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Adverse events related to procedural sedation for gastrointestinal endoscopy

Jonathan Cohen, MD
Section Editors
John R Saltzman, MD, FACP, FACG, FASGE, AGAF
Girish P Joshi, MB, BS, MD, FFARCSI
Deputy Editor
Kristen M Robson, MD, MBA, FACG


The development of gastrointestinal (GI) endoscopy has greatly expanded the diagnostic and therapeutic capabilities of gastroenterologists. Adequate patient tolerance is essential for successful completion of a safe examination and compliance with subsequent follow-up. As a result, endoscopists have developed skills in administering a variety of sedative and analgesic agents to facilitate procedures and enhance patient comfort. However, a number of adverse events related to procedural sedation have been described.

This topic review will focus on the adverse events related to procedural sedation for GI endoscopy. An overview of procedural sedation for endoscopic procedures, issues related to endoscopic procedures without sedation, and the management of patients who are difficult to sedate are discussed elsewhere. (See "Overview of procedural sedation for gastrointestinal endoscopy" and "Sedation-free gastrointestinal endoscopy" and "Alternatives and adjuncts to moderate procedural sedation for gastrointestinal endoscopy".)


Aspiration — The main concern related to topical pharyngeal anesthesia is inhibition of the gag reflex and the risk of aspiration. Oversedation may exacerbate this risk. This is particularly important in the management of patients with acute upper gastrointestinal (GI) bleeding. Endotracheal intubation for airway protection should be considered to prevent life-threatening aspiration in patients with active hematemesis. It may also be advisable to avoid topical inhibition of the gag reflex in such patients and in other individuals at high risk for aspiration (table 1). (See "Aspiration pneumonia in adults", section on 'Predisposing conditions'.)

Local anesthetic toxicity — Systemic effects such as arrhythmias and seizures due to absorption of the topical local anesthetic have been observed, although they are uncommon [1]. These drugs have also rarely been associated with the development of methemoglobinemia (benzocaine more than lidocaine) [1-3]. (See "Clinical features, diagnosis, and treatment of methemoglobinemia".)

Methemoglobinemia — Significant methemoglobinemia may be clinically suspected by the presence of clinical "cyanosis" and an oxygen saturation (SaO2) of approximately 85 percent in the face of a normal arterial PO2 (PaO2). The blood in methemoglobinemia has been variously described as dark-red, chocolate, or brownish to blue in color, and unlike deoxyhemoglobin, the color does not change with the addition of oxygen. Pulse oximetry is inaccurate in monitoring oxygen saturation in the presence of methemoglobinemia. (See "Clinical features, diagnosis, and treatment of methemoglobinemia".)

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Literature review current through: Nov 2017. | This topic last updated: Mar 23, 2016.
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