The effect of different ventilation strategies on lung mechanics in the patients with one lung ventilation

Objective: In our study, we compared the effect of different tidal volume (TV) applications on lung mechanics during one lung ventilation. Materials and Methods: Patients scheduled for elective VATS (Video-Assisted Thoracoscopic Surgery), ASA I-II, age between 18-65 years (n=46) were included in this study. Age, gender, weight, height, diagnosis, operation type, pre-op FEV1, pre-op FEV1 / FVC values and history of smoking were recorded preoperatively. Patients divided into 3 groups by computerized randomization method. Anesthesia induction was introduced with 1,5-2 mg/kg 1% propofol and 0,5 mg/kg rokuronyum. All the patients were intubated with double lumen tube and confirmed by fiberoptic bronchoscopy (FOB). During double lung ventilation, all the patients were ventilated as VT 6-8 ml/kg, FiO2 %21-70, PEEP 5 mmHg, frequency 10/dk, I/E:1/2. During the one lung ventilation the patients were ventilated as follows; Grup I: FiO2 %21-70, tidal volume 8 ml/kg, frequency 10/dk, I/E:1/2, PEEP 5 mmHg Grup II: FiO2 %21-70, tidal volume 6 ml/kg, PEEP 5 mmHg, frequency set to be PaCO2 35-45 mmHg Grup III: FiO2: %21-70, tidal volume 4 ml/kg, PEEP 5 mmHg, frequncy set to be PaCO2 35-45 mmHg. Arterial blood gas values were obtained at the beginning of the operation (entry), 10 minutes after the onset of one lung ventilation, 10 minutes after the end of one lung ventilation and 10 minutes after extubation in all groups. Hemodynamic data (HR, MAP, SpO2), respiratory pressures (Ppeak, Pplato, PEEP), arterial blood gas values (PaO2, PaCO2, pH, BE) and FiO2, minute volume (MV), EtCO2, frequency were recorded simultaneously. The duration of extubation, the duration of surgery and the amount of blood products if they were used were recorded. The patients were followed up daily until they were discharged in terms of intensive care need/duration, postoperative complications, discharge time and 28 days mortality. Results: There was no statistically significant difference in arterial oxygenation between the groups as the primary outcome of our study. Although PaCO2 values of entry and the onset of one lung ventilation were significantly higher in the Group II than the other groups, however they were clinically acceptable values (35-45 mmHg). There were no significant differences between the groups in terms of postoperative oxygenation, the length of stay intensive care unit, discharge time, postoperative complications and 28 days mortality. Conclusions: In video assisted thoracoscopic surgery, 4 ml/kg, 6 ml/kg and 8 ml/kg tidal volume applications have similar effects on hemodynamics and pulmonary mechanics provided that the appropriate minute volume is maintained and double lumen tube's location is confirmed with FOB during one lung ventilation. They have not negative effects on hospital stay, intensive care need, mortality and postoperative complication so they can be used safely during one lung ventilation. Key words: Fiberoptic bronchoscope, one lung ventilation, tidal volume, video assisted thoracoscopic surgery,