Effect of Different Administrations of Propofol on Emergence Agitation in Preschool Children Undergoing Ambulatory Surgery

This study evaluates the influence of different dose and methods of propofol on emergence agitation(EA) through a randomized controlled trial when preschool children undergoing ambulatory surgery of inguinal hernia.

Emergency agitation (EA) is the manifestation of excitement, high irritability, intense struggle, and increased blood pressure and heart rate during the recovery period of general anesthesia. It is a common adverse reaction after general anesthesia. The incidence in preschool children is 10%-80%, which is currently considered to be mainly related to factors such as the use of inhalation anesthetics, pain stimulation, drug types, surgical methods, and environmental changes. EA not only increases children's risks, such as drains and dehiscence, but also increases caregiver stress and reduces parental satisfaction with the method of anesthesia.

This trial is a randomized single-blind clinical trial. The padiatric patients were randomly divided into 4 groups.The block randomization is generated by statistical professionals using SAS9.2 software. The block size is fixed at 8 and randomly changed. Each random number and the corresponding assignment result are placed in a sealed in a transparent envelope. The investigator is responsible for including subjects according to the requirements of the program. When the subjects meet the inclusion criteria but not the exclusion criteria, the field staff will open the envelopes in order to group them.The clinical anesthesia and data statistical analysis were completed by different anesthesiologists and participants.

The four groups of children were fasted for 6 hours and 2 hours before operation, and no preoperative medication was given. After the children were awake and entered the room, the heart rate (HR), non-invasive blood pressure (NIBP), pulse oxygen saturation (SpO2), respiratory rate (RR) and end-tidal carbon dioxide partial pressure (PetCO2) were continuously monitored. Both groups were given routine standard anesthesia induction: intravenous injection of midazolam at 0.05-0.1 mg/kg of predicted body weight (PBW), propofol at 2-4 mg/kg of PBW, and remifentanil at 1-2 ug/kg of PBW, rocuronium at 0.5-1mg/kg of PBW.After adequate pre-oxygenation,laryngeal mask was placed.Anesthesia was maintained by inhalation of 2%-3% sevoflurane and continuous pumping of remifentanil at 0.2-0.4ug/kg/min remifentanil, with an oxygen flow of 2L/min. The tidal volume method was used in all mechanical ventilation. The tidal volume was between 6 and 8 mL/kg, the respiratory rate was between 18 and 24 breaths/min, and the PetCO2 was maintained between 30 and 35 mmHg. Three minutes before the end of surgery, the oxygen flow was adjusted to 6 L/min, sevoflurane was stopped, and the infusion of remifentanil was stopped. At the end of the operation, the children in all groups received local infiltration anesthesia with 0.3% ropivacaine around the incision by the surgeon.

The children in group A were given 1 mg/kg propofol intravenous bolus 3 minutes before the end of the operation.Children in group B were given continuous pumping of 1 mg/kg propofol 3 minutes before the end of the operation, and the infusion time was 3 minutes. Children in group C 1 mg/kg propofol was given intravenously at the end of the operation. Children in group D were not given propofol and served as a blank control group.

All data were collected, aggregated and maintained by a single investigator.The primary outcome measure was the anesthesia emergence delirium scale (PAED). The observation was performed during the recovery period of the child, and the child opened his eyes voluntarily to the stage of complete recovery of consciousness. Mainly from the three aspects of eye contact, behavior and consciousness, the total score is 20 points. 15 points for severe agitation.In addition, the indicators we collected also include age, gender, weight, ASA classification, operation method, operation time, discharge time and occurrence of adverse reactions and so on.

The full analysis set was used for analysis. According to the basic principle of Intention-to-Treat (ITT), the analysis of the main indicators includes all randomized subjects, regardless of whether they completed the trial or not, that is, subjects who were lost to follow-up should also be included in the statistical analysis. Statistical software SPSS 26.0 was used for data processing and statistical analysis. Shapiro-Wilk test was first performed on the data, and continuous variable data (such as blood pressure, heart rate, driving pressure, oxygenation index, etc.) were determined to use Analysis of variance or Kruskal-Wallis H test according to their normal distribution. Categorical variables (such as age,incidence of EA, etc.) were tested by χ² test, Fisher's exact test, and the results were expressed as mean ± standard deviation (SD), percentage (%) or median (interquartile range, IQR), P \<0.05 is statistically significant.

Eligibility Criteria:
Inclusion Criteria:

* Children aged 2-5 years
* ASA classification 1
* Written informed consent
* Children undergoing ambulatory surgery of inguinal hernia
* The operation will take no more than 20 minutes

Exclusion Criteria:

* Allergic to drugs used in the study
* Neurological disorders
* Congenital heart insufficiency
* Recent respiratory illness