Sedation 2012
Dr. Alain F. Kalmar, MD, PhD
Dep. Of Anaesthesia
University Medical Center Groningen
The Netherlands
What is adequate sedation ?
ASA definition of levels of sedation
Copyright® [1999] American Society of Anesthesiologists
Benefits of sedation
 Facilitates & expedites procedures
 Reduces discomfort & unpleasant memories
 Allows for avoidance of invasive airway intervention
 Cost -effective
 Promotes early recovery & discharge
 Improves overall patient satisfaction
Prior to sedation : Patient history
 Patient sensitivity to sedatives/analgesics
 patient risk of respiratory/cardiopulmonary complications





- Cardiopulmonary disease : decreased drug dosage
- Hepatic /renal disease : Altered pharmacokinetics
- Medication interactions
Patient allergies
Alcohol / Substance abuse : may increase/decrease effects
Tobacco use : increase airway irritability ; bronchospasm
Prior adverse reactions
difficulty in managing complications
Prior to sedation : Patient history
 Airway assessment
- Airway class
- Mouth opening
- Thyromental distance
Lam B et al. Thorax 2005;60:504-510
Patient education
 helps alleviate concerns associated with conscious
sedation.
 Prevention of “Awareness experience”
 Key points : duration of sedation
potential for sedation failure
alternatives to sedation
potential for adverse events
Monitoring
 Informed Consent
Preprocedural
ASA Fasting Guidelines
To Minimize Aspiration Risk
Substance
Ingested
Clear Liquids
Breast Milk
Infant Formula
Food
Minimum Fasting
Period (hours)
2
4
6
8
Required equipment
 Oxygen
 Suction
 Crash cart with ACLS drugs
 Defibrillator
 Bag/Valve/Mask device ; ventilator
 Oral & nasal airways
 ETT’s sizes 5.0, 6.0, 7.0, 8.0
 Laryngoscopes with Mac 3, 4 and Miller 2, 3 blades
 Reversal agents
Optimal Sedation
 Pt maintains consciousness
 Independent maintenance of airway
 Retains protective reflexes (swallow & gag)
 Responds to verbal & physical commands
 Is not anxious & has acceptable pain control
 Has minimal change in baseline vital signs
 Remains relatively cooperative
 Has mild amnesia
 Recovers to baseline safely & promptly
Farmacology for Conscious Sedation
propofol
barbiturates
benzodiazepines
opiates
inhalational an.
Local an.
Pharmacology For Conscious
Sedation
Allows the patient to be calm, comfortable and cooperative.
 Mostly, a combination of hypnotics and opiates is used.
 Analgesia
 Benzodiazepines or other sedatives
 Sedation, anxiolysis, and amnesia.
Sedative drugs do not provide analgesia.
 A drug should be allowed to exert its full effect before administering
additional doses or another drug.
 When combining opioids and sedatives, administer the opioid first
to ensure the patient receives analgesia prior to painful stimulation.
 Opioids
Conscious Sedation :
Monitoring
Patients must be monitored during moderate sedation. The person
monitoring the patient can not have additional assignments.
 Heart rate and Oxygenation : continuously by Pulse Oxymetry
 Respiratory rate & pulmonary ventilation
Clinical endpoints for conscious sedation may include a respiratory
rate of 10-12 in an adult and a slurring of speech.
 Blood pressure and EKG
Does this provide safe conditions ?
 Observational study (University Hospital Groningen 2011).
 Sedation for colonoscopy : Business as usual
 Midazolam / Pethidine
 230 patients breathing room air.
 Standard monitoring of ECG, NIBP, SpO2, HR
 Additional recorded parameters : PetCO2, PtcCO2, BIS
 All data were recorded for subsequent analysis.
Main safety parameters :
 Oxygenation (SpO2)
 Ventilation (PEtCO2 / PTcCO2 )
 Depth of sedation (BIS) – Risk of pulmonary aspiration
 Blood Pressure (MAP)
Does this provide safe conditions ?
SpO2
SpO
2
100
Median
10th / 90th percentile
95
90
85
80
75
70
65
0
5
10
15
20
25
30
35
40
45
50
55
60
SpO2 < 90 : 36% (226 sec)
65
70
75
80
Time (min)
Does this provide safe conditions ?
BIS
BIS
100
95
90
85
80
75
70
65
60
55
50
0
5
10
15
20
25
30
35
40
45
50
55
60
BIS < 75 : 29% (224 sec)
BIS < 70 : 17% (126 sec)
65
70
75
80
Time (min)
Does this provide safe conditions ?
MAP Pressure
Mean Arterial
200
180
160
140
120
100
80
60
40
20
0
0
5
10
15
20
25
30
35
40
45
50
55
60
MAP < 70 : 36% (564 sec)
65
70
75
80
Time (min)
Does this provide safe conditions ?
PTcTcCO2
CO2
9
8
7
6
5
4
3
2
1
0
0
5
10
15
20
25
30
35
40
45
50
55
60
Incidence SpO2 < 90 : 36%
65
70
75
80
Time (min)
Does this provide safe conditions ?
PEtEtCO2
CO2
8
7
6
5
4
3
2
1
0
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Time (min)
Does this provide safe conditions ?
Hardly !
What goes wrong ?
 Insufficient attention of the sedation caregiver ?
 Insufficient knowledge on pharmacology of Midazolam / Pethidine ?
“If a combination of opioids and sedatives is used, the opioid should be given first and
allowed time to become maximally effective before any sedative is added.”
U.K. ACADEMY OF MEDICAL ROYAL COLLEGES
 Insufficient awareness of the depth of anesthesia ?
Conclusion :
 Conscious sedation should be performed by a skilled personnel with
adequate knowledge of anesthesia, pharmacology and basic and
advanced life support.
 Anesthesiologists or Trained sedation practitioners
 Individual who monitors the sedated patient should do this as his/her
sole task and not have other concurrent responsibilities.
 Choice of medication (Pethidine /Midazolam) ?
Conscious Sedation 2012 ?
 Preference to short-acting drugs
A quick therapeutic response on a rapid change of peri-operative
situation without “hang-over” effects.
 Take into account population variability
Target controlled infusion (TCI) instead of mg/kg/hr
 Attempt to individualize dose-response relation.
Careful titration with knowledge of pharmacology
Percent of peak effect site opioid concentration
Suitable Opiates ?
Time to Peak-effect
100
sufentanil
80
fentanyl
60
40
alfentanil
20
remifentanil
0
0
2
4
6
8
Minutes since bolus injection
10
Context sensitive Half-Time
Time for the effect site concentration of a drug
to fall 50% after a variable length infusion
Egan et al. Anesthesiology 1993, 79(5) : 881-892.
End of procedure
Analgesic
Effect
End of Procedure
*
Remifentanil
Fentanyl
Alfentanil
Time
* Discontinuation of alfentanil infusion/no more fentanyl boluses
Hypnotic-based procedure ?
opiate-based procedure ?
Plasma remifentanil (ng/ml)
Propofol-Remifentanil interaction
10
9
8
7
6
Adequate anesthesia
Awakening
5
4
3
2
1
0
0
2
4
6
8
10
Blood propofol (µg/ml)
12
14
16
Sedation for lung-reduction valve placement
Patient characteristics :
 ASA 4
 High-grade emphysema patients
 Often important comorbidity
Requirements :
 Preserved hemodynamics
 Preserved ventilation with spontaneous ventilation
 Allowing bronchoscopy and intrabronchial valve placement
 Full-coöperative patient for diagnostic and therapeutic reasons.
Sedation for lung-reduction valve placement
Preferred technique :
Conscious sedation with Propofol/Remifentanil
 TCI-guided.
 Take into account pharmacology of agents
1. Start Remifentanil CeT 1 ng/ml
2. Wait 60 seconds until clear subjective effects
3. Start Propofol CeT 1 ug/ml
4. Wait for sedative effect to occur
5. Carefully titrate drugs depending on patients reports (anxiety /pain)
 Keep talking with patient (Population variability)
Sedation for lung-reduction valve placement
Advantages :
 Fully-coöperative patient, good tollerance for the procedure
 Optimal conditions for the procedure
 Preserved hemodynamics
 Fast recovery (extremely important for these high-risk patients)
 High patient satisfaction (complete amnesia of the procedure)
 Fast patient turn-over
Conclusion 2012
TCI Remifentanil / Propofol
- Very advantageous farmacokinetics.
- Good safety profile
Future …
 Dexmedetomidine ?
 Patient controlled sedation ?
Similar to principles of PCA, based on patient feedback
 Target Controlled Sedation ?
(i.e. BIS guided propofol administration)
Questions ?