Soru

Currently admitted to the intensive care unit, a $76$-year-old man with ischemic cardiomyopathy (left ventricular ejection fraction $20\%$) is being managed for a severe heart failure exacerbation. He has been receiving continuous intravenous furosemide for the past four days. Over the last $48$ hours, his net fluid balance is negative $6$ liters. Today, he develops an insidious onset of severe, diffuse abdominal pain. He is grimacing in bed and requesting intravenous analgesia.

Vital signs include a temperature of $37.1^\circ\text{C}$, heart rate of $112$/min (irregularly irregular), blood pressure of $85/55$ mmHg, and respiratory rate of $22$/min. Physical examination reveals a flat, soft abdomen that is surprisingly non-tender to deep palpation. There is no guarding, rigidity, or rebound tenderness. Bowel sounds are diminished.

Laboratory studies are significant for:
Leukocyte count: $16,500/\text{mm}^3$
Blood urea nitrogen: $55 \text{ mg/dL}$
Creatinine: $2.1 \text{ mg/dL}$ (baseline $1.0 \text{ mg/dL}$)
Lactate: $4.8 \text{ mmol/L}$ (Normal: $0.5-2.2 \text{ mmol/L}$)

CT angiography of the abdomen and pelvis demonstrates diffuse, smooth narrowing of the superior mesenteric artery and its primary branches with an alternating pattern of spasm and dilation. No distinct endoluminal filling defects or abrupt vascular cutoffs are visualized. The bowel wall appears mildly thickened, but no pneumatosis intestinalis or free intraperitoneal air is present.

Which of the following is the most appropriate next step in management?