Final answer:
The recommended initial dose of atropine for an adult with symptomatic sinus bradycardia and signs of poor perfusion is 0.5 mg intravenously, which may be repeated as needed.
Step-by-step explanation:
A patient presenting with sinus bradycardia and a heart rate of 43 beats per minute (bpm), accompanied by diaphoresis (sweating) and hypotension (low blood pressure) at 80/60 mmHg, is experiencing significant symptomatic bradycardia. In such cases, the initial treatment involves the administration of atropine. The recommended initial dose of atropine for an adult with symptomatic bradycardia is 0.5 milligrams (mg), administered intravenously, which may be repeated every 3 to 5 minutes as needed, not to exceed a total dose of 3 mg.