SQUINT SURGERY IN YOUNG-CHILDREN - INFLUE NCE OF PARACETAMOL AND BUPIVACAINE

Postoperative vomiting is induced by different mechanisms such as age, anaesthetic technique and medications, postoperative analgesia, and s urgical traction on the extra-ocular muscles. The influence of anticho linergic premedication and the use of benzodiazepines as factors affec ting the incidence of vomiting is controversial. In a prospective, ran domised, single-blind study we examined two different treatments with regard to postoperative pain, vigilance, and vomiting in young childre n undergoing strabismus repair. Methods. After institutional ethical c ommittee approval, informed written consent was obtained from all pare nts. The children were randomly assigned to three groups: (1) paraceta mol (P) - 17 patients who received 250-500 mg paracetamol rectally (de pendent on body weight) immediately after intubation of the trachea; ( 2) bupivacaine (B) - 17 patients who received two drops 0.5% bupivacai ne hydrochloride on the conjunctiva of the eye(s) being corrected foll owing intubation of the trachea and again 10 min after intubation. Aft er the surgeon had exb posed the extra-ocular muscle and before readap tation of the conjunctiva, two drops of the same solution were applied again each time directly on the muscle; and (3) controls (C) - 16 pat ients who received rectal paracetamol after completion of the operatio n but before extubation. The children were premedicated with 0.05mg/kg flunitrazepam sublingually. After 0.25 mg atropine i.v., anaesthesia was induced with 0.1mg/kg vecuronium, 5 mg/kg thiopentone, 1.5 vol% en flurane, and N2O/O-2 50:50. When the trachea was intubated anaesthesia was maintained with enflurane as required and 70% N2O in oxygen. Extu bation was performed only if the patient could touch or did not tolera te the tube. Oral diet was allowed 6 h after extubation at the earlies t. Examination of vigilance and analgesia. The degrees of vigilance an d pain were evaluated preoperatively and after extubation over 24 h us ing two different scales. Evaluation of the scales was performed durin g the first 3 postoperative h at 12 different time points (Figs 1, 2) and 6, 12 and 13 and 24 h after extubation. The evaluation was conduct ed by nursing staff who were blinded to the treatment (single-blind st udy). Postoperative analgesia consisted of 250-500 mg rectal paracetam ol (all patients). Parametric data were expressed as meant SD, and com parisons were made with the one-way analysis of variance. Fisher's exa ct test was applied to ordinal data. P<0.05 indicates a statistically significant difference. Results. Two patients (P) were excluded from t he study postoperatively because of refusing rectal paracetamol in spi te of pain and postoperative infection of the upper airways, which had manifestated on the afternoon of the operative day. No significant di fferences were found between the three groups in patient characteristi cs (Table 1). The quantity of enflurane administered, rate, postoperat ive consumption of rectal paracetamol, and postoperative emesis were h ighest in the control group (Tables 2, 3), but the incidence of postop erative vomiting ranged only between 13% and 24% (Table 3). Children w ith preoperative paracetamol needed more time to fulfill the criteria to ''stick out the tongue'' and ''recognising the mother''. Vigilance. The time to postoperative crying or screaming and restlessness was sh orter in the control group. The values reached significant difference at 10 min (P) and 25 min (P and B) after extubation compared with the other groups (Fig. 1). Analgesie. At 5, 10, and 150 min after extubati on pain was significantly higher in patients the control group (Fig. 2 ). Conclusions. Intraoperative administration of rectal paracetamol or topical 0.5% bupivacaine was most effective in the treatment of posto perative pain for strabismus surgery in younger children. Sublingual f lunitrazepam and i.v. atropine given as premedication probably decreas e postoperative vomiting. Postoperative administration of rectal parac etamol cannot be recommended because peak plasma levels of rectal para cetamol occur after 2 to 4h. Intraoperative topical 0.5% bupivacaine s eems to be an alternative treatment for reducing postoperative pain in squint surgery.