A question
A 72-year-old man is brought to a metropolitan emergency department with sudden, severe breathlessness that woke him from sleep two hours earlier. He has a history of hypertension and ischaemic heart disease. He is sitting bolt upright, distressed and diaphoretic, and can speak only in single words. His respiratory rate is 34 breaths/min, oxygen saturation is 86% on room air, heart rate is 112 beats/min and regular, and blood pressure is 198/112 mmHg. He is afebrile. Auscultation reveals widespread fine inspiratory crackles to the mid-zones bilaterally and an audible third heart sound; there is no wheeze. His jugular venous pressure is elevated. An electrocardiogram shows sinus tachycardia with left ventricular hypertrophy and no acute ischaemic changes, and his initial high-sensitivity troponin is mildly elevated. He is placed on high-flow oxygen. His portable chest radiograph is shown.
Which of the following is the most appropriate initial pharmacological management?