Subinternship Surgery · Year 4 · from Subinternship Surgery
Case 2: ARDS Management After Aspiration
Clinical Image
Source: Wikimedia Commons - ARDS Chest X-ray - CC BY-SA 3.0
Case Presentation
A 55-year-old woman undergoes emergent laparotomy for small bowel obstruction. Post-extubation in the PACU, she vomits and aspirates gastric contents. She develops progressive hypoxemia over the next 12 hours, requiring re-intubation. CXR shows bilateral diffuse infiltrates. Her P/F ratio (PaO2/FiO2) is 85 on FiO2 1.0 and PEEP 10, meeting Berlin criteria for severe ARDS. The surgical ICU team implements lung-protective ventilation: tidal volume is set at 6 mL/kg of ideal body weight (IBW 60 kg, so Vt = 360 mL), respiratory rate 22 to maintain minute ventilation, and PEEP titrated up to 16 cm H2O per the ARDSNet PEEP/FiO2 table. Plateau pressure is monitored and kept below 30 cm H2O. Despite optimization, her P/F ratio remains less than 100. The team initiates prone positioning: she is positioned prone for 16 hours, then supine for 8 hours, cycling daily. Within 2 days of prone positioning, her P/F ratio improves to 150. Neuromuscular blockade with cisatracurium is used for the first 48 hours to improve ventilator synchrony and reduce oxygen consumption. Conservative fluid management targets even to slightly negative fluid balance after initial resuscitation to reduce pulmonary edema. By day 7, she is back supine full-time with improving oxygenation. She is extubated on day 10 and discharged from ICU on day 14.
Key Learning Points
- Berlin criteria for ARDS: acute onset (within 1 week), bilateral opacities on imaging, not fully explained by cardiac failure/fluid overload, P/F ratio determines severity (mild 200-300, moderate 100-200, severe less than 100)
- Lung-protective ventilation is the cornerstone: low tidal volume (6 mL/kg IBW), plateau pressure less than 30 cm H2O, higher PEEP, permissive hypercapnia (accept pH greater than 7.20)
- Prone positioning for 12-16 hours/day in severe ARDS (P/F less than 150) reduces mortality by improving V/Q matching and recruiting dependent lung
- Conservative fluid management after initial resuscitation improves oxygenation without compromising outcomes