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%

Perioperative analgosedation

Time

Block

placement

„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 ++

CNS Toxicity

time

LA concentration

threshold

)

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

Interaction Propofol - Remifentanil

Perioperative analgosedation

Time

Block

placement Surgery

Surgery : facts to consider

• boredom, anxiety

• occurrence of pain

• side-effects due to analgosedation

• discomfort

adapt and change your drug

administration quickly

Sedation

Blood levels

Conscious sedation

Deep sedation

General anesthesia

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%

Antonucci et al.

Minerva Anestesiologica 2006;72:995,

Smith et al

J. Shoulder Elbow Surg 2008; 17:415,

Perioperative analgosedation

Time

Block

placement Surgery Postoperative

period

Postoperative period :

facts to consider

• Side-effects due to sedation

• Level of sedation

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“

Third

Compartment Second

Compartment

Fat Musclel

Effect

Compartment Central

Compart-

ment

Keo

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

Midazolam 2mg bolus

(peak effect at 13.5 min)

Propofol 20mg bolus

(peak effect at 3.5 min)

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

Techniques of sedation

• Repeated administration of bolus

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

Techniques of sedation

• Repeated administration of bolus

• TCI sedation

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

Patient-controlled sedation

Sedation / Monitoring

• Scores : Ramsay, OAA/S, Wilson

• BIS, AEP

• Standard monitoring

Sedation / Monitoring

• BIS, AEP

• Scores : Ramsay, OAA/S, Wilson

• To observe and to communicate with

the patient

• Standard monitoring

Pk/Pd Variability

Dose

Pd variability ~ 200%

Response

Pk variability ~ 25%

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

Thank you for you attention