Lightning rounds 68: Setting PEEP in the obese with Olivia Serigano

Setting optimal PEEP for obese patients requires balancing extrinsic chest wall pressure against alveolar recruitment to prevent atelectasis. While esophageal manometry serves as the gold standard for measuring transpulmonary pressure, its limited clinical availability necessitates practical alternatives. Using a simple heuristic—dividing BMI by three—provides a useful baseline for estimating necessary PEEP, though this calculation only aligns with individualized manometry measurements in approximately one-third of cases. Clinicians should utilize this formula as a tool to challenge the dogma of low-PEEP settings, particularly when patients exhibit refractory hypoxemia or small lung volumes. In morbidly obese populations, PEEP levels in the high teens or twenties may be physiologically necessary to overcome external compression. Ultimately, effective ventilation in these patients demands moving beyond standardized, low-pressure protocols toward individualized titration that accounts for specific body habitus and real-time clinical response.