Conscious Sedation

Conscious Sedation

David Ray Velez, MD and Martin Hannon, MD

Table of Contents

Definitions
Pre-Procedure Evaluation
Monitoring
Drugs/Dosing

See Also:
*See Airway Assessment
*See Rapid Sequence Intubation (RSI)

Definitions

Analgesia: A Drug-Induced Relief of Pain without Produced Sedation

Minimal Sedation (Anxiolysis): A Drug-Induced State During Which Patients Respond Normally to Verbal Stimulation

Moderate Sedation/Analgesia: A Drug-Induced State During Which Patients Respond Purposefully to Verbal or Tactile Stimulation

  • Also Known as “Conscious Sedation” or “Procedural Sedation”

Deep Sedation/Analgesia: A Drug-Induced State During Which Patients Cannot Be Easily Aroused but Respond Purposefully Following Repeated or Painful Stimulation

General Anesthesia: A Drug-Induced State During Which Patients Cannot Be Aroused, Even with Painful Stimulation

  Minimal Sedation Moderate Sedation Deep Sedation General Anesthesia
Responsiveness Normal Response to Verbal Stimulation Purposeful Response to Verbal or Tactile Stimulation Purposeful Response Following Repeated or Painful Stimulation Unarousable Even with Painful Stimulation
Airway Unaffected No Intervention Required Intervention May Be Required Intervention Often Required
Spontaneous Ventilation Unaffected Adequate May Be Inadequate Frequently Inadequate
Cardiovascular Function Unaffected Usually Maintained Usually Maintained May Be Impaired

Pre-Procedure Evaluation

Components of the Pre-Sedation Assessment

  • Height/Weight
  • Age
  • Allergies
  • Current Medications
  • Last Oral Intake
  • Social History (Smoking, Alcohol, and Drug Use)
  • Past Medical/Surgical History
  • History of Problems with Sedation/Anesthesia
  • Airway Assessment
  • Prior Difficult Intubation
  • Physical Exam

Airway Assessment

American Society of Anesthesiologists (ASA) Fasting Guidelines

  • Clear Liquids: 2 Hours
  • Breast Milk: 4 Hours
  • Infant Formula: 6 Hours
  • Non-Human Milk: 6 Hours
  • Light Meal: 6 Hours
  • Heavy Meal (Fried Food, Fatty Food, or Meat): 8 Hours or More
  • *May Be Altered for Urgent or Emergent Procedures

American Society of Anesthesiologists (ASA) Physical Status Classification

  • Class I: Healthy, No Smoking, Minimal Alcohol Use
  • Class II: Mild-Moderate Systemic Disease with No Functional Impact on Activity
    • Ex: Smoking, Pregnant, Obesity (BMI 30-40), Well-Controlled DM/HTN, Social Alcohol Use, Mild Lung Disease
    • Unlikely to Affect Anesthesia
  • Class III: Severe Systemic Disease with Functional Limitations to Activity
    • Ex: Poorly-Controlled DM/HTN, COPD, Morbid Obesity (BMI ≥ 40), Stable Angina, Pacemaker, Prior MI, CAD/Stents, Controlled CHF, CKD, Alcohol Abuse
    • Likely to Affect Anesthesia
  • Class IV: Severe Systemic Disease with a Constant Threat to Life
    • Ex: Unstable Angina, Recent (< 3 Months) MI or CVA, ESRD, Shock, Sepsis, DIC, Severe Reduction of Ejection Fraction
    • Likely to Significantly Affect Anesthesia
  • Class V: Moribund and Not Expected to Survive 24 Hours
    • Ex: Ruptured Abdominal/Thoracic Aneurysm, Massive Trauma, Intracranial Bleed with Mass Effect
  • Class VI: Brain Dead
  • *Add “E” if Emergency Surgery

Monitoring

The Minimum Number of Clinicians Present Varies Based on the Patient, Setting, and Procedure

  • In General, At Least Two Clinicians are Required at Minimum: One Physician to Perform the Procedure and Another/Nurse to Administer Medication and Monitor Vital Signs/Status
  • Many Recommend a Separate Physician Present to Perform Sedation Separate from the Physician Performing the Procedure

Equipment

  • Suction with Yankauer to Manage Secretions/Emesis
  • Airway Adjuncts: Bag-Valve Mask (BVM), Oral/Nasal-Pharyngeal Airways (OPA/NPA)
  • Equipment to Perform Rapid Sequence Intubation (RSI) if Needed
  • Advanced Cardiac Life Support (ACLS) Equipment and Medications
  • 1:1,000 IM Epinephrine in Case of Anaphylaxis to Medications
  • Appropriate Reversal Medications (Naloxone/Flumazenil)

Supplemental Oxygenation

  • Supplemental Oxygenation Reduces the Frequency of Desaturation Events
    • Non-Rebreather Mask at 10-15 L/min is Generally Preferred
    • Lower Concentrations (2 L/min Nasal Cannula) May Be Insufficient
  • Supplemental Oxygen is Generally Recommended for Unscheduled Conscious Sedation
  • Caution: Supplemental Oxygen Can Delay the Detection of Apnea by Pulse Oximetry

Monitoring

  • Frequent Vital Signs (BP/HR/RR) at Least Every 3 Minutes
  • Continuous Pulse Oximetry
  • Continuous Mental Status Monitoring
  • Continuous Cardiac Rhythm Monitoring
  • Continuous End-Tidal Carbon Dioxide (EtCO2) by Capnography
  • Continuous Monitoring of Cardiorespiratory Status
  • Continuous Monitoring of Pain and Sedation Levels

May Consider Prophylactic Antiemetics Although There is No Definitive Data to Support Their Routine Use

Patient Should Be Closely Monitored After the Procedure Until No Longer at Risk for Cardiorespiratory Depression

Post Sedation 

  • Assess Vital Signs
  • Activity and Mental Status
  • Pain
  • Bleeding
  • Ability to Tolerate PO Intake
  • Scoring Systems Such as Post-Anesthesia Discharge Scoring System (PADSS) or the Modified Aldrete Score Can Assist in Determining Readiness for Discharge from the PACU

Drugs/Dosing

The Ideal Agent Would Provide Sedation and Analgesia with a Rapid Onset and Short Duration of Action to Easily Titrate with Minimal Hemodynamic or Respiratory Depression

Begin with Low Doses and Increase Slowly to Monitor the Impact (“Start Low and Go Slow”)

Fentanyl

  • Not Used for Primary Sedation – Used as a Secondary Agent to Provide Analgesia in Addition to Another Agent that Provides Sedation
  • Rapid-Onset Short-Acting Narcotic
  • Mechanism of Action: CNS Mu-Opioid Receptor Agonist
  • Dosing:5-1.0 mcg/kg and Repeat Every 5-10 Minutes as Needed
  • Effects: Primarily Analgesia
  • Timing:
    • Onset: IV Almost Immediately; IM 7-8 Minutes; Intranasal (Children): 5-10 Minutes
    • Half Life: 2-4 Hours
  • Side Effects:
    • Respiratory Depression
    • Histamine Release with Morphine and Meperidine (Causes Hypotension)
  • Reversal: Naloxone (Narcan)
    • Dosing:
      • IV: 0.4-2.0 mg and Repeat Every 2-3 Minutes as Needed
      • Intranasal: x1 (4 mg) Nasal Spray and Repeat Every 2-3 Minutes in Alternating Nostrils Until Respiratory Depression Resolves
    • Goal is Adequate Ventilation (Not Normal Level of Consciousness)
    • Half-Life is Shorter than Opioids and May Need to Further Repeat Dosing Even After Reversal Has Been Seen

Midazolam (Versed)

  • Short-Acting Benzodiazepine
  • Mechanism of Action: GABA Receptor Agonist
    • Also Act as a Potent Anticonvulsant and Decreases Cerebral Metabolic Demand
  • Dosing: 5-2.5 mg Given Over 1-2 Minutes and Repeat Every 2-5 Minutes as Needed
  • Effects: Sedation and Amnesia (No Analgesia)
    • Generally Given with a Narcotic (Fentanyl) for Analgesia
  • Timing:
    • Onset:
      • IV: 1-5 Minutes
      • Oral: 10-20 Minutes
      • Intranasal: Within 10 Minutes
    • Half Life: 3 Hours
  • Side Effects:
    • Respiratory Depression
    • Hypotension
    • Can Worsen Delirium – Avoid in the Elderly
  • Reversal: Flumazenil (Anexate)
    • Dosing: 0.2 mg Initially and Repeat 0.2 mg Every Minute as Needed (Up to 4 Times)
    • Increased Risk of Seizures if Benzodiazepines are Used to Control

Ketamine

  • Mechanism of Action: NMDA Receptor Antagonist
  • Effects: Sedation, Amnesia, and Analgesia
  • Dosing:
    • Initial Bolus: 1.0-2.0 mg/kg
    • Repeat Dosing: 0.5-1.0 mg/kg Every 5-10 Minutes as Needed
  • Timing:
    • Onset: 30 Seconds
    • Duration: 5-10 Minutes
  • Advantages:
    • Provides Analgesia
    • No Clinically Significant Respiratory Depression
  • Side Effects:
    • Laryngospasm (Risk Factors: Higher IV Doses, IM Administration, Pediatric Patients, Active Pulmonary Infection/Disease, History of Airway Instability, Tracheal Surgery, or Stenosis)
    • Catecholamine Release (Tachycardia, Hypertension, and Increased Myocardial Oxygen Consumption)
    • Emergence Reactions
      • Hallucinations and/or Delirium
      • “K-Hole” Refers to a Possible Transient Dissociative State Caused by Ketamine
    • Increased Airway Secretions
  • Avoid with Severe Cardiac Decompensation (MI or Unstable Angina)
  • *Historically Contraindicated in TBI Due to Increased Cerebral Blood Flow/ICP – Now Questioned

Propofol

  • Mechanism of Action: GABA Receptor Agonist and Perhaps NMDA Receptor Blockade
  • Effects: Sedation and Amnesia (No Analgesia)
    • Generally Given with a Narcotic (Fentanyl) for Analgesia
  • Dosing:
    • Initial Bolus: 0.5-1.0 mg/kg
    • Repeat Dosing: 0.25-0.5 mg/kg Every 1-3 Minutes as Needed
    • Alternatively, Some Recommend Intermittent Boluses of 10-20 mg and Repeating as Needed to Achieve Adequate Sedation (Usually Requires Around 1.0 mg/kg)
  • Timing:
    • Onset: 10-60 Seconds
    • Duration: 3-10 Minutes
  • Advantages:
    • Decreases ICP
    • Anticonvulsant
    • Antiemetic (Decreased Risk of PONV) and Antipruritic
  • Side Effects:
    • Significant Cardiovascular Effects (Bradycardia and Hypotension)
    • Respiratory Depression
    • Metabolic Acidosis
    • Burning Pain with Infusion – May Prevent with Lidocaine
  • Avoid in Egg or Soy Allergies – Debated

Etomidate

  • Mechanism of Action: GABA Receptor Agonist
  • Effects: Sedation and Amnesia (No Analgesia)
    • Generally Given with a Narcotic (Fentanyl) for Analgesia
  • Dosing:
    • Initial Bolus: 0.1-0.2 mg/kg
    • Repeat Dosing: 0.05 mg/kg Every 3-5 Minutes as Needed
  • Timing:
    • Onset: 30-60 Seconds
    • Duration: 2-5 Minutes
  • Advantages:
    • Least Cardiovascular Side Effects
  • Side Effects:
    • Can Cause Transient Adrenocortical Suppression if Given by Continuous Infusion
    • Injection Site Pain
    • Nausea and Vomiting

Dexmedetomidine (Precedex)

  • Mechanism of Action: CNS Alpha-2 Receptor Agonist
  • Effects: Sedation and Some Analgesia (No Reliable Amnesia)
  • Dosing: Initial Loading Dose of 0.5-1.0 mcg/kg Given Over 10 Minutes, Followed by a Continuous Infusion of 0.2-1.0 mcg/kg/hr
  • Not Appropriate as an Induction Agent or for Deep Sedation
  • Timing:
    • Onset: 5-10 Minutes
    • Duration: 1-2 Hours
  • Advantages:
    • Provides Some Analgesia
    • No Significant Respiratory Depression
  • Side Effects:
    • Bradycardia
    • Atrial Fibrillation
    • Hypotension (Sometimes Hypertension)
    • Nausea and Vomiting

Ketamine-Propofol (“Ketofol”)

  • Two Definitions:
    • A 1:1 Mixture of Ketamine and Propofol in the Same Syringe
    • Pretreatment with a Half Dose Ketamine Followed by a Half Dose Propofol
  • Initial Bolus: 0.5-1.0 mg/kg
  • Repeat Dosing: 0.25-0.5 mg/kg Every 5-10 Minutes if Needed
  • Recommended by Some to Have the Benefits of Both Medications with Possibly Decreased Time to Sedation and Length of Sedation but Data is Not Clear

References

  • “Post Anesthetic Discharge Scoring System (Pads) Score Calculator.” MDApp, www.mdapp.co/post-anesthetic-discharge-scoring-system-pads-score-calculator-609/. Accessed 14 May 2025.
  • Postanaesthesia Care Unit Discharge Criteria and Considerations for the Paediatric Patient : Virtual Library, resources.wfsahq.org/atotw/postanaesthesia-care-unit-discharge-criteria-and-considerations-for-the-paediatric-patient/. Accessed 14 May 2025.
  • “Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures.” Anesthesiology, vol. 126, no. 3, Mar. 2017, pp. 376–393, https://doi.org/10.1097/aln.0000000000001452.
  • Statement on ​Asa Physical Status Classification System, www.asahq.org/standards-and-practice-parameters/statement-on-asa-physical-status-classification-system. Accessed 14 May 2025.
  • Miller KA, Andolfatto G, Miner JR, Burton JH, Krauss BS. Clinical Practice Guideline for Emergency Department Procedural Sedation With Propofol: 2018 Update. Ann Emerg Med. 2019 May;73(5):470-480.
  • Dexmedetomidine: Drug Information. Wolters Kluwer; 2025. Available at: 25. Accessed May 14, 2025.
  • Etomidate: Drug Information. Wolters Kluwer; 2025. Available at: 21. Accessed May 14, 2025.
  • Fentanyl: Drug Information. Wolters Kluwer; 2025. Available at: 13. Accessed May 14, 2025.
  • Flumazenil: Drug Information. Wolters Kluwer; 2025. Available at: 2. Accessed May 14, 2025.
  • Midazolam: Drug Information. Wolters Kluwer; 2025. Available at: 11. Accessed May 14, 2025.
  • Naloxone: Drug Information. Wolters Kluwer; 2025. Available at: 17. Accessed May 14, 2025.
  • Propofol: Drug Information. Wolters Kluwer; 2025. Available at: 6. Accessed May 14, 2025.