Drugs for conscious sedation
- Conscious sedation, part of what is now expanded into procedural sedation, is now a routine part of ED management.
- The aim is to provide analgesia, sedation, muscle relaxation and ideally amnesia during what might otherwise be uncomfortable procedures (wound debridement, fracture/dislocation reduction, chest tube insertion, cardioversion, FB removal, and as necessary in diagnostic procedures that require high degree of compliance e.g. LP, CT, MRI).
- Most frequently a combination of drugs is employed as a single drug may not provide all the desired effects. Most often drugs are given where possible by the IV route as this is the most rapid and predictable option.
- The ideal level of sedation is that where the patient:
- tolerates the procedure with no or minimal discomfort
- depressed but not full loss of consciousness
- maintains protective airway reflexes
- responds to command
- There is a risk of deeper sedation which may result in depressed respiration and the loss of airway protective reflexes, so expertise and equipment for managing such a situation must be anticipated, assessed and available before commencing the procedure.
- In general conscious sedation should include:
- Assessment of patient
- ASA I or II, airway anatomy, medical status (incl. any respiratory/CVS disease), allergies, medications
- Fasting time should be ascertained – ideally from 2hrs (clear fluids) to 6hrs (solids).
- Consent should be obtained where possible.
- Often 2 dcotors may be required – one to perform the procedure and the other to manage the sedation and airway.
- Monitoring (pulse oximetry. NIBP) should be attached,
- Oxygen provided for the patient usually by Hudson mask,
- Resuscitation/intubation trolleys to hand.
- Frequent recording of vitals until dischargable – usually 1-4hrs post most procedures depending on the drugs used.
- Documentation of drugs used, procedure, complications & outcome in medical notes.
- Assessment of patient
- Most of the drugs used are covered in the IV induction agents and inhaled anaesthetic agents pages of this chapter. Links for them are listed below. Choice of a particular drug or combination can be dependent on:
- Patient contraindications
- Length of procedure
- Familiarity of a doctor with a drug
- Local protocols
- Commonly used drugs:
Summary of doses
|Drug||Initial dose (Top-up dose is half)||Route||Onset||Duration||Notes (all bar N2O may cause ↓RR & ↓BP)|
|Nitrous Oxide||50-70% mixed with O2||Demand valve mask||3-5min until 3-5min after removal||N & V, expansion of air-filled cavities.|
|Midazolam||0.05-0.1mg/kg||IV||1-3min||1hr||Paradoxical agitation. PO route unpredictable but used in children. Usually combined with an opioid for analgesia.|
|0.5-1mg/kg (max 15mg)||PO||20-30min||1-2hr|
|Fentanyl||1-3mcg/kg||IV||1-2min||peak 10min||Bradycardia. Usually given with a sedative agent.|
|Morphine||0.1mg/kg||IV||3min||15-30min||Histamine release, prolonged sedation. May be given with a sedative.|
|Ketamine||1-2mg/kg||IV||1-3min||10-20min||Give with atropine 0.01-0.2mg/kg.|
|Propofol||0.5-1mg/kg||IV||<30s||10mins per bolus||Mix with 2ml 1% lignocaine to ease pain of injection. Beware apnoea/hypotension. May be combined with an analgesic.|
Sedation level scoring
|Ramsay Sedation Scale|
|1||Patient is anxious and agitated or restless, or both|
|2||Patient is co-operative, oriented, and tranquil|
|3||Patient responds to commands only|
|4||Patient exhibits brisk response to light glabellar tap or loud auditory stimulus|
|5||Patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus|
|6||Patient exhibits no response|
|Sedation Scoring Scale (based on the Ramsey Sedation Scale, but confusingly reverses order)|
|6||Agitated, anxious, or in pain above baseline|
|5||Spontaneously awake without stimulus; may exhibit anxiolysis|
|4||Drowsy but easily arouses to consciousness to light tactile or verbal/tactile stimulus|
|3||Arouses to consciousness with moderate tactile or loud verbal stimulus|
|2||Arouses slowly to consciousness with sustained painful tactile stimulus|
|1||Arouses, but not consciousness, with painful stimulus|
|0||Unresponsive to painful stimulus|
- A sedation score of 5 corresponds to minimal sedation. Sedation scores of 4-3 correspond to moderate sedation. Sedation scores of 3-2 correspond to deep sedation.
|Another Sedation Score|
|1||Awake = fully alert and oriented|
|2||Mild – Arousable with verbal stimulation = drowsy/ eyes closed but rousable to command|
|3||Moderate – Arousable with tactile stimulation = eyes closed but rousable to mild physical stimulation|
|4||Severe – Not arousable by tactile stimulation = to mild physical stimulation|
- Dunn R. The Emergency Medicine Manual 3rd Ed.
- Katung B. Basic & Clinical Pharmacology 8th Ed.
- Cameron P. et al. Textbook of Adult Emergency Medicine 2nd Ed.
- Mahadevan S. & Garmel G. An Introduction to Clinical Emergency Medicine
- Neal M. Medical Pharmacology at a Glance 3rd Ed.