A 62-year-old man (80 kg) is admitted to the critical care unit for septic shock. He is receiving assist-control ventilation and a continuous norepinephrine infusion at 0.1 mcg/kg/min via a central venous catheter. His current vital signs are blood pressure 85/50 mm Hg, heart rate 120/min, and temperature 38.1 °C. During evening rounds, the nurse reports new-onset, large-volume hematochezia. Over the past 6 hours his hemoglobin has dropped from 9.8 g/dL to 7.1 g/dL despite ongoing resuscitation. Which of the following is the MOST likely primary underlying pathophysiological mechanism contributing to this patient’s bleeding?

A 72-year-old man with a history of hypertension and coronary artery disease is admitted to the medical ICU with septic shock. He is mechanically ventilated, receiving norepinephrine at 0.15 µg/kg/min via a right internal jugular central line, and has received 2 L of crystalloid without sustained improvement in mean arterial pressure (current MAP 58 mm Hg). Overnight, he develops bright red hematochezia and his hemoglobin falls from 10.5 g/dL on admission to 7.8 g/dL. Lactate is 4.2 mmol/L, heart rate 115 bpm, and he remains hypotensive despite vasopressors. After transfusing one unit of packed red blood cells, which of the following is the most appropriate next diagnostic step?

A 62-year-old man is admitted to the ICU for refractory septic shock on vasopressin infusion and pressure support ventilation. He has a central line for medications. On rounds, the nurse notes new-onset melena. Vital signs are stable (BP 110/70 mmHg, HR 88 bpm, SpO₂ 96% on 40% FiO₂). Hemoglobin is 9.8 g/dL (baseline 10.2 g/dL). There is no prior history of GI bleeding. Given current guideline definitions of clinically significant GI bleeding in critically ill patients, what is the most appropriate initial interpretation of this melena?

A 72-year-old man with hypertension and diverticulosis presents after two episodes of large-volume, bright red blood per rectum over three hours. His initial vital signs are heart rate 105 bpm, blood pressure 105/65 mmHg, and respiratory rate 18 breaths/min. After 2 L of IV crystalloid, his heart rate improves to 92 bpm and blood pressure to 120/75 mmHg. His hemoglobin is 9.8 g/dL. Given his presentation and hemodynamic response, what is the most appropriate timing for colonoscopy?

A 65-year-old man (weight 75 kg) is in the intensive care unit for septic shock. He is intubated, receiving mechanical ventilation, and on a norepinephrine infusion. Overnight, he develops multiple large-volume, maroon-colored stools. His blood pressure is 88/52 mmHg (MAP 64 mmHg), and heart rate is 118 bpm. Six hours ago his hemoglobin was 9.8 g/dL; the new value is 7.2 g/dL. Which of the following is the most appropriate immediate action?

A 68-year-old man is admitted to the critical care unit for severe sepsis secondary to pneumonia, currently on assist-control mechanical ventilation with a continuous norepinephrine infusion through a central venous catheter. On hospital day 3, he develops new-onset hematochezia, with approximately 500 mL of bright red blood per rectum over 4 hours. His hemoglobin drops from 9.8 g/dL to 7.5 g/dL. Coagulation studies are within normal limits. A rapid colonoscopy is performed, which reveals no active bleeding source or definitive lesions in the colon. The patient remains hemodynamically unstable despite fluid resuscitation and continues to have intermittent hematochezia. Given the patient’s clinical presentation and initial diagnostic findings, which of the following is the most appropriate next step to identify the source of bleeding?

A 62-year-old man in the intensive care unit for severe pneumonia is intubated and receiving mechanical ventilation. He is on a continuous norepinephrine infusion for blood pressure support. During evening rounds, he is noted to have new-onset hematochezia. His blood pressure is 88/52 mmHg (MAP 64 mmHg) and heart rate is 118 bpm. A stat hemoglobin is 7.1 g/dL, down from 9.8 g/dL this morning. He received 2 units of packed red blood cells and requires further transfusion to maintain a target hemoglobin of 7–9 g/dL. Which of the following best classifies this bleeding event?

A 62-year-old male is in the intensive care unit for acute respiratory failure secondary to pneumonia. During morning rounds, the nurse reports a large volume of maroon-colored stool. His vital signs are stable: BP 118/72 mmHg, HR 88 bpm, RR 16 breaths/min, SpO₂ 96% on FiO₂ 0.4. Laboratory results show hemoglobin 6.5 g/dL (down from 10.2 g/dL the previous day), platelet count 180,000/mm³, and INR 1.1. He has no history of cardiovascular disease. Considering this hemodynamically stable patient with acute lower gastrointestinal bleeding, what is the MOST appropriate hemoglobin transfusion goal?

A 72-year-old man with end-stage renal disease on hemodialysis and severe aortic stenosis presents with ongoing melena and right colonic bleeding. Colonoscopy reveals multiple dilated, tortuous vascular lesions consistent with angiodysplasia in the ascending colon. Despite endoscopic argon plasma coagulation, he continues to have brisk bleeding and requires recurrent transfusions. Which pharmacologic agent should be used as adjunctive first-line therapy to reduce rebleeding risk?

A 65-year-old man with septic shock is on mechanical ventilation and a continuous norepinephrine infusion via a central line. He receives standard stress ulcer prophylaxis with pantoprazole. During evening rounds he has new-onset bright red hematochezia. Over the past 6 hours his hemoglobin has fallen from 9.8 to 7.2 g/dL, and his mean arterial pressure has decreased from 75 to 60 mmHg despite stable vasopressor dosing. Nasogastric tube aspiration returns clear, nonbilious fluid. Laboratory studies show an INR of 1.1 and platelet count of 200,000/µL. He has no history of peptic ulcer disease or chronic liver disease. He has received one unit of packed red blood cells; a restrictive transfusion threshold (hemoglobin <7 g/dL) is being used. Which of the following is the most appropriate pharmacotherapeutic approach at this time?