A 52-year-old man, 12 hours after pancreatic abscess drainage, is intubated with FiO2 100%, tidal volume 1000 mL, PEEP 2.5 cm H2O; O2 saturation remains low and arterial blood gas shows acidosis. What is the next step in management?

A 52-year-old man, 12 hours after pancreatic abscess drainage, is intubated with FiO2 100%, tidal volume 1000 mL, PEEP 2.5 cm H2O; O2 saturation remains low and arterial blood gas shows acidosis. What is the next step in management?

• A. Increase FiO2
• B. Increase PEEP
• C. Increase tidal volume
• D. Decrease PEEP

Answer: (B)

When a mechanically ventilated patient stays hypoxemic despite 100% FiO2, the issue is often alveolar collapse and shunt from derecruitment. The PEEP is very low here (2.5 cm H2O), so keeping alveoli open at end expiration is not happening, leading to poor oxygenation. Increasing PEEP raises mean airway pressure, promotes alveolar recruitment, improves ventilation–perfusion matching, and raises the oxygenation and helps correct the acidosis caused by hypoxemia. Raising FiO2 further isn’t possible beyond 100%, and the tidal volume is already high—raising it further risks volutrauma without reliably solving the recruitment problem. Decreasing PEEP would worsen derecruitment and oxygenation. So the best next step is to increase PEEP to recruit collapsed lung units and improve oxygenation. Monitor for potential hemodynamic effects as PEEP increases.

When a mechanically ventilated patient stays hypoxemic despite 100% FiO2, the issue is often alveolar collapse and shunt from derecruitment. The PEEP is very low here (2.5 cm H2O), so keeping alveoli open at end expiration is not happening, leading to poor oxygenation. Increasing PEEP raises mean airway pressure, promotes alveolar recruitment, improves ventilation–perfusion matching, and raises the oxygenation and helps correct the acidosis caused by hypoxemia.

Raising FiO2 further isn’t possible beyond 100%, and the tidal volume is already high—raising it further risks volutrauma without reliably solving the recruitment problem. Decreasing PEEP would worsen derecruitment and oxygenation. So the best next step is to increase PEEP to recruit collapsed lung units and improve oxygenation. Monitor for potential hemodynamic effects as PEEP increases.