Effect of Intravenous Infusion of Dexmedetomidine Combined with Inhalation of Isoflurane on Arterial Oxygenation and Intrapulmonary Shunt During Single-Lung Ventilation

To investigate the changes in arterial oxygenation and intrapulmonary shunt during one-lung ventilation (OLV) with intravenous infusion of dexmedetomidine combined with isoflurane inhalation. ASA I–II 60 patients aged 18–70 year, undergoing OLV during elective thoracic surgery were randomly allocated to two groups: (1) isoflurane + saline (group NISO, n = 30) and (2) isoflurane + dexmedetomidine (group DISO, n = 30). After induction, anesthesia was maintained with intravenous infusion of remifentanil 0.1–0.2 μg kg^?1 min^?1 and inhalation isoflurane (1.0–2.0 %). In addition, anesthesia was maintained with intravenous infusion of dexmedetomidine 0.7 μg kg^?1 h^?1 in DISO group and saline 0.25 ml kg^?1 h^?1 in NISO group. Bispectral Index values were maintained within 40–60 by changing the concentration of isoflurane in all groups. Arterial blood gas samples and central venous blood gas samples were taken as follows: during two-lung ventilation before OLV and during the first 40 min of OLV. 45 Patients completed the study, with 23 patients in DISO group and 22 patients in NISO group. The two groups were comparable in terms of demographic variables, hemodynamic, PaO₂, Qs/Q_T, end expiration isoflurane and BIS levels during the operation. Compared with patients in the group NISO, there were significant increases with PaO₂, significant decrease with Qs/Q_T, significant decrease with end expiration isoflurane, and significant decrease with HR in the group DISO during the first 40 min of OLV (P < 0.05). Dexmedetomidine infusions decrease the requirement for isoflurane, decrease intrapulmonary shunt, and moderate the change in PaO₂ and may be useful in managing OLV.