The Severe Asthmatic: Intubation, Mechanical Ventilation, and Complications

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September 10, 2012 by EmerJencyWEBB

THIS great narrative from Emergency Medicine News lead to a morning reading from the literature about intubation, mechanical ventilation, and complications associated with the severe asthmatic.  I found two great papers on the topic with links below.

Brenner B, et al.  Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure.  PATS.  2009. Volume 6.  371-379.

Medoff, BD.  Invasive and Noninvasive Ventilation in Patients With Asthma.  Respiratory Care.  June 2008.  Vol. 53.  No. 6.  p 740-750

What follows are some pearls gathered from the above texts.

CONSIDER PRE-TREATMENT

  • glycopyrolate, atropine, lidocaine, albuterol have all been studied to blunt bronchospasm initiated by intubation.
  • lidocaine dose 1.5mg/kg, 3 minutes before intubation.
  • THIS STUDY showed superiority of 4 puffs albuterol to IV lidocaine for pre-treatment

OTHER PRE-INTUBATION THOUGHTS

  • IVF bolus
  • Pick out the largest bore endotracheal tube you think will go in.  The key is to reduce airway resistance.

INTUBATION PEARLS

  • Method of choice is RSI
  • Induction Agents:  Consider Ketamine (1.5-2mg/kg IBW IV, hypotensive/normotensive patient) or Propofol (hypertensive patient, 2mg/kg IV over 2 minutes) as both have bronchodilatory effect.
  • Paralytics: Succinylcholine or Rocuronium (theoretical histamine release associated with sux has not been proven to be detrimental in clinical setting, however if the patient is hyperkalemic prior to intubation, use caution)

MECHANICAL VENTILATION

  • Set up post-intubation therapy/mechanical ventilation strategy to reduce hyperinflation, as these patients are prone to develop
  • If you have to choose, pick hypercapnia over hyperinflation

Know initial ventilator settings:

Brenner B, et al.  Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure.  PATS.  2009. Volume 6.  371-379.

Medoff, BD.  Invasive and Noninvasive Ventilation in Patients With Asthma.  Respiratory Care.  June 2008.  Vol. 53.  No. 6.  p 740-750

Recognize air-trapping on the ventilator waveform:

http://emedicine.medscape.com/article/305120-overview#a1

Know how to estimate lung hyperinflation using the vent:

In common practice 2 relatively easy-to-measure pressures are used as surrogate markers of lung inflation: auto-PEEP and plateau pressure (Pplat). Auto-PEEP is an estimate of the lowest average alveolar pressure achieved during the respira- tory cycle. It is obtained by measuring airway-opening pressure during an end-expiratory hold maneuver. The presence of expiratory gas flow at the beginning of inspiration (which can be detected by means of auscultation or flow tracings) also suggests auto-PEEP. Auto-PEEP can underestimate the sever- ity of hyperinflation when there is poor communication between the alveoli and the airway opening (35).

Pplat (or lung distension pressure) estimates average end- inspiratory alveolar pressure. Pplat is affected by the entire respiratory system, including lung parenchyma, the chest wall, and the abdomen. It is determined by temporarily stopping flow at end-inspiration during a single delivered breath.

Brenner B, et al.  Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure.  PATS.  2009. Volume 6.  371-379.

Initiate Sedation/Short Term Paralysis 

  • Key for patient-ventilator synchrony
  • Consider benzodiazepine/fentanyl combination
  • Propofol may also be useful, but know complications of extended use
  • Long term paralysis (>24 hrs) not recommended, due to myopathy, decreased weaning from vent.

Be ready for post-intubation complications:


Brenner B, et al.  Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure.  PATS.  2009. Volume 6.  371-379.

Another great algorithm, putting it all together:

Medoff, BD.  Invasive and Noninvasive Ventilation in Patients With Asthma.  Respiratory Care.  June 2008.  Vol. 53.  No. 6.  p 740-750

 

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