The initial treatment for an unstable patient with sinus bradycardia and symptoms such as syncope and diaphoresis is administering atropine, as it is an antimuscarinic that increases heart rate and improves stability.
The most appropriate initial treatment for a patient with sinus bradycardia who is unstable and experiencing syncope and diaphoresis is d) Atropine administration. Atropine is an antimuscarinic agent that increases heart rate by blocking vagal effects on the sinoatrial node. It is indicated for the treatment of bradycardia in unstable patients, especially when the condition is affecting their blood pressure and consciousness.
Other options such as adenosine, amiodarone, and amlodipine are not first-line treatments for acute, symptomatic bradycardia. Adenosine is typically used to manage supraventricular tachycardia, amiodarone for ventricular fibrillation or unstable ventricular tachycardia, and amlodipine is a calcium channel blocker with no role in emergency bradycardia management.
So, the priority in treating unstable sinus bradycardia is to address symptomatic effects quickly to reduce the risk of serious complications. Giving atropine is the recommended course of action to temporarily increase the patient's heart rate and stabilize their condition.