Conscious sedation: pharmacology
Exam Pass Notes
Key Takeaways
- Understand pharmacology principles and drug properties
- Consider patient factors and procedure complexity
- Use minimum effective doses and agents
- Monitor patients closely, individualise treatment
- Manage drug interactions and adverse effects
Training Requirements
- The Dentaljuce course meets the Royal Colleges syllabus for dental sedation training in pharmacology
- 12 hours of sedation-based CPD are required every 5 years for sedation practitioners
- Valuable for non-sedation dentists to understand sedation referrals
Definition of Conscious Sedation
- Conscious sedation involves using drugs to produce a depressed CNS state while maintaining verbal contact
- Drugs and techniques should have a wide margin of safety to avoid loss of consciousness
- Allows treatment while preventing pain and anxiety
Basic vs Advanced Techniques
Basic Techniques
- Inhalation sedation with nitrous oxide for all ages
- Midazolam sedation for ages 12+ via any route
Advanced Techniques
- Midazolam for under 12 years old
- Combined routes or drugs
- Ketamine, propofol, other agents
Levels of Sedation
- Minimal: Reduced anxiety
- Moderate: Conscious, maintains reflexes
- Deep: Reduced responsiveness and reflexes
- General: Complete unconsciousness
Nitrous Oxide/Oxygen
- Inhaled sedative gas mixture, safe for all ages
- Works by enhancing GABA and inhibiting excitatory neurotransmitters
- Provides mild to moderate sedation and analgesia
- Rapid onset and recovery time
- Reduces anxiety and improves patient cooperation
Midazolam
- Benzodiazepine sedative given IV, IM, oral, nasal
- Enhances GABA activity, causing sedation and amnesia
- Rapid onset and short duration
- Lingering drowsiness, confusion, impaired coordination
Propofol
- IV sedative-hypnotic, used for deep sedation
- Enhances GABA activity
- Very rapid onset and short duration
- Respiratory depression and hypotension common
- Requires close monitoring
Opioids
- Fentanyl, remifentanil, sufentanil commonly used
- Act on opioid receptors to reduce pain and anxiety
- Given IV, IM, transmucosal
- Can cause respiratory depression, nausea
- Reversed by naloxone
- Require careful monitoring and titration
Ketamine
- Dissociative anaesthetic given IV, IM, nasal
- Blocks glutamate, causes detachment from surroundings
- Rapid onset and short duration
- Analgesic and sedative without respiratory depression
- Side effects include hallucinations, agitation, nausea
Sevoflurane
- Inhaled anaesthetic gas
- Enhances GABA activity
- Rapid onset and short duration
- Minimal respiratory depression
- Side effects include nausea, coughing
- Often occur during induction/emergence
Drug Interactions
Between Sedatives
- Benzodiazepines + opioids: Increased respiratory depression
- Ketamine + opioids: Increased respiratory depression
- Sevoflurane + opioids: Respiratory depression, hypotension
- Propofol + benzodiazepines: Respiratory depression, hypotension
- Nitrous + opioids: Respiratory depression, hypotension
- Nitrous + midazolam: No major interaction, monitor respiration
With Other Drugs
- Antidepressants: Increased sedation
- Antibiotics: Altered metabolism, increased sedative levels
- Antifungals: Altered metabolism, increased sedative levels
- Anti-seizures: Reduced sedative levels
- Blood pressure medications: Increased sedation
- Naloxone: Sudden opioid withdrawal
Pharmacokinetics and Pharmacodynamics
Different Routes
- Oral: Slower onset, lower bioavailability, longer duration
- IV: Most rapid onset, highest bioavailability
- IM: Faster than oral but slower than IV, moderate bioavailability, longer duration than IV
- Inhalation: Rapid onset, variable bioavailability
Co-Administration
- Pharmacokinetic interactions alter absorption, distribution, metabolism, elimination
- Pharmacodynamic interactions alter pharmacological response
- Can increase or decrease effects compared to alone
- Must consider interactions when combining agents
Infusion Pharmacokinetics
- Steady drug levels compared to bolus dosing
- Onset slower than bolus but longer duration
- Clearance affected by patient factors
- Allows predictable sedation levels
- Important for drugs like propofol
Choosing IV Drugs
Benzodiazepines
- Indications: Anxiety, patient management, special needs
- Contraindications: Allergies, respiratory depression, glaucoma
Propofol
- Indications: Long procedures, patient management, special needs
- Contraindications: Allergies, hypotension, respiratory depression
Opioids
- Indications: Moderate to severe pain
- Contraindications: Allergies, respiratory depression, head injury
Minimum Intervention
- Use lowest effective dose of single agent
- Minimises risk of adverse effects
- Especially important in vulnerable patients
- Emphasises monitoring and individualised plans
Patient Selection Factors
- Procedure type and complexity
- Age, body weight
- Degree of anxiety
- Medical history, physical exam
- Social history
- Healthcare environment
- Team training and experience