Final answer:
The initial dose for synchronized cardioversion in patients with unstable tachycardia and a narrow QRS complex is typically 50-100 joules, with higher energies used for refractory cases or different types of tachycardia.
Step-by-step explanation:
In a patient with unstable tachycardia and a narrow QRS complex, the recommended initial dose for synchronized cardioversion is typically 50-100 joules. For refractory cases, the energy level might be increased. Proper patient assessment and treatment are imperative since tachycardia may lead to significant hemodynamic compromise. Defibrillation differs from synchronized cardioversion as it is an unsynchronized shock used in the event of cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia and typically starts at higher energies like 120-200 joules for biphasic defibrillators or 360 joules for monophasic defibrillators.
It's important to note that medication may be used in concert with or in lieu of electrical cardioversion, depending on the specifics of the clinical scenario. Health professionals are trained to follow algorithms provided by the American Heart Association (AHA) and Advanced Cardiac Life Support (ACLS) guidelines to determine the best course of action in treating arrhythmias such as unstable tachycardia.