PEEP guided by electrical impedance tomography during one-lung ventilation in elderly patients undergoing thoracoscopic surgery

Background: To examine the influence of positive end-expiratory pressure (PEEP) settings on lung mechanics and oxygenation in elderly patients undergoing thoracoscopic surgery. Methods: One hundred patients aged >65 years were randomly allocated into either the PEEP5 or the electrical impedance tomography (EIT) group (PEEP EIT ). Each group underwent volume-controlled ventilation (tidal volume 6 mL/kg predicted body weight) with the PEEP either fixed at 5 cmH 2 O or set at an individualized EIT setting. The primary endpoint was the ratio of the arterial oxygen partial pressure to the fractional inspired oxygen (PaO 2 /FiO 2 ). The secondary endpoints included the driving pressure, and dynamic respiratory system compliance (C dyn ). Other outcomes, such as the mean airway pressure (P mean ), mean arterial pressure (MAP), lung complications and the length of hospital stay were explored. Results: The optimal PEEP set by EIT was significantly higher (range from 9–13 cmH 2 O) than the fixed PEEP. PaO 2 /FiO 2 was 47 mmHg higher (95% CI: 7–86 mmHg; P=0.021), C dyn was 4.3 mL/cmH 2 O higher (95% CI: 2.1–6.7 cmH 2 O; P 2 O lower (95% CI: 2.2–5.1 cmH 2 O; P EIT group than in the PEEP5 group. At 1 h during OLV, PaO 2 /FiO 2 was 93 mmHg higher (95% CI: 58–128 mmHg; P dyn was 4.4 mL/cmH 2 O higher (95% CI: 1.9–6.9 mL/cmH 2 O; P=0.001), and the driving pressure was 4.9 cmH 2 O lower (95% CI: 3.8–6.1 cmH 2 O; P EIT group than in the PEEP5 group. PaO 2 /FiO 2 was 107 mmHg higher (95% CI: 56–158 mmHg; P EIT group than in the PEEP5 group during double-lung ventilation at the end of surgery. Conclusions: PEEP values determined with EIT effectively improved oxygenation and lung mechanics during one lung ventilation in elderly patients undergoing thoracoscopic surgery.