Peak Airway Pressure and Arterial Blood Gas Analysis Following Variable Tidal Volume and Respiratory Rate during One Lung Ventilation

Abstract

Background: One lung ventilation (OLV) offers special advantages such as good surgical exposure, prevention from contamination of intact down lung, prevention of bleeding from the lung to the noninvolved lung, etc. during many types of thoracic surgery including video-assisted thoracoscopic surgery (VATS). However, it has the disadvantage of possible hypoxemia due to an inevitable shunt. In general, the tidal volume (TV) has been known to have little influence on arterial oxygenation during OLV. The purpose of this study was to examine the changes in peak airway pressure (PAP) and arterial blood gas analysis (ABGA) following a variable TV and respiratory rate (RR) during OLV. Methods: Twenty-one spontaneous pneumothorax patients scheduled for a VATS were selected randomly. Patients were anesthetized with -air-isoflurane (Fi 60%)-vecuronium after 35F-37F double lumen endotracheal tube intubation. Patient data (PAP, ABGA) was checked after two lung ventilation (: 10 ml/kg TV and 12 f/min RR), OLV (: 10 ml/kg TV and 12 f/min RR), OLV (: 8 ml/kg TV and 12 f/min RR) and OLV (: 8 ml/kg TV and 14 f/min RR) in 20 minutes interval. Patient data between groups was compared and analyzed statistically. Results: The PAP of (31 4.3 cm), (27 4.2 cm) and (28 4.3 cm) were significantly higher than (20 2.9 cm). Pa of (132 26.3 mmHg), (101 11.8 mmHg) and (114 13.1 mmHg) were significantly lower than (302 33.5 mmHg), and values were lower than significantly. However, the Sa of all tests were over 98% during OLV. Only the PaC of (45 4.1 mmHg) was higher than (38 3.8 mmHg) and (40 5.5 mmHg) significantly. Changes of End-tidal C (EtC) were insignificant between TLV and OLV. Conclusions: In terms of OLV, comparing 10 ml/kg TV to 8 ml/kg TV showed an advantage of decreasing PAP but disadvantages of decreasing Pa and increasing PaC. So, 8 ml/kg TV during OLV may need corrections of RR following a patient's status.