ian seppelt: time is brain: the neurocritical airway
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DESCRIPTIONSeppelt joins to dots on the big picture of neuro-critical airway management.
- 1.The Neurocritical Airway Dr Ian Seppelt FANZCA FCICM Dept of Intensive Care Medicine, Nepean Hospital, and George Institute for Global Health, University of Sydney and Neuroanaesthesia Division, Dept of Anaesthesia, Macquarie University
2. What might scare you? 1. Airway management with a broken neck 2. Airway management in acute SAH 3. Basic Principles Stick to what you are used to and are good at Most experienced person available Assess the airway properly first Have Plan A, B and C prepared, articulated and thought through It is (almost) impossible to intubate with a correctly fitting cervical collar Consider what neutral position means Get position right first [in sex, real estate and anaesthesia] 4. Any history? MNO Medic Alert/ Notes/ Old Trache Predict Difficult Ventilation - BONES Beard Obese No Teeth Elderly Snores Predict Difficult Laryngoscopy Four Ds Distortion Dentition Disproportion Dysmobility Airway Assessment 5. Plan A: Initial tracheal intubation plan Plan B: Secondary tracheal intubation plan Plan C: Maintenance of oxygenation, ventilation, postponement of surgery and awakening Plan D: Rescue techniques for "can't intubate, can't ventilate" situation Direct laryngoscopy failed intubation succeed succeed succeed Tracheal intubation ILMATM or LMATM failed oxygenation failed oxygenation Revert to face mask Oxygenate & ventilate LMATM increasing hypoxaemia or fail Cannula cricothyroidotomy Surgical cricothyroidotomy improved oxygenation Awaken patient Confirm - then fibreoptic tracheal intubation through ILMATM or LMATM Postpone surgery Awaken patient failed intubation http://www.das.uk.com 6. Unanticipated difficult tracheal intubation - during rapid sequence induction of anaestheia in non-obstetric adult patient failed intubation Tracheal intubation Direct laryngoscopy Any problems Call for help Plan A: Initial tracheal intubation plan Plan B not appropriate for this scenario failed oxygenation (e.g. SpO2 < 90% with FiO2 1.0) via face mask Pre-oxygenate Cricoid force: 10N awake 30N anaesthetised Direct laryngoscopy - check: Neck flexion and head extension Laryngoscopy technique and vector External laryngeal manipulation - by laryngoscopist Vocal cords open and immobile If poor view: Reduce cricoid force Introducer (bougie) - seek clicks or hold-up and/or Alternative laryngoscope Use face mask, oxygenate and ventilate 1 or 2 person mask technique (with oral nasal airway) Consider reducing cricoid force if ventilation difficult LMATM Reduce cricoid force during insertion Oxygenate and ventilate failed ventilation and oxygenation Plan D: Rescue techniques for "can't intubate, can't ventilate" situation Difficult Airway Society Guidelines Flow-chart 2004 (use wit h DAS guidelines paper) Not more than 3 attempts, maintaining: (1) oxygenation with face mask (2) cricoid pressure and (3) anaesthesia Maintain 30N cricoid force Verify tracheal intubation (1) Visual, if possible (2) Capnograph (3) Oesophageal detector "If in doubt, take it out" Postpone surgery and awaken patient if possible or continue anaesthesia with LMATM or ProSeal LMATM - if condition immediately life-threatening Plan C: Maintenance of oxygenation, ventilation, postponement of surgery and awakening succeed succeed succeed http://www.das.uk.com 7. Neutral position 8. Hyperextension 9. Hyperflexion 10. Morbidly Obese - Intubation Morbidly obese patient, head on one pillow (Anesthesia for Obstetrics, 3rd Ed, Sol M Shnider) 11. Same patient with shoulders and occiput elevated - can now assume the sniffing the morning air position (Anesthesia for Obstetrics, 3rd Ed, Sol M Shnider) Morbidly Obese - Intubation 12. Incidence of cervical injury Between 1 and 3% of pts admitted with blunt trauma have a cervical fracture 20% are missed on lateral C/Spine 7% missed on trauma series Baltimore Shock Trauma Database SCIWORA Ligamentous injury, esp transverse ligament of dens, < 1:1000 incidence 13. No neurological sequelae 14. Anaesthetic implications Cervical spine is either definitively cleared or it is not If intubation or surgery is urgent then by definition the neck is not clear Treat as if unstable cervical spine No well documented case of new spinal cord injury after properly conducted trauma intubation Large forces required to cause damage 15. Approach Neutral position, remove collar Manual in-line stabilisation Pre-oxygenate Drugs: thiopentone or (careful) propofol NMBAs: suxamethonium or rocuronium Sugammadex available if using aminosteroids Place of videolaryngoscopy Magrath Mac or Storz C-MAC [choice of Mac and D blades] 16. Are nasal tubes an option? 17. The facts 3 reported cases of nasocranial intubation 2 uncontrolled tubes in acute trauma Horellou et al, Anaesthesia, 1978, 33:73 Marlow et al, J Emerg Med, 1997, 15:187 1 routine neonatal intubation Cameron, Arch Dis Child, 1993, 69:79 Inexperienced operators, unusual circumstances 18. Planned maxillofacial surgery? Goodisson, Shaw and Snape, Intracranial intubation in patients with maxillofacial injuries associated with base of skull fractures, J Trauma, 2001, 50:363 Nasotracheal tubes are safe in absence of midline anterior skull base fracture Even in these, gentle intubation over a bronchoscope or bougie is safe in skilled hands Tracheostomy rarely required 19. (Awake) Blind nasal intubation (Awake) Fibreoptic intubation Retrograde intubation Emergency or elective surgical airway Other options? 20. Guiding ETT into the nasopharynx Do not use force (firm but gentle pressure) Cephalad distraction of the tube Rotation / Malleable introducers Suction catheter brought out of the mouth 21. Retrograde intubation 22. ILMA 1 ILMA (Fastrach)Easy insertionNo neck movementTube insertion easyAirway protected by cuffed ETT 23. Principles of airway management 1. Secure definitive airway 2. Avoid hypoxia and hypotension 3. Avoid hypertensive response to laryngoscopy 4. Basically, just keep the BP where it is, okay (+/- 10%) 24. Preparation Assessment, plans A,B,C,D Some degree of hypertension is normal physiological autoregulation Hypotension = brain ischaemia Arterial line pre-induction if possible 25. Rebleeding Unsecured aneurysms: 4% rebleed on day 0 then 1.5%/day for next 13 days [ 27% for 2 weeks] Not on my shift . Be ready to actively manage hypotension AND hypertension SNP infusion, esmolol Nimodipine Noradrenaline infusion 26. BP in unsecured aneurysms 27. Choice of drugs for intubation Pretreatment lignocaine IV or tracheal? Opioids fentanyl, or remifentanil infusion Induction agent thiopentone or propofol or ketamine Ketamine??? Are you serious?? Neuromuscular blocker sux vs aminosteroid Subsequent sedation drugs that will wear off Neurological examination Propofol, remifentanil 28. Lignocaine pretreatment Controversial used to prevent BP and ICP rises due to coughing and straining. Contradictory evidence for neuroprotection in cardiac surgery Some evidence for neuroprotection in decompression illness Do the risks outweight the benefits? 29. Lignocaine in cardiac surgery 30. Answer: dont know Pro argument: Probably safe and possibly beneficial Con argument: Evidence of hypotension lasting several minutes Time-course to effect 1.5 2.0 mg/kg probably insufficient anyway Lignocaine for neuroprotection in TBI and SAH 31. Ketamine and ICP Small series from 1970s suggest elevated ICP More recent data contradicts this Weak evidence of neuroprotection But thiopentone and propofol have clear evidence of neuroprotection 32. Harm from oversedation Neuroemergency patients are best managed with minimal sedation allowing clinical examination After immediate resuscitation and stabilisation phase complete Midazolam and esp Morphazolam or Fentazolam saturate fat stores and have very long elimination times Adverse neurosychological effects of BZDs Propofol and remifentanil unique with extrahepatic clearance and short T1/2cs 33. Summary Airway management in neuroemergencies 1.Dont panic 2.Proper assessment right time, right place, right people? 3.No clear indication for neuroprotectants 4.Maintain cerebral perfusion and keep BP close to baseline 5.Do what you are good at. 34. [email protected] Questions ?