Assessment of Blood pH and pCO2 as Predictors of Febrile Seizures in Paediatric Patients: A Cross-sectional Study

Abstract

Introduction: Febrile seizures commonly occur in the age group of six months to five years. Hypocarbia and alkalosis are known to enhance neuronal excitability and promote epileptiform activity. Neuronal excitability and seizure activity are strongly suppressed by various manoeuvre that lead to a decrease in brain pH, including exposure to elevated Carbon Dioxide (CO2) levels, which results in hypercapnia. Aim: To study blood pH and partial pressure of Carbon Dioxide (pCO2) levels in febrile children and to correlate these parameters with the occurrence of febrile seizures. Materials and Methods: This cross-sectional study was conducted in the Department of Paediatrics at Dr. BC Roy Postgraduate Institute of Paediatric Sciences, Kolkata, West Bengal, India, from January 2019 to December 2019. Infants and children aged six months to five years with clinical features compatible with the diagnosis of febrile seizures were enrolled as cases, while children with fever but without convulsions were included as controls. A total of 50 children were selected as cases and 50 as controls. Venous blood gas analysis was performed within one hour and 24 hours after the onset of seizures in cases and one hour after the febrile episode in controls. Data were statistically analysed using t-tests, one-way analysis of variance, Chi-square tests, or Fisher’s exact test. A p-value ≤0.05 was considered statistically significant. Results: The mean age of the febrile seizure cases was 24±16 months, while that of the controls was 31±23 months. Of the cases, 40 (80%) were male and 33 (66%) of the controls were male. The blood pH of cases within one hour of the febrile seizure was (mean±SD) 7.43±0.03 (indicative of respiratory alkalosis) and 24 hours after the febrile seizure, it was 7.41±0.05, showing a significant difference (p=0.017). The blood pCO2 of cases measured within one hour of the febrile seizure was (mean±SD) 30±5 (indicative of hypocapnia), while the pCO2 of controls measured one hour after the febrile episode was 36.5±6.5 mmHg. A significant difference (p<0.0001) was found between these two pCO2 values. Conclusion: Respiratory alkalosis and hypocapnia are associated with febrile seizures. Medical carbogen may be used as treatment or prophylaxis for febrile seizures; however, further studies are required to establish this.

Keywords

• convulsion
• fever
• hypocarbia
• respiratory alkalosis