trial to optimizing the values of positive end expiratory pressure to the dependent lung for patients undergoing video-assisted thoracic surgery during one-lung ventilation

This prospective, randomized, controlled study evaluated the effects on oxygenation by applying a selective and patient-specific value of positive end-expiratory pressure [PEEP] to the dependent lung during one-lung ventilation [OLV]. Forty patients undergoing video- assisted thoracic surgery for sympathectomy [VATS] under combined epidural general anesthesia were randomly allocated to receive the preventive application of PEEP, optimized on the best thoraco-pulmonary compliance [group PEEP, n=20], or zero PEEP [group ZEEP, n=20]. Mechanical ventilation was the same setting to all patients of both groups during two- and one-lung ventilation [FIO[2]= 0.5; VT=9 ml/kg, inspiratory: expiratory =1:1, inspiratory pause = 10%]. In this study the Lung-chest wall compliance decreased in both groups during one-lung ventilation, but patients of group PEEP had higher values than patients with no end-expiratory pressure [ZEEP] applied- group ZEEP [at 10minolv and 60 minolv, P<0.05]. During closed chest OLV, the PaO[2] / FiO[2] ratio was similar in the two study groups. After the start of VATS by 10 mm Pa[2]O/FiO[2] ratio was lower in group PEEP than in group ZEEP [P<0001], thereafter, the Pa[2]O/FiO[2] ratio significantly increase in the patients of group PEEP [P<0.0001] at 30 and 60 min after the start of VATS. No differences were reported between the two groups in the need for 100% oxygen ventilation [P=0.60] or re-inflation of the operated lung during VATS [P=0.78]. In conclusion, the selective application of PEEP to the dependent, non-operated lung increases the lung-chest wall compliance during one-lung ventilation, and could improve the patient oxygenation