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Sedation during Regional Anesthesia
A. Borgeat
Orthopedic University Clinic of Zurich/Balgrist
Switzerland
The goal of sedation is
to produce a relaxed patient who is
comfortable and cooperative
throughout the duration of surgery
analgesia sedative conscious
sedation
Predictors of patient satisfaction
with regional anesthesia
De Andrés et al.
Reg Anesth 1995;20:498,
N = 154; Spinal 85%, Epidural 9%, Peripheral nerve block 6%
Advantages
• Speaking with
relatives 73%
• Staying awake 72%
• Absence of immediate
postoperative pain 37%
Disadvantages
• Performance of the block 18%
• Fear of pain 10%
Patient attitude
• Favorable 48%
• Indifferent 45%
• Negative 7%
„See one,
McDonald et al.
Reg Anesth Pain M 2002:27:456,
21 residents were recipients
of a total of 72 regional anesthetic
procedures as volunteers
do one, teach one, have one“
Block placement :
the resident experiences
McDonald et al.
Reg Anesth Pain M 2002;27:456,
• Preoperative consultation +++
• Physical contact, „gentle touch“ +++
• Communication, explain action +++
• Paresthesias +++++
• Value of analgosedation ++++
• Local anesthesia infiltration ++
Seizures after PNB (prospective study)
Interscalene block 3‘459 0
Supraclavicular block 1‘899 1
Axillary block 11‘024 1
Mid-humeral block 7‘402 1
Psoas compartment block 394 1
Femoral block 10‘309 0
Sciatic block 8‘507 2
Popliteal block 952 0
Performed Seizure
Auroy et al.
Anesthesiology 2002;97:1274,
Alexander et al. Can J Anaesth 1987; 34:343,
Rendoing et al. Anesth Analg 1969;26,445,
Effect of pH and pCO2 on Toxicity
Surgery : facts to consider
• boredom, anxiety
• occurrence of pain
• side-effects due to analgosedation
• discomfort
adapt and change your drug
administration quickly
Clinical case I
• Subacromial decompression and
arthroscopic rotator cuff repair
• ISB
• Beach chair position
• Patient 49 yrs, ASA I
Clinical case II
• Patient was unconscious, but able to
be aroused and continued to breathe
spontaneously
± DEEP SEDATION
• SpO2 97-98%
• Continuous infusion of propofol for sedation
Clinical case III
• Audible stridor, severe neck and chest
edema
• GA, LM, fibroscopic intubation ...
• After 3h SpO2 67%
Sieber et al
Mayo Clin Proc 2010;85:18,
L
S
L
S D
S
D
S
Po
sto
pe
rative
de
liriu
m
Du
ratio
n o
f
de
liriu
m
1.
4 0.5*
19*
40
day %
Light Sed : BIS > 80
Deep Sed : BIS ~ 50
NNT : 4.7
*p > 0.05
> 65 y
Sedation :
remifentanil vs propofol
% • Remi. 0.2µg/kg/min
(5 min before block placement
50% after block placement)
* P < 0.05
Mingus et al.
J Clin Anesth 1998;10:46,
• Prop. 100µg/kg/min
(5 min before block placement
50% after block placement)
Pa
in s
co
re
0 1 2
81
60
13 13 4
26
%
Sid
e-e
ffe
cts
N V Apnea
60
17* 21
6 8 0
Remifentanil sedation vs Propofol
during regional anesthesia
* P < 0.05
Servin et al.
Acta Anaesth Scand 2002;46:309,
%
15
92 P 500 µg/kg, 50 µgkg/min
5 *
P R
R 0.5 µg/kg, 0.1 µgkg/min
Postoperative
pain
%
2 *
27
P R
Perioperative
NV
%
19 *
46
P R
Respiratory
depression
Sedation : uncontrolled movements
• are unpredictable
• are most often associated with hypno-
sedatives
- Propofol: effect site < 0.5-0.8ug/ml
- Midazolam ?
• combination hypnosedative-opioid may
limit their occurrence
Midazolam Propofol
Dreamers 12 % 40 %*
Kim DK et al
Anesth Analg 2011;112:1076,
*p <0.05
1 very negative
5 very positive
1 only remember dreaming
5 very memorable
1 not at all vivid
5 very vivid
1 not at all intense
5 very intense
1 Not at all strange
5 very strange
Sedation : what conditions ?
• Sedation has to be easy to manage,
predictable and quickly reversible
Sedation : what conditions ?
• Sedation has to be targeted
anxiolytic, sedative
analgesic
analgo-anxiolytic
multimodal sedation
Sedation : what conditions ?
Pharmacokinetic conditions
• short onset time and short „time to peak effect“
Pharmacokinetics : T ½ Keo
Propofol
(Thiopental)
Midazolam
Remifentanil
Alfentanil
Fentanyl
(Sufentanil)
min
2.6
1.2
5.8
1.2
1.1
5.8
5.8
Pharmacokinetics
Propofol
(Thiopental)
Midazolam
Remifentanil
Alfentanil
Fentanyl
(Sufentanil)
T ½ Keo
min
2.6
1.2
5.8
1.2
1.1
5.8
5.8
TPE
min
3.5
1.4
13.5
1.5
3.0
3.5
5.8
Pharmacokinetics : clearance
Propofol
(Thiopental)
Midazolam
Remifentanil
Alfentanil
Fentanyl
(Sufentanil)
L/h
113.6
12.9
25.8
156.3
21.3
36.4
61.3
3020100
Concentr
ation µ
g/m
l
2
1
0
Infu
sio
n R
ate
(ml/h
r)
1000
900
800
700
600
500
400
300
200
100
0
TCI sedation
• Easy to handle
• Predictable
• Easy to adjust
Change to GA
(TCI sedation TCI-GA is easy)
Moerman et al
Anesth Analg 2009;108:828
*p < 0.05
289
Propofol (mg) Remi (ug)
318
381
40 36
*
tota
l d
ose
E movem
.
Apnea
Drowsin
ess
11
44 *
14 * 11
27
14
%
TCI
propofol
Remi MCI
Remi TCI
Placebo
n = patient scheduled for colonoscopy
Techniques of sedation
• Repeated administration of bolus
• TCI Sedation
• Target-controlled patient-
maintained sedation
Sedation / Monitoring
• BIS, AEP
• Scores : Ramsay, OAA/S, Wilson
• To observe and to communicate with
the patient
• Standard monitoring
Guidelines
• Start at a low dose and titrate
• Supplementary nasal 02
• Allow time for effect-site equilibration
• Assess patient regularly. Respiratory rate
• Use appropriate monitoring (Sp02)
• NB sedation should not be used as analgesia
Conclusions
• Propofol and remifentanil are particularly
well suited for TCI sedation (multimodal
approach)
• Observation and communication with the
patient are fundamental during sedation
• TCI sedation is actually the technique of
choice for perioperative sedation