A 70-year-old man is hospitalized for new-onset abdominal pain and nausea. He has had little to eat or drink for the past 24 hours. The patient had a cerebrovascular accident 1 year ago and since then has resided in a nursing home. He has long-standing congestive cardiomyopathy, hypertension, type 1 diabetes mellitus with peripheral neuropathy, and chronic kidney disease. He is mostly bedbound but is able to sit in a chair with assistance for several hours each day. Medications are amlodipine, enalapril, furosemide, insulin, and metoprolol.
On physical examination, the patient appears chronically ill. Temperature is 37.7 °C (99.9 °F), blood pressure is 150/85 mm Hg, pulse rate is 80/min, and respiration rate is 12/min. BMI is 21. The sclerae are icteric, and mucous membranes are dry. There are crackles at the bilateral lung bases. Heart examination is significant for an S3 heart sound. The abdomen is moderately distended with diffuse mild tenderness but without rebound or guarding. The liver edge is palpable. There is bilateral pitting edema of the extremities.
The patient's Eastern Cooperative Oncology Group/World Health Organization performance status level is assessed to be 4 (completely disabled, totally confined to a bed or chair, and unable to do any self-care).
The serum albumin level is 2.8 g/dL (28 g/L), the serum total bilirubin level is 2.3 mg/dL (39.3 μmol/L), and the serum creatinine level is 2.6 mg/dL (229.8 μmol/L).
A CT scan of the abdomen without contrast shows hepatomegaly with multiple metastatic lesions, enlarged retroperitoneal lymph nodes, abdominal carcinomatosis, moderate ascites, and a nonobstructing mass lesion in the cecum. A diagnostic paracentesis is performed, and 2 liters of bloody ascitic fluid are removed; cytology samples are positive for adenocarcinoma.
Gentle intravenous hydration is begun, and the patient is given parenteral morphine, which provides adequate relief of pain.
Which of the following is the most appropriate management?