Transversus Abdominis Plane Block on Stress Response

This study evaluates the effect of transversus abdominis plane(TAP) block combined with general anesthesia on perioperative stress response in patients undergoing radical gastrectomy. One third of participants will receive TAP block combined with general anesthesia, another one third of participants will receive epidural anesthesia combined with general anesthesia, while the rest will receive only general anesthesia.

Clinically, combining epidural with general anaesthesia may confer many advantages to patients undergoing major thoracic, abdominal or orthopaedic surgery. Epidural anaesthesia can attenuate sympathetic hyperactivity and the stress response, maintain bowel peristalsis, spare the use of opioids, and facilitate postoperative feeding and physiotherapy. However, establishing epidural anesthesia is not without risks and contraindications, including refusal by the patient, technical failure, unintentional dural puncture, waist and back pain and local anaesthetic toxicity. When neurologic complications do occur, the resulting morbidity and mortality is considerable. Transversus abdominis plane (TAP) block, is another new regional anesthesia technique, has been introduced as an abdominal wall block capable of providing effective analgesia, reducing opioid consumption, and lessening opioid-related side effects. In addition,TAP block, somewhat as a pre-emptive analgesia approach, is a way of pain intervention before noxious stimulation which has been reported to be potent to attenuate the stress response. Although the analgesia efficiency of TAP block has been widely studied, its effectiveness to suppress stress response has little comparison with classic epidural block and general anesthesia. Unlike epidural anaesthesia, TAP block is easy to administer and lower incidence for side-effects.The investigators hypothesize that the TAP block reduces the stress response of surgery to the similar extent to epidural anaesthesia when combined with a standard general anaesthesia for abdominal surgery.