To prevent a Valsalva maneuver in a client recovering from an acute myocardial infarction, the nurse would:

Administering stool softeners daily as prescribed is essential to prevent straining during defecation, which can lead to a Valsalva maneuver. Straining can increase intra-abdominal pressure, hinder venous return, and elevate blood pressure, risking cardiac complications in a client recovering from a heart attack. Using a bedside commode might be useful to minimize exertion during toileting but does not directly address the risk of a Valsalva maneuver. Administering antidysrhythmics PRN is not the primary intervention for preventing a Valsalva maneuver; these medications are used to manage dysrhythmias if they occur. Keeping the client on strict bed rest is not the best option as early mobilization is encouraged in post-myocardial infarction recovery to prevent complications such as deep vein thrombosis and muscle weakness.