Background: Postoperative nausea and vomiting (PONV) is still one of the major problems in strabismus surgery, especially in children. In recent years many studies have been published, suggesting that choosing propofol as the anaesthetic agent may help to reduce the high incidence of PONV in children undergoing strabismus surgery. Experience with remifentanil in children is still very limited and little is known, whether propofol in combination with this new short acting opioid is also superior regarding PONV in squint surgery compared to sevoflurane/N2O. Additionally, little is known, whether the type of operation or the muscle which is operated on has any influence with respect to PONV.
Methods: Following sample size estimation, ethics committee approval and parents informed consent in a prospective, randomised, observer-blind study 105 ASA I and II children aged 3-8 years scheduled for elective strabismus surgery were assigned into one of the following groups: Group TIVA (propofol/remifentanil, n = 53): anaesthesia was induced by remifentanil 0.5 microgram kg-1 min-1 over 2 min (loading phase), followed by 3 mg kg-1 propofol along with 30% O2 in air. After endotracheal intubation anaesthesia was maintained initially with remifentanil 0.25 microgram kg-1 min-1 and propofol 10 mg kg-1 h-1 by constant infusion. In the course of the operation the infusions of the anaesthetics were adjusted to the decreasing need for anaesthesia. Group VOLATIL (sevoflurane/N2O, n = 52): anaesthesia was induced by inhalation of sevoflurane along with 50% O2 in N2O. After endotracheal intubation anaesthesia was maintained with sevoflurane 1.0-1.5 MAC along with 30% O2 in N2O and in the course of the operation the administration of the inhaled anaesthetics was adjusted correspondingly. Preoperatively collected data included gender, age, weight and history of PONV. Intraoperatively collected data consisted of data belonging to routine monitoring (heart rate, blood pressure, peripheral oxygen saturation and temperature) as well as the duration of the operation and anaesthesia and specific data regarding the operation (including the number and type of muscles as well as the kind of operation). Data collected within the first 24 hours postoperatively in the recovery room and on the ward by blinded observers included any PONV events as well as the antiemetics and analgesics applied.
Results: Vomiting was observed less frequently in the TIVA-group than in the VOLATIL-group (21 of 53 vs. 32 of 52, p = 0.03) within the first 24 hours postoperatively. Posterior fixation suture ("faden-operation") compared to other operations was followed rather frequently by nausea and vomiting (30 of 44 and 33 of 44, respectively), whereas recessions were rarely associated with nausea and vomiting (12 of 35 and 9 of 35, respectively).
Conclusions: TIVA with propofol/remifentanil proved to be a suitable form of anaesthesia for children in this setting. Propofol showed advantages over sevoflurane/N2O with respect to PONV after squint surgery in children also when applied in the combination with remifentanil. TIVA with propofol/remifentanil may therefore be one way to reduce the high incidence of PONV in this setting, bearing in mind, that PONV is not only influenced by the regimen of the general anaesthesia but rather by the combination of many other factors, in particular the type of operation.