Evaluation of respiratory parameters in thoracic surgery operations with one lung ventilation

In recent years, for improving oxygenation and prevention of barotrauma during one lung ventilation (OLV) there are different studies about pressure or volume controlled mode, which one of it's available and more advantageous. Although there is no certainty of winning an opinion, lately, PCV-VG mode in which combines the advantages of PCV and VCV are attracting the attention of the anesthesiologist. We aimed to find out which one of the two modes, VCV and PCV-VG provides better respiratory and hemodynamic data, intraoperatively, in patients with OLV in thoracic surgery under low tidal volume and FiO2. ASA I-II, 18-90 age, BMI <40 of 70 patients were included in a prospective randomized clinical trials. Patients were ventilated by VCV mode with the ventilator settings of FiO2 0,5, TV 6-8 mLkg-1, thirthy minutes period before OLV (TLV1). Patients were divided into two groups during the OLV. In the first group (Group VCV) ventilator settings were VCV mode, FiO2 0,7-0,8, TV 5 mLkg-1and in the second group (Group PCV-VG) were PCV-VG mode FiO2 0,7-0,8, TV 5 mLkg-1. After OLV, beginnig of TLV (TLV2) initial ventilator settings with VCV were applied and followed for 30 min. At the beginning of all periods respiratory rate have been determined as 12, but was changed to be held ETCO2 between 30-35 mmHg. At regular intervals throughout the study, hemodynamic data, respiratory parameters and arterial blood gas analysis was performed. During OLV with PCV-VG mode, we found Ppeak significantly lower at 20th and 30th min and compliance significantly higher 10th and 60th minutes,also. Although there was no significant difference about oxygenation between the two groups, in PCV-VG group PaCO2 levels were determined significantly lower in TLV2 at 20th and 30th min. As a result; although clinically the PCV-VG mode isn't demonstrable superiority to VCV, may be an alternative method. On this issue with further study, in selected patients especially with high airway pressure, the comparision of two mode may give more meaningful results.