Oesophageal Pressure As A Surrogate Of Pleural Pressure In Mechanically Ventilated Patients

Background: Oesophageal pressure (P-oes) is used to approximate pleural pressure (P-pl) and therefore to estimate transpulmonary pressure (P-L). We aimed to compare oesophageal and regional pleural pressures and to calculate transpulmonary pressures in a prospective physiological study on lung transplant recipients during their stay in the intensive care unit of a tertiary university hospital.Methods: Lung transplant recipients receiving invasive mechanical ventilation and monitored by oesophageal manometry and dependent and nondependent pleural catheters were investigated during the post-operative period. We performed simultaneous short-time measurements and recordings of oesophageal manometry and pleural pressures. Expiratory and inspiratory P-L were computed by subtracting regional P-pl or P-oes from airway pressure; inspiratory P-L was also calculated with the elastance ratio method.Results: 16 patients were included. Among them, 14 were analysed. Oesophageal pressures correlated with dependent and nondependent pleural pressures during expiration (R-2=0.71, p=0.005 and R-2=0.77, p=0.001, respectively) and during inspiration (R-2=0.66 for both, p=0.01 and p=0.014, respectively). P-L values calculated using P-oes were close to those obtained from the dependent pleural catheter but higher than those obtained from the nondependent pleural catheter both during expiration and inspiration.Conclusions: In ventilated lung transplant recipients, oesophageal manometry is well correlated with pleural pressure. The absolute value of P-oes is higher than P-pl of nondependent lung regions and could therefore underestimate the highest level of lung stress in those at high risk of overinflation.