Abstract
OBJECTIVES: To determine whether administration of local anaesthetic at the site of skin incision during open lacrimal drainage surgery under general anaesthesia alters the total dosage of anaesthetic drugs required during total intravenous anaesthesia (TIVA), and whether it alters postoperative pain and recovery. STUDY DESIGN: Masked comparison of a randomized, two-group interventional study. PATIENTS AND METHODS: Patients undergoing unilateral external dacryocystorhinostomy under total intravenous general anaesthesia were recruited from the lacrimal service at Moorfields Eye Hospital between September 2012 and February 2014. The patients were randomised to receive, after induction and stabilisation of general anaesthesia, infiltration of the ipsilateral paranasal tissues with 2.5 ml of 0.5% bupivacaine with 1:100000 epinephrine ("treatment" group), or a sham injection ("control" group); the infiltration was performed about 7 min prior to the skin incision. The infusion rates for propofol and remifentanil were adjusted to maintain a steady intra-operative mean blood pressure of 55-70 mmHg and BIS score of 40-60%. The time taken for extubation of the patient after cessation of TIVA was recorded, and postoperative pain scores (on a Likert scale from 0-10) were taken at regular intervals after extubation. The average intra-operative mean blood pressures, total drug usage, extubation time and pain scores for each of the two groups were compared using two-tail Student's t-testing and Wilcoxon rank sum testing. RESULTS: There were 12 patients (7 female; 58%) in the treatment group and 11 (7 female; 64%) in the control group, with similar average age at surgery (59 years treatment, 53 years control; p = 0.38) The average operative time was 45 min in the treatment group (median 42, range 30-55) and 47 min (median 45; range 37-61) in the control group (p = 0.52). The mean dosage of propofol required to maintain satisfactory GA was significantly less in the "treatment" group (89.8 mcg/kg/min) as compared to the "control" group (mean 126 mcg/kg/min) (p = 0.0007). Likewise, remifentanil dosage was significantly less in the "treatment" group (100 ng/kg/min) as compared to controls (259 ng/kg/min) (p = 0.00007). The mean non-invasive blood pressure was consistently lower during surgery in the "treated" group, and showed less intra-operative variation. After surgery, the patients receiving LA had a significantly shorter extubation time (mean time 6.0 min in "treated" group, 12.1 min in "controls"; P < 0.0002) and also significantly lower pain scores at 10, 30, 60, 120 and 180 min after extubation (p < 0.01, p < 0.01, p < 0.01, p < 0.01 and p < 0.05, respectively). CONCLUSIONS: Ipsilateral infiltration of local anaesthesia containing epinephrine in the paranasal tissues just prior to open dacryocystorhinostomy under total intravenous anaesthesia is associated with a 28% reduction in mean propofol usage, and a 61% reduction in remifentanil usage. LA usage during GA also produces improved and less variable intra-operative mean blood pressures, a significantly shorter extubation time and significantly lower postoperative pain scores.