A 58-year-old man with a history of hypertension and diabetes mellitus is brought to the emergency department after collapsing at home. His wife initiated CPR immediately. On arrival, the monitor shows ventricular fibrillation (VF). After 3 cycles of CPR (2 minutes each) with defibrillation attempts, the rhythm remains VF. The team administers epinephrine 1 mg IV and continues CPR. At the 5-minute mark, the rhythm converts to pulseless electrical activity (PEA). After 2 more minutes of CPR, a weak carotid pulse is palpated. Blood pressure is 65/40 mmHg, heart rate 45/min, respiratory rate 8/min (on bag-mask ventilation). Arterial blood gas shows pH 7.18, PaCO₂ 58 mmHg, PaO₂ 92 mmHg, HCO₃⁻ 18 mEq/L. What is the most appropriate immediate next step in management?