Safe Sedation for patients with special needs

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

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

5. Reducing sympathetic activity

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

7. Sedation vs G A

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. O2 / N2O /Sevoflurane • Excellent for induction (paediatrics) • Short exposure to allow for i.v. access • Unsuitable for long term use

11. Intra nasal spray

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

13. 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

14. 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

15. Patient Positioning • Soft elastic belt (for children) • Safety belt (adults) • Blanket (sympatholysis) • Minor movement tolerable

16. Patient Positioning

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

19. Propofoldi-isopropyl phenol

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 1.5-6 μg/ml • Maintenance with infusion pump • No atmospheric pollution

21. Propofol – Pharmacokinetics

22. Propofol – Pharmacokinetics Guaranteed sedation…..

23. Propofol Pharmacokinetics

24. Propofol Pharmacokinetics for the rest of us

25. Propofol Pharmacokinetics for the rest of us

26. Propofol Pharmacokinetics for the rest of us

27. Bathtub Pharmacokinetics

28. In practice • 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

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”

30. Individual Titration

31. Supplementary Agents • 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)

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

33. Monitoring and iv infusion

34. Oxygen supply

35. Contingency Equipment: Vital SignsTM Airway Pack

36. Contingency Equipment

37. Contingency Equipment

38. Contingency Equipment

39. Contingency Equipment

40. Utility Trolley

41. Utility Trolley

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.,

46. Fasting Instructions • 6 hours - solids • Food and snacks • Milk • Milky drinks • Fresh orange juice • 2 Hours – clear fluids • Water • Ribena • Apple juice • Orange squash

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

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

49. Range of Dental Procedures • Adult – M O S • Dental Implants • Aesthetic dentistry • Mentally handicapped

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