Acute pain management and procedural sedation

• Acute pain in the emergency department should be treated as a vital sign: severe pain is treated promptly, and good analgesia does not usually have to wait for a diagnosis. ^[5]
• The backbone of care is multimodal analgesia, combining paracetamol, an NSAID and, when needed, an opioid and a regional block or ketamine, rather than one drug at full dose.
• Procedural sedation is a carefully titrated reduction in consciousness that keeps the airway open and breathing adequate; it is not general anaesthesia and its main dangers are unintended deeper sedation, hypoxia and aspiration.
• Ketamine is the preferred sedative for painful emergency procedures because airway reflexes, breathing and blood pressure are largely preserved; midazolam with fentanyl is the standard reversible regimen for non-painful and endoscopic procedures. ^[2]
• Nitrous oxide gives brief, self-limiting analgesia and sedation for short procedures, but it needs scavenging, gives no airway control and is avoided in early pregnancy.
• Safe sedation needs full preparation: fasting that is reasonable but not a rigid delay, continuous monitoring with pulse oximetry and preferably capnography, an observer who does nothing else, reversal agents drawn up, and clear written discharge criteria.

By the end of this page you should be able to:

1. Plan an analgesic regimen for common emergency presentations using a multimodal approach that limits opioid exposure.
2. Explain when and how to use low-dose ketamine and nitrous oxide for pain and as sedatives, including their advantages and cautions.
3. Define procedural sedation, identify who is suitable and who is not, and list its contraindications.
4. Prepare a patient for procedural sedation, including consent, fasting advice and airway assessment.
5. Describe the monitoring, reversal agents and discharge criteria used after sedation.
6. Outline the Royal College of Emergency Medicine, ACEP and ASA positions on fasting, monitoring and propofol.

Acute pain is the reason many patients come to the emergency department, and procedural sedation is one of the reasons they can be treated there rather than in an operating theatre. The two topics belong together: good analgesia is part of sedation, and the same safeguards (airway, breathing, monitoring, reversal) apply whenever sedative drugs are given.

This page covers two related clinical skills. The first is the assessment and drug treatment of acute pain in adults in the emergency department, drawing on recent reviews of multimodal analgesia in emergency medicine. The second is procedural sedation and analgesia for a diagnostic or therapeutic procedure performed in the department, guided by the Royal College of Emergency Medicine (RCEM) best practice guideline of August 2022, the American College of Emergency Physicians (ACEP) policy statement of February 2023 and clinical policy of 2014, and the American Society of Anesthesiologists (ASA) practice guidelines of 2018. A regional note is appropriate: ACEP and ASA guidance reflects US practice, while the RCEM guidance reflects UK practice, but the core safety principles are the same. ^[1]

Pain in the emergency department is often undertreated. A common reason is the fear that analgesia will mask a diagnosis, but current evidence shows that early analgesia does not generally compromise diagnostic accuracy when it is followed by reassessment and documented examination. Timely analgesia improves satisfaction and outcomes, and pain should be reassessed after each intervention.

Assessment should be simple and repeatable. The numeric rating scale from 0 to 10, the visual analogue scale and the Wong-Baker faces scale are the common tools. Reassessment at 15 to 30 minutes is part of treatment, not an afterthought. ^[1]

For mild pain, and as the foundation of almost every regimen, paracetamol and a non-steroidal anti-inflammatory drug (NSAID) are used together, because they act by different mechanisms and their effect can be synergistic. Paracetamol is widely used first line for mild to moderate pain, including by the intravenous route when the gut cannot be used. NSAIDs are particularly effective when inflammation drives the pain: renal colic, soft tissue injury, musculoskeletal trauma and some kinds of headache. They reduce prostaglandin synthesis by inhibiting cyclo-oxygenase. ^[1]

Safety selection matters more in the emergency department than the choice of drug. NSAIDs should be avoided or used with care in renal impairment, gastrointestinal ulcer or bleeding risk, cardiovascular disease and pregnancy, and in patients taking anticoagulants. Paracetamol has a more favourable general safety profile and is the safer default when these factors are present.

Opioids remain essential for moderate to severe pain. The principles that keep them safe are titration rather than a single large bolus, frequent reassessment and monitoring for sedation and respiratory depression.

• Morphine is usually given intravenously in titrated doses of 0.05 to 0.1 mg per kilogram, with time allowed for peak effect before the next dose. ^[1]
• Fentanyl has rapid onset and short duration and is particularly useful for acute pain and procedural analgesia.

Opioids are now chosen more selectively. Renal colic is usually better treated with an NSAID, because prostaglandin-mediated ureteral spasm is the main mechanism. Primary headache disorders such as migraine are better treated with NSAIDs and antiemetics, since opioids in this setting increase the risk of medication-overuse headache and have poorer long-term outcomes. Constipation and opioid-related adverse effects should be anticipated.

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has become a central opioid-sparing analgesic. At sub-dissociative doses of 0.1 to 0.3 mg per kilogram intravenously it gives rapid analgesia, preserves airway reflexes and has minimal respiratory depression. It is especially useful in trauma, in opioid-tolerant patients and in patients who are hypotensive, for whom opioid hypotension and sedation are hazardous. Emerging evidence supports its use both as a primary analgesic and as an adjunct to opioids for severe pain, with the aim of reducing total opioid dose. Psychomimetic reactions can occur but are uncommon at low dose. ^[1]

Because ketamine preserves airway reflexes and blood pressure, it is also the preferred single agent for painful procedural sedation in the emergency department, discussed below.

Nitrous oxide 50% with oxygen (Entonox-type mixtures) provides rapid, patient-controlled analgesia and mild sedation within 2 to 3 minutes, with full recovery within about 5 minutes. It is useful for brief painful procedures and for prehospital care, because it needs no intravenous access. As a sedative-analgesic it is less controllable than intravenous drugs, does not provide airway control and requires scavenging to limit occupational exposure. Prolonged or repeated use is teratogenic and it is contraindicated in the first trimester of pregnancy. Supplemental oxygen for 5 minutes after it is stopped reduces diffusion hypoxia. ^[2]

The approach scales with pain:

• Mild pain: paracetamol plus an NSAID. ^[1]
• Moderate pain: paracetamol plus an NSAID plus a low-dose opioid.
• Severe pain or trauma: a titrated opioid plus low-dose ketamine, with early consideration of a nerve block. ^[1]
• Specific presentations: renal colic favours NSAIDs; migraine favours NSAIDs and antiemetics; older patients with hip fracture do well with a fascia iliaca block plus paracetamol and cautious opioid.

Regional anaesthesia is an important pillar and is covered in the related topic on regional and local anaesthesia; in the emergency department the fascia iliaca block and femoral block for hip fracture, and upper extremity blocks for shoulder dislocation, give strong opioid-sparing analgesia.

Procedural sedation is the administration of one or more pharmacological agents to allow a diagnostic or therapeutic procedure while a state is maintained in which airway patency, spontaneous respiration, protective airway reflexes and cardiovascular stability are preserved. It is not general anaesthesia. The target for a non-anaesthetist is moderate sedation: the patient is purposefully responsive to voice or touch, keeps an open airway without intervention, breathes adequately and maintains blood pressure. ^[2]

The continuum runs from minimal through moderate and deep sedation to general anaesthesia. Moderate sedation is the only depth appropriate for non-anaesthetist practice in the emergency department. Deeper planes can be entered accidentally, which is why drug selection, monitoring and rescue capability matter so much.

Procedural sedation is used when a procedure is too painful or distressing for local anaesthesia alone: fracture and joint reduction, burns dressings, wound repair, incision and drainage, imaging in claustrophobic or young patients, cardioversion and other brief but painful interventions. It should be considered alongside alternatives. Local or regional anaesthesia and non-pharmacological techniques such as explanation, positioning, splinting and distraction may make sedation unnecessary, and informed consent should reflect this.

Patients who are well or who have mild systemic disease (ASA physical status I and II) are generally excellent candidates. Severe systemic disease (ASA III or greater) increases the risk of adverse events and calls for careful consideration of alternatives, anaesthetic involvement or referral. Other factors that raise risk are:

• Inadequate fasting in an elective setting, or a recently fed patient
• Difficult airway or anticipated airway problems
• Significant cardiorespiratory disease
• Active infection, bleeding disorder, or coagulopathy when the procedure or position requires it
• Prior adverse reaction to the intended agents
• Gastro-oesophageal reflux with aspiration risk
• Active delirium, alcohol intoxication or uncontrolled seizures
• Sedation solely for restraint, or when there is no clinician with rescue skills available

Preparation starts with the team. RCEM recommends a sedationist, a separate person performing the procedure and a nurse, in a designated area such as the resuscitation room, with a documented pre-procedure safety brief. ACEP notes that two personnel are the minimum: one responsible for sedation and one whose primary role is continuous monitoring.

Drugs are only part of the assessment. A focused history covers allergies, current medicines, comorbidities (especially cardiac, respiratory and renal), airway history and previous sedation or anaesthesia problems. Airway assessment includes prediction of difficulty in managing the airway. Informed consent is obtained and documented; in younger patients and those lacking capacity this is done with the legally appropriate substitute decision maker.

Fasting is where old practice and current evidence diverge. The ASA 2018 guideline still quotes the elective standard of 2 hours for clear liquids and 6 hours for solids before a procedure. In emergency practice, current guidance is not to delay procedural sedation in adults or children solely on fasting time. The risks of an emergency procedure usually outweigh the small chance of aspiration, provided this is a deliberate decision and the airway is assessed. This is a regional and institutional matter too, so follow local policy, but rigid fasting rules should not be used to deny timely care. ^[2][4]

Monitoring is the safety net. The ASA 2018 guideline calls for continuous pulse oximetry, blood pressure every 3 to 5 minutes, continuous electrocardiography in older patients and those with cardiac disease, and a dedicated observer whose only role is the patient. The RCEM guidance adds three-lead electrocardiogram, oxygen saturation, continuous capnography, non-invasive blood pressure and a nurse monitor. ^[2][4]

Capnography deserves emphasis. Pulse oximetry falls only after hypoxia has developed and is especially slow when supplemental oxygen is given. End-tidal carbon dioxide monitoring detects apnoea and hypoventilation 60 to 90 seconds before desaturation, and a Cochrane review found that capnography reduces episodes of desaturation during emergency department sedation. It should be standard whenever ventilation could be compromised. ^[2]

Baseline and continuous monitoring of oxygen saturation, heart rate, blood pressure, respiratory rate and level of consciousness are recorded. Equipment must be present and tested before drugs are drawn up: supplemental oxygen, suction, a correctly sized bag-valve-mask, flumazenil 0.2 mg per millilitre and naloxone 0.4 mg per millilitre drawn up, and a resuscitation trolley within reach. ^[2]

No single agent satisfies every requirement. The practical division is between the emergency department's standard regimens and agents that are restricted to anaesthetist-led practice.

Midazolam and fentanyl (the standard reversible regimen). Midazolam is a water-soluble benzodiazepine with onset within 2 to 3 minutes, peak effect at 5 to 7 minutes and duration of 30 to 60 minutes. It provides sedation, anxiolysis and amnesia but no analgesia, so it is combined with fentanyl for painful procedures. Flumazenil, 0.2 mg intravenously and repeatable to 1 mg total, is its specific reversal agent. Doses are reduced by 25 to 50% in patients over 65 years, in hepatic impairment and with other central nervous system depressants. Fentanyl has onset within 1 to 2 minutes and lasts 30 to 60 minutes, with little cardiovascular depression; naloxone 0.1 to 0.4 mg intravenously reverses it. Rapid fentanyl injection above 5 micrograms per kilogram risks rigid chest syndrome, which is negligible at standard doses of 1 to 2 micrograms per kilogram. ^[2]

Ketamine (the dissociative agent). Ketamine 1 to 2 mg per kilogram intravenously gives onset within 30 to 60 seconds and dissociation lasting 5 to 15 minutes; further 0.5 to 1 mg per kilogram doses extend it safely. It preserves airway reflexes, spontaneous ventilation and blood pressure while providing strong analgesia, which is why it is the preferred agent for painful emergency procedures. The concern that ketamine raises intracranial pressure is not supported by contemporary systematic reviews, which found no increase compared with opioids at standard sedative doses. Emergence phenomena (vivid dreams, hallucinations, agitation) occur in about 5 to 20% of adults and are reduced by low-dose midazolam 1 to 2 mg intravenously at the end of the procedure. Co-administration of glycopyrrolate 0.2 mg intravenously can be used to reduce secretions where relevant. Compared with midazolam plus fentanyl, ketamine-containing regimens produce less oxygen desaturation, which is clinically important when the sedationist is also responsible for monitoring. ^[2]

Commonly used combinations with adult doses:

Nitrous oxide has already been described; it is an additional option for very brief procedures.

Propofol and dexmedetomidine (restricted). These agents should not be used for moderate sedation by non-anaesthetists. Propofol has a steep, unpredictable dose-response curve, has no reversal agent, has no analgesia and causes hypotension in up to 30% of patients. The ASA position is that patients given propofol should be managed as if deep sedation is intended, with staff able to rescue a patient who briefly enters general anaesthesia. Dexmedetomidine, a selective alpha-2 agonist, causes bradycardia with an odds ratio of 3.60 and hypotension with an odds ratio of 1.95 compared with comparators, needs a loading infusion and an infusion pump, has no reversal agent and has a recovery of 60 to 120 minutes. Neither suits ward- or department-based moderate sedation. ^[2]

The presence of a reversal agent is the single most important safety feature of a sedation regimen in the emergency department. Reversal is supportive, not curative: correcting hypoxia, airway positioning and ventilation come first.

• Flumazenil 0.2 mg intravenously, repeated to a total of 1 mg, reverses benzodiazepines. Its effect can wear off before the benzodiazepine, so re-sedation must be watched for; it can also precipitate withdrawal in benzodiazepine-dependent patients.
• Naloxone 0.1 to 0.4 mg intravenously reverses opioids, including respiratory depression. Its half-life is shorter than many opioids, so repeated dosing and observation are needed. ^[2]
• Ketamine has no specific reversal agent; its effects are managed supportively.
• Nitrous oxide is allowed to dissipate; 100% oxygen counters diffusion hypoxia.
• Intravenous lipid emulsion is used in local anaesthetic systemic toxicity, which is the relevant reversal approach if a local anaesthetic block accompanies sedation.

Recovery can be biphasic: the patient may wake and then become sedated again as stimulation is removed. Highest risk occurs during the first 20 minutes after the drug and in the post-procedure period, which is why continuous nursing care until return to baseline matters as much as the monitoring record.

Discharge is safe only when all of the following are met: the patient is awake and age-appropriately alert; vital signs have returned to pre-sedation baseline; there is no respiratory depression; written discharge instructions have been given; and, for outpatients, a responsible adult escort is available. Objective criteria published in the guidance include oxygen saturation above 95% on room air for at least 15 minutes, haemodynamic stability within 20% of baseline and orientation to person and place. ^[2][7]

Written discharge advice should be routine rather than verbal only, ideally in the patient's language. Content includes the expected course, warning symptoms such as recurrent drowsiness, vomiting, breathing difficulty or pain, the restriction on driving and operating machinery for 24 hours and when and where to seek help.

The list is short and should be checked every shift:

• Monitoring: pulse oximeter, non-invasive blood pressure, three-lead electrocardiogram, capnography.
• Airway and breathing: oxygen, masks, nasal cannulae, suction, bag-valve-mask of suitable size and, for children, paediatric sizes.
• Drugs drawn up: the sedative regimen, flumazenil and naloxone in ready doses.
• Resuscitation trolley and defibrillator within reach.
• Discharge leaflets and documentation proforma.

1. Decide that sedation is the best option, with a named sedationist, procedurist and nurse, in a designated area.
2. Take consent and record a focused history, airway assessment and ASA grade.
3. Check fasting with the patient but do not delay emergent sedation for fasting alone; plan analgesic and monitoring needs.
4. Complete a safety brief with the team, including the procedure, drugs and expected complications.
5. Record baseline vital signs and apply oxygen and monitoring, including capnography where available.
6. Prepare and check rescue equipment.
7. Titrate the chosen drugs slowly, allowing time for peak effect and reassessing the depth of sedation.
8. Perform the procedure while an observer monitors and documents throughout.
9. Reduce painful stimulation gradually and observe closely through recovery; avoid premature discharge.
10. Apply objective discharge criteria and give written advice before the patient leaves.

Sedation is generally safe, but complications are predictable:

• Respiratory: hypoxia, apnoea, hypoventilation and airway obstruction. Hypoxia occurs in roughly 40 per 1000 adult sedations, apnoea in about 12 per 1000. ^[7]
• Circulatory: hypotension, reported in about 15 per 1000 adult sedations; tachycardia or bradycardia with ketamine. ^[7]
• Gastro-intestinal: vomiting, in about 16 per 1000 adult sedations; aspiration is rare but catastrophic. ^[7]
• Neurological and psychological: oversedation, emergence phenomena and agitation; with ketamine the latter occurs in about 20% of children. ^[7]
• Local or systemic toxicity if regional anaesthesia accompanies sedation.
• Medication errors, particularly in dosing by weight.

Most complications are prevented by sensible drug selection, weight-based dosing, slow titration, proper monitoring and rescue readiness. They are treated by stopping drugs, supporting the airway and ventilation, giving reversal where it exists and calling for help early.

Children need doses calculated by weight and have different pharmacokinetics; many departments restrict paediatric procedural sedation to clinicians with specific paediatric credentialing. The RCEM guideline specifies a nominated paediatric sedation lead and paediatric guidelines where paediatric sedation is offered.

Older adults are the highest-risk group for adverse events. Reduced clearance prolongs drug half-life, lower protein binding raises free drug concentration and diminished respiratory reserve compounds the risk. Doses are reduced by 25 to 50%, with intervals of at least 3 to 5 minutes between increments.

Pregnant patients require attention to aspiration risk, airway anatomy and drug safety; prolonged or repeated nitrous oxide is teratogenic in the first trimester. Patients with significant cardiac, respiratory or renal disease, and those classified ASA III or greater, are better served by anaesthetic involvement.

Safe sedation does not depend on expensive technology. A trained sedationist, a nurse observer, a bag-valve-mask, oxygen, suction and reversal agents are the essentials. Capnography is valuable but its absence should not be the reason to deny needed care, provided patients are observed closely until they reach baseline. Midazolam and ketamine remain affordable and effective; the same attention to airway, monitoring, gradual dosing and written discharge advice still applies. Regional and local anaesthesia should be used wherever they can replace sedation entirely.

• Acute pain in the emergency department should be treated promptly, including for patients in whom the diagnosis is not yet final, with reassessment documented after each intervention.
• Multimodal analgesia, built on paracetamol and an NSAID with low-dose opioids, ketamine or nerve blocks added as needed, is the standard approach and reduces opioid exposure.
• Ketamine at sub-dissociative doses (0.1 to 0.3 mg/kg IV) offers rapid opioid-sparing analgesia with preserved airway reflexes and blood pressure.
• Procedural sedation targets moderate sedation, with airway patency, spontaneous breathing and cardiovascular stability maintained; it is not general anaesthesia.
• RCEM (August 2022), ACEP (clinical policy 2014 and policy statement 2023) and ASA (2018) agree on preparation, monitoring and rescue readiness, while differing on pharmacology detail and regional emphasis.
• Fasting is based on elective standards of 2 hours for clear liquids and 6 hours for solids, but emergent sedation should not be delayed in adults or children solely on fasting time.
• Monitoring includes pulse oximetry, blood pressure at least every 3 to 5 minutes, electrocardiography in higher-risk patients, and continuous capnography whenever ventilation may be impaired.
• Reversal agents are the key safety feature: flumazenil 0.2 mg IV (to 1 mg total) for benzodiazepines and naloxone 0.1 to 0.4 mg IV for opioids; ketamine and nitrous oxide have no specific reversal.
• Discharge requires the patient to be awake and alert, with vital signs back to baseline, no respiratory depression, written discharge instructions and, for outpatients, an escort.
• Propofol and dexmedetomidine are restricted to anaesthetist-led practice because of the lack of reversal, unpredictability or haemodynamic risk.

• Regional and local anaesthesia
• General anaesthesia and airway management
• Acute pain assessment and analgesia in specific populations
• Analgesia in trauma and resuscitation
• Perioperative care and preoperative assessment
• Consent and capacity in emergency medicine