The Deep Sedation Conundrum and Paediatric Endoscopy.

Abstract

See “Dexamethasone Reduces Postoperative Nausea in Pediatric Upper Endoscopy With Deep Sedation: A Randomized Controlled Trial” by Moheimani and Yaseri on page 281. There is a definition of “deep sedation” that must be understood—propofol administration, for instance, is essentially general anaesthesia (GA), as is ketamine use and “total intravenous anaesthesia” (TIVA). “Deep sedation” in children is invariably a synonym for GA. Postprocedure nausea with these techniques is common. Its prevention is important. Moheimani and Yaseri (1) describe the reduction in postendoscopy nausea with dexamethasone after endoscopy in children under deep sedation. Single-dose dexamethasone is 1 element of nausea prevention and management following GA (2). Prevention and treatment strategies for postoperative nausea and vomiting include both pharmacological and nonpharmacological therapies. Pharmacological agents include 5-HT3 receptor antagonists, neurokinin-1 receptor blockers, anti-histamine H1 antagonists, haloperidol and droperidol, prokinetic agents such as metoclopramide, dexamethasone, and a variety of other agents. Nausea after procedures under so-called “deep sedation” is infrequently studied when compared with nausea after GA—one could identify these techniques as similar, however, as noted above. Nausea affects at least 30% of patients after GA with volatile agents but after intravenous anaesthesia with propofol the incidence of early nausea (0–6 hours) is reduced (3). It is likely that comparable patient and procedure factors influence postoperative nausea after procedures performed under sedation or GA. The observation that nausea after procedural sedation for endoscopy was reduced with the coadministration of dexamethasone is comparable with studies observing dexamethasone prophylaxis administered in GA (4). Indeed, an antiemetic policy should form part of the procedure as a standard in children. Moheimani and Yaseri (1) describe provided “deep sedation” for upper gastrointestinal endoscopy. Sedation and anaesthesia are not binary options but represent a continuum from awake to unconsciousness. The American Society of Anesthesiology has defined 4 levels of pharmacologically induced sedation: mild; moderate; deep; and anaesthesia. Differentiation between “deep sedation” and anaesthesia depends upon the presence or absence of a response to painful stimuli. Processed EEG techniques may also differentiate between levels of sedation. A Spanish group observed the processed EEG signal provided with the bispectral index (BIS) during paediatric upper gastrointestinal endoscopy (5). Endoscopy success was likely with a BIS index < 59—a BIS value that represents anaesthesia (6,7). Differentiation between “deep sedation” and anaesthesia is more than semantics, it is about risk. Moheimani and Yaseri (1) reported 4.1% of subjects developed either laryngospasm or bronchospasm—and airway complications can be challenging and costly (8). Invasive diagnostic and therapeutic procedures provided by endoscopy have evolved and may be delivered in a theatre or nontheatre environment. Anaesthetic techniques and agents have also evolved alongside these techniques, with intravenous techniques being deliverable in nontheatre environments with minimal equipment. Traditional airway interventions such as supraglottic devices and formal intubation are being supplanted by the delivery of oxygen through a face mask, nasal cannulae, or high-flow oxygen devices—heated high-flow therapy. Procedural respiratory and cardiac risks can be mitigated through presedation assessment and adherence to published professional standards and guidelines for sedation and anaesthesia (9). Notwithstanding the delivery of “deep sedation” or GA, the objective of the process is to provide an environment acceptable to both operator and patient. This requires care from the practitioner that balances the depth of sedation whilst avoiding respiratory and cardiovascular deterioration. The delivery of “deep sedation” probably carries no less risk than GA (10). The use of volatile agents requires the exhaustion of the waste gases, which is challenging with mask anaesthesia and may compromise the safety of personnel in the immediate environment (11). The avoidance of airway manipulation, such as intubation or supraglottic airways, does not mitigate airway risks. The delivery of the procedure in a formal theatre environment does not reduce the cost of delivery of the procedure. The application of volatile anaesthesia increases the risks of early nausea when compared with propofol-based sedation techniques. Therefore the delivery of a deep sedation technique for upper gastrointestinal endoscopy needs to have careful consideration of the aims and objectives of the service. Deaths are rare, and unlikely to be observed in the small sample reported by Moheimani and Yaseri (1). The benefits of the delivery of a sevoflurane-based anaesthetic technique in a theatre environment are not clear, although the adoption of an antiemetic policy may lead to an improvement in outcomes (12).