Abstract:To evaluate the effect of thoracic paravertebral block (TPVB) combined with Dexmedetomidine on stress reaction in patients undergoing thoracic surgery. Methods Seventy-two patients scheduled for esophageal surgery were randomly divided into three groups: pure general anesthesia group (group C), Ropivacaine group (group R) and Dexmedetomidine combined with Ropivacaine group (group DR).TPVB (T4-T9) guided by ultrasound was applied to the patients of the group R and the group DR before induction: the patients in the group R and the group DR received paravertebral injection of 0.5% Ropivacaine 30 ml and 30 ml mixture of 1μg/kg Dexmedetomidine combined with 0.5% Ropivacaine respectively. All three groups received patient-controlled intravenous analgesia (PCIA) after operation. Heart rate (HR) and mean arterial pressure (MAP) were recorded before anesthesia (T0), immediately after endotracheal intubation (T1), 2 hafter incision (T2), at the end of operation (T3), and 1, 6, 12, 24, 36 and 48 h after operation (T4-T9). The analgesic effect was measured by Visual Analog Scale (VAS) scores at T4-T9. Blood samples were obtained via internal jugular vein at T0, T2, T3, T6, T7 and T9. The plasma concentrations of epinephrine and norepinephrine and the value of blood glucose (BG) were determined. Results The VAS scores, the plasma concentrations of epinephrine and norepinephrine, and the value of BG were significantly different between different time points(p < 0.05). There was no difference in MAP or HR between different time points (p > 0.05). The VAS scores,the plasma concentrations of epinephrine and norepinephrine, and the value of BG were significantly different among the three groups (p < 0.05). The analgesic effect was better and the stress reaction was milder in the group DR. The change trends of the VAS scores, the plasma concentrations of epinephrine and norepinephrine, and the value of BG were significantly different among the three groups (p < 0.05). Conclusions Dexmedetomi-dine combined with thoracic paravertebral block can significantly enhance the effect of nerve block, prolong the duration with Ropivacaine, and decrease the stress reaction in the patients undergoing thoracic surgery.