Lung-Protective Ventilation: TV, PEEP, Plateau
Critical Care + Pulmonary · 8 min read
ARDSnet established the TV-6 mL/kg standard in 2000. Twenty-five years later, the same principles apply intraoperatively. Three numbers — VT, PEEP, plateau — control ventilator-induced lung injury risk.
Why this matters intraoperatively
Ventilator-Induced Lung Injury (VILI) was once thought to be an ICU problem; we now know that intraoperative tidal volumes >10 mL/kg + zero PEEP cause measurable lung injury within 4-6 hours of surgery. PROVHILO trial (2014) and IMPROVE trial (NEJM 2013) established that lung-protective ventilation intraoperatively reduces postoperative pulmonary complications by ~30-50%. The intervention is free; not using it is malpractice in 2026.
Tidal volume — by IDEAL body weight
Target VT 6-8 mL/kg of IDEAL BODY WEIGHT (NOT total body weight). For 70-kg male IBW: 420-560 mL VT. Use formula IBW (males) = 50 + 2.3 × (height in inches − 60); IBW (females) = 45.5 + 2.3 × (height in inches − 60). Why IBW: lung volume scales with height, not weight. A 150-kg patient with 6-foot height still has the same alveolar surface as a 70-kg patient of the same height. Using TBW would cause volutrauma. The single most common ventilator error is overdosing VT in obese patients.
PEEP — recruit and stay recruited
Start PEEP 5 cm H₂O routine. Increase to 8-10 in obese, supine, Trendelenburg, laparoscopic, or cardiac surgery. Goal: prevent end-expiratory alveolar collapse → maintains FRC, reduces atelectasis, improves V/Q matching. CONTROVERSY: high PEEP (>10) does NOT improve outcomes in routine cases (PROBESE trial), and may impair venous return + increase RV afterload. Routine moderate PEEP (5-8) with periodic recruitment maneuvers (sustained inflation 30 cm H₂O × 30 sec) every 30 minutes restores collapsed lung. Document recruitment + PEEP.
Plateau pressure — the hard ceiling
PLATEAU PRESSURE ≤30 cm H₂O is the limit. Plateau (= alveolar pressure during inspiratory pause) reflects alveolar distention, not airway resistance. If plateau >30: reduce VT, accept permissive hypercapnia (PaCO₂ up to 60-70 OK as long as pH >7.20), increase RR to maintain minute ventilation. Plateau below 30 + PEEP 5-10 + driving pressure (plateau − PEEP) <15 cm H₂O is the goal. Driving pressure is increasingly recognized as the key VILI determinant — Amato NEJM 2015.
Lung-protective ventilation calculator →FiO₂ — minimum effective
Target SpO₂ 92-96% (avoid both hypoxia AND hyperoxia). High FiO₂ (>0.6) accelerates absorption atelectasis and may cause oxidative injury. Most stable cases run at FiO₂ 0.4-0.5 after intubation. Higher (1.0) at induction + emergence + during apneic periods. Pre-cementing in TKA/THA is one of the few times to crank FiO₂ up to 1.0 prophylactically (BCIS prevention). Persistent FiO₂ >0.6 to maintain SpO₂ should trigger re-evaluation: ETT position, mucus plug, atelectasis, pneumothorax, embolism.
Modes — VCV vs PCV vs PRVC
VCV (volume-controlled, constant flow): predictable VT, high peak airway pressures. Default for routine adult cases. PCV (pressure-controlled, decelerating flow): better gas distribution + lower peak pressures, but VT varies with compliance — must monitor closely. PRVC: hybrid — set target VT, ventilator adjusts pressure cycle-by-cycle to deliver target. Modern default for ARDS, pediatric, severe pulmonary disease. Mode matters less than the three numbers above; use what your machine + your habit prefer.
Pearl: the three-number checklist
Every case, before you turn your back on the ventilator, verify: VT 6-8 × IBW. PEEP 5-10 (case appropriate). Plateau ≤30. If all three are within range, you are doing modern protective ventilation. If any are outside, fix it. This single habit reduces postop pulmonary complications more than any drug intervention available.
References
- · ARDSnet ARMA Trial NEJM 2000 (TV 6 mL/kg)
- · IMPROVE NEJM 2013 (intraop lung protection)
- · PROBESE JAMA 2018 (PEEP titration in obese)
- · Amato NEJM 2015 — Driving pressure and ARDS mortality