In the present study, Aono’s scores as determinants of EA were found to be higher in the ketamine group compared to the propofol group at the 5th minute in children who were taken to the postoperative care unit (PACU). The difference was statistically significant. Aono’s value was set above 3 at 5th minute and was defined as EA.
Previous studies have generally examined the effects of sevoflurane on EA. In a meta-analysis including 14 studies in which patients undergoing sevoflurane and propofol anesthesia were examined, a total of 560 patients who were anesthetized with sevoflurane and 548 patients who were anesthetized with propofol were investigated. The meta-analysis concluded that propofol anesthesia was shown to result in a lower EA incidence [14]. In line with the meta-analysis study, we also found that the incidence of EA was low in the group anesthetized with propofol. At minutes 0, 5, and 10, the average Aono’s value representing EA in the propofol group did not exceed. Emergence from anesthesia with propofol is similar to waking up from a night’s sleep, and the patient regains his cognitive functions as the drug leaves the system. In our study, the short half-life and administration of a single dose at the beginning of the operation did not affect the elimination rate of propofol. In the group which was given sevoflurane in addition to propofol, although the Aono’s value at minute 0 was found to be lower than that of the sevoflurane group, this value was not sufficient in terms of EA. No EA was observed in the propofol group (Table 7).
In a randomized study of children aged between 2 and 6 undergoing strabismus surgery, Chandler et al. compared TIVA (propofol and remifentanil) and inhalational sevoflurane anesthesia. The study concluded that there is a lower incidence of emergence delirium (ED) after TIVA [15]. Similarly, in many studies, propofol has been shown to reduce or prevent EA caused by sevoflurane [16, 17].
In another review, the effects of prophylactic propofol dose on the incidence and severity of EA versus placebo in children aged 0–13 years receiving general inhalation anesthesia were evaluated, and 9 studies including 997 children were investigated. Based on high quality evidence, it has been declared that prophylactic propofol is effective in reducing the incidence and severity of EA in children recovering from general anesthesia [18].
The results of the evaluation of 13 randomized controlled trials (1125 patients) comparing intravenous ketamine in addition to inhalational anesthetics versus placebo for preventing EA in children yielded that the incidence of EA was 14.7% in the ketamine group and 33.3% in the placebo group. Being statistically insignificant, it was stated that it is difficult to claim that ketamine is a postoperative EA inhibitor [19].
In our study, there was no need to add sevoflurane to ketamine before the operation, and all patients completed the operation with ketamine anesthesia. As the added ketamine dose increased, Aono’s value at the 10th minute was found to be higher in those who needed additional ketamine compared to those who did not (p = 0.042). As the ketamine dose increases, the risk of developing EA increases and this difference becomes statistically significant at the 10th minute.
In a study carried out by Hesse et al., during the postoperative EA examination of 626 patients, EEG records in the intraoperative period were kept. Among these patients, it was observed that the groups receiving nitrogen and ketamine were especially associated with PACU-Delirium. There is an interaction between anesthetic regimens that involve nitrous oxide or ketamine and the EEG trajectories most associated with PACU-D [20].
Postoperative pain alone is not a risk factor for EA. Even patients who underwent a “painless” procedure under general anesthesia for MRI are reported to have experienced EA [21]. Likewise, Costi et al. compared 3 mg/kg propofol and seveflurane anesthesia with sevoflurane anesthesia alone using 218 MRI imaging. EA was higher in the group without propofol [22]. In our study, pudendal block was applied to prevent postoperative pain. Surgery was performed after ascertaining that the patients did not feel pain. By doing so, a factor thought to cause EA was eliminated.
The time taken for the Modified Steward score to be 6 and above, as a prerequisite condition for discharge from the postoperative care unit (PACU) to the ward, was found to be longer in the ketamine group compared to the propofol group. Here, the different half-life of drugs is effective. Meanwhile, observation of EA in the ketamine group delayed discharge to the ward. Propofol is a safe drug with a low side effect profile and provides rapid discharge to the ward.
There are limiting factors for our study. Patients who were first added to sevoflurane anesthesia were not excluded from the study. Sevoflurane was used in some patients in the propofol-only group. This group was evaluated among themselves, and Aono’s scores were examined. Second, the group receiving only sevoflurane was not established. Propofol and ketamine were evaluated among themselves. Large-scale studies are needed to examine the effects of intravenous anesthetics on EA.