Tuesday, February 24, 2009

What the heck is P0.1?

Airway Occlusion Pressure at 0.1 Second (P0.1)

P0.1 demonstrated, however it must be quantified due to the rapid occlusion (100 milliseconds).

P0.1 is the maximal slope of the airway pressure drop during the first 0.1 second when the airway is occluded.
Known as a mechanical index of respiratory drive it correlates with the patient workload of inspiration.

May be useful in appropriately setting:
  • Trigger sensitivity.
  • Flow.
  • Rise time.
  • Drive pressure.
  • Amount of pressure support.
P0.1 is measured in cmH2O:
  • -1 to -2 cmH2O, low range, normal
  • -4 to -5 cmH2O, large effort
  • < -6 cmH2O, excessive workload and/or high central drive. 
Low P0.1
Associated with a low level of muscular inspiratory activity, which is good in patients with no respiratory disease or damage in the central nervous system in relation to the respiratory muscles. 
A low P0.1 may also due to respiratory center depression:
  • Sedation.
  • Drug overdose.
  • Sleep cycles.
  • Brain trauma.
note- Evaluate additional parameters to assess if P0.1 shows comfort versus respiratory system depression or muscle dysfunction (e.g. sedation scales). 
Elevated P0.1 Values
May indicate inadequate trigger sensitivity and/or ventilator support.
Associated with a higher risk of fatigue or failure during spontaneous breathing trials.