1. Safe Sedation for patients with special needs
Dr John M LOW
MA. (Oxford University) BM.BCh. (Oxford University)
FRCA., FHKCA., FANZCA., FHKAM.(Anaesthesiology)
Partner, Dr. Roger Hung and Partners

2. Overview Sedation vs General Anaesthesia Achieving sympatholysis
Pharmacology
Practical aspects of M A C - equipment
Regulatory aspects
Managing patient work flow

3. ↑sympathetic activity
Psychological and emotional
Physical
Instrumentation / Surgical Incision
Pharyngeal/ Laryngeal stimulation
Tomori Z, & Widdicombe J G (1969) J Physiol (London) 200:25
Exogenous catecholamines (LA)
Cold
Full bladder
JM Low et al (1986)B J A 58:

4. Noxious stimulation JM Low et al (1986) B J Anaesth 58:471-477
Adrenergic Responses to Laryngoscopy
JM Low et al (1986)B J A 58:

5. Reducing sympathetic activity
Anxiety
Cold, Pain, Noxious Stimulus
Fear Factor Sympathetic activation
Sedation
Sympatholysis
Analgesia
Anxiolytics
JM Low et al (1986)B J A 58:

6. Reducing sympathetic activity
Anxiolytics (benzodiazepines / propofol)
Local analgesia - ↓ pain stimulus
Fentanyl - ↓ pain stimulus; sympatholysis
↓ non-pharmacological factors (eg. cold)
β - adrenergic blockade
α - adrenergic blockade
JM Low et al (1986)B J A 58:

7. Sedation vs G A Minimal Moderate Deep G A Response to deep pain
Responsiveness
Verbal commands
Purposeful response
Response to deep pain
Unrouseable
Airway
Normal
No need for intervention
May need chin lift
Airway / chin lift needed
Spontaneous ventilation
Adequate
May not be adequate
Often inadequate
CVS function
Usually maintained
May be impaired

8. Common drugs for sedation
IV Sedation:
Pethidine / Morphine
Midazolam / Diazepam/Diazemuls
Monitored Anaesthetic Care
Propofol / Dexmetatomidine (Precedex)
Fentanyl / Alfentanil / Remifentanil
Dynastat / Pethidine

9. Typical sequence - M A C Assessment and Informed consent
Preparation of equipment
Inhalational induction (paediatric case)
IV access – Bolus and Maintenance
Maintenance of patient’s airway
Monitoring
Recovery and Discharge

10. Dr John M LOW <johnmlow@Uusa.net>
O2 / N2O /Sevoflurane
Excellent for induction (paediatrics)
Short exposure to allow for i.v. access
Unsuitable for long term use
HKIDEAS 2010

11. Intra nasal spray

12. Maintenance of the airway
Dr John M LOW
Maintenance of the airway
AMBU Bag readily accessible
+ / - Oxygen supplement
Chin lift (teach D S A)
Practical “tricks of the trade”
HKIDEAS 2010

13. Dr John M LOW <johnmlow@Uusa.net>
Practical “tricks”
Posture – (take advantage of pharyngeal curvature)
Horizontal position
Neck extension
Shoulder support
Nasopharyngeal airway
Loose gauze swab in pharynx
Oral Dam
Double suction (DSA)
No irrigation – soft debris
HKIDEAS 2010

14. Irrigation without aspiration
Dr John M LOW
Irrigation without aspiration
Suction…..Suction……Suction…….
Neck extension – double articulation headrest
Cough / swallowing reflex present
Oral Dam – if possible
Loosely packed gauze swab
Chin Lift -Train D S A
Minimise irrigation
HKIDEAS 2010

15. Dr John M LOW <johnmlow@Uusa.net>
Patient Positioning
Soft elastic belt (for children)
Safety belt (adults)
Blanket (sympatholysis)
Minor movement tolerable
HKIDEAS 2010

16. Dr John M LOW <johnmlow@Uusa.net>
Patient Positioning
HKIDEAS 2010

17. M A C – typical sequence

18. M A C – a pragmatic approach
Inhalational techniques
Excellent for paediatric induction
No scavenging – closed ventilation
Limited supply of gas / agent
Complex equipment needed for maintenance
Intravenous Techniques
Propofol……propofol……propofol
+ / - Adjunct agents
JM Low et al (1986)B J A 58:

19. Propofol di-isopropyl phenol
JM Low et al (1986)B J A 58:

20. Propofol Pharmacology
Non-barbituarate hypnotic anaesthetic
Lipid soluble – preparation as emulsion
Rapid hepatic & extra-hepatic metabolism
Very rapid onset and recovery
Half Life: T½= 2; 30; 180 mins
Metabolites not active
Hypnosis at μg/ml
Maintenance with infusion pump
No atmospheric pollution
JM Low et al (1986)B J A 58:

21. Propofol – Pharmacokinetics
JM Low et al (1986)B J A 58:

22. Propofol – Pharmacokinetics
Guaranteed sedation…..
JM Low et al (1986)B J A 58:

23. Propofol Pharmacokinetics
JM Low et al (1986)B J A 58:

24. Propofol Pharmacokinetics for the rest of us
JM Low et al (1986)B J A 58:

25. Propofol Pharmacokinetics for the rest of us
JM Low et al (1986)B J A 58:

26. Propofol Pharmacokinetics for the rest of us
JM Low et al (1986)B J A 58:

27. Bathtub Pharmacokinetics
JM Low et al (1986)B J A 58:

28. In practice Loading dose – 40-80 mg (1 mg/kg)
Maintenance dose – mls/hr (80 μg/kg/min)
20mg bolus prn.
Titrating to patient’s threshold
JM Low et al (1986)B J A 58:

29. Titrating to patient’s threshold
At steady state
Reduce rate by 10% every few minutes
Slight non-purposeful movement (threshold)
Add 10% and maintain
Switch off when no more stimulation
“Every anaesthetic is a pharmacological experiment”
JM Low et al (1986)B J A 58:

30. Individual Titration
JM Low et al (1986)B J A 58:

31. Supplementary Agents Midazolam (1-2 mg) Fentanyl (25 mcg / 0.5 mls)
Pethidine mg/kg
Remifentanil (20μg μg/min)
Dynastat (40 mg iv Q12H)
Arcoxia (90 – 120 mg po.)
Dexmetatomidine (Precedex)
Labetalol (!) (5 – 15 mg)
JM Low et al (1986)B J A 58:

32. Sedation - equipment IV equipment Monitoring Oxygen / AMBU bag
Simple airway management
Treatment of major side effects
Anaphylaxis
Extremes of HR
Extremes of BP
Bronchospasm
Angina
P O N V
JM Low et al (1986)B J A 58:

33. Monitoring and iv infusion
Dr John M LOW
Monitoring and iv infusion
HKIDEAS 2010

34. Dr John M LOW <johnmlow@Uusa.net>
Oxygen supply
HKIDEAS 2010

35. Contingency Equipment: Vital SignsTM Airway Pack
Dr John M LOW
Contingency Equipment: Vital SignsTM Airway Pack
HKIDEAS 2010

36. Contingency Equipment
Dr John M LOW
Contingency Equipment
HKIDEAS 2010

37. Contingency Equipment
Dr John M LOW
Contingency Equipment
HKIDEAS 2010

38. Contingency Equipment
Dr John M LOW
Contingency Equipment
HKIDEAS 2010

39. Contingency Equipment
Dr John M LOW
Contingency Equipment
HKIDEAS 2010

40. Dr John M LOW <johnmlow@Uusa.net>
Utility Trolley
HKIDEAS 2010

41. Dr John M LOW <johnmlow@Uusa.net>
Utility Trolley
HKIDEAS 2010

42. Patient selection ASA I or II Age less than 70 years BMI less than 30
Satisfactory pre-op assessment questionnaire
Easy access to hospital if necessary
Escort available following procedure

43. What procedures are appropriate ?
Patient factors – ASA I / II
Assessment of surgical risk
Exclude risk of major bleeding
Minimal risk of P O N V
Satisfactory post-op pain control
Patient’s domestic circumstances
Why does this surgery justify hospitalisation ?

44. Patient Work Flow Presentation and decision to operate
Screening Questionnaire
Concurrent medications / Allergies / Cardio- respiratory status
Fasting instructions
Day of procedure – Consent; Contact; Re-assessment; Payment
Recovery Stage I Stage II
Escort to and from clinic
Written Instructions – Medication; Analgesia;
driving, machinery, signing of legal documents, cooking, etc.,
JM Low et al (1986)B J A 58:

46. Fasting Instructions 6 hours - solids 2 Hours – clear fluids
Food and snacks
Milk
Milky drinks
Fresh orange juice
2 Hours – clear fluids
Water
Ribena
Apple juice
Orange squash
JM Low et al (1986)B J A 58:

47. Range of procedures Examination -/+ x-ray Dental Hygiene Restoration
S S crown
R C T
Extraction
Orthodontics -/+ impression

48. Range of Dental Procedures
Dr John M LOW
Range of Dental Procedures
Paediatric – M O S
Paediatric –dental restoration
Often minimal stimulation
Pulpectomy will need LA
Combative / mentally handicapped
HKIDEAS 2010

49. Range of Dental Procedures
Dr John M LOW
Range of Dental Procedures
Adult – M O S
Dental Implants
Aesthetic dentistry
Mentally handicapped
HKIDEAS 2010

50. Clinic Selection Preliminary visit to clinic – assess environment
Establish rapport with surgeon
“Check List” of mandatory equipment
Second visit – check all facilities
Then – (third visit) - book patient
JM Low et al (1986)B J A 58:

51. Practical Aspects Equipment – Mandatory ←→ Best Practice
Protocols / Check List – for nursing staff
Documentation
Pre-operative diagnosis – justify procedure
Pre-operative assessment – questionnaire
Written pre-operative instructions / fasting time
Consent for surgery – informed / explicit
Consent for sedation – informed / explicit
Sedation - vital signs record / positioning / drugs / timetable of events
Operation Record – diagnosis / findings/ procedure / closure
Written Post-Operative instructions – escort present

54. Regulatory aspects American Society of Anesthesiologists
American Dental Association
Task Force of Sedation & Analgesia
Practice Guidelines for Sedation
Anesthesiology :
JM Low et al (1986)B J A 58:

55. Regulatory aspects International Guidelines
ASA / ADA*
AAGBI / NICE Guidelines NHS UK*
ASA Day Case Surgery Guidelines*
Hong Kong College of Anaesthesiologists*
Hong Kong Academy of Medicine*
HK Society of Paediatric Dentistry*
Mid Lothian Day Case Surgery Process Chart*
* Copies included in CD-ROM

56. Useful Reference Texts
Manual of Office-Based Anesthesia Procedures
Fred E Shapiro Lippincott Williams & Wilkins
Guidelines on Sedation for Dental Procedures
HKSPD Task Force
American Heart Association – Emergency Cardiac Care
A H A / Worldpoint

57. Are there additional risks ?
No greater or less than hospital setting
ASA Closed Claims analysis
Greater need for contingency planning
Emergency Protocols
Staff training in BCLS ACLS
Simulate Drills (e.g. hypoxia)

58. Contingency Planning Oxygen (Cylinder /Oxygen Concentrator)
Sedation Drugs
Resuscitation Drugs
Prolonged Recovery
P O N V
Vaso-vagal sycope
Protocol for hospitalisation
Local Analgesia Toxicity
(Malignant Hyperpyrexia)

59. Emergency Drugs P O N V – metoclopramide / odansetron / dexamethasone
Hypotension – phenylephrine / ephedrine
Hypertension – nifedepine / labetalol / hydrallazine
Bradycardia – atropine / isoprenaline / dobutamine
Tachycardia – esmolol / fentanyl
Bronchospasm – ventolin inhaler / aminophylline
Acute Angina – nitroglycerine patch / sl.
Anaphylaxis – adrenaline / Ca++ / hydrocortisone / dexamethasone
Allergy – chlorpheniramine
Antagonists – naloxone / flumazenil

60. Fitness for discharge Stable vital signs
Orientation – time, place, person
Satisfactory pain control
Able to dress; walk; pass urine
No bleeding ; No P O N V ;
Escort present

61. Modified Aldrete Score

62. Post Anaesthesia Discharge Score (Korttila)

63. Discharge Work Flow
Discharge Criteria- Modified Aldrete Score / PADSS (Korttila)
Post-operative Instructions – written
Escort is mandatory
Supply of post-op drugs – analgesic; antibiotics
Emergency contact number - nurse / surgeon
Initiate telephone follow up on the next day
Post operative follow up in clinic
Alert system for pathology result (malignancy)

64. Benefits of O B A One Stop for the patient / client
Control over scheduling
No waiting for hospital beds
Less competition for OT schedule
No delay because of emergency OT
Minimal risk of hospital acquired infection
Reduced cost for patient and insurance

65. Dr John M LOW <johnmlow@Uusa.net>
Summary
M A C is safe
Separate Operator and Sedationist
M A C is a growing market
Trends in USA: OBA - >50% services
Recent adverse publicity locally
(gynaecology; liposuction; mammoplasty)
Follow guidelines
HKIDEAS 2010

66. Dr John M LOW <johnmlow@Uusa.net>
Summary
M A C is safe ( “Big MAC” may not be)
Separate Operator and Sedationist
M A C is a growing market
Trends in USA: OBA - >50% services
Recent adverse publicity locally
(gynaecology; liposuction; mammoplasty)
Follow guidelines
HKIDEAS 2010

67. CD-ROM Contents EQUIPMENT Specifications
GUIDELINES for clinical practice
TEMPLATES for documentation
POWERPOINT

68. Thank you very much
Mount Yotei, 羊蹄山, Shikotsu Toya National Park, Hokkaido, Japan