Residency · Residency · Emergency Medicine
Procedural Sedation in the ED
Introduction
Procedural sedation and analgesia (PSA) allows emergency physicians to perform painful or anxiety-provoking procedures while maintaining patient safety. It is distinct from general anesthesia in that protective airway reflexes are generally preserved. Competency in agent selection, monitoring, and rescue from deeper-than-intended sedation is essential for every emergency medicine resident.
Definitions and Sedation Continuum
Sedation exists on a continuum with four recognized levels. Minimal sedation (anxiolysis) allows the patient to respond normally to verbal commands, with cognitive function possibly impaired but ventilation and cardiovascular function unaffected. Moderate sedation (conscious sedation) produces a purposeful response to verbal or light tactile stimulation, with adequate spontaneous ventilation and cardiovascular function usually maintained. Deep sedation results in a purposeful response only to repeated or painful stimulation, with ventilatory function potentially impaired though cardiovascular function usually maintained. General anesthesia renders the patient unarousable even with painful stimuli, and airway intervention is often required. It is essential to recognize that this continuum is a spectrum, and patients may move unpredictably from one level to another during the procedure.
Pre-Sedation Assessment
The pre-sedation assessment includes a focused history covering last oral intake (though NPO status does not determine candidacy for emergency PSA), medications, allergies, prior sedation experiences, and substance use. The airway is assessed using the Mallampati score, neck mobility, presence of a beard, obesity, and obstructive sleep apnea. The ASA physical status classification is applied: patients classified as ASA I or II are low risk, while ASA III or IV patients require additional risk-benefit analysis. Informed consent should address the risks of respiratory depression, aspiration, and the potential need for intubation. Traditional pre-sedation fasting guidelines have been challenged by large ED-based studies that show no association between fasting time and adverse events in emergency PSA.
Monitoring and Equipment
Monitoring during PSA includes continuous pulse oximetry with waveform display, capnography (end-tidal CO2) which detects hypoventilation and apnea 60 to 90 seconds before oxygen desaturation occurs and is strongly recommended for all PSA, continuous ECG monitoring, and blood pressure measurement at regular intervals. A dedicated sedation nurse provides continuous clinical observation. Equipment at the bedside should include a bag-valve-mask, oral and nasal airways, suction, a laryngoscope, endotracheal tubes, and rescue medications including flumazenil and naloxone.
<image>Emergency department procedural sedation setup showing a monitored patient on a stretcher with capnography, pulse oximetry, cardiac monitor, and a bedside table with airway equipment including bag-valve-mask, oral airways, suction, and intubation supplies</image>
Pharmacologic Agents
| Agent | Dose (IV) | Onset | Duration | Analgesia | Key Advantage | Key Risk |
|---|---|---|---|---|---|---|
| Ketamine | 1–2 mg/kg | 30–60 sec | 15–20 min | Yes | Preserves airway reflexes; bronchodilation | Emergence reactions, laryngospasm (0.3%) |
| Propofol | 0.5–1 mg/kg | 15–30 sec | 5–10 min | No | Rapid recovery, antiemetic | Hypotension, apnea |
| Etomidate | 0.1–0.15 mg/kg | 15–30 sec | 5–15 min | No | Hemodynamically stable | Myoclonus (30–40%) |
| Ketofol (1:1) | 0.5–0.75 mg/kg each | 30 sec | 10–15 min | Yes | Balanced hemodynamics | Similar to each alone |
| Midazolam + Fentanyl | 0.02–0.05 + 1–1.5 mcg/kg | 1–2 min | 30–60 min | Yes (fentanyl) | Reversible (flumazenil/naloxone) | Respiratory depression, prolonged recovery |
Ketamine
Ketamine is a dissociative agent that provides sedation, analgesia, and amnesia simultaneously. The dose is 1 to 2 mg/kg IV over 60 seconds or 4 to 5 mg/kg IM. Onset is 30 to 60 seconds when given IV, with a duration of 15 to 20 minutes. It preserves airway reflexes and respiratory drive and causes bronchodilation. Side effects include emergence reactions (which can be reduced with co-administration of midazolam at 0.02 to 0.05 mg/kg in adults), laryngospasm (rare, occurring in approximately 0.3 percent), emesis, and hypersalivation. Ketamine is the preferred agent in children and in patients with reactive airway disease.
Propofol
Propofol is an ultra-short-acting sedative-hypnotic with no analgesic properties. The initial dose is 0.5 to 1 mg/kg IV, followed by 0.5 mg/kg every 3 to 5 minutes as needed. Onset is 15 to 30 seconds with a duration of 5 to 10 minutes. It causes dose-dependent respiratory depression and hypotension. Its advantages include antiemetic properties and rapid, clear-headed recovery.
Etomidate
Etomidate is an imidazole derivative with rapid onset and short duration. The dose is 0.1 to 0.15 mg/kg IV, with an onset of 15 to 30 seconds and a duration of 5 to 15 minutes. It has minimal hemodynamic effects but does not provide analgesia. Myoclonus occurs in 30 to 40 percent of patients, and transient adrenal suppression occurs but is clinically insignificant with a single dose used for PSA.
Ketofol (Ketamine + Propofol)
Ketofol combines ketamine and propofol, aiming to balance the sympathomimetic effects of ketamine with the hypotensive properties of propofol. A typical preparation uses a 1:1 ratio in a single syringe (for example, 50 mg of each per mL). Evidence shows a similar safety profile to either agent used alone.
Midazolam + Fentanyl
This traditional combination provides anxiolysis and analgesia. Midazolam is dosed at 0.02 to 0.05 mg/kg IV and fentanyl at 1 to 1.5 mcg/kg IV. Recovery time is longer compared to propofol or ketamine. The combination carries higher rates of respiratory depression, so both agents should be titrated slowly. Both are reversible: flumazenil at 0.2 mg IV reverses midazolam, and naloxone at 0.04 to 0.4 mg IV reverses fentanyl.
<image>Pharmacokinetic comparison chart of common procedural sedation agents showing onset time, peak effect, duration of action, and recovery profiles for ketamine, propofol, etomidate, and midazolam-fentanyl combinations</image>
Adverse Events and Rescue
Hypoventilation and apnea are the most common serious adverse events and are detected early by capnography. Management includes jaw thrust and bag-valve-mask ventilation. Laryngospasm is the most feared complication of ketamine and is treated with positive pressure ventilation; if refractory, succinylcholine at 0.5 to 1 mg/kg IV is used. Hypotension is most common with propofol and is managed with an IV fluid bolus and dose reduction for subsequent doses. Emesis and aspiration risk are managed by positioning the patient in the lateral decubitus position and having suction immediately available. For oversedation, stimulation should be maintained, ventilation supported, and reversal agents considered if benzodiazepines or opioids were used.
Special Populations
In pediatric patients, ketamine is the most extensively studied and widely used agent, with lower rates of adverse events than in adults. For elderly patients, initial doses should be reduced by 25 to 50 percent because of increased sensitivity to all agents. Obese patients should be dosed on ideal body weight for most agents, and advanced airway equipment should be readily available. In pregnant patients, PSA should be performed only when necessary; ketamine is relatively contraindicated in the first trimester, and propofol is preferred when sedation is required.
Discharge Criteria
Patients must return to baseline mental status and verbal function before discharge. Vital signs should be stable for at least 15 to 30 minutes after the last dose. The patient should be able to sit unassisted, tolerate oral fluids, and ambulate (as appropriate for age). A responsible adult must be available for the discharge escort, and written discharge instructions with activity restrictions should be provided.
<image>Flowchart decision algorithm for selecting the appropriate procedural sedation agent based on patient characteristics including age, hemodynamic status, airway risk, and procedure type</image>
Clinical Pearls
Capnography is the single best monitoring tool for early detection of respiratory depression during PSA. NPO status should not delay necessary emergency procedural sedation, as large prospective studies show no increased aspiration risk. Ketamine is the safest agent when airway protective reflexes must be maintained. The worst-case scenario should always be prepared for by having a full intubation setup at the bedside before initiating any sedation. The combination of a dedicated sedation provider, capnography, and standardized protocols has been shown to reduce adverse events.
References
- Green SM, Roback MG, Kennedy RM, et al. Clinical practice guideline for emergency department ketamine dissociative sedation: 2011 update. Ann Emerg Med. 2011;57(5):449-461.
- Bellolio MF, Gilani WI, Barrionuevo P, et al. Incidence of adverse events in adults undergoing procedural sedation in the emergency department: a systematic review and meta-analysis. Acad Emerg Med. 2016;23(2):119-134.
- Godwin SA, Burton JH, Gerardo CJ, et al. Clinical policy: procedural sedation and analgesia in the emergency department. Ann Emerg Med. 2014;63(2):247-258.
- Saunders R, Struys MMRF, Pollock RF, et al. Patient safety during procedural sedation using capnography monitoring: a systematic review and meta-analysis. BMJ Open. 2017;7(6):e013402.
