Can venous blood gas analysis be used for predicting seizure recurrence in emergency department?

BACKGROUND Epileptic seizures account for 1%-2% of all admissions of patients to the emergency department (ED). The present study aimed to determine whether venous blood pH, bicarbonate, base excess, and lactate levels taken within 1 hour of the last seizure episode help to determine seizure recurrence in emergency departments. METHODS A cross-sectional study was conducted in the emergency department (ED) between January and July, 2012. Patients who were admitted to the emergency department consecutively were included in the study if they were 14 years or older and within 1 hour after last seizure. Demographics, seizure type, use of antiepileptic drugs, observation period at the emergency department, seizure recurrence, pH, bicarbonate, base excess, and lactate levels from venous blood gas analysis were determined. RESULTS A total of 94 patients aged 14 years or older were included in the study. Of these patients, 10.6% (n=10) experienced recurrent seizures in the observation period at the emergency department. To predict recurrent seizures in ED, threshold venous blood gas values were determined as follows: pH<7.245 [sensitivity 80% (95%CI: 44-96), negative predictive value 96.9% (95%CI: 88.3-99.4)], bicarbonate<17.1 mmol/L [sensitivity 80% (95%CI: 44-96), negative predictive value 97% (95%CI: 89-99.5)], base excess<-11.1 mEq/L [sensitivity 80% (95%CI: 44-96), negative predictive value 97% (95%CI: 89-99)], and lactate>7.65 mmol/L [sensitivity 80% (95%CI: 44-96), negative predictive value 96.6% (95%CI: 87-99)]. CONCLUSION If venous blood gas analysis is made on pH, base excess, lactate and bicarbonate immediately one hour after the last epileptic seizure episode, it is possible to predict whether the patient will have seizure recurrence.