Final answer:
In refractory v-fib with CPR in progress after administering epinephrine and an antiarrhythmic, the next step is to give another shock, followed by additional epinephrine every 3-5 minutes.
Step-by-step explanation:
If a patient is in refractory ventricular fibrillation (v-fib), ongoing CPR is crucial, and one dose of epinephrine has already been administered following the second shock. If an antiarrhythmic drug was given after the third shock, the Advanced Cardiovascular Life Support (ACLS) guidelines suggest that if the ventricular fibrillation persists.
After this, if v-fib still persists, it would be appropriate to consider an additional dose of epinephrine every 3-5 minutes and potentially another round of antiarrhythmic drug, or an alternative antiarrhythmic if the first one was unsuccessful.
In addition to medication, ensuring high-quality CPR with minimal interruptions, checking for reversible causes, and following ACLS protocols are key factors in managing refractory v-fib. This includes correcting electrolyte imbalances, considering advanced airway management if not already in place, and continuing defibrillation attempts as indicated.