Acute Pain & Procedural Sedation — Part 3: Topical & Local Anesthesia and Procedural Sedation
LET gel, EMLA cream, lidocaine buffering, hematoma block, intra-articular injection, sedation continuum, pre-sedation assessment, sedation agents with complete dosing, ketamine considerations, modified Aldrete score, and recovery criteria.
5. Topical and Local Anesthesia
Topical and local anesthetic techniques are fundamental to ED practice, reducing pain from procedures and reducing the need for systemic analgesics. When applied correctly, these techniques can eliminate procedural pain entirely for many common ED procedures.1 2
5.1 LET Gel (Lidocaine-Epinephrine-Tetracaine)
LET gel is the standard topical anesthetic for laceration repair in the ED, providing excellent anesthesia to wound edges without the need for injectable local anesthetic in many cases. It has largely replaced TAC (tetracaine-adrenaline-cocaine) due to equal efficacy and superior safety profile.1 3
| Parameter | Detail |
|---|---|
| Composition | Lidocaine 4% + epinephrine 0.1% (1:1,000) + tetracaine 0.5% |
| Application | Apply 1–3 mL directly into and around the wound; cover with an occlusive dressing (e.g., Tegaderm) or hold gauze soaked with LET over the wound |
| Contact time | 20–30 minutes for full effect (onset may be apparent by 15 minutes) |
| Efficacy indicator | Blanching of wound edges (due to epinephrine vasoconstriction) indicates adequate absorption |
| Volume | 1–3 mL for most lacerations; maximum 3 mL in children |
| Efficacy | Provides adequate anesthesia in 75–90% of facial and scalp lacerations; less effective on extremities (thicker skin) |
| Supplementation | If inadequate after 30 minutes, supplement with infiltrated buffered lidocaine at wound margins |
| Contraindications | Do not apply to mucous membranes, eyes, ears (tympanic membrane), or large wounds with significant absorption potential; avoid on digits, penis, nose tip, or ear pinna (epinephrine-containing preparations — though the evidence for digital danger is weak, many institutions still maintain this restriction for topical preparations) |
| Advantages | Painless application; eliminates needle fear (especially valuable in pediatrics); no sedation required |
5.2 EMLA Cream (Lidocaine-Prilocaine)
EMLA (Eutectic Mixture of Local Anesthetics) provides anesthesia to intact skin and is primarily used before needle procedures (IV cannulation, lumbar puncture, venipuncture, vaccination).1 2
| Parameter | Detail |
|---|---|
| Composition | Lidocaine 2.5% + prilocaine 2.5% in an emulsion cream |
| Application | Apply a thick layer (1–2 g per 10 cm²) to intact skin; cover with an occlusive dressing (Tegaderm) |
| Minimum contact time | 60 minutes for superficial procedures (venipuncture); 90–120 minutes for deeper procedures (lumbar puncture) |
| Depth of anesthesia | 3 mm at 60 minutes; 5 mm at 120 minutes |
| Duration after removal | Anesthetic effect persists for 1–2 hours after cream removal |
| Pediatric dosing | Neonates (≤28 days): max 1 g over 10 cm² for 1 hour; Infants 1–3 months: max 1 g over 10 cm² for 1 hour; 3–12 months: max 2 g over 20 cm² for 4 hours; 1–6 years: max 10 g over 100 cm² for 5 hours; 7–12 years: max 20 g over 200 cm² for 5 hours |
| Caution | Prilocaine may cause methemoglobinemia, especially in neonates and infants <3 months or with G6PD deficiency; avoid excessive application areas |
| Limitations | Requires 60+ minutes of application time (significant in a busy ED); does not work on open wounds; occlusive dressing may shift |
| Alternatives | Lidocaine 4% cream (LMX-4): similar efficacy, 30-minute application time, no methemoglobinemia risk; J-Tip needleless injection system (lidocaine powder); vapocoolant spray (ethyl chloride) for immediate brief anesthesia |
5.3 Lidocaine Buffering
The injection of standard lidocaine is painful due to its acidic pH (3.5–5.5). Buffering with sodium bicarbonate raises the pH closer to physiologic, converting more lidocaine to its non-ionized (active) form, which provides faster onset and dramatically reduced injection pain.1 4
| Parameter | Detail |
|---|---|
| Ratio | 9:1 (9 parts lidocaine to 1 part 8.4% sodium bicarbonate) |
| Example | 9 mL of lidocaine 1% + 1 mL of sodium bicarbonate 8.4% = 10 mL of buffered lidocaine |
| For bupivacaine | Use 30:1 ratio (30 parts bupivacaine to 1 part sodium bicarbonate) — bupivacaine precipitates at lower bicarbonate concentrations |
| Stability | Buffered lidocaine should be used within 24 hours of preparation (buffered lidocaine with epinephrine should be used within 1 week if refrigerated, though immediate use is preferred) |
| Evidence | Meta-analysis demonstrates a statistically and clinically significant reduction in pain with buffered lidocaine injection compared with unbuffered |
| Additional pain-reduction strategies | Warm the solution to body temperature (37°C); use small-gauge needle (27–30 gauge); inject slowly; inject through wound edges (less painful than intact skin); use a needle-free system where available |
5.4 Hematoma Block for Fractures
The hematoma block is a simple, effective technique for providing analgesia for displaced fractures, particularly distal radius fractures (Colles fracture, Smith fracture). It involves injection of local anesthetic directly into the fracture hematoma.5
| Parameter | Detail |
|---|---|
| Indication | Closed fractures with palpable hematoma, particularly distal radius, distal ulna, and ankle fractures |
| Preparation | Sterile technique; prep skin with chlorhexidine or povidone-iodine |
| Needle | 20–22 gauge, 1.5-inch needle |
| Technique | 1. Identify the fracture site by palpation and/or radiographic correlation. 2. Insert the needle at the fracture site (often dorsal for distal radius). 3. Aspirate — dark blood return confirms placement in the fracture hematoma. 4. Inject 10–15 mL of lidocaine 1–2% (plain, without epinephrine) into the hematoma. 5. Wait 5–10 minutes for onset. |
| Onset | 5–10 minutes |
| Duration | 1–3 hours |
| Efficacy | Provides adequate analgesia for closed reduction in 70–90% of distal radius fractures; may need supplementation with procedural sedation for complex reductions |
| Advantages | Simple; rapid; avoids systemic sedation in many cases; can be performed at triage to provide immediate pain relief before reduction |
| Risks | Infection (rare with aseptic technique); theoretical risk of converting closed fracture to open (very rare); local anesthetic toxicity if excessive volume |
5.5 Intra-Articular Injection
Injection of local anesthetic directly into a joint space provides effective analgesia for joint reductions, arthrocentesis, and joint-related pain.5
| Parameter | Detail |
|---|---|
| Common ED indications | Shoulder reduction (glenohumeral joint), knee effusion aspiration, ankle joint procedures |
| Shoulder (intra-articular) | Patient seated or supine; identify the posterior approach (2 cm inferior and 2 cm medial to the posterolateral corner of the acromion) or the lateral approach; insert needle and aspirate to confirm intra-articular placement; inject 10–20 mL of lidocaine 1% |
| Knee (intra-articular) | Suprapatellar approach: patient supine with leg extended; insert needle 1 cm superior and 1 cm lateral to the superolateral corner of the patella, directing slightly inferior and medial; aspirate joint fluid; inject 10–20 mL of lidocaine 1% |
| Onset | 5–15 minutes |
| Efficacy | Intra-articular lidocaine for shoulder reduction has been shown in randomized trials to be equivalent to procedural sedation for anterior shoulder dislocations, with shorter ED stays |
6. Procedural Sedation and Analgesia
Procedural sedation and analgesia (PSA) is the use of sedative, analgesic, and/or dissociative agents to induce an altered state of consciousness that allows the patient to tolerate painful or unpleasant procedures while maintaining cardiorespiratory function. Procedural sedation is one of the most commonly performed procedures in emergency medicine, with more than 1 million ED procedural sedations performed annually in the United States. When performed by emergency physicians with appropriate training, monitoring, and equipment, procedural sedation has an excellent safety record.6 7 8
6.1 Continuum of Sedation
The sedation continuum describes increasing depth of sedation from anxiolysis through general anesthesia. Clinicians must understand that sedation is a continuum; patients may progress to a deeper level than intended, and the practitioner must be prepared to manage the next deeper level of sedation.7 8
| Level | Responsiveness | Airway | Spontaneous Ventilation | Cardiovascular Function | Example Agents/Scenarios |
|---|---|---|---|---|---|
| Minimal sedation (anxiolysis) | Normal response to verbal stimulation | Unaffected | Unaffected | Unaffected | Low-dose benzodiazepine; nitrous oxide 50:50; single low-dose anxiolytic |
| Moderate sedation (conscious sedation) | Purposeful response to verbal or light tactile stimulation | No intervention required | Adequate | Usually maintained | Midazolam + fentanyl; low-dose propofol; low-dose ketamine IV |
| Deep sedation | Purposeful response only after repeated or painful stimulation | Intervention may be required | May be inadequate | Usually maintained | Propofol (higher doses); ketamine IV dissociative doses; etomidate |
| General anesthesia | Unarousable even with painful stimulation | Intervention often required (intubation) | Frequently inadequate | May be impaired | Not intended in standard ED procedural sedation; requires anesthesiology |
Critical principle: The clinician performing procedural sedation must be competent to rescue the patient from at least one level deeper than the intended level of sedation. For deep sedation, this means the ability to manage a patient who progresses to general anesthesia (loss of protective reflexes, apnea).
6.2 Pre-Sedation Assessment
6.2.1 ASA Physical Status Classification
| Class | Definition | Sedation Risk | ED Relevance |
|---|---|---|---|
| ASA I | Normal, healthy patient | Low risk | Routine procedural sedation by emergency physicians |
| ASA II | Mild systemic disease (well-controlled DM, mild obesity, current smoker, social drinker, pregnancy) | Low risk | Routine procedural sedation by emergency physicians |
| ASA III | Severe systemic disease (poorly controlled DM, morbid obesity, moderate COPD, active hepatitis, chronic alcohol dependence, pacemaker, moderate EF reduction, ESRD on dialysis) | Moderate risk | May proceed with enhanced monitoring; consider anesthesiology consultation for complex patients |
| ASA IV | Severe systemic disease that is a constant threat to life (recent MI <3 months, CVA, ongoing cardiac ischemia, severe valve dysfunction, severe sepsis, ARDS) | Higher risk | Anesthesiology consultation recommended; proceed only if the benefit of the procedure outweighs the sedation risk |
| ASA V | Moribund patient not expected to survive without the operation | Very high risk | Rarely appropriate for elective ED procedural sedation; only for emergent life-saving procedures |
6.2.2 Airway Assessment
Before procedural sedation, a focused airway assessment should be performed to identify patients at increased risk for airway complications:7 8
| Assessment | Method | Concerning Findings |
|---|---|---|
| Mallampati classification | Patient opens mouth fully, protrudes tongue; classify view of oropharynx (Class I–IV) | Class III (soft palate, base of uvula visible) or IV (hard palate only) predict more difficult intubation |
| Mouth opening | Inter-incisor distance | <3 cm (2 fingerbreadths) suggests limited access |
| Thyromental distance | Distance from mentum to thyroid notch | <6 cm (3 fingerbreadths) suggests anterior airway |
| Neck mobility | Range of extension | Limited extension reduces intubation success |
| Obesity | BMI assessment | BMI >30 increases risk of desaturation during sedation; pre-oxygenation is critical |
| Obstructive sleep apnea | STOP-BANG screening | Score ≥3 suggests OSA; increased sensitivity to sedatives; prolonged recovery |
| Facial hair | Beard assessment | May impair bag-mask seal |
| Dentition | Assess for loose teeth, dental hardware | Risk of aspiration; adjust airway management |
6.2.3 Fasting Status
Fasting status and procedural sedation in the emergency department:6 7 9
| Organization | Fasting Recommendation for ED Sedation |
|---|---|
| Major emergency medicine professional societies | Fasting status does not need to delay procedural sedation in the ED. Multiple large studies and systematic reviews demonstrate no association between fasting duration and aspiration risk during ED procedural sedation. The risk of aspiration during ED procedural sedation is exceedingly low (approximately 1 in 10,000). The urgency of the procedure and the patient’s pain should take precedence over fasting status. |
| Anesthesiology societies | Traditional guidelines (2-4-6-8 rule: 2 hours clear liquids, 4 hours breast milk, 6 hours light meal, 8 hours full meal) were designed for operating room general anesthesia and may not be directly applicable to the ED setting. Even this organization’s most recent practice guidelines acknowledge that ED procedural sedation differs from operating room anesthesia. |
Practical guidance for ED procedural sedation and fasting:
- Fasting is ideal but should not delay procedural sedation for urgent or emergent indications
- Recent oral intake is a consideration but not a contraindication
- Document the fasting status and the clinical rationale for proceeding
- Consider the depth of sedation planned: lighter sedation (with preserved protective reflexes) carries less aspiration risk than deep sedation
- The risk of withholding the procedure (pain, delayed reduction, fracture complications) must be weighed against the very low risk of aspiration
- Dissociative ketamine maintains laryngeal protective reflexes and has an extremely low aspiration rate regardless of fasting status
6.3 Required Equipment and Monitoring
6.3.1 Minimum Equipment
| Category | Equipment | Notes |
|---|---|---|
| Monitoring | Continuous pulse oximetry; continuous cardiac monitor (ECG); automated blood pressure cuff (cycling every 3–5 min); capnography (see below) | All monitors applied before sedation and continued through recovery |
| Capnography | End-tidal CO₂ (ETCO₂) monitoring via nasal cannula or facemask | Strongly recommended for all moderate and deep sedation; provides early warning of hypoventilation (approximately 60 seconds before desaturation); multiple studies demonstrate that capnography detects respiratory depression earlier than pulse oximetry |
| Oxygen | Supplemental oxygen via nasal cannula (2–6 L/min) or non-rebreather mask; pre-oxygenation recommended for 3–5 minutes before deep sedation | Apneic oxygenation during sedation reduces desaturation |
| Airway equipment | Bag-valve-mask (appropriate size); oral and nasal airways (assorted sizes); suction (Yankauer); endotracheal intubation equipment immediately available; laryngeal mask airways (LMA) available | Must be prepared for one level deeper than intended sedation |
| Resuscitation | Reversal agents (see below); emergency medications (epinephrine, atropine); IV access established; crash cart/defibrillator immediately available | |
| Reversal agents | Naloxone 0.4 mg IV (opioid reversal); flumazenil 0.2 mg IV (benzodiazepine reversal — use with caution in chronic benzodiazepine users, seizure risk) | Note: no reversal agent exists for propofol, etomidate, or ketamine |
| Suction | High-flow wall suction with Yankauer tip | Immediately accessible at the head of the bed |
6.3.2 Personnel
| Requirement | Detail |
|---|---|
| Physician | Credentialed for procedural sedation; responsible for the sedation plan, drug administration decisions, and patient management |
| Dedicated sedation nurse | A nurse whose sole responsibility during the procedure is monitoring the patient’s cardiorespiratory status; this nurse should not be simultaneously performing the procedure |
| Additional personnel | Depending on institutional policy: a second physician or provider available for rescue; procedure-specific assistants |
6.4 Procedural Sedation Agents: Complete Dosing Guide
6.4.1 Propofol
Propofol is the most commonly used agent for ED procedural sedation in adults. It is an ultra-short-acting sedative-hypnotic with no analgesic properties (requires co-administration of an analgesic or local/regional anesthesia for painful procedures).6 7 10
| Parameter | Detail |
|---|---|
| Class | Alkylphenol sedative-hypnotic; GABA-A receptor agonist |
| Induction dose | 0.5–1 mg/kg IV |
| Supplemental doses | 0.25–0.5 mg/kg IV every 1–3 minutes as needed to achieve target sedation depth |
| Typical total dose | 1–2 mg/kg for most ED procedures |
| Onset | 15–45 seconds |
| Duration | 5–10 minutes per dose (ultra-short redistribution half-life) |
| Recovery | Rapid and clear-headed; typically 10–15 minutes to full recovery |
| Administration | IV push over 10–30 seconds; may use a slow push (over 30–60 seconds) to reduce the incidence of apnea |
| Analgesia | None — propofol has no analgesic properties; must be combined with local/regional anesthesia or an opioid (e.g., fentanyl 0.5–1 mcg/kg) for painful procedures |
| Advantages | Rapid onset; rapid recovery; predictable; antiemetic properties; well-studied in ED procedural sedation |
| Adverse effects | Dose-dependent respiratory depression and apnea (10–30%); hypotension (vasodilation + myocardial depression); injection site pain (reduce with lidocaine 20–40 mg IV through the same line before propofol) |
| Contraindications | Egg allergy is NOT a contraindication (propofol contains soy lecithin and egg phosphatide, but the allergenic proteins are in egg white; the egg lecithin in propofol is from egg yolk); true soy allergy is a caution; hemodynamic instability (relative contraindication — propofol reduces preload and contractility) |
| Special populations | Elderly: reduce dose by 30–50% (0.25–0.5 mg/kg); obese: dose on lean body weight for induction, then titrate; children: similar dosing (1 mg/kg induction) but may require slightly higher total doses than adults |
6.4.2 Ketamine (Dissociative Sedation)
Ketamine is unique among sedation agents: at dissociative doses, it produces a cataleptic state (dissociative anesthesia) characterized by profound analgesia, amnesia, and sedation while maintaining airway reflexes, spontaneous respiration, and cardiovascular stability. It is the agent of choice for pediatric procedural sedation and is also widely used in adults.6 7 11 12
| Parameter | Detail |
|---|---|
| Class | Phencyclidine derivative; NMDA receptor antagonist; produces dissociative anesthesia |
| IV dose | 1–2 mg/kg IV administered over 1–2 minutes (rapid push increases risk of laryngospasm and apnea) |
| Supplemental IV doses | 0.5–1 mg/kg IV every 5–10 minutes if additional sedation needed |
| IM dose | 4–5 mg/kg IM (use when IV access is not available or in uncooperative patients) |
| Supplemental IM doses | 2–3 mg/kg IM if additional sedation needed after 10–15 minutes |
| Onset | IV: 30–60 seconds; IM: 3–5 minutes |
| Duration of dissociation | IV: 10–20 minutes; IM: 20–30 minutes |
| Full recovery | IV: 30–60 minutes; IM: 60–120 minutes |
| Analgesia | Profound — ketamine provides complete analgesia; no additional analgesic required |
| Airway | Laryngeal reflexes maintained (relative protection); spontaneous respiration maintained; mild bronchodilation (useful in asthmatic patients) |
| Cardiovascular | Sympathomimetic: increases heart rate and blood pressure (maintains hemodynamic stability) |
| Eyes | Nystagmus is expected; eyes may remain open with a characteristic “dissociative gaze” |
| Advantages | Provides sedation + analgesia + amnesia; maintains airway reflexes; maintains respiratory drive; supports hemodynamics; no IV required (IM route available); extensive safety data in pediatrics; can be used in hemodynamically unstable patients |
Ketamine-Specific Considerations:
| Consideration | Detail |
|---|---|
| Emergence reactions | Occur in 10–30% of adults (much less common in children <10 years: 0–5%); characterized by vivid dreams, visual disturbances, confusion, agitation, or hallucinations during recovery; usually self-limited (5–15 minutes) |
| Emergence prevention | Midazolam 0.025 mg/kg IV (typical: 1–2 mg in adults) co-administered with ketamine reduces emergence reaction incidence; alternatively, keep the environment quiet and calm during recovery; age <10 years does not routinely require co-administered benzodiazepine |
| Emergence treatment | If severe agitation occurs: midazolam 0.05 mg/kg IV (1–2 mg); verbal reassurance; quiet environment; avoid physical stimulation |
| Laryngospasm | Rare (0.3–0.4%); more common in infants <3 months and with rapid IV push; management: jaw thrust, positive pressure ventilation via BVM with 100% O₂; if refractory: succinylcholine 0.1–0.5 mg/kg IV or 4 mg/kg IM; intubation rarely needed |
| Emesis | Occurs in 5–15% (more common with IM route and older children/adults); prophylaxis: ondansetron 0.15 mg/kg IV (max 4 mg) 15 minutes before ketamine administration — recommended routinely by many experts |
| Hypersalivation | Common; generally does not require treatment; some protocols include glycopyrrolate 0.005 mg/kg IV (max 0.2 mg) or atropine 0.01 mg/kg IV as pre-medication, though evidence for routine antisialagogue use is weak |
| Recovery agitation (pediatric) | More common than true emergence reaction in children; managed with calm environment, parental presence, minimal stimulation |
Ketamine Contraindications:
| Contraindication | Rationale | Evidence Level |
|---|---|---|
| Age <3 months | Increased risk of airway complications, laryngospasm | Strong consensus |
| Known psychotic disorder | May exacerbate psychosis (relative in ED setting for brief sedation) | Moderate |
| Uncontrolled hypertension or conditions where elevated BP is dangerous | Sympathomimetic effects elevate BP and HR | Moderate |
| Conditions previously thought to be contraindications but no longer considered so: | ||
| — Elevated ICP | Current evidence does not support ketamine-induced ICP elevation as clinically significant; ketamine may actually be neuroprotective | Traditional contraindication overturned by evidence |
| — Globe injury | Evidence at dissociative doses is reassuring that IOP elevation is not clinically significant | Traditional contraindication increasingly questioned |
| — Thyroid disease | No evidence of clinical adverse effects from ketamine’s sympathomimetic properties in thyroid disease | Weak traditional contraindication |
6.4.3 Ketofol (Ketamine-Propofol Combination)
Ketofol combines ketamine’s analgesic and airway-preserving properties with propofol’s rapid, clear-headed recovery, theoretically offsetting each agent’s adverse effects.6 13
| Parameter | Detail |
|---|---|
| Mixture | 1:1 ratio by mg: typically ketamine 50 mg + propofol 50 mg in a single syringe (or 1 mL ketamine 10 mg/mL + 1 mL propofol 10 mg/mL per unit) |
| Dose | 0.5–0.75 mg/kg of each component IV (i.e., 0.5 mg/kg ketamine + 0.5 mg/kg propofol) |
| Supplemental doses | 0.25–0.5 mL/kg of the mixture every 2–3 minutes as needed |
| Advantages | Ketamine’s analgesia and hemodynamic support counterbalances propofol’s hypotension and lack of analgesia; propofol’s antiemetic properties and rapid recovery counterbalance ketamine’s emergence phenomena and emesis |
| Evidence | Mixed; some studies show reduced adverse events compared with propofol alone; other studies show no significant advantage over propofol alone; reasonable option when clinician is experienced with the combination |
| Preparation note | The mixture is physically compatible and stable for at least 6 hours; some practitioners administer them sequentially rather than mixed |
6.4.4 Etomidate
Etomidate is an ultra-short-acting imidazole-based sedative-hypnotic that provides rapid onset, brief duration sedation with minimal hemodynamic effects. It has no analgesic properties.6 7
| Parameter | Detail |
|---|---|
| Dose | 0.1–0.15 mg/kg IV (typical: 8–16 mg for adults) |
| Supplemental doses | 0.05 mg/kg IV every 3–5 minutes if needed (though single-dose sedation is typical) |
| Onset | 15–45 seconds |
| Duration | 5–15 minutes |
| Recovery | Generally rapid; comparable to propofol |
| Hemodynamics | Minimal: etomidate is the most hemodynamically stable sedative agent; excellent for patients with cardiovascular compromise |
| Adverse effects | Myoclonus (30–60% — involuntary muscle movements; benign but may interfere with procedures; pre-treatment with fentanyl 1 mcg/kg reduces incidence); injection site pain; nausea/vomiting (more common than propofol); adrenal suppression (clinically significant only with repeated/prolonged dosing; single procedural sedation dose is safe) |
| Analgesia | None — requires co-administration of analgesic for painful procedures |
| Advantages | Hemodynamic stability; reliable onset and duration; useful in elderly, hypotensive, or cardiac patients |
| Limitations | Myoclonus may complicate fracture reduction; emesis more common than with propofol; less extensively studied for ED procedural sedation than propofol or ketamine |
6.4.5 Midazolam + Fentanyl Combination
The combination of a benzodiazepine (midazolam) and an opioid (fentanyl) provides both sedation and analgesia. This was historically the most common ED sedation regimen but has been largely supplanted by propofol and ketamine due to their superior recovery profiles.6 7
| Parameter | Detail |
|---|---|
| Midazolam dose | 0.05 mg/kg IV (typical: 1–2 mg initial dose, titrated in 0.5–1 mg increments every 2–3 minutes) |
| Fentanyl dose | 1 mcg/kg IV (typical: 50–100 mcg, titrated in 25–50 mcg increments every 2–3 minutes) |
| Onset | Midazolam: 1–3 minutes; Fentanyl: 1–2 minutes |
| Duration | 30–60 minutes (midazolam); 30–60 minutes (fentanyl) |
| Recovery | Slower than propofol or ketamine; 60–120 minutes to full recovery |
| Advantages | Reversible (flumazenil for midazolam, naloxone for fentanyl); provides both sedation and analgesia; familiar to most practitioners |
| Disadvantages | Synergistic respiratory depression (the combination is more likely to cause apnea than either agent alone); prolonged recovery compared with propofol and ketamine; paradoxical agitation with midazolam (especially in elderly and children); less predictable depth of sedation |
| Key safety concern | Combined opioid-benzodiazepine respiratory depression is the leading cause of procedural sedation adverse events; titrate carefully; monitor closely; have reversal agents immediately available |
| Reversal | Flumazenil 0.2 mg IV every 1 minute (max 1 mg total) — caution: may precipitate seizures in chronic benzodiazepine users or patients with seizure disorder; Naloxone 0.04–0.4 mg IV every 2–3 minutes |
6.4.6 Nitrous Oxide for Procedural Sedation
| Parameter | Detail |
|---|---|
| Concentration | 50% N₂O / 50% O₂ (Entonox) for self-administered anxiolysis/analgesia; 50–70% N₂O / 30–50% O₂ via continuous-flow or demand valve for deeper analgesia |
| Administration | Self-administered via demand-valve mask or mouthpiece for anxiolysis; physician-titrated via continuous flow for procedural analgesia |
| Level of sedation | Minimal to moderate sedation (anxiolysis with analgesia) |
| Onset | 30–60 seconds |
| Recovery | 3–5 minutes after discontinuation |
| Indications for procedural use | Abscess I&D; laceration repair; fracture reduction (as adjunct to local anesthesia or hematoma block); lumbar puncture; pediatric procedures; IV cannulation in anxious patients |
| Advantages | Extremely rapid onset and offset; self-administration provides safety margin; minimal hemodynamic effects; no IV required; well-accepted by patients |
| Contraindications | Same as listed in Part 1, Section 2.6.2 (pneumothorax, bowel obstruction, etc.) |
| Combination | Can be safely combined with local or regional anesthesia, topical anesthetics, or low-dose IV analgesics to achieve a multimodal approach |
6.4.7 Dexmedetomidine
Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that provides sedation and anxiolysis without respiratory depression. Its primary ED use is for pediatric non-painful imaging (MRI sedation).14
| Parameter | Detail |
|---|---|
| Loading dose | 1–3 mcg/kg IV over 10 minutes; or 2–3 mcg/kg IN (via MAD device) |
| Maintenance | 0.5–1 mcg/kg/hr IV infusion (if prolonged sedation needed) |
| Onset | IV: 10–15 minutes; IN: 20–30 minutes |
| Duration | 30–60 minutes after single dose; depends on infusion duration |
| Pediatric MRI sedation | 2–3 mcg/kg IV over 10 minutes; may supplement with 1 mcg/kg boluses; or 3–4 mcg/kg IN (higher doses needed for intranasal route due to bioavailability) |
| Advantages | No respiratory depression (patients are arousable with stimulation); minimal airway complications; sedation resembles natural sleep; no emergence agitation |
| Disadvantages | Slow onset (not suitable for brief ED procedures); bradycardia (most common adverse effect; usually does not require treatment); hypotension; expensive; not useful for painful procedures (provides sedation/anxiolysis but minimal analgesia) |
| ED role | Primarily for pediatric MRI sedation when chloral hydrate alternatives are needed; may be useful for agitated patients requiring non-painful procedures; not commonly used for standard ED procedural sedation |
6.5 Modified Aldrete Score: Recovery Criteria
The Modified Aldrete Score is the standard tool for assessing readiness for discharge from procedural sedation. A score of ≥9 out of 10 is generally required for safe discharge. Scoring should be documented at regular intervals during recovery (every 5–15 minutes).6 7
| Category | 2 Points | 1 Point | 0 Points |
|---|---|---|---|
| Activity | Moves all 4 extremities voluntarily or on command | Moves 2 extremities voluntarily or on command | Unable to move extremities |
| Respiration | Able to breathe deeply and cough freely | Dyspnea, shallow or limited breathing | Apneic |
| Circulation | Blood pressure ±20 mmHg of pre-sedation level | Blood pressure ±20–50 mmHg of pre-sedation level | Blood pressure ±50 mmHg of pre-sedation level |
| Consciousness | Fully awake | Arousable on calling | Not responding |
| SpO₂ | SpO₂ >92% on room air | Needs supplemental O₂ to maintain SpO₂ >90% | SpO₂ <90% even with supplemental O₂ |
Total score: 0–10. Discharge criterion: ≥9.
6.6 Pediatric Procedural Sedation: Agent Selection
| Age Group | Preferred Agents | Notes |
|---|---|---|
| Infants (3–12 months) | Ketamine IM (4–5 mg/kg) for painful procedures; dexmedetomidine or chloral hydrate for imaging | Avoid propofol in infants <2 months (limited data); ketamine is safest in this age group; avoid ketamine <3 months |
| Toddlers (1–3 years) | Ketamine IV (1–2 mg/kg) or IM (4–5 mg/kg); propofol if IV access established | Ketamine preferred due to reliable sedation and maintained airway; IM route avoids need for IV in uncooperative toddlers |
| Preschool (3–6 years) | Ketamine IV or IM; propofol; intranasal midazolam (0.3–0.5 mg/kg) for anxiolysis | Emergence reactions rare in this age group (<5%); ketamine is first-line for painful procedures |
| School-age (6–12 years) | Ketamine IV; propofol; nitrous oxide (for minor procedures) | Emergence reaction incidence begins to increase; consider midazolam co-administration with ketamine |
| Adolescents (≥12 years) | Propofol (as in adults); ketamine; ketofol; nitrous oxide | Approach similar to adults; emergence reactions more common with ketamine (similar to adult rates) |
6.7 Geriatric Procedural Sedation
| Principle | Detail |
|---|---|
| Dose reduction | Reduce initial doses by 30–50% for all sedation agents; elderly patients have decreased cardiac output, reduced hepatic metabolism, decreased protein binding, and increased CNS sensitivity |
| Propofol | Start with 0.25–0.5 mg/kg (reduce from standard 0.5–1 mg/kg); titrate in small increments (0.25 mg/kg); expect longer duration of action |
| Ketamine | Reduce to 0.5–1 mg/kg IV; emergence reactions may be more pronounced; co-administer midazolam |
| Etomidate | 0.1 mg/kg IV (use lower end of dosing range); myoclonus may be concerning in elderly |
| Midazolam/fentanyl | Avoid if possible due to prolonged effect and risk of delirium; if used, start at 50% of standard doses |
| Monitoring | Extend monitoring period by at least 30 minutes beyond standard recovery; monitor for delayed respiratory depression; assess for postprocedural delirium |
| Discharge criteria | More stringent: ensure return to pre-sedation cognitive baseline; assess gait stability; responsible adult must accompany patient |
References
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