This study investigates whether discontinuing the continuous intravenous infusion of propofol immediately after cecal intubation would reduce the patient's recovery time without compromising their comfort or convenience. It would also reduce procedural costs and the risk of medical hazards due to potentially excessive sedation.

Colonoscopy is usually conducted after inducing depression in the patient's level of consciousness through sedation, ranging from minimal anxiolysis to general anesthesia, to establish relief from potential anxiety, discomfort, and pain during the procedure; in addition to diminishing the patient's memory of the event and minimizing the risk of adverse events related to agitation. It is traditionally done under endoscopist-directed conscious sedation via the administration of a benzodiazepine and a narcotic. However, anesthesia-assisted sedation has significantly risen for the last decade using almost exclusively propofol continuous intravenous drip, with propofol being a non-analgesic sedating agent marked by its rapid distribution and elimination and stronger sedating effect than the standard regimen, leading to faster induction and recovery from sedation and higher physician and patient satisfaction rates. Several anesthesia techniques were also introduced to ease the visceral pain associated with colonoscopy, such as intravenous lidocaine infusion, low-dose intravenous ketamine, and inhalation of an anesthetic mixture of oxygen with nitrous oxide.

Nevertheless, procedural sedation can induce mild cognitive decline after seemingly full recovery. Padmanabhan and colleagues report a significant decrease in visual attention and psychomotor function from baseline after sedation for colonoscopy. It is recommended by the guidelines for conscious sedation and monitoring during gastrointestinal endoscopy (ASGE, 2003) and the Institute Review of Endoscopic Sedation (AGA, 2008) that patients should be accompanied home by a responsible individual after endoscopic sedation, in addition to be instructed to avoid driving, make legally binding decisions, or operate heavy or potentially harmful machinery. The investigators have recently shown that an important proportion of patients experience periods of general anesthesia and/or a deep hypnotic state during endoscopy.

Prolonged systemic anesthesia is noted to increase the risk for serious complications in colonoscopy patients, either hemodynamically or psychomotorly. Additionally, Wernli and colleagues showed that the overall risk of complications after colonoscopy within 30 days increases when individuals receive anesthesia services, namely, the increased risk of perforation, abdominal pain, and stroke. Thus, minimizing the time systemic anesthesia is administered to the patient as possible during the procedure will likely reduce its potential side effects.

The withdrawal time following cecal intubation is quite controversial and operator-dependent. However, it is recommended to be between 6 and 9 minutes. Thus, withholding anesthetic agents during this phase might be beneficial. It would reduce the patient's exposure to anesthesia without causing any significant under-sedation until the near end of the procedure. At the same time, this intervention may accelerate the patient's post-procedure psychomotor recovery by terminating systemic sedation at an earlier checkpoint. Moreover, Adenoma detection rate (ADR), which refers to the rate of detecting colonic adenomas, is typically assessed during the withdrawal of the scope after cecal intubation. It is well known that this rate is influenced by the withdrawal time, meaning the duration the colonoscopist spends withdrawing the scope from the patient. Early discontinuation of anesthesia could limit the time available for the colonoscopist to detect adenomas during withdrawal, making it a significant outcome to evaluate after each colonoscopy.

This study explores whether discontinuing the continuous intravenous infusion of propofol directly following cecal intubation would shorten the patient's recovery time without affecting his comfort or convenience. It would also reduce procedural costs and the risk of medical hazards due to potentially excessive sedation.

Inclusion Criteria:

• Age between 18 and 80 years.
• Scheduled ambulatory elective screening or surveillance colonoscopy under MAC.

Exclusion Criteria:

• Medical contraindication to anesthesia (i.e., respiratory/cardiac/neurologic compromise, known allergy or adverse reaction to propofol, midazolam, lidocaine, or opiates, …)
• History of ischemic or hemorrhagic cerebrovascular accident.
• Baseline cognitive dysfunction (impaired memory, attention deficit, language disorders, …) - in other words, any dysfunction that prevents the subject from understanding the study protocol and/or completing the requested tests and assessments (e.g., playing the minigames, …)
• Use of more than one psychoactive drug.
• History of partial colectomy.
• Unable to give consent.