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Dr John M LOW
MA. (Oxford University) BM.BCh. (Oxford University)
FRCA., FHKCA., FANZCA., FHKAM.(Anaesthesiology)
Partner, Dr. Roger Hung and Partners
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Sedation vs General Anaesthesia
Achieving sympatholysis
Pharmacology
Practical aspects of M A C - equipment
Regulatory aspects
Managing patient work flow
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Psychological and emotional
Physical
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Instrumentation / Surgical Incision
Pharyngeal/ Laryngeal stimulation
Tomori Z, & Widdicombe J G (1969) J Physiol (London) 200:25
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Exogenous catecholamines (LA)
Cold
Full bladder
JM Low et al (1986) B J Anaesth 58:471-477
Adrenergic Responses to Laryngoscopy
Anxiety
Sedation
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Anxiolytics (benzodiazepines / propofol)
Local analgesia - ↓ pain stimulus
Fentanyl - ↓ pain stimulus; sympatholysis
↓ non-pharmacological factors (eg. cold)
β - adrenergic blockade
α - adrenergic blockade
Minimal
Moderate
Deep
GA
Unrouseable
Responsiveness
Verbal commands Purposeful
response
Response to
deep pain
Airway
Normal
No need for
intervention
May need chin lift Airway / chin lift
needed
Spontaneous
ventilation
Normal
Adequate
May not be
adequate
Often inadequate
Normal
Usually
maintained
Usually
maintained
May be impaired
CVS function
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IV Sedation:
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Pethidine / Morphine
Midazolam / Diazepam/Diazemuls
Monitored Anaesthetic Care
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Propofol / Dexmetatomidine (Precedex)
Fentanyl / Alfentanil / Remifentanil
Dynastat / Pethidine
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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
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Excellent for induction (paediatrics)
Short exposure to allow for i.v. access
Unsuitable for long term use
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AMBU Bag readily accessible
+ / - Oxygen supplement
Chin lift (teach D S A)
Practical “tricks of the trade”
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Posture – (take advantage of pharyngeal curvature)
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Horizontal position
Neck extension
Shoulder support
Nasopharyngeal airway
Loose gauze swab in pharynx
Oral Dam
Double suction (DSA)
No irrigation – soft debris
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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
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Soft elastic belt (for children)
Safety belt (adults)
Blanket (sympatholysis)
Minor movement tolerable
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Inhalational techniques
 Excellent for paediatric induction
 No scavenging – closed ventilation
 Limited supply of gas / agent
 Complex equipment needed for maintenance
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Intravenous Techniques
 Propofol……propofol……propofol
 + / - Adjunct agents
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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 1.5-6 μg/ml
Maintenance with infusion pump
No atmospheric pollution
Guaranteed sedation…..
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Loading dose – 40-80 mg (1 mg/kg)
Maintenance dose – 25-60 mls/hr (80 μg/kg/min)
20mg bolus prn.
Titrating to patient’s threshold
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At steady state
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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”
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Midazolam (1-2 mg)
Fentanyl (25 mcg / 0.5 mls)
Pethidine 0.5-1 mg/kg
Remifentanil (20μg + 2.5 μg/min)
Dynastat (40 mg iv Q12H)
Arcoxia (90 – 120 mg po.)
Dexmetatomidine (Precedex)
Labetalol (!) (5 – 15 mg)
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IV equipment
Monitoring
Oxygen / AMBU bag
Simple airway management
Treatment of major side effects
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Anaphylaxis
Extremes of HR
Extremes of BP
Bronchospasm
Angina
PONV
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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
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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
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Why does this surgery justify hospitalisation ?
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Presentation and decision to operate
Screening Questionnaire
 Concurrent medications / Allergies / Cardio- respiratory status
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Fasting instructions
Day of procedure – Consent; Contact; Re-assessment; Payment
Recovery Stage I Stage II
Escort to and from clinic
Written Instructions – Medication; Analgesia;
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driving, machinery, signing of legal documents, cooking, etc.,
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6 hours - solids
Food and snacks
Milk
Milky drinks
Fresh orange juice
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2 Hours – clear fluids
Water
Ribena
Apple juice
Orange squash
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Examination -/+ x-ray
Dental Hygiene
Restoration
S S crown
RCT
Extraction
Orthodontics -/+ impression
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Paediatric – M O S
Paediatric –dental restoration
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Often minimal stimulation
Pulpectomy will need LA
Combative / mentally handicapped
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Adult – M O S
Dental Implants
Aesthetic dentistry
Mentally handicapped
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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
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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
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American Society of Anesthesiologists
American Dental Association
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Task Force of Sedation & Analgesia
Practice Guidelines for Sedation
 Anesthesiology 2002 96:1004-1017
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International Guidelines
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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
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Manual of Office-Based Anesthesia Procedures
 Fred E Shapiro
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Guidelines on Sedation for Dental Procedures
 HKSPD Task Force
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Lippincott Williams & Wilkins www.amazon.com
www.hkspd.org
American Heart Association – Emergency Cardiac Care
 A H A / Worldpoint
www.eworldpoint.com)
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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)
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http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2011.06651.x/pdf
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Oxygen (Cylinder /Oxygen Concentrator)
Sedation Drugs
Resuscitation Drugs
Prolonged Recovery
PONV
Vaso-vagal sycope
Protocol for hospitalisation
Local Analgesia Toxicity
(Malignant Hyperpyrexia)
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P O N V – metoclopramide / odansetron / dexamethasone
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Hypotension – phenylephrine / ephedrine
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Hypertension – nifedepine / labetalol / hydrallazine
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Bradycardia – atropine / isoprenaline / dobutamine
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Tachycardia – esmolol / fentanyl
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Bronchospasm – ventolin inhaler / aminophylline
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Acute Angina – nitroglycerine patch / sl.
Anaphylaxis – adrenaline / Ca++ / hydrocortisone / dexamethasone
Allergy – chlorpheniramine
Antagonists – naloxone / flumazenil
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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
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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)
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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
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M A C is safe
Separate Operator and Sedationist
M A C is a growing market
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Trends in USA: OBA - >50% services
Recent adverse publicity locally
 (gynaecology; liposuction; mammoplasty)
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Follow guidelines
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M A C is safe
( “Big MAC” may not be)
Separate Operator and Sedationist
M A C is a growing market
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Trends in USA: OBA - >50% services
Recent adverse publicity locally
 (gynaecology; liposuction; mammoplasty)
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Follow guidelines
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EQUIPMENT Specifications
GUIDELINES for clinical practice
TEMPLATES for documentation
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Mount Yotei, 羊蹄山, Shikotsu Toya National Park, Hokkaido, Japan