The effect of Dexmethmedin on Oxygenation in patient with One lung Ventilation in Thoracic Surgery

Abstract

One-lung ventilation (OLV) is commonly used during thoracic surgery. During OLV, the ventilation of one lung is interrupted, while the perfusion persists that can cause an imbalance of the ventilation/perfusion (V/Q) ratio and hypoxemia. Hypoxic pulmonary vasoconstriction (HPV) is an important protective mechanism by which blood flow is diverted from the nonventilated lung toward a better ventilated region, thereby maintaining adequate arterial oxygenation. On the other hand, anesthetics are among other key factors affecting the contraction of HPV. Therefore, the use of drugs with minimal inhibitory effects on this vital mechanism is of great importance. Dexmedetomidine is a selective agonist of α2 receptors. It is a widely used anaesthetic adjunct. In the last few years, a number of studies have evaluated the effect of Dex on OLV. The results of these studies are markedly variable, Therefore, the aim of this study was to investigate the effect of infusion of Dexmedetomidine on improving oxygenation during OLV among adults undergoing thoracic surgery. Method: A total of 42 patients undergoing OLV under general anesthesia with isoflurane inhalation were randomly categorized into two groups: IV infusion of Dexmedetomidine at 0.9 mg/kg/h (D) and IV infusion of normal saline (N/S). Three arterial blood gas (ABG) samples were obtained throughout the surgery. Hemodynamic parameters, PaO2, and complications at recovery phase were recorded. The collected information was analyzed using SPSS 22. Results: PaO2 was not statistically significant in both groups. Administration of Dexmedetomidine resulted in significant reduction in PaO2 when changing from two-lung ventilation to OLV, where PaO2 reached its minimum value within 10 min following OLV in D group. In D group, the mean hemodynamic variable at 60 minutes following OLV had a significant reduction. The duration of the recovery phase, also complications at the recovery phase decreased significantly in D group.