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Airway management and Mechanical Ventilation
- 1. Airway Management and Mechanical Ventilation John Angelo Perez St. Luke’s Medical Center International Institute of Neurosciences October 21, 2015
- 2. Management of ICP is multi-modal Increased ICP Head Positioning Osmotherapy Sedation and Analgesia Seizure Control Hypothermia BP Control Ventilation
- 3. Questions for today • What makes neurologic patients special? Some considerations • What are the steps for intubation? Intubation as a life-saving intervention • What is the role of ventilation in neurocritical care? Ventilation in the NCCU
- 4. Part 1: Some considerations What makes neuro patients special?
- 5. More patients require intubation in the NCCU Bhardwaj and Mirski. Handbook of Neurocritical Care 2nd Ed. 2011
- 6. The airway is divided into parts Butterworth et al. Morgan and Mikhail's Clinical Anesthesiology 5th Edition. 2013
- 7. Cranial nerves supply the airway Butterworth et al. 2013
- 8. Conditions Requiring Intubation • Strokes • TBI • Status epilepticus • Encephalopathies • CNS Infections • Hydrocephalus • Cerebral Edema • Neuromuscular disorders Bhardwaj and Mirski. Handbook of Neurocritical Care 2nd Ed. 2011
- 9. Three principles guide intubation Failure to Protect or Maintain Airway Failure to Oxygenate or Ventilate Anticipate a deteriorating course
- 10. Conditions Requiring Intubation • Strokes • TBI • Status epilepticus • Encephalopathies • CNS Infections • Hydrocephalus • Cerebral Edema • Neuromuscular disorders Failure to Protect or Maintain Airway Failure to Oxygenate or Ventilate Anticipate a deteriorating course
- 11. Part 2: A life-saving intervention
- 14. PLAN: use LEMON to evaluate difficult airways L – Look! E – Evaluate the 3-3-2 rule M – Mallampati Score O - Obstructions N – Neck mobility
- 16. Butterworth et al. 2013
- 17. POSITION: Extend the neck to align the oro-pharyngo-tracheal axis
- 18. PRE-OXYGENATE: An ill patient has 6 minutes to be intubated Torbey, Michael. Neurocritical Care. 2010
- 19. PREPARE: Keep everything within reach
- 20. Patients must intubated within 60 seconds
- 23. PARALYZE: three classes of drugs are used in RSI
- 25. Part 3: Ventilation in the NCCU
- 26. Hyperventilation
- 28. Hypocapnea decreases CBF 30 Butterworth et al. . 2013
- 29. Decreased CBF decreases ICP Hyperventilation
- 30. How long? How fast? How deep? Which diseases?
- 31. Secondary infarction is the most important complication of hyperventilation Normal: 50mL/100g/min Stochetti et al. Hyperventilation in Head Injury: A Review. Chest 2012
- 33. The meta-analysis did not find sufficient evidence of improved outcomes
- 34. What have we learned today? Failure to Protect or Maintain Airway Failure to Oxygenate or Ventilate Anticipate a deteriorating course Increased ICP Head Positioning Osmotherapy Sedation and Analgesia Seizure ControlHypothermia BP Control Ventilation
- 35. Questions? Failure to Protect or Maintain Airway Failure to Oxygenate or Ventilate Anticipate a deteriorating course Increased ICP Head Positioning Osmotherapy Sedation and Analgesia Seizure ControlHypothermia BP Control Ventilation
Editor's Notes
- Setting the big picture of this talk. There many several strategies in the management of increased intracranial pressure (ICP). Each deserves their own talk, but for today, we will talk about ventilation.
- Some questions that we will answer today. This will also serve as our outline.
- In a general medical ICU, 25% of patients need intubation. In a neuro ICU, up to 85% need intubation
- Neurologic insults impair cranial nerve function. Tendency of the tongue to occlude Dysregulation of ventilatory drive Paralysis Loss of reflexes Impaired swallowing Prophylactic intubation, if unintubated and neuro status does not improve within 24-72h, may intubate
- Many neurologic etiologies may require intubation.
- A physician is guided by these 3 general problems and applies clinical judgment to determine if a patient needs intubation.
- All these conditions can simply be grouped into these 3 general criteria.
- Once we have determined the need to intubate, what do we do?
- Should there be a need for intubation, Rapid Sequence Intubation (RSI) is an algorithm we can follow. There are many intubation algorithms (Crash Airway, Failed Airway, Awake Intubation), but RSI has the highest success rate of up to 90% in experienced operators.
- The 3-3-2 rule. Three fingers should fit the mouth, 3 fingers between the mentum and the hyoid bone (hyomental distance) and 2 fingers should fit between the thyroid notch and the hyoid bone (thyrohyoid distance).
- In neurologic patients, since their cranial nerves are impaired, we see a lot of Class III-IV patients.
- The Three-Axis theory of airway management. Extending the neck aligns all 3 axes to visualize the airway and facilitate oxygenation.
- “Moderately ill” patients have up to 6 minutes to be intubated.
- These medications are given during RSI. Premedication agents are used to minimize the side-effects of instrumentation. Induction agents are used to sedate the patient, while muscle relaxants are used to prevent ventilator asynchrony.
- Hyperventilate!
- As minute ventilation increases, CO2 is blown off. This results in deliberate hypocapnea.
- Hypocapnea in turn reduces cerebral blood flow since CO2 is a potent vasodilator. Less CO2, less dilation. Less dilation, less blood flow. The reported therapeutic range is 25-30mmHg.
- Therefore, hyperventilation, through vasocontriction, can decrease ICP. However, this effect is only temporary, ranging from 10-20 hours. Hyperventilation is only used as a temporizing measure for some other more definite intervention.
- The details of hyperventilation are still being debated. Unfortunately, there are have been no RCTs to date that analyze each of these variables. For now, only hyperventilation in trauma has only been studied.
- The most important hurdle to the use of therapeutic hyperventilation is the risk of secondary infarction.
- Roberts and Schierhout found no evidence for improved outcomes in TBI. Evidence is so scarce that a meta-analysis has only found 1 RCT studying 77 patients. However, the meta-analysis is inconclusive as it only evaluated one RCT. More research needs to be done in order to investigate hyperventilation further.