ARDS in the surgical patient — define, ventilate, rescue with the trials

Examiner probes

1. Define him by Berlin — band, mortality, and what you must exclude before the label sticks.^[1][20]
2. His ventilator reads 9 mL/kg actual weight with plateau 31. Reset it with trial numbers, then tell me about driving pressure.^[3][15]
3. He meets P/F below 150, pressors are off, fluids are +7 L. Prone, fluids, steroids — with numbers.^{[4][12][14][11]}
4. He is synchronous but the registrar wants routine cisatracurium, and the family asks when ECMO enters. Answer both with the trials.^[9][10][5]

Model responses

1. Moderate ARDS — 32% band — after excluding the postoperative mimics. Three Berlin hypoxemia bands with the 27/32/45 mortality ladder; P/F 124 is moderate at 32%.^[1] Before committing: overload (+7 L needs echo/volume assessment), atelectasis, cardiac failure, embolism — postoperative ARDS forms 42% of intubated ARDS yet its mimics dominate early films, and LUNG SAFE shows half of mild disease is missed so screen protocolised.^[20][2]

2. 6 mL/kg predicted weight, plateau 30 ceiling, then minimise driving pressure. ARDSNet: 861 patients, 12 vs 6 mL/kg with plateau 50 vs 30 — death 31.0% vs 39.8% with more ventilator-free days.^[3] His 9 mL/kg actual weight with plateau 31 is the exact error ARDSNet retired. Then compute driving pressure: best risk variable, +7 cm H2O carrying RR 1.41 even under protective settings, with VT/PEEP counting only through it.^[15]

3. Prone 16+ hours, dry the lung, dexamethasone 20-to-10. He matches PROSEVA entry (P/F below 150 on FiO2 0.6+ with PEEP 5+): prone sessions of at least 16 hours cut 28-day death 16.0% vs 32.8% (HR 0.39) with 90-day 23.6% vs 41.0%.^[4] Pressors off means FACTT-dry now: conservative fluids added ventilator-free days (14.6 vs 12.1) without shock or renal cost, and the surgical 244 gained ventilator-free and ICU-free days dry.^[12][14] Established moderate disease at 48 hours earns dexamethasone 20 mg daily x5 then 10 mg x5: 60-day death 21% vs 36% with balanced harms.^[11]

4. No routine blockade; ECMO by EOLIA thresholds with early referral. ACURASYS (340 early severe, 48 h cisatracurium, adjusted HR 0.68, no extra paresis) versus ROSE (1006 patients, stopped second interim for futility at 42.5% vs 42.8% with less activity and more cardiovascular events) — routine early blockade is not supported; reserve it for dyssynchrony, which he lacks.^[9][10] ECMO enters at very-severe refractory thresholds (P/F below 50 for 3+ hours, below 80 for 6+ hours, or acidemia with hypercapnia): EOLIA was 35% vs 46% (RR 0.76, ns) with 28% crossover — so refer early to an ECMO centre rather than declaring futility or improvising rescue.^[5]