A client in the cardiac unit is on a continuous telemetry monitor. The nurse observes the rhythm suddenly change to a wide-complex, rapid, regular rhythm at 180 bpm. The client is now unresponsive. What is the PRIORITY?

PULSELESS VENTRICULAR TACHYCARDIA or VENTRICULAR FIBRILLATION is a shockable cardiac arrest rhythm requiring immediate CPR and defibrillation. RECOGNITION: Wide-complex tachycardia (QRS wider than 0.12 seconds) at 180 bpm + unresponsive client = likely PULSELESS VT or VF; do not waste time trying to perfectly identify the rhythm before acting — the patient is in cardiac arrest. ACLS ALGORITHM for pulseless VT/VF: (1) CALL for help immediately / activate Code Blue; (2) Start HIGH-QUALITY CPR — 30 compressions : 2 breaths; compressions at 100-120/min, depth 2-2.4 inches, full chest recoil, minimise interruptions; (3) DEFIBRILLATE AS SOON AS POSSIBLE — biphasic 120-200J (or device-recommended); monophasic 360J; (4) Resume CPR immediately after shock (2 minutes); (5) IV/IO access; (6) EPINEPHRINE 1 mg IV/IO every 3-5 minutes; (7) AMIODARONE 300 mg IV/IO for pulseless VT/VF refractory to defibrillation; (8) Identify and treat REVERSIBLE CAUSES (Hs and Ts: Hypovolemia, Hypoxia, Hydrogen ion/acidosis, Hypo/hyperkalaemia, Hypothermia; Tension pneumothorax, Tamponade, Toxins, Thrombosis — pulmonary/coronary). TIME MATTERS: Every 1-minute delay in defibrillation for VF reduces survival by 7-10%. Chest compressions maintain perfusion until defibrillation is possible.