Comparison of target-controlled infusion and manual infusion for propofol anaesthesia in Children.
This prospective, randomised controlled clinical trial compared a Propofol TCI infusion regime (Paedfusor) with a manual infusion regime in a variety of surgical procedures. Propofol accumulates when used as an infusion, potentially prolonging recovery after long operations. This study intended to see if a current TCI regime, that adjusts for this potential accumulation by reducing the infusion rate whilst maintaining a prescribed target concentration leads to a quicker extubation and wake up when compared to manually operated infusion regimes.
Methods: Children received either TCI (Cp 3-5microg/ml) or manually with a loading dose of propofol of 2.5 mg kg/1 and a step down maintenance infusion regimen at 15, 13, 11, 10, and 9 mg/ kg/ h. Attending anaesthetists were then able to adjust /give further boluses to keep BIS value between 40-60 and/or according to clinical need. Remifentanil infusion was also used and good non opiate analgesia provided. Propofol infusion was stopped 5-10 min before anticipated completion of surgery and the remifentanil infusion was ceased when surgery was completed. The primary outcome was time to extubation after cessation of propofol. Various secondary outcomes included total dose of propofol and remifentanil used, time to obey commands after cessation of propofol and incidence of emergence agitation. The percentage of time when BIS < 40 or > 60, and the number of setting changes between the two group were also compared. For the manual infusion group, the number of extra boluses given and adjustment of infusion rate were counted and compared with the number of target plasma concentration changes in the TCI group.
Findings: The time taken to extubate the trachea after cessation of propofol was similar between the two groups, 15.1 (5.5) and 16.2 (6.1) min for children who had TCI and manual infusion of propofol, respectively (P=0.42). The mean propofol infusion rate was 16.7 (4.2) mg kg/hr in children receiving TCI propofol and 14.6 (3.1) mg kg/hr in children who had manual infusion (P=0.036). No difference was observed in the remifentanil infusion rate, time to obeying commands and BIS between groups. Only two children who had TCI and no children who had manual infusion of propofol experienced emergence agitation. The percentage of time when the BIS was > 60 was significantly lower in the TCI group than the manual infusion group (P=0.016). The median number of setting changes was significantly higher in the TCI group compared to the manual infusion group, (P<0.0001).
The TCI regime resulted in the administration of statistically significantly higher total doses of propofol compared to a manual regime. However, this did not translate into a significantly prolonged recovery time. The TCI system produced “better” control of BIS scores with less patient time spent > 60; although there were no incidences of recall or awareness. Although a well conducted study the major drawback was that almost all of the patients received an IV bolus of Dexmedetomidine at the end of the procedure to reduce the incidence of emergence delirium, routine practice in the authors’ institution. The routine use of dexmedetomidine in a TIVA anaesthetic technique might be considered unnecessary by many and may well have contributed to the lack of difference in extubation times between the two regimes.
Potential take home message: There may be no important benefits in terms of quicker wake up / reduction of total propofol used when using the Paedfusor TCI regime compared to a manual regime at least in short to medium length surgical procedures.
Reviewed by: Dr H.Hack