Does preemptive hydromorphone and ropivacaine thoracic epidural analgesia have clinical benefits?

patients scheduled for open thoracotomy with a thoracic epidural catheter inserted on the previous day of the surgery, were randomly allocated to one of two groups. The Preemptive Group is the intervention group in this trial. 1) thoracic epidural analgesia (TEA) applied preemptively before surgery (Preemptive group) 2) thoracic epidural analgesia (TEA) applied at the end of surgery (Nonpreemptive group) After induction of anesthesia, patients in Preemptive group received 10ml 0.1% ropivacaine with 100 ug hydromorphone via an indwelling epidural catheter followed by a continuous infusion with an infusion pump (Aim(Registered Trademark) plus, Abbott Laboratories, U.S.A) at least 30 minutes before surgical incision. Patients in Nonpreemptive group received the same epidural 10ml drug administration and a continuous TEA regimen at the end of surgery. A continuous TEA regimen for both groups was comprised of 0.15% ropivacaine with 8ug/ml hydromorphone at the rate of basal 5ml/hr and a 3ml bolus with a 15 minute lockout interval. The incidence of hypotension during surgery was recorded. Hypotension was defined as a persistent decrease of systolic blood pressure greater than 30% of baseline or mean blood pressure less than 60 mmHg, that was not due to a bleeding episode, and that required a continuous infusion of inotropics or vasopressors despite three or more consecutive intravenous (IV) bolus injections of ephedrine or phenylephrine. The amount of TEA and IV fentanyl administered during surgery was recorded. Postoperative analgesia was controlled with TEA and rescue IV morphine or oral tramadol and acetaminophen combination (Ultracet(Registered Trademark)). The duration of this trial is 48 hours. Postoperative follow up of study 1. Consumption of TEA after surgery was recorded. Numerical rating scales at rest and cough (NRS, a scale of 0 – 10 in which 0 is no pain and 10 is worst pain) were used to assess the pain severity. 2. The incidence of intraoperative hypotension, and side effects including nausea, pruritis, sedation, hypotension and respiratory depression were recorded at postoperative 2, 6, 24, and 48 hr. 3. Functional vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were measured by a portable spirometry (Micro, Micro Medical Limited, Rochester, U.K.) before surgery and at postoperative 24 and 48 hr. 4.Persistence of pain and its characteristics on the surgical wound at postoperative 6 month was also investigated.