Effects of Dexmedetomidine Used in Continuous Thoracic Paravertebral Blocks

Thoracic surgical procedures are among the most painful operations, and their outcomes are affected adversely by postoperative discomfort. Post-thoracotomy pain syndrome (PTPS) is a well-recognized complication of thoracotomy. Post-thoracotomy pain control improves patient satisfaction and decreases postoperative complication morbidity. Epidural analgesia used to be considered as the best method of pain relief after major surgery despite its side-effects, which includes hypotension, respiratory depression, incomplete or failed block, etc. Recently, paravertebral block is an alternative technique that may offer a comparable analgesic effect and a better side-effect profile for post-thoracotomy pain. Dexmedetomidine(DEX) is a Food and Drug Administration-approved, parenteral, selective α2-agonist that induces anxiolytic and analgesia without respiratory depression. It could provide dose-dependent sedation , analgesia , anti-anxiety and inhibition of sympathetic nerves and other effects . Current studies with regard to the effectiveness of DEX as an adjunctive medicine, used in ultrasound-guided continuous thoracic paravertebral blocks for PTPS. The mechanical withdrawal threshold and VAS scores are recorded. The consumption of opioid and general anesthetics during perioperative period are also recorded. To compare the incidence rates of side effects, such as nausea, vomiting, dizziness, hypotension and bradyarrhythmia in the first 3 days after operation among the groups.Also,to measure and compare the level of inflammatory factor in different group.A questionnaire is adopted to investigate whether there are chronic pain symptoms happen at 6 months after the operation which aim to PTPS.

Inclusion criteria

• ASA Ⅰ～Ⅲ patient undergoing thoracotomy;
• Written informed consent from the patient or the relatives of the participating patient.
• BMI:18～25kg/m2

Exclusion criteria

• Mental illness;
• Epidural anesthesia or thoracic paravertebral blocks contraindicated;
• People who have Slow-type arrhythmias or hypotension;
• People who have lung infection or sleep apnea syndrome;
• People who have chronic renal failure;
• Alcohol or drug abuse;
• Already taking gabapentin, pregabalin, benzodiazepin or antidepression drug;
• Local anesthetics allergy;