Procedural Sedation and Analgaesia (Conscious Sedation)

Question 1

Define Procedural Sedation and Analgaesia (Conscious sedation)

Answer 1

Short acting sedative/analgaesic medications to perform painful procedures whilst monitoring the patient closely for potential adverse effects

Question 2

Describe the continuum of levels of sedation

Answer 2

1. Analgaesia - awake
2. Minimal sedation - Respond normally to verbal
3. Moderate sedation -Respond normally to verbal with light touch
4. Deep sedation - Responds to noxious stimulation (ABC assistance may be required)
5. General anaesthesia - ABC always required
6. Dissociative sedation - Profound analgaesia and amnesia with ABCs intact

Question 3

List the relative contraindications to procedural sedation and analgaesia

Answer 3

Patient factors

1. ASA > 2
2. Difficult airway anticipated
3. Haemodynamic instability
4. Reduced level of consciousness
5. Children < 2 yrs / Elderly

Anaesthetic factors

1. Inexperienced/unqualified providers
2. Inadequate equipment: emergency/monitoring

Surgical
1. Procedure too painful for conscious sedation (e.g. laparotomy)

Question 4

Is fasting necessary prior to procedural sedation and analgaesia (PSA)

Answer 4

No. But the urgency of the procedure should be considered and the PSA delayed as long as possible to aim for a fasted state.

E.g. May be reasonable to wait if the patient’s stomach is full the procedure is not a true emergency with a potentially difficult airway or increased risk for aspiration exists.

Question 5

What is the RASS and when is it used?

Answer 5

Richmond Agitation Sedation Scale - used in determination of appropriate titration of sedatives during long term procedures (mechanical ventilation) and has not been adequately studied for use in PSA

+4 Combative (violent)
+3 Very agitated (pulls tubes/catheters)
+2 Agitated (intolerant of ventilator)
+1 Restless (Anxious but movement not vigorous)

0 Alert and calm

• 1 Drowsy (Eye opening/contact to voice > 10s)
• 2 Light sedation (Eye contact to voice < 10s)
• 3 Moderate sedation (Eye opening to voice without eye contact
• 4 Deep sedation (Eye opening without contact to physical stimulation
• 5 Unrousable to voice and physical stimulation

Question 6

What are the clinical parameters that should be monitored during procedural sedation and analgaesia

Answer 6

1. Level of sedation/alertness
2. Respiration: depth and rate
3. Response to painful stimuli

Question 7

How long does propofol take to work and how long does it work for

Answer 7

Onset: 40 seconds
Duration: 6 minutes

Question 8

Describe dosing for sedation using propofol

Answer 8

Load: 0.5 - 1 mg/kg
Supplement and maintain: 0.25 - 0.5 mg/kg

(Reduce by 20 - 60% in elderly)

Question 9

What techniques can be used to reduce pain caused by propofol injection

Answer 9

1. Site: ante-cubital rather than hand
2. Lidocaine (0.5mg/kg) pretreatment with or without vein occlusion
3. Opioid pretreatment
4. Ketamine pretreatment
5. Larger veins and cannulas
6. Tourniquet + lidocaine 2 minutes

Question 10

What are the side effects of propofol

Answer 10

Hypotension

Respiratory depression

Question 11

Describe the dosing of etomidate for PSA

Answer 11

Dose: 0.1 - 0.15 mg/kg
Repeat after 3 to 5 minutes if needed

Duration: 5 - 15 minutes

Question 12

List 5 side effects of etomidate

Answer 12

1. Respiratory depression
2. Myoclonus
3. Adrenal suppression
4. Nausea and vomiting
5. Pain on injection

Question 13

What is the treatment of severe myoclonus subsequent to etomidate administration

Answer 13

Airway and ventilation support PLUS Midazolam 1 - 2mg every 60 seconds until myoclonus abates.

Question 14

How can myoclonus with etomidate be prevented

Answer 14

1. Small dose 0.3 - 0.5 mg/kg 50 seconds before PSA
2. Pretreatment: Midaz
3. Pretreatment: MgSO4

Question 15

What is the onset and duration of midazolam

How is midazolam administered for PSA

Answer 15

Onset: 2 - 5 minutes
Duration: 30 - 60 minutes

Administration: 0.5mg - 1mg every 2 - 5 minutes. No single dose > 2.5 mg

Elderly/Obese/Renal/Hepatic
- Reduce dosage with longer dosing intervals

Question 16

Why is midazolam preferred to lorazepam/diazepam for PSA

Answer 16

Lorazepam/Diazepam

• prolonged onset and duration
• Inferior amnestic
• more side effects

Question 17

What is the onset and duration of fentanyl and how is it adminstered

Answer 17

Onset: 3 minutes
Duration: 30 - 60 minutes

Administration: 0.5 - 0.1 mcg/kg every 2 mins

Question 18

Does fentanyl cause hypotension and histamine release

Answer 18

Hypotension - very rarely

Histamine release - no

Question 19

What is the dose, onset, duration and administration of ketamine for PSA

Answer 19

Dose: 0.5 - 1.5 mg/kg followed by 0.25 - 0.5 mg/kg every 5 - 10 minutes

Duration: 10 - 20 minutes

Question 20

What are the side effects of ketamine

Answer 20

Tachycardia (mild and transient)
Hypertension (mild and transient)
Laryngospasm
Emergence reactions (avoid in SCZ)
Nausea and vomiting
Increased intracranial and intraocular pressure
Hypersalivation

Question 21

What is the mechanism of action of dexmedetomidine

Answer 21

Alpha agonist that acts at the locus coerulus in the pons to reduce release of norepinephrine

—> Sedation approximates natural sleep like state

Question 22

What are the advantages and disadvantages of dexmedetomidine for use in PSA

Answer 22

Advantages

1. Sleep-like sedation
2. Preserved airway reflexes and respiratory effort
3. Rousable and patients able to obey simple instructions

Disadvantage

1. Inferior sedation
2. Hypotension and bradycardia