Epidural Analgesia and Postoperative Respiratory Functions (EPAPRES)

lung cancer patients (between ages 18 to 75 and American Society of Anesthesiologists -ASA- Class I to III), undergoing an elective thoracic surgical procedure with posterolateral thoracotomy, were enrolled. The study was approved by the local ethical committee in Yedikule Chest Diseases and Thoracic Surgery Ed. and Research Hospital and therefore had been performed in accordance with global ethical standards. Written informed consent was received from all participants.

Individuals beyond defined age limits, patients who have psychiatric problems, auditory deficit, drug abuse, severe cardiovascular system disorders or severe respiratory depression depicted as having less than 50% of the predicted value of forced expiratory volume were excluded. Patients refusing to give consent and to whom inserting an epidural catheter is contraindicated were not involved either. Surgical procedures were performed by the same team. In the operating room, if serratus anterior muscle could not be spared or chest wall resection was performed, these patients were also excluded even though they had met other qualifications. Finally, patients who could not be extubated before transfer were not involved.

Regarding pre-operative evaluation, age, gender, weight, height, smoking status (package/years) and ASA score of patients were recorded.

For assessing the impact of method of analgesia on target parameters, patients were allocated to TEA and intravenous analgesia (IVA) groups. Randomisation was performed by closed envelope method.

2.2 Features of anesthetic technique and intraoperative analgesia Before the initiation of procedure, in TEA group epidural catheter was inserted by loss of resistance method at the level of T3-T7 with the help of a 18 G Thuohy needle (Pajunk, Geisingen, Germany) while patient was on sitting position. A test dose of 2 ml, 2% Lidocaine HCL was administered through the catheter. Once, efficacy was confirmed, 10 ml bolus dose of 0.1% Bupivacaine was injected. Analgesia maintanence was provided by infusion of 0.1% Bupivacaine (0.1 ml/kg/hour) both intra- and postoperatively for 24 hours.

Anesthesia was induced with midazolam (0.04 mg/kg), propofol (2 mg/kg) and fentanyl (1mcg/kg) in both groups and the neuromuscular blockage was provided with cisatracurium besilate (0,2 mg/kg). Then, insertion of a double-lumen tracheal tube was performed. After standard patient positioning, localization of the tube was checked with a fiberoptic bronchoscope. Pressure controlled ventilation was used (Primius, Drager, Luebeck, Germany) and invasive arterial pressure, electrocardiography, arterial blood gas analysis, end-tidal carbon dioxide concentration, central venous pressure and urine output were closely monitored in the operating room. Hypothermia was avoided with the help of a warming system and body temperature was kept over 36°C. In TEA group, absolute intraoperative analgesia was warranted with 0,5-2 MAC sevoflurane. In IVA group, remifentanyl infusion (0.1-0.2 mcg/kg/min) was additionally used for this purpose. If arterial pressure exceeds a value of 20% or more of baseline recordings, 1 mcg/kg fentanyl was administered. Every one hour, an additional dose (0.25 mg/kg) of cisatracurium besilate was administered to ensure complete myorelaxation.

The intercostal blockage was applied by the surgical team to the entire population before closing the wound by injecting 4 ml of 0.25% bupivacaine to the region of incision and two intercostal regions above and below the incision site. Once closure was started, morphine sulphate (0,1 mg/kg), tramadol (100 mg), paracetamol (100 mg) and tenoxicam (20 mg) was given intravenously. Anterior 28 Ch and posterior 32 Ch drainage tubes were inserted to the patients to whom lobectomy or bilobectomy was performed. For pneumectomy, only posterior 32 Ch tube was placed. After reversal of neuromuscular blocking agents, patients with adequate spontaneous ventilation and verbal response were transferred to the critical care unit.

Regarding to peri-operative data, procedure time, type of the operation (lobectomy or pneumectomy), duration of tube drainage and presence of operation related complications were recorded.

Visual Analogue Score (VAS) was used to estimate the severity of pain. A score of 0 cm represented "no pain at all" and 10 cm did "intractable pain" so.