Lung ultrasound to monitor the development of pulmonary atelectasis in gynecologic oncologic surgery

BACKGROUND: Atelectasis formation is considered the major cause of hypoxemia during general anesthesia (GA). Gynecologic oncologic surgery (GOS) often requires pneumoperitoneum and steep bed angulation that further reduce lung compliance by shifting bowels and diaphragm. The aim of our study was to assess the impact of intraoperative variables on lung aeration using lung ultrasound (LUS) score and their correlation with postoperative oxygenation in women undergoing GOS. METHODS: In this prospective observational study 80 patients scheduled for GOS were enrolled. After three minutes pre-oxygenation, propofol-sufentanil-sevoflurane GA and standard mechanical ventilation (MV) were administered (tidal volume of 8 mL/kg of predicted body weight, FiO(2) 40%, I:E ratio of 1:2 and PEEP 5 cm H2O). A 0-36 LUS score was calculated considering 12 pulmonary areas, and arterial blood gas analysis were performed before GA (T1) and in recovery room (T2). RESULTS: LUS score increased significantly between T1 (1.79 +/- 2.39) and T2 (11.08 +/- 4.40, Delta LUS=9.29 +/- 4.10, P<0.05), mostly in basal and posterior areas. Changes in LUS score correlated significantly with time of MV (r=0.246, P<0.05), cumulative time in TR position (r=0.321, P<0.05) and worsening in oxygenation (Delta PaO2/FiO(2), r=-0.260, P<0.05). Delta LUS score significantly correlated with colloid infusion. The linear regression analysis showed that TR time can predict Delta LUS score (F-1,F-78=8.97, P=0.004). No correlation was found with pneumoperitoneum, apnea time at induction and TR angle. CONCLUSIONS: Aeration loss after GOS detected using LUS correlates with TR time, MV time, colloid infusion and worsening in oxygenation.