Procedural sedation and analgesia

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Procedural sedation and analgesia (PSA) can be used to reduce pain and awareness during painful or distressing procedures performed outside of the operating room. The level of awareness is typically adjusted according to patient risk factors and the type of procedure. In contrast to patients under general anesthesia, patients undergoing PSA typically maintain airway reflexes and spontaneous respiration. While the risk to patients undergoing PSA is low, both oversedation and adverse effects from the medication are possible. Therefore, PSA should only be performed by trained providers and in patients who have been screened for conditions that are high risk for complications. The choice of sedatives and analgesics should be adapted to the procedure and the patient's physiological parameters, and patients should be monitored closely both during and after the procedure. Patients may be discharged after PSA once they return to their baseline level of functioning.

Recommendations in this article are consistent with the 2018 American Society of Anesthesiologists (ASA) guidelines, the 2019 American College of Emergency Physicians (ACEP) guideline, and the 2014 ACEP clinical policy statement relating to PSA. ^[2][3][4]

• Procedural sedation ^[4]
  • Administration of sedatives and/or analgesics to reduce pain, anxiety, and awareness
  • Applied during diagnostic or therapeutic procedures outside of the operating room
  • Cardiorespiratory function is typically maintained with minimal external support.
• General anesthesia
  • Administration of sedatives and/or analgesics to induce a loss of consciousness and complete unresponsiveness
  • Applied in the operating room
  • Typically leads to loss of airway patency and spontaneous respiration requiring intubation and mechanical ventilation
  • Cardiovascular function may also be impaired, occasionally requiring fluids and pressors.
• Monitored anesthesia care
  • Sedation provided by an individual (typically an anesthesiologist) who is exclusively responsible for sedating and monitoring the patient
  • Used in patients at a high risk of adverse events or if it is likely that procedural sedation will need to be converted to general anesthesia ^[5]

Levels of sedation

PSA typically requires a moderate, deep, or dissociative level of sedation. For most agents used in PSA (except those used in dissociative sedation), the level of sedation follows a dose-response relationship.

Practitioners administering moderate or deep sedation should be experienced in airway management, as the level of sedation may become deeper than anticipated.

Goals

• Analgesia
• Amnesia
• Anxiolysis
• Immobilization

Types of procedures that often require PSA ^[4][6]

• Urgent
  • Electrical cardioversion
  • Closed reduction of fractures or dislocations
  • Chest tube placement
  • Abscess drainage
• Elective
  • Endoscopy
  • Cardiac catheterization
  • Bone marrow aspiration
  • Minor surgical procedures

Situations in which PSA may be harmful ^[2][3][6]

• General principles
  • Risks of complications may outweigh benefits for:
    • Patients with high-risk preexisting conditions
    • Complex or severely painful procedures
  • Monitored anesthesia care or general anesthesia (with mechanical ventilation) may be more appropriate for these patients.
  • PSA may still proceed with extra precautions for urgent procedures under the following circumstances:
    • Transfer to the operating room is not possible or would cause unreasonable delay
    • An anesthesiologist is not available to provide monitored anesthesia care.
• Higher risk conditions: Patients with these conditions often have an ASA class ≥ III, particularly if their condition affects the cardiac or respiratory systems. ^[7]
  • Airway-related
    • Known or anticipated difficult airway
    • Increased risk of aspiration: e.g., due to pregnancy, gastric outlet obstruction, a recent large meal, or obesity
    • Obstructive sleep apnea (OSA) ^[8]
  • Respiratory
    • Severe obstructive pulmonary disease
    • Obesity hypoventilation syndrome
    • Signs of progressive respiratory failure
  • Cardiac
    • Coronary artery disease and/or congestive heart failure
    • Severe hypotension: e.g., due to shock
• Higher risk procedures
  • High complexity: Procedures of longer duration are at higher risk of medication dose-dependent and time-dependent complications.
  • Severely painful: I.e., required analgesic doses are high enough to risk respiratory depression, e.g., during fracture manipulation

Any form of sedation must be used with caution in patients with hypotension and those at risk of developing shock, as most sedating agents further reduce blood pressure.

Approach

• Evaluate the patient and consider if an alternative to procedural sedation may be more appropriate.
  • If sedation is only being considered to reduce patient anxiety, consider anxiolysis, e.g., with diazepam. (off-label)
  • Consider general anesthesia in the operating room in patients with ASA class ≥ III.
• Obtain informed consent from the patient or legal guardian.
• Determine the most appropriate regimen and prepare medications.
• Assemble the team and necessary equipment.
• Set up monitoring. ^[2]

Always consult local protocols for procedural sedation, as they may vary between institutions!

Preprocedural patient evaluation ^[2][3]

For nonurgent sedation, a full patient history is appropriate. For emergency procedures in unstable patients, focus evaluation on conditions that may predispose the patient to potentially life-threatening complications (e.g., anaphylaxis, laryngospasm, aspiration, cardiorespiratory compromise) and airway assessment.

• Focused history
  • Determine the patient's ASA class based on past medical history; review medical records if available.
  • Ask the patient if they have had any previous experiences of anesthesia and/or sedation.
  • Note any relevant allergies, current medication, and any prior or current tobacco, alcohol, or recreational drug use. ^[9]
  • Ask the patient when they last consumed food and liquids. ^[4][7][10]
    • Planned or nonurgent procedures: no solid food for > 6 hours and no liquids for > 2 hours prior to the procedure (see also “Preoperative preparation”)
    • Emergency procedures should not be delayed because the patient has eaten within the previous 6 hours.
    • Patients at high risk of aspiration (e.g., those with obesity): Involve anesthesiology early and consider dissociative sedation. ^[2][10]
  • Review laboratory studies and order additional tests as required (see “Preoperative assessment” for further information).
• Focused physical examination
  • Evaluate the patient's cardiovascular and respiratory systems.
  • Look for signs of a difficult airway, e.g., using the LEMON assessment.
  • Measure vital signs.

LEMON airway assessment: Look for concerning features, Evaluate mouth opening and larynx position, assess oral accessibility using the Mallampati score, evaluate for Obesity and conditions that can cause airway Obstruction, and assess Neck mobility. ^[6]

In unscheduled sedation, routinely evaluate the patient for intoxication. Alcohol and recreational drugs can have an additive effect on sedation and, therefore, lower induction doses may be indicated.

Team ^[2][3][4]

A minimum of two practitioners are required to perform procedural sedation, at least one of whom should be trained in safe sedation. Additional team members (e.g., an anesthesiologist, emergency physician) may be required depending on local protocols, the complexity of the patient's health needs, and the procedure.

Equipment ^[3]

Trained personnel and devices required for ACLS should be readily available. The following equipment should be present in the room where the procedure is being performed:

• Monitoring equipment (see “Monitoring”)
• Vascular access devices ^[6]
• Oxygen supply and oxygen delivery devices ^[3][6]
• Medication: sedatives for PSA and analgesics for PSA (labeled), saline flushes
• Equipment to treat complications
  • Suction device
  • Airway management equipment
  • Positive pressure ventilation device, e.g., for bag-mask ventilation (BMV)
  • Defibrillator
  • Resuscitation drugs, e.g., epinephrine for anaphylaxis
  • Reversal agents: naloxone and flumazenil
  • IV fluids if hypotension occurs

Before procedural sedation, remember to review the SOAP ME checklist: Suction, Oxygen, Airway equipment, Pharmacy, Monitoring, and Equipment for resuscitation (e.g., defibrillator).

Monitoring ^[3][4]

Monitoring intensity depends on the level of sedation.

• Clinical ^[2][3]
  • Observe chest wall motion and check for signs of hypoxia.
  • Consider evaluating the level of sedation periodically using verbal or tactile stimuli. ^[2]
• Device-based
  • Pulse oximetry
  • Heart rate
  • Blood pressure
  • Capnography ^[2][3][4]
  • Consider ECG

Clinical observation during moderate sedation or deep sedation is essential, as it may help to detect apnea earlier than monitoring devices alone.

General principles

• Medications commonly used for PSA: ^[2]
  • May have sedating and/or analgesic effects
  • May be used as single agents or in combination.
• Short-acting agents have a better safety profile for PSA compared to long-acting ones since they allow for: ^[4]
  • More responsive titration
  • Less time under sedation
• IV administration is preferred in adults. ^[6]
  • IV titration is generally well-tolerated, predictable, and has the most rapid onset of action compared with other routes of administration.
  • Other routes of administration may be chosen in select patients, e.g., if venous access cannot easily be obtained.
• Principles of titration ^[3]
  • Agents are given in small doses intravenously followed by a saline flush, or by IV infusion.
  • The effect of the previous dose must be assessed before the next dose is administered.
• For nonintravenously administered drugs, there must be sufficient time for absorption before the next dose is administered.

Follow all IV doses of a sedating agent with a saline flush. Failing to flush can cause the medication to accumulate in the IV tube, which can lead to undersedation, or oversedation if the buildup is dislodged.

Choice of regimen ^[2][6]

The type of procedure (painful and/or anxiety-inducing), the duration, and other procedural requirements (e.g., immobility for radiographic studies) must be taken into account when selecting a regimen, alongside patient factors (e.g., alcohol use, comorbidities, current clinical condition) and clinician experience and comfort with the medications.

• In emergencies: Consider first administering an analgesic, followed by an anxiolytic or sedative.
• Nonpainful, short procedures: Consider IV midazolam, propofol, or etomidate.
• Nonpainful, long procedures: Consider anxiolysis or a propofol infusion.
• Painful procedures: Consider ketamine or the combination of an opioid with midazolam or propofol.

Not all sedatives have analgesic properties! Both sedation and analgesia are required for painful procedures.

Sedatives and analgesics for PSA

The following example dosages are based on adult patients. For pediatric dosages, see “Medication for PSA in children.”

Sedatives

Analgesics

Combination regimens ^[3][4][6]

Potential benefits of combination regimens include lower dose requirements of individual drugs, lower risk of adverse effects, and greater ability to tailor regimens to individual patient needs and harness synergistic drug effects . Commonly used combinations include:

• Ketamine PLUS propofol
  • Benefits: quick and reliable deep sedation and analgesia with potentially less respiratory depression than the combination of opioids and propofol ^[11]
  • Dosage
    • Simultaneous administration (commonly referred to as “ketofol”): Agents are premixed in varying ratios and administered intravenously, e.g., 0.75 mg/kg IV in a 1:1 ratio over 15–30 seconds; can be repeated at half dose after 1–3 minutes if required. ^[6]
    • OR ketamine 0.1–0.5 mg/kg IV, followed by titrated propofol ^[11]
  • The onset and duration are similar to those for ketamine alone. ^[6]
• Ketamine PLUS a benzodiazepine
  • Benefits: potentially reduced incidence of the emergence reactions associated with ketamine
  • Administration and dosage: Pretreatment with a benzodiazepine, e.g., with midazolam , is given before a standard dose of ketamine. ^[14]
• Propofol OR etomidate PLUS an opioid: e.g., propofol PLUS alfentanil OR fentanyl
  • Benefits: The opioid provides additional analgesia during deep sedation, allowing for lower doses of sedatives to be used. ^[6]
  • Dosage: Titrate to the desired effect of each drug class.
    • Start with analgesic (see “Analgesics for procedural sedation” for suggested dosing)
    • Add sedative once the analgesic has been fully absorbed, starting at a reduced dose (e.g., ½ the initial dose outlined in “Sedatives for procedural sedation”)
• A benzodiazepine PLUS an opioid: e.g., midazolam PLUS fentanyl ^[6]
  • Benefits: pain control, sedation, and amnesia during moderate sedation
  • Caution: additive effect on respiratory function
  • Dosage: Titrate to the desired effect of each drug class.
    • Start with analgesic (see “Analgesics for procedural sedation” for suggested dosing)
    • Add sedative once the analgesic has been fully absorbed, starting at a reduced dose (e.g., ½ the initial dose outlined in “Sedatives for procedural sedation”)

Combinations of certain sedatives, especially opioids and benzodiazepines, can exacerbate adverse effects on cardiorespiratory function.

Recovery and discharge criteria may vary between institutions and local protocols should be consulted. In general, patients should be monitored in a suitable environment until they are alert, with stable vital signs that are within their normal parameters. The duration of monitoring also depends on the drugs used during sedation and the patient's health status.

Monitoring during recovery ^[3]

• Location: conducted in an area with access to resuscitation equipment where constant observation is possible
• Monitoring parameters
  • Continuous saturation monitoring until the patients is alert and has reached their target SpO₂
  • Intermittent (every 5–15 minutes) monitoring of ventilation and blood pressure until their cardiorespiratory status and level of consciousness are at or near baseline
• Additional consideration: If reversal agents were administered, sufficient time must have passed since the last administration before observation ends.

Serious complications from PSA most commonly occur at the end of the procedure after the painful stimulus has been removed (e.g., reduction of a dislocated joint).

Requirements for discharge ^[3][6]

• Patient requirements
  • Vital signs should be stable and the airway patent.
  • Patients should be at their baseline level of:
    • Consciousness
    • Mobility
    • Communication
• Discharge of outpatients
  • Address postprocedural pain and nausea before discharge.
  • Ensure that the patient is accompanied by a responsible adult.
  • Provide the patient with discharge instructions, including those for the presenting complaint.
  • Ask the patient to return to the hospital if they experience confusion or respiratory symptoms.
  • Instruct the patient to avoid driving for 24 hours after discharge.

Inadequate emergence after anesthesia

Delayed emergence ^[16]

• Definition: inability to regain full consciousness 30–60 minutes after general anesthesia
• Etiology
  • Residual effect of one or more perioperative agents (e.g., opioids, benzodiazepines, propofol, muscle relaxants), due to, e.g.:
    • Dosing errors
    • Drug interactions ^[17]
    • Hypothermia
    • Underlying medical conditions (e.g., liver or kidney disease)
    • Metabolic alterations (e.g., hypoglycemia, electrolyte imbalances)
  • Hypoventilation (e.g., due to inappropriate ventilation technique)
  • Neurological complications (e.g., intraoperative cerebral hypoxia, stroke)
• Clinical features
  • Sedation
  • Slowed and/or impaired reaction to stimuli
  • Impairment of protective airway reflexes
  • Bradypnea
  • Hypoxia
• Management ^[18]
  • Immediate assessment, including:
    • Primary survey, blood glucose measurement
    • Treatment of hypothermia, hypotension, and hypoxia if present
  • If euglycemia with stable vital signs: secondary assessment (serum electrolytes, arterial blood gas analysis, physical examination, neuromuscular blockade testing)
  • If suspicion for a specific causative agent is high, administer appropriate medication.
    • Opioid overdose: administer naloxone.
    • Benzodiazepine overdose: administer flumazenil.
    • Residual neuromuscular blockade: administer sugammadex, consider airway protection.
    • Central anticholinergic syndrome: administer physostigmine.
  • If symptoms persist, evaluate for potential causes of delayed emergence including drug interactions, conditions predisposing for slow metabolism (e.g., liver or kidney dysfunction), and neurological causes (e.g., hemorrhagic or ischemic stroke)
• Prevention
  • Intraoperative neuromuscular monitoring
  • Avoidance of hypothermia

Although hypothermia, metabolic alterations, and underlying medical conditions can interfere with drug metabolism, they can also be the primary cause of delayed emergence.

Emergence agitation ^[19]

• Definition: a typically brief, self-limited state of psychomotor hyperactivity during emergence from general anesthesia or procedural sedation before becoming fully conscious
• Epidemiology: most common in children ^[16]
• Risk factors
  • Use of volatile anesthetic agents
  • Inadequate pain control
  • Male sex
  • Smoking
  • Mental health disorders (e.g., posttraumatic stress disorder)
  • Associated with specific types of surgery
• Clinical features
  • Agitation
  • Disorientation
  • Purposeless thrashing movements
  • Psychosis
  • Combative behavior resulting in injury to self or health care providers
• Management
  • Exclude alternative causes of altered mental status.
  • For severe agitation: administer dexmedetomidine, benzodiazepines, and/or propofol.
  • See also “Approach to the agitated or violent patient.”
• Prevention
  • Identification of at-risk patients
  • Intraoperative administration of dexmedetomidine
  • Optimized pain management during emergence

Serious complications from PSA are very rare. ^[4]

Airway repositioning and mask ventilation are the most important skills for the sedation provider. Intubation should only be attempted by experienced providers, and only when necessary. ^[2]

The general procedural steps are the same for all patients who require PSA. Only divergences from standard procedures for children and pregnant patients are outlined in this section.

Children ^[22][23]

General principles

• Common clinical applications
  • The applications are similar to those for adults, but young children may also require sedation for imaging and minor procedures such as suturing or the removal of foreign bodies.
  • Sedation during painful procedures, e.g., the management of burns or lumbar puncture, helps to reduce trauma and anxiety around future procedures.
• Preparation
  • Perform a similar preprocedural assessment as for adult patients. In addition, ask whether the child was born prematurely.
  • Try to establish a positive rapport with the child and caregivers to reduce anxiety. If successful, some patients may be able to tolerate the procedure without sedation.
  • Delay sedation and obtain anesthesiology consult if there is a high risk of adverse events (e.g., ASA ≥ III, patients with an intellectual disability, anticipated difficult airway).
  • Ensure that correctly sized equipment is available (e.g., child-sized masks and supraglottic devices).
  • Ensure that a clinician experienced in pediatric life support is available.
  • Perform the necessary dose calculations based on age and/or weight to avoid dosage errors.
• Procedure and monitoring
  • Topical anesthetic should be applied in addition to sedation whenever possible for painful procedures.
  • Perform age-appropriate interventions to reduce anxiety (e.g., distracting the patient with videos). ^[2]
  • If possible, parents or guardians should be allowed into the procedure room.
  • Avoid immobilization devices if possible. ^[2]
  • Ventilation monitoring via capnography or stethoscope is required for children who are not able to communicate appropriately.
• Recovery and discharge
  • Children are not required to be able to ambulate unassisted or drink fluids before discharge.
  • They should, however, be able to sit unassisted, have stable vital signs, and be alert and talking.

While age-appropriate interventions for anxiety are important and can reduce the need for sedation in children, pharmacological interventions for anxiolysis and sedation should not be avoided in procedures that may cause trauma.

Commonly used sedatives and analgesics

Weight-based dosing for a single agent can differ between children of different age groups and adults.

Pregnant women ^[26]

• General principles
  • Consider physiological changes during pregnancy.
    • Increased oxygen demand and reduced functional residual capacity can cause a rapid decline in PaO₂ during even brief episodes of apnea.
    • Changes in the airway can lead to difficult intubation conditions.
    • Vasodilatation and aortocaval compression can cause systemic hypotension.
    • Reflux can increase the risk of aspiration. ^[7]
  • Hypoxemia, hypotension, and hypercapnia have detrimental effects on the fetus and can lead to fetal death.
  • All efforts should be made to ensure that the patient has normal systemic blood pressure and oxygen saturation throughout the procedure.
  • Ideally, a practitioner experienced in obstetric anesthesia should be present during sedation.
• Commonly used medications for sedation
  • There is a paucity of data on the best sedative to use during pregnancy. ^[2]
  • Midazolam, ketamine, and propofol are commonly used sedatives.

Hypoxemia, hypercapnia, and hypotension affect the fetus and the pregnant patient.

Preprocedural checklist

• Evaluate the patient, confirm that procedural sedation is indicated, and consider alternatives.
• Obtain informed consent.
• Determine the appropriate regimen and prepare medications.
• Assemble the team and equipment.
• Set up monitoring: e.g., pulse oximetry, continuous cardiac monitoring, intermittently cycled BP monitoring, capnography if available.

Procedure checklist

• Administer analgesia before sedation, if required.
• Titrate sedating agents until the desired level of sedation has been reached (apart from ketamine).
• Ensure all procedural requirements (analgesia, anxiolysis, immobilization) are met.
• Conduct continuous pulse oximetry and clinical monitoring; Measure EtCO₂ if available.
• Measure BP at regular intervals.

Recovery and discharge checklist

• Transfer the patient to a suitable recovery area.
• Continue continuous pulse oximetry and intermittent BP measurements.
• Ensure the following prior to discharging outpatients:
  • Stable vital signs and patent airway
  • Level of consciousness and communication back to baseline
  • Mobility back to baseline
  • Pain and nausea under control
• Provide outpatients with discharge instructions and ensure they are accompanied by a responsible adult.