This study showed that intravenous lidocaine can be safely used in paediatric patients undergoing colonoscopy, reducing the required propofol by 35.5%. Awakening and recovery times were significantly reduced in the lidocaine group, as well as the number of involuntary body movements. Patients in the lidocaine group had significantly lower pain scores after colonoscopy than those in the control group.
The discomfort associated with colonoscopy is primarily due to visceral injury, followed by colon dilation and traction. Intravenous administration of lidocaine has been shown to be effective in reducing visceral pain [18, 19]. It should be noted that in our study, the propofol dose reduction did not sacrifice the working conditions of the endoscopist. On the contrary, the use of lidocaine reduced the number of involuntary movements, providing a better procedural environment.
Another intravenous anaesthetic, ketamine, has been shown to have a good analgesic effect, fast awakening time, in addition to reducing the amount of propofol needed as well as cardiopulmonary complications [20,21,22]. However, it has been shown to have psychological side effects such as nightmares, hallucinations, and fears, which increase the difficulty of postoperative management, affect the mental health of children and increase the medical costs [23].
The effects of propofol on hemodynamics and respiratory depression were dose-dependent, and the reduction of propofol dose could lower the occurrence of cardiopulmonary adverse events [24]. In addition, relevant studies showed that reduce the dosage of propofol could shorten the recovery time, which was consistent with the results we obtained [25].
Hypoxia and respiratory depression are occasional cardiopulmonary complications associated with endoscopy. Although there was a marked propofol synergistic effect in the lidocaine group, there was no significant difference in the decreased oxygen saturation between the two groups. In our study, the incidence of hypoxemia was approximately 10%, but in previous studies of adults it was higher, reaching 25% [15]. One of the reasons could be because we used a nasopharyngeal tube, which is superior to the nasal cannula [26]. Moreover, we used TCI combined with BIS to stabilise the blood concentration of propofol, reducing excessive anaesthesia.
In our study, we found that as the endoscope was passing through the colonic splenic flexure, the vital signs fluctuated easily, SBP and HR increased to varying degrees, and the children were more likely to have involuntary body movements. This may be due to the anatomical structure that makes it difficult for the endoscope to pass through. Therefore, the appropriate addition of propofol prior to reaching the colonic splenic flexure may reduce the occurrence of this phenomenon.
It should be pointed out that the rate of bradycardia was not significantly different between both groups due to the use of atropine before induction to prevent the sharp fluctuation of HR caused by propofol.
Our study found that the pain score after colonoscopy in the lidocaine group was significantly lower than in the control group. Postoperative pain can make children nervous, scared, and restless, which can have a long-term psychologic impact [27]. The use of lidocaine can reduce postoperative pain and may be more beneficial for the postoperative management of these patients.
One of the limitations of this study is the lack of transcutaneous carbon dioxide monitoring. Although there was no difference in the oxygen saturation between the two groups, timely monitoring of carbon dioxide accumulation may help in detecting early respiratory inhibition.
In conclusion, intravenous lidocaine significantly reduced the amount of propofol needed in paediatric patients undergoing colonoscopy. The incidence of involuntary movements, the amount of postprocedural pain, and the recovery time were also reduced. Larger trials are required to confirm these results.