22 (44%) had severe disease.Hypoxemia (SpO <90%) was observed exclusively in the severe group.Although abnormal arterial blood gas findings-including low PaO, altered pH, and reduced HCO-were more frequent in severe cases, the differences in pH (p=0.503),PaO (p=0.432),PaCO (p=0.453), and HCO (p=0.231) were not statistically significant between severity groups. Conclusion:Arterial blood gas parameters did not show a significant correlation with bronchiolitis severity.Clinical assessment and pulse oximetry remain the most reliable tools for severity evaluation in pediatric bronchiolitis.