A patient who underwent a percutaneous, transluminal coronary angioplasty four weeks ago has a subsequent ejection fraction of 30%. The patient returns for a follow-up visit. Examination reveals lungs that are clear to auscultation and slight pedal edema. The patient's medications are digoxin (Lanoxin), furosemide (Lasix), enalapril maleate (Vasotec), and aspirin. The patient reports a 5-lb (2.27-kg) weight gain over the past two days. The cardiac-vascular nurse's initial action is to