Effect of Dexmedetomidine Combined with Inhalation of Isoflurane on Oxygenation Following One-Lung Ventilation in Thoracic Surgery.

BACKGROUND: One-lung ventilation (OLV) is commonly used during thoracic surgery. At this time, hypoxemia is considered one of the remarkable consequences of the anesthesia management. Hypoxic pulmonary vasoconstriction (HPV) is the defense mechanism against hypoxia. OBJECTIVES: The aim of the present study was to investigate the effect of infusion of dexmedetomidine on improving the oxygenation during OLV among the adult patients undergoing thoracic surgery. METHODS: A total of 42 patients undergoing OLV by general anesthesia with isoflurane inhalation were randomly assigned into two groups: IV infusion of dexmedetomidine at 0.3 microgram/kg/h (DISO) and IV infusion of normal saline (NISO). Three Arterial Blood Gas (ABG) samples were obtained throughout the surgery. Hemodynamic parameters, PaO2, PaCO2, and complications at recovery phase were recorded. The collected information was analyzed using SPSS software version 22. RESULTS: In the dexmedetomidine group, the mean hemodynamic parameters had a significant reduction at 30 and 60 minutes following OLV. Administration of dexmedetomidine resulted in a significant increase in the PaCO2 and a reduction in the PaO2 when changing from two-lung ventilation to OLV, where PaO2 reached its maximum value within 10 minutes after OLV in the DISO group, and it began to gradually increase to the end of operation. The duration of the recovery phase, also complications at the recovery phase decreased significantly in DISO group. CONCLUSIONS: The results of the study showed that, dexmedetomidine may improve arterial oxygenation during OLV in adult patients undergoing thoracic surgery, and can be a suitable anesthetic agent for thoracic surgery.

Impact of high-fat diet and hypoxia on the serum levels of main vasoconstrictors in male rabbits.

Introduction: During atherosclerosis process, vasoconstriction phenomenon occurs which in turn leads to tissue hypoxia. A few studies have been performed on the combination of atherosclerosis and hypoxia as stressors that may accelerate secretion of constrictors. The aim of present study was to evaluate the effects of atherosclerosis and hypoxia on serum levels of main vasoconstrictors (epinephrine, norepinephrine and renin). Methods: In this interventional study, 32 New Zealand white rabbits were randomly divided into four groups (n = 8): normal diet (control group), normal diet exposed to hypoxia (11%, 10 days), high-fat diet (cholesterol-2%, 8 weeks), and high-fat diet with hypoxia. Later, serum levels of renin, epinephrine and norepinephrine were measured on second, 56th and 66th days. Results: High-fat diet and hypoxia caused significant increase in epinephrine and norepinephrine concentrations on days 56 and 66 compared to the control group (P < 0.05). Also, renin showed significance increase in high-fat diet and high-fat diet+ hypoxia groups compared to the control group (P < 0.05). Conclusion: Both high-fat diet and hypoxia increase renin levels in male rabbits. Furthermore, the combination of high-fat diet and hypoxia immensely increases renin levels. Both hypoxia and combined of high-fat diet and hypoxia increase norepinephrine levels. However epinephrine is only increased in the combination of high-fat diet and hypoxia. So the presence of hypoxia in combination with high-fat diet, cause accelerated and aggravated atherosclerosis.