Final answer:
The therapy that is now indicated for the patient is epinephrine 2 to 10 mcg/min. Atropine has already been administered and failed to increase the heart rate. Epinephrine is a sympathomimetic drug that acts on beta-1 adrenergic receptors to increase heart rate and cardiac output.
Step-by-step explanation:
The therapy that is now indicated for the patient with sinus brady, a failed transthoracic pacemaker, confusion, and low blood pressure is epinephrine 2 to 10 mcg/min (Option B).
The patient's condition indicates a state of hemodynamic instability due to sinus bradycardia and hypotension. Atropine was already administered, but it failed to increase the heart rate. Therefore, the next appropriate therapy is to initiate a continuous infusion of epinephrine. Epinephrine is a sympathomimetic drug that acts on beta-1 adrenergic receptors in the heart to increase heart rate and cardiac output. The recommended dose range for epinephrine infusion in this situation is 2 to 10 mcg/min, titrated based on the patient's response.
Other options in the question, such as atropine 1 mg (Option A), adenosine 6 mg (Option C), and NS 250 mL to 500 mL bolus (Option D), are not appropriate for the patient's current condition and would not address the underlying cause of the bradycardia and hypotension.