Introduction
What is sedation?
Sedation is a continuum of reduced consciousness and it is difficult
to maintain patients at a predetermined sedation depth. Sedation
varies between minimal, moderate, conscious, deep and dissociative
sedation. Deeper levels of sedation are indistinguishable from general
anaesthesia and should be treated as such.
Why would we need it?
Sedation can facilitate a number of painful procedures in the
Emergency Department. It can be achieved by a number of agents,
each of which requires specific training and knowledge to perform
safely and effectively.
A must
read
Although the document alludes to choosing a desired level of
sedation it also states ‘Sedation is a continuum and it is not always
possible to maintain patients at a pre-determined sedation depth’. It
would therefore seem prudent that clinicians involved in delivering
sedation to patient prepare for any depth of sedation to occur
Level of sedation
Features
Appropriate agents
Minimal - anxiolysis
Respond to verbal commands
Entonox
Moderate – conscious
May require light tactile stimuli to
respond to verbal commands
CVS function maintained
Opioids & benzodiazep
combined
Deep
Not Easily roused, may respond to
painful stimuli
Ventilatory function may be
maintained but CVS normally
maintained
Multiple agents
Depth dose dependan
General Anaesthesia
Not rousable even to pain
Ventilatory function often lost &
some CVS impact
Multiple agents
Depth dose dependan
Dissociative Sedation
Trance like state
Ketamine
Starving
Fasting is not needed for minimal sedation, sedation with nitrous oxide
(in oxygen) alone, or moderate sedation where verbal contact is
maintained.
For elective procedures using all other sedation techniques (deep
sedation, dissociative sedation and moderate sedation where the
patient might not maintain verbal contact with the healthcare
professional), apply the fasting rule used for general anaesthesia: two
hours for clear fluids and six hours for solids.
For an emergency procedure in someone who is not fasted, base the
decision to proceed with sedation on the urgency of the procedure
and the target depth of sedation.
An American dual centre prospective study looking at 7304 patients aged 1
month-21 years found the risk of regurgitation with aspiration during
sedation to be 0.05%. A further study by Green et al published in Academic
Emergency Medicine in 2002 found ‘insufficient data to test the hypothesis
that procedure of pre-fasting results in a decreased incidence of adverse
outcomes in patients undergoing sedation/analgesia (as distinct from
patients undergoing
general anesthesia)’.
In summary consideration is required to the risk-benefit of sedation
without full starving periods. This assessment and the resulting
decision should be recorded in the clinical notes, and discussed with
the patient whenever possible.
Assessing your patients prior to sedation
As per the recommendations in the document for safe sedation the
clinician need to be able to assess the ASA, just as you would for a
pre anaesthetic assessment. This is designed to give a feel for the risks
that you are taking
ASA Grade
Patient charactersitics
I
Healthy person
II
Mild systemic disease
III
Severe systemic disease
IV
Systemic disease with a constant threat to life
V
Moribund patient who is not expected to survive
without the procedure
VI
Declared brain-dead, organs being removed for donor
purposes
In addition to assessment of the patient as a whole a review of
characteristics that may point towards a difficult airway should be
performed.
It is important to appreciate that the ability of clinicians to accurately
predict which patients will be a difficult airway is extremely difficult
as demonstrated by the following paper;
Picking the right agent for the patient and pathology
Once you have assessed your patient you have a vast array of agents at
your fingertips to achieve sedation. It is vital that the selection of
agent is tailored towards each individual patient and case. Factors
such as the duration of sedation, muscle relaxation required and
pharmacodynamics effects of each agent should all be considered
Sedating
Agent
Effect
Propofol
Sedation
Duration
of effect
(minutes)
5-10 mins
Side
effects
Cautio
ns
Onset
time
Initial
dose
Further doses
Pain on
injection
Reduce
dose in
elderly
&
in CVS
instabili
ty (upto
90%
dose
reducti
onrequi
red)
40
second
s
0.5-1.0
mg/kg
0.5 mg/kg
1-2 mins
0.5mg/kg
Titrate to a
Hypnosis
Hypotensio
n
Amnesia
Apnoea
Rash
Ketamine
Anxiolysis
30 mins
Vomiting
post
procedure
Analgesia
Amnesia
IV
i.v.
Lacrimation
& salivation
Dissociati
ve
properties
Rash
5 mins
IM
2-4mg/kg
IM with
maximum 1.5
mg/kg i.v.
Additional I.M.
doses of 1mg/kg
as required
Transient
clonic
movements
Midazolam
Anxiolysis
Amnesia
Hypnosis
Muscle
relaxant
20-60 mins
Agitation
Apnoea
Hypotensio
n
Flumaz
enil can
be used
if
urgent
reversal
is
needed
(not to
be used
as a
routine)
3-5 mins
Adult 2mg
over 30
secs
200mcg
dose
Elderly
1-1.5mg
Trying to combine the properties of agents??
Due to many opposing pharmacodynamics effects of Propofol and
Ketamine many clinicians have attempted to gain a better sedative
effect by combing these two agents. Two recent papers look at this;
Ketofol versus propofol. Andolfatto G et al. 2012.
This was a randomized, double blind study between December 2010
and September 2011 in a 250-bed community teaching hospital and
level III trauma centre in Canada.
284 patients were randomised to receive either ketofol (n=142) or
propofol (n=142) alone. The most commonly performed procedures
were orthopaedic (60% in both).
All study medications were prepared in indentical 20-ml syringes
containing either 10mg/mL or propofol alone or a 1:1 mixture of
0.5-1.0mg every 2
minutes until
sedation is
achieved
Normal adult
dose 3.5-5.0mg
total
10mg/mL ketamine and 10mg/mL propofol (containing a total of 5mg
each of ketamine and propofol).
The primary outcome measure was the number and proportion of
patients experiencing a respiratory adverse event as defined by the
‘Quebec’ Criteria. These are outlined fully in the article but in
summary include oxygen desaturation, central apnoea, partial or
complete upper airway obstruction, laryngospasm, pulmonary
aspiration. Secondary outcomes included sedation consistency, total
medication dosage, sedation efficacy, induction time, procedure time,
sedation time, recovery time, and the incidence of adverse events.
Forty-three (30%) patients experienced an adverse respiratory event in
the ketofol group compared with 46 (32%) in the propofol group
(difference 2%; 95% confidence interval �-9% to 13%; P�.80).
Three ketofol patients and 1 propofol patient received bag-valvemask ventilation. Sixty-five (46%) patients receiving ketofol and 93
(65%) patients receiving propofol required repeated medication dosing
or progressed to a Ramsay Sedation Score of 4 or less during their
procedure (difference 19%; 95% confidence interval 8% to 31%;
P=.001). Six patients receiving ketofol were treated for recovery
agitation. Other secondary outcomes were similar between the
groups.
The authors concluded that the purported benefits of ketofol over
propofol alone were not proven by the current and largest study to
date. Whilst ketofol demonstrated a slightly enhanced sedation
consistency, as measured by the Ramsay Sedation Score, the
confidence intervals were widely split and the clinical significance of
this is unknown.
Respiratory events and interventions are presented in Table 1:
Result
Ketofol No. (%)
[95% CI]
(n�=142)
Propofol, No.
(%) [95% CI]
(n=142)
Difference, %
(95% CI)
Patients experiencing
a respiratory event
43 (30) [23 to 38]
46 (32) [25 to 41]
2 (-9 to 13)*
Incidence of respiratory events
Oxygen desaturation
38 (27) [20 to 35]
36 (25) [19 to 33]
2(-9to12)
Central apnoea
15 (11) [7 to 17]
13(9)[6to15]
2(-5to9)
Partial upper airway
obstruction
11(8)[4to13]
11(8)[4to13]
0
Complete upper
airway obstruction
6 (4) [2 to 9]
4 (3) [1 to 7]
1(-3to6)
Laryngospasm
0
0
0
Pulmonary aspiration
0
0
0
‡
Respiratory interventions Stimulation/airway
repositioning
5 (4) [2 to 8]
14 (10) [6 to 16]
6 (0.4 to 13)
Stimulation/airway
repositioning plus
oxygen
35 (25) [18 to 32]
31 (22) [16 to 29]
3(-7to13)
Stimulation/airway
repositioning, oxygen,
plus bag-valve-mask
3 (2) [0.7 to 6]
1 (1) [0.1 to 4]
1(-2to5)
*P�.80.
†Some patients had more than 1 event.
‡No patients received
oral airway placement or endotracheal intubation.
Propofol versus 1:1 ketofol versus 4:1 ketofol
This was also a randomised, double blind study between October 2010
to February 2013 in an urban county medical centre. Patients were
identified by the treating emergency physician who was blinded to the
study randomisation. Participants were excluded is they were unable
to give consent, ASA grade >2, known hypersensitivity to either study
medication, pregnant or intoxicated.
Study medication was prepared by a pharmacist in identical syringes
containing either propofol alone, a 1:1 propofol (5mg) and ketamine
(5mg) mixture, or a 4:1 propofol (8mg) and ketamine (2mg) mixture.
Each was prepared with propofol 10mg/mL and ketamine 10mg/mL.
Opioid analgesia was provided as required at least 20 minutes before
study medication was administered. Vital signs, monitoring data, and
depth of anaesthesia were recorded from one minute before initial
medication, every minute thereafter, immediately before and after any
repeated dosing and after any changes in the observer’s assessment of
sedation score.
The primary outcome measure was the relative number and proportion
of subjects experiencing airway or respiratory adverse events leading
to an intervention. These are presented in the table 2.
Two hundred seventy-one subjects completed the trial, 90 receiving
propofol, 85 receiving 1:1 propofol and ketamine, and 96 receiving 4:1
propofol and ketamine. Airway or respiratory adverse events leading
to an intervention were similar between groups: 29%, 19%, and 32%,
respectively (P=0.21). There were no serious adverse events in any
group. Secondary outcomes were generally similar between groups,
with greater recovery agitation observed in the 1:1 ketofol group (8%,
21%, and 10%, respectively).
The authors concluded that neither ketofol 1:1 or 4:1 showed any
benefit over propofol alone in terms of primary respiratory adverse
events and secondary outcome measures.
Discharge
Once the sedation is complete you need to ensure your patient is fit
for discharge. The AAGBI/RCEM joint document recommends that
the following criteria must be met prior to discharge:





The patient has returned to their baseline level of
consciousness. Vital signs are within normal limits for that patient. Respiratory status is not compromised. Pain and discomfort have been addressed. Patients meeting discharge criteria following sedation who go
on to be discharged home from the Emergency Department
should be discharged into the care of a responsible third party.
Verbal and written instructions should be given. That’s it for a whistle stop tour of sedation. F to leave any questions
or comments and we’ll be back with anther blog and podcast really
soon.
References
Safe Sedation of Adults in the Emergency Department. Report and
recommendations by the Royal College of Anaesthetists and the
College of Emergency Medicine, Working Party on Sedation,
Anaesthesia and Airway Management in the Emergency Department
November 2012
Latency of pulse oximetry signal with use of digital probes associated
with inappropriate extubating during prehospital rapid sequence
intubation in head injury patients: Case examples. Journal of
Emergency Medicine, April 2012. 42/4(424-428) Emerg Med J
doi:10.1136/emermed-2012-202147
Vespasiano, Michael, Marsha Finkelstein, and Stephen Kurachek.
"Propofol sedation: intensivists' experience with 7304 cases in a
children's hospital." Pediatrics 120.6 (2007): e1411-e1417.
Arenal J J, Bengoechea-Beeby M. Mortality associated with
emergency abdominal surgery in the elderly. Can J Surg 2003; 46: 111116.
British Medical Association and the Royal Pharmaceutical Society of
Great Britain. British National Formulary. 65th ed. UK: BMJ
Publishing Group. 2013.
Pulmonary Aspiration Risk during Emergency Department Procedural
Sedation—An Examination of the Role of Fasting and Sedation Depth
GREEN.S et al. ACADEMIC EMERGENCY MEDICINE: January
2002;9: 1. 35-42
Dawson D et al. Association between ASA grade and complication
rate in patients receiving procedural sedation for relocation of
dislocated hip prostheses in a UK emergency department. Emerg Med
J doi:10.1136/emermed-2012-202147
Risk factors for sedation-related events during procedural sedation in
the emergency department. Taylor D et al. Emergency Medicine
Australasia. 2011. 23. 466-473
Andolfatto, Gary, et al. "Ketamine-propofol combination (ketofol)
versus propofol alone for emergency department procedural sedation
and analgesia: a randomized double-blind trial." Annals of emergency
medicine 59.6 (2012): 504-512.