In the particle, selected  patients received standard ACLS, including chest compression, intubation, ventilation, defibrillation, drug administration, including epinephrine and antiarrhythmic drugs if indicated, in the ED. After 10 minutes of ACLS, femoral arterial blood samples were obtained for ABGA from patients who failed to achieve ROSC. Blood samples were analyzed by a point-of-care-testing blood gas analyzer  3,000 analyzer (Patients with severe metabolic acidosis (pH <7.1 or bicarbonate <10 mEq/L) on ABGA were enrolled. 

 Patients fulfilling the study inclusion criteria were randomly assigned (1:1) to the study group, receiving sodium bicarbonate 50 mEq/L, or to the control group, receiving normal saline 50 mL injection over 2 minutes, in a double-blinded fashionThe primary end point was the change of acidosis, evaluated as the pH and bicarbonate levels. The secondary end points were sustained ROSC, defined as the restoration of a palpable pulse ≥20 minutes, survival to hospital admission, and good neurologic survival at 1 and 6 months, defined as cerebral performance category (CPC) 1 or 2; CPC scores are categorized as follows: 1 (no significant impairment), 2 (moderate impairment but able to complete activities of daily living), 3 (severe impairment but conscious), 4 (vegetative state or coma) and 5 (death). The results indicated that the use of sodium bicarbonate improve the acid-base state, while it had no effect on the improvement of the rate of ROSC and good neurologic survival. Among adult non-traumatic OHCA patients with prolonged CPR and severe metabolic acidosis, the use of sodium bicarbonate during CPR with transient hyperventilation improve acid-base status without CO2 elevation which is one of the most concerned adverse effects of sodium bicarbonate administration, but it had no effect on the improvement of the rate of ROSC and good neurologic survival.