Efficacy of pre-emptive analgesia and continuous extrapleural intercostal nerve block on post-thoracotomy pain and pulmonary mechanics.

OBJECTIVE: Thoracotomy results in severe pain and deleterious changes in pulmonary physiology. The literature suggests that these alterations in pulmonary mechanics are inevitable and can only be minimised but not prevented by effective analgesia. We have re-evaluated this concept and assessed the efficacy of pre-emptive analgesia [preincisional afferent block, premedication with opiate and/or non-steroidal anti-inflammatory drug (NSAID)] in conjunction with postoperative extrapleural continuous intercostal nerve block on postoperative pain and pulmonary function. MATERIALS AND METHODS: A prospective randomized study was conducted on 56 patients undergoing elective thoracotomy. Subjective pain relief was assessed on a linear visual analogue scale. Pulmonary function was measured on the day before operation and 12 hourly for 48 hours after operation. There were seven patients in each of the eight groups. RESULTS: The balanced analgesia group comprising preincisional block and premedication with opiate and NSAID (Group 1) had significantly better analgesia, needed less postoperative supplementary analgesics and maintained their preoperative pulmonary function postoperatively irrespective of the nature of the operation. The ranking of importance of the three components of the pre-emptive analgesia as assessed in this study are preincisional block, opiate premedication and premedication with NSAID's. No significant change in plasma levels of cortisol or glucose occurred in Group 1 patients from prior to induction of anaesthesia to 24 hours postoperatively, suggesting effective somatic and sympathetic afferent blockade had been achieved in these patients. There were no complications related to the infusion or the use of NSAID's. CONCLUSIONS: We conclude that a balanced analgesic regime comprising preoperative pain prophylaxis and postoperative maintenance analgesia by NSAID and continuous extrapleural intercostal nerve block will minimise and even reverse the expected decline in lung function after thoracotomy. The postoperative decline in lung function is not obligatory but primarily due to incisional pain and thus is preventable by effective analgesia. An ideal balanced pre-emptive analgesic regime should include preincisional local anaesthetic afferent block and premedication with opiates and a NSAID:

Gastric fluid volume and pH in elective surgical patients: triple prophylaxis is not superior to ranitidine alone.

The effect of oral ranitidine alone was compared with sequentially administered ranitidine, metoclopramide, and sodium citrate on gastric fluid volume and pH in 196 healthy, elective surgical inpatients, each of whom was randomly assigned to one of four groups. Patients in all groups received oral ranitidine 150 mg 2-3 hr before the scheduled time of surgery. Those in Group 1 also received oral metoclopramide 10 mg one hour before surgery, and sodium citrate 0.3 M 30 ml on call to the operating room; Group 2 received sodium citrate but no metoclopramide; Group 3 received metoclopramide but no sodium citrate; Group 4 received ranitidine alone. Following induction of anaesthesia a #18 Salem sump tube was passed into the stomach and all available gastric fluid was aspirated. Volumes were recorded and pH measured. In all groups mean pH was greater than 5.8, although at least one patient in each group had pH less than 2.5. Mean volumes were significantly greater in patients who received citrate (Groups 1 and 2: 22 and 19 ml) than in those in those who did not (Groups 3 and 4: 10 and 8 ml). One patient in Group 2 and one in Group 3 had pH less than 2.5 with volume greater than 25 ml. Our results do not demonstrate any advantage of double or triple prophylaxis over ranitidine alone. The practical difficulty of correctly administering two or even three medications, each at different but exact preoperative intervals, is emphasized.

Adrenal cortical reserve in patients undergoing muscle biopsy for malignant hyperthermia screening.

Stress has been suggested as a factor involved in the development of a malignant hyperthermia (MH) reaction. This study has compared the hormonal response of a group of patients susceptible to MH (MHS), with that of a control group, during diagnostic muscle biopsy under general anaesthesia. Preoperative adrenal cortical reserve was assessed using the Short Synacthen Test (SST). There was no significant difference between the groups in their hormonal response to the procedure, both groups showing a peroperative reduction in plasma cortisol concentration from an initially high value, and the SST was within accepted normal limits for both groups. It was concluded that patients susceptible to MH have normal adrenal cortical reserve and responded normally to the psychological and surgical stress encountered during this study.

Anaesthesia for valvuloplasty.

Two years' experience of anaesthesia for percutaneous balloon valvuloplasty in children is presented and the problems associated with this procedure are discussed.