Double-lumen endotracheal tubes and bronchial blockers exhibit similar lung collapse physiology during lung isolation

Purpose Double-lumen endotracheal tubes (DL-ETT) and bronchial blockers (BB) are frequently used to allow one-lung ventilation (OLV) during video-assisted thoracic surgery (VATS). Recently, faster lung collapse has been documented with a BB than with a DL-ETT. The physiologic mechanisms behind this faster collapse remained unknown. We aimed to measure ambient air absorption (V resorb ) and intra-bronchial pressure (P airway ) into the non-ventilated lung during OLV using DL-ETT and BB. Methods Patients undergoing VATS and OLV for lung resection were randomly assigned to have measurements made of V resorb or P airway within the non-ventilated lung using either a DL-ETT or BB. Results Thirty-nine patients were included in the analyses. The mean (standard error of the mean [SEM]) V resorb was similar in the DL-ETT and BB groups [504 (85) vs 630 (86) mL, respectively; mean difference, 126; 95% confidence interval [CI], -128 to 380; P = 0.31]. The mean (SEM) P airway became progressively negative in the non-ventilated lung in both the DL-ETT and the BB groups reaching [-20 (5) and -31 (10) cmH 2 O, respectively; mean difference, -11; 95% CI, -34 to 12; P = 0.44] at the time of the pleural opening. Conclusions During OLV before pleural opening, entrainment of ambient air into the non-ventilated lung occurs when the lumen of the lung isolation device is kept open. This phenomenon is prevented by occluding the lumen of the isolation device before pleural opening, resulting in a progressive build-up of negative pressure in the non-ventilated lung. Future clinical studies are needed to confirm these physiologic results and their impact on lung collapse and operative outcomes. Trial registration www.clinicaltrials.gov (NCT02919267); registered 28 September 2016.