Procedural Sedation

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Procedural Sedation

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Procedural Sedation

  1. 1. Procedural sedation Dave Mcilroy
  2. 2. What is it ?  The American College of Emergency Physicians (ACEP) defines procedural sedation as "a technique of administering sedatives or dissociative agents with or without analgesics to induce a state that allows the patient to tolerate unpleasant procedures while maintaining cardiorespiratory function. Procedural sedation and analgesia (PSA) is intended to result in a depressed level of consciousness that allows the patient to maintain oxygenation and airway control independently.
  3. 3. Minimal sedation  Response to verbal stimulation is normal.  Cognitive function and coordination may be impaired.  Ventilatory and cardiovascular functions are unaffected.
  4. 4. Moderate (formerly conscious) sedation  Depression of consciousness is drug-induced.  Patient responds purposefully to verbal commands.  Airway is patent, and spontaneous ventilation is adequate.  Cardiovascular function is usually unaffected.
  5. 5. Deep sedation  Depression of consciousness is drug-induced.  Patient is not easily aroused but responds purposefully following repeated or painful stimulation.  Independent maintenance of ventilatory function may be impaired.  Patient may require assistance in maintaining a patent airway.  Spontaneous ventilation may be inadequate.  Cardiovascular function is usually maintained.
  6. 6. General anaesthesia  Loss of consciousness is drug-induced, where the patient is not able to be aroused, even by painful stimulation.  Patient's ability to maintain ventilatory function independently is impaired.  Patient requires assistance to maintain patent airway, and positive pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function.  Cardiovascular function may be impaired.
  7. 7. A light anaesthetic ?  Guedel in 1937, first widely accepted guide to depth of anaesthesia (I – IV)  Artusio later divided stage 1 into 3 planes, first plane no analgesia no amnesia, second amnesia no analgesia and 3rd both analgesia and amnesia  Entropy and Bis , (around 60 – 80 )
  8. 8. When is it used? Fracture reduction Joint relocation Painful procedures, esp children Radiological procedures, eg CT , MRI Cardioversion Foreign body removal Suturing , and other procedures
  9. 9. Other options  GA in theatre with Image intensifier and anaesthetic support  Bier’s block  Haematoma block  Regional techniques  Just don’t do it
  10. 10. Assessment  Your own level ability and experience, and that of your assistants  The state of the department, resource hungry procedure  Availability of appropriate area and equipment  Plan for it all to go wrong, don’t just have a plan A  Patient factors
  11. 11. Patient factors  ASA grade (3+), co-morbidities  Fasted ?  Airway assessment  Obesity or pregnancy  Intoxicated  Allergies , previous anaesthetic  Am I happy to RSI this patient?
  12. 12. Patient selection  Short painful procedure (<20 mins )  Age  ASA 1 and 2  Airway assessment  PMHx  fasting
  13. 13. fasting  How important is it?  Several studies studies , with several different agents , maybe not as important as we once thought 1,2,3
  14. 14. urgency  Emergency  Urgent  Semi-urgent  elective
  15. 15. Other considerations  Carers / parents  Informed consent  Documentation, what was given, how much when and by whom and any problems  Post sedation observation  Instructions on driving and alcohol
  16. 16. Staffing  Minimum 3 trained staff  Practitioner administering sedation must be familiar with the agent, experience and able to monitor and detect problems  Airway competent  Anaesthetist ?  ALS competent
  17. 17. Equipment (ACEM minimum)  Adequate room and appropriate lighting  Tiltable table, preferable but not mandatory  Suction  Oxygen  Means to inflate the lungs, readily available airway equipment  Appropriate drugs
  18. 18. continued  Pulse oximeter  BP measurement  Ready access to ECG and defib  Means to summon assistance  ET CO2 monitoring
  19. 19. Choice of agent  Midazolam, diazepam  Morphine, fentanyl, remifentanyl  Propofol  Ketamine  Etomidate  Promethazine ( twice now )
  20. 20. Choices, choices  Use what you are familiar with and know how to use  Titrate dose, it is easier to put more in than take some out
  21. 21. ketamine  Safe  IV / IM  Laryngospasm  Role of atropine / glycopyrolate  Emergence phenomenon  Dissociative agent, powerful analgesic
  22. 22. Ketamine 2  Effect on ICP  Co administration of anxiolytics eg midazolam or propofol  Dose 0.5 – 2 mg /kg iv  2 – 4 mg / kg IM  10 mg / kg IM via syringe dart ( dangerous animal gun )
  23. 23. Propofol  Rapid  Short acting  Easily titrated  Respiratory depression 50% +  Hypotension  0.5 – 2 mg /kg iv  Amnesic
  24. 24. midazolam  Amnesic, but no analgesia  Fairly rapid and predictable  Slower recovery than propofol  Reversable (big advantage for some operators )
  25. 25. fentanyl  Fast acting  Powerful analgesic  Duration of action 20 – 40 minutes (at low doses)  Reversible  IV or IN popular, but all routes
  26. 26. What could possibly go wrong ?  Loss of airway reflexes  Depression of respiration  CV depression  Drug interactions, adverse reactions and anaphylaxis  Variations in expected response to drugs used  Possible deeper sedation than expected  Risks from the procedure
  27. 27. Preoxygenation  Good idea or not  How is it best achieved?  Nasal prongs, hudson, non-rebreather mask, self inflating bag with reservoir, CPAP mask ?
  28. 28. Preoxygenation or denitrogenation  Lungs can hold much more oxygen than blood (about 20 times)  Lungs full of air equals about 0.4 l available oxygen (FiO2 0.21 x 2l)  Lungs full of oxygen equal 2 l (FRC x FiO2)  Body oxygen consumption about 250 ml under normal conditions  All the oxygen reserve is provided by preoxygenation
  29. 29.  Rate of preoxygenation is a predictor of rate of deoxygenation, as represents the relationship between alveolar minute volume FRC  Technique big breaths v TV x longer time  Really should measure FeO2 (>90%)
  30. 30. Prolonging DAWD, apnoiec oxygenation  General aspects  Preoxygenation, position, technique, and method of O2 delivery  Apnoeic oxygenation
  31. 31. Duration of apnoea without desaturation  DAWD = time from onset of apnoea to saturation <90%  DAWD depends on  Initial oxygen reserve  Rate of O2 consumption  Ongoing apnoeic oxygen delivery or not
  32. 32. DAWD  <1 minute – 8 minutes without apnoeic oxygenation depending on various factors  Obesity  Pregnancy  Increase rate of consumption, fever, tachycardia  Inadequate preoxygenation
  33. 33. Study Endpoint Tidal Volume Breaths 4 (in 30 sec) Deep Breaths 8 (in 60 sec) Deep Breaths Gambee DAWD 8.9 (1.0) min 6.8 (1.8) ----- Nimmagadd a FeO2 % 88 (5) % 80 (5) 87 (3) Pandit FeO2 % 92 (1) % 83 (2) 91 (4) Gagnon FeO2 % 89 (3) % 76 (7) ----- Gambee et al Preoxygenation techniques: comparison of three minutes and four breaths. Anesth Analg 1987; 66: 468–70. Nimmagadda et al. Preoxygenation with tidal volume and deep breathing techniques: the impact of duration of breathing and fresh gas flow. Anesth Analg 2001; 92: 1337–41. Pandit etal Total oxygen uptake with two maximal breathing techniques and the tidal volume breathing technique: a physiologic study of preoxygenation. Anesthesiology 2003; 99: 841-6 Gagnon et al When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing. Can J Anesth 2006; 53: 86–91.
  34. 34. High flow nasal vs high flow mask oxygen delivery: tracheal gas concentrations through a head extension airway model 2002 Open Forum Abstracts, Am Assoc Resp Care High flow nasal cannula delivery > non-rebreather mask at equivalent flows
  35. 35. Apnoeic oxygenation  250 ml oxygen leaving lung per minute  10 – 20 ml CO2 entering lung  Results in slightly subatmospheric alveolar pressure  Net gas flow 240 ml / minute
  36. 36. Techniques of O2 delivery  Nasal cannula  10 Fc catheter into nasopharynx (distance of mouth angle to ear tragus) @5l/min O2  Paediatic south facing Rae tube to angle of the mouth
  37. 37. “apneic diffusion oxygenation, diffusion respiration, and mass flow ventilation”
  38. 38. Hypotension under anaesthesia, sedation  Usually temporary  ? Best agent or way to resolve ?  Elevate legs, fluid bolus,. Metaraminol ?
  39. 39. laryngospasm  PEEP  Deepen  Sux low dose  Sux full dose  Iv lignocaine
  40. 40. documentation  consent  Make sure its clear  What was given, when, how much, problems encountered  How long to stay monitored  How long until fit to discharge  Driving, avoidance of alcohol
  41. 41.  1 Treston G. Prolonged pre –procedure fasting time is unnecessary when using titrated intravenous ketamine for paediatric procedural sedation. Emergency medicine Australasia 2004; 16(2): 145-150  2 Agrawal D, Manzi SF, Gupta R et al. Preprocedural fasting state and adverse events in children undergoing procedural sedation and analgesia in a paediatric emergency department. Annals of emergency medicine 2003: 42(5) 636-646  3 Roback MG, Bajaj L, Wanthan JE, et al. Preprocedural fasting and adverse events in procedural sedation and analgesia in a paediatric emergency department are they related? Annals of Emergency Medicine 2004; 44(5): 454 - 459
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