EFFICACY OF PREEMPTIVE ANALGESIA AND CONTINUOUS EXTRAPLEURAL INTERCOSTAL NERVE BLOCK ON POST-THORACTOMY PAIN AND PULMONARY MECHANICS

Objective. Thoracotomy results in severe pain and deleterious changes in pulmonary physiology. The literature suggests that these alteration s in pulmonary mechanics are inevitable and can only be minimised but not prevented by effective analgesia. We have reevaluated this concept and assessed the efficacy of pre-emptive analgesia [preincisional aff erent block, premedication with opiate and/or non-steroidal anti-infla mmatory drug (NSAID)] in conjunction with postoperative extrapleural c ontinuous intercostal nerve block on postoperative pain and pulmonary function. Materials and Methods. A prospective randomized study was co nducted on 56 patients undergoing elective thoracotomy. Subjective pai n relief was assessed on a linear visual analogue scale. Pulmonary fun ction was measured on the day before operation and 12 hourly for 48 ho urs after operation. There were seven patients in each of the eight gr oups. Results. The balanced analgesia group comprising preincisional b lock and premedication with opiate and NSAID (Group 1) had significant ly better analgesia, needed less postoperative supplementary analgesic s and maintained their preoperative pulmonary function postoperatively irrespective of the nature of the operation. The ranking of importanc e of the three components of the pre-emptive analgesia as assessed in this study are preincisional block, opiate premedication and premedica tion with NSAID's. No significant change in plasma levels of cortisol or glucose occurred in Group 1 patients from prior to induction of ana esthesia to 24 hours postoperatively, suggesting effective somatic and sympathetic afferent blockade had been achieved in these patients. Th ere were no complications related to the infusion or the use of NSAID' s. Conclusions. We conclude that a balanced analgesic regime comprisin g preoperative pain prophylaxis and postoperative maintenance analgesi a by NSAID and continuous extrapleural intercostal nerve block will mi nimise and even reverse the expected decline in lung function after th oracotomy. The postoperative decline in lung function is not obligator y but primarily due to incisional pain and thus is preventable by effe ctive analgesia. An ideal balanced pre-emptive analgesic regime should include preincisional local anaesthetic afferent block and premedicat ion with opiates and a NSAID.