What is the most common adverse event associated with procedural sedation in the emergency department?

Most Common Adverse Event in ED Procedural Sedation

Hypoxia is the most common adverse event associated with procedural sedation in the emergency department, occurring at a rate of approximately 40 per 1,000 sedations in adults and 15 per 1,000 sedations in children. 1, 2

Evidence Supporting Hypoxia as Most Common Adverse Event

Adult Population Data

• A systematic review and meta-analysis of 9,652 adult procedural sedations demonstrated hypoxia as the most frequent adverse event with an incidence of 40.2 per 1,000 sedations (95% CI = 32.5 to 47.9) 1
• This was followed by vomiting at 16.4 per 1,000 sedations and hypotension at 15.2 per 1,000 sedations 1
• A prospective Dutch multicenter study of 1,711 adults confirmed this pattern, with an overall adverse event rate of 11%, predominantly consisting of hypoxia or apnea 3

Pediatric Population Data

• In children, hypoxia occurs at 14.8 per 1,000 sedations (95% CI 10.2 to 19.3), making it the third most common adverse event after vomiting (55.5 per 1,000) and agitation (17.9 per 1,000) 2
• The American College of Emergency Physicians clinical policy emphasizes that respiratory depression is the most concerning side effect related to sedation agents, though careful preparation and administration prevent harmful sequelae 4

Clinical Significance and Context

Severity Considerations

• While hypoxia is common, serious adverse events requiring emergent intervention are exceedingly rare: laryngospasm occurred in only 1 of 883 sedations (4.2 per 1,000), aspiration in 1 of 2,370 sedations (1.2 per 1,000), and intubation in 2 of 3,636 sedations (1.6 per 1,000) 1
• Most hypoxic episodes are transient and respond to simple interventions like supplemental oxygen, jaw thrust, or verbal/tactile stimulation 4
• Studies demonstrate that transient desaturation below 90% occurs without clinical consequence, similar to what occurs during normal sleep in healthy volunteers (43% of asymptomatic men desaturate below 90% during sleep) 4

Drug-Specific Risk Patterns

• Benzodiazepine-opioid combinations significantly increase respiratory depression risk: hypoxemia occurred in 92% of volunteers and apnea in 50% when midazolam and fentanyl were combined, compared to no hypoxemia with midazolam alone 4, 5
• Apnea was more frequent with midazolam (51.4 per 1,000 sedations) 1
• Hypoxia was less frequent when ketamine/propofol combinations were used compared to other drug combinations 1

Why Not the Other Options

Agitation (Option A)

• Agitation occurs at much lower rates: 17.9 per 1,000 sedations in children 2
• Agitation is primarily associated with ketamine (164.1 per 1,000 ketamine sedations) but remains less common overall than hypoxia 1

Hypertension (Option B)

• Hypertension is not commonly reported as an adverse event in procedural sedation studies 4
• Hypotension is more frequently documented (15.2 per 1,000 sedations) but still less common than hypoxia 1

Laryngospasm (Option D)

• Laryngospasm is rare, occurring in only 4 of 431 pediatric ketamine sedations (approximately 9 per 1,000) 4
• In the adult systematic review, only 1 case occurred in 883 sedations (4.2 per 1,000) 1
• In pediatric meta-analysis, 34 cases occurred among 8,687 sedations (2.9 per 1,000), with 33 of 34 cases involving ketamine 2

Monitoring Implications

• Pulse oximetry is essential for detecting hypoxia, though it should complement rather than replace clinical assessment 4
• The highest risk period for serious adverse events is within 25 minutes of the last medication dose, with median occurrence at 2 minutes after final administration 4
• Capnometry may provide earlier detection of hypoventilation before hypoxia develops, though its impact on patient outcomes remains unproven 4, 5

Answer: C. Hypoxia