Procedural Sedation and Analgaesia (Conscious Sedation) Flashcards
Define Procedural Sedation and Analgaesia (Conscious sedation)
Short acting sedative/analgaesic medications to perform painful procedures whilst monitoring the patient closely for potential adverse effects
Describe the continuum of levels of sedation
- Analgaesia - awake
- Minimal sedation - Respond normally to verbal
- Moderate sedation -Respond normally to verbal with light touch
- Deep sedation - Responds to noxious stimulation (ABC assistance may be required)
- General anaesthesia - ABC always required
- Dissociative sedation - Profound analgaesia and amnesia with ABCs intact
List the relative contraindications to procedural sedation and analgaesia
Patient factors
- ASA > 2
- Difficult airway anticipated
- Haemodynamic instability
- Reduced level of consciousness
- Children < 2 yrs / Elderly
Anaesthetic factors
- Inexperienced/unqualified providers
- Inadequate equipment: emergency/monitoring
Surgical
1. Procedure too painful for conscious sedation (e.g. laparotomy)
Is fasting necessary prior to procedural sedation and analgaesia (PSA)
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.
What is the RASS and when is it used?
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
What are the clinical parameters that should be monitored during procedural sedation and analgaesia
- Level of sedation/alertness
- Respiration: depth and rate
- Response to painful stimuli
How long does propofol take to work and how long does it work for
Onset: 40 seconds
Duration: 6 minutes
Describe dosing for sedation using propofol
Load: 0.5 - 1 mg/kg
Supplement and maintain: 0.25 - 0.5 mg/kg
(Reduce by 20 - 60% in elderly)
What techniques can be used to reduce pain caused by propofol injection
- Site: ante-cubital rather than hand
- Lidocaine (0.5mg/kg) pretreatment with or without vein occlusion
- Opioid pretreatment
- Ketamine pretreatment
- Larger veins and cannulas
- Tourniquet + lidocaine 2 minutes
What are the side effects of propofol
Hypotension
Respiratory depression
Describe the dosing of etomidate for PSA
Dose: 0.1 - 0.15 mg/kg
Repeat after 3 to 5 minutes if needed
Duration: 5 - 15 minutes
List 5 side effects of etomidate
- Respiratory depression
- Myoclonus
- Adrenal suppression
- Nausea and vomiting
- Pain on injection
What is the treatment of severe myoclonus subsequent to etomidate administration
Airway and ventilation support PLUS Midazolam 1 - 2mg every 60 seconds until myoclonus abates.
How can myoclonus with etomidate be prevented
- Small dose 0.3 - 0.5 mg/kg 50 seconds before PSA
- Pretreatment: Midaz
- Pretreatment: MgSO4
What is the onset and duration of midazolam
How is midazolam administered for PSA
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
Why is midazolam preferred to lorazepam/diazepam for PSA
Lorazepam/Diazepam
- prolonged onset and duration
- Inferior amnestic
- more side effects
What is the onset and duration of fentanyl and how is it adminstered
Onset: 3 minutes
Duration: 30 - 60 minutes
Administration: 0.5 - 0.1 mcg/kg every 2 mins
Does fentanyl cause hypotension and histamine release
Hypotension - very rarely
Histamine release - no
What is the dose, onset, duration and administration of ketamine for PSA
Dose: 0.5 - 1.5 mg/kg followed by 0.25 - 0.5 mg/kg every 5 - 10 minutes
Duration: 10 - 20 minutes
What are the side effects of ketamine
Tachycardia (mild and transient) Hypertension (mild and transient) Laryngospasm Emergence reactions (avoid in SCZ) Nausea and vomiting Increased intracranial and intraocular pressure Hypersalivation
What is the mechanism of action of dexmedetomidine
Alpha agonist that acts at the locus coerulus in the pons to reduce release of norepinephrine
—> Sedation approximates natural sleep like state
What are the advantages and disadvantages of dexmedetomidine for use in PSA
Advantages
- Sleep-like sedation
- Preserved airway reflexes and respiratory effort
- Rousable and patients able to obey simple instructions
Disadvantage
- Inferior sedation
- Hypotension and bradycardia
