ARDS: Lung-Protective Strategy

• Berlin definition: non-cardiogenic bilateral infiltrates appearing ≤1 wk after the insult, with PaO₂/FiO₂ ≤300 while on PEEP ≥5 — mild 200–300, moderate 100–200, severe <100; the 2024 global definition also accepts HFNO ≥30 L/min and SpO₂:FiO₂ ≤315.
• Ventilate at VT 6 mL/kg PBW, plateau ≤30, driving pressure ≤15; accept permissive hypercapnia (pH >7.25).
• When P/F <150, prone ≥16 h/day; run conservative fluids post-resuscitation; neuromuscular blockade is conditional, only for dyssynchrony — not routine.
• Refer early for VV-ECMO in refractory disease (P/F <80, pH <7.25).

Ventilator Strategies in Acute Lung Injury/ARDS

• ARDS diagnosis (Berlin criteria): bilateral infiltrates ≤1 week after insult, not due to cardiac failure, PaO₂/FiO₂ ≤300 on PEEP ≥5
• PBW (predicted body weight): men 50 + 2.3 kg for every inch above 5 ft; women 45.5 + 2.3 kg for every inch above 5 ft
• Start tidal volume at 6 mL/kg PBW (acceptable range 4–8 mL/kg PBW); adjust based on plateau pressure (target ≤30 cmH₂O) and patient tolerance
• Set rate to hold minute ventilation (≤35/min); begin FiO₂ 100%, then adjust via PEEP/FiO₂ table targeting SpO₂ 88–95% (PaO₂ 55–80 mm Hg)
• Plateau >30 cm H₂O?
• Lower tidal volume in 1 mL/kg steps, down to a floor of 4 mL/kg PBW
• VT <6 mL/kg with plateau <25 cm H₂O and no breath-stacking/dyssynchrony → VT may go up by 1 mL/kg
• Target arterial pH 7.30–7.45: pH <7.30 → raise RR (max 35); if pH <7.15 → optimize ventilation first (raise RR up to 35/min if appropriate, check ventilator settings, reduce dead space if possible) — bicarbonate is not routinely recommended for respiratory acidosis from permissive hypercapnia
• Targets: plateau ≤30 cm H₂O · SpO₂ 88–95% · pH 7.30–7.45 · prone if PaO₂/FiO₂ <150

Fluid Strategies in Acute Lung Injury/ARDS

• After initial resuscitation, run a CONSERVATIVE (dry) fluid strategy in ARDS — FACTT showed shorter ventilator time with no mortality penalty
• MAP ≥65 mm Hg without vasopressors?
• Fluids / vasopressors
• Assess fluid responsiveness with dynamic indices — passive leg raise with CO change ≥10%, pulse pressure variation, or a mini-fluid challenge — NOT with CVP
• Fluid responsive AND hypoperfused (oliguria, rising lactate, mottling)?
• Fluid bolus: balanced crystalloid 250–500 mL over 10–20 min, then reassess; consider PRBC if anemic
• No further fluids
• Once perfusion is adequate and the patient is stable: diurese (furosemide 20 mg IV, titrate) and/or restrict fluids, aiming for an even-to-negative balance
• The 2006 FACTT CVP-based cell protocol is historical — CVP does not guide fluid management; dynamic indices do