Máscara laríngea versus tubo traqueal: consumo de isoflurano em cirurgia pediátrica sob bloqueio caudal com ou sem fentanil / Laryngeal mask vs endotracheal tube: isoflurane consuption in pediatric surgery under caudal block with or without fentanyl

RESUMO

Background and objectives - Caudal block has shown to be a useful technique for orthopedic or urologic procedures in childern. However, in such circumstances, the maintenance of airway permeability is a priority. This can be achieved by the use of endotracheal tubes (TT) or laryngeal mask airways (LMA). The purposes of this study were a) to compare isoflurane consumption for maintenance of LMA and TT; b) to evaluate the influence of caudal fentanyl on the isoflurane consumption; c) to compare hemodynamic alterations following extubation or LMA removal. Methods - Forty-four children allocated into 3 groups were studied. In the first stage of the protocol, 2 groups were studied Group 1 (TT) received a balanced anesthesia (propofol, atracurium, N2O/O2 and isoflurane) and underwent tracheal intubation; Group 2 (LMA) received a balanced anesthesia (propofol, N2O/O2 and isoflurane) and patients were kept under laryngeal mask airway. All patientes in both groups also underwent caudal anesthesia with 0,25 per cent bupivacaine. Isoflurane consumption was evaluated in both groups. After detecting that isoflurane consumption was significant less in Group 2, a third group was studied, in wich the same anesthetic technique as in Group 2 was used, but fentanyl was added to the caudal block. Isoflurane consumption and hemodynamic alterations during extubation or LMA removal were compared in the 3 groups. Results - Isoflurane consumption was significantly different in the study groups, being Group 1 (TT) > Group 2 (LMA) > Group 3 (LMA plus feantnyl). During extubation or LMA removal, Group 1 patients showed higher values of heart rate and blood pressure as compared to Groups 2 and 3. Conclusions - The use of LMA provided good conditions for maintenance of pediatric patients undergoing caudal blockade light general anesthesia. There was a significant reduction in the consumption of the inhalational agent, particularly when fentanyl was added to the caudal block. There were also advantages regarding hemodynamic responses during its removal as compared to extubation