Effects of thoracic epidural anaesthesia on pulmonary venous admixture and oxygenation during one-lung ventilation.

Background:  In this clinical randomized study, the effects of four anaesthesia techniques during one-lung ventilation [total intravenous anesthesia (TIVA) with or without thoracic epidural anaesthesia (TEA) (G-TIVA-TEA and G-TIVA), isoflurane anaesthesia with or without TEA (G-ISO-TEA and G-ISO)] on pulmonary venous admixture (Qs/Qt) and oxygenation (OLV) were investigated. Methods:  In 100 patients (four groups, 25 patients in each) undergoing thoracotomy, a thoracic epidural catheter was inserted pre-operatively. In G-TIVA-TEA and G-ISO-TEA, bupivacaine 0.1% + 0.1 mg/ml morphine was administered intra-operatively (10 ml of first bolus + 7 ml/h infusion). Propofol infusion or isoflurane concentration was adjusted to keep a bispectral index (BIS) of between 40 and 50 in all groups. FiO2 was 0.8 during OLV and 0.5 before and after OLV. Partial arterial and central venous oxygen pressures (PaO2 and PvO2), arterial and venous oxygen saturations and Qs/Qt values were recorded before, during and after OLV. Results:  During OLV, PaO2 was significantly higher and Qs/QT significantly lower in G-TIVA-TEA and G-TIVA compared with G-ISO-TEA and G-ISO (PaO2: 188 ± 36; 201 ± 39; 159 ± 33; 173 ± 42 mmHg, respectively; Qs/Qt: 31.2 ± 7.4; 28.2 ± 7; 36.7 ± 7.1; 33.7 ± 7.7%, respectively). No statistical changes were observed in patients with TEA compared with without TEA in any measurement. Conclusion:  During OLV, TEA does not significantly affect the oxygenation and Qs/Qt and can be used safely regardless of whether TIVA or inhalation techniques are used.