How do Hamilton Medical ventilators monitor P0.1

Author: Clinical Experts Group, Hamilton Medical, Reviewer: N/A

P0.1 is a parameter mainly known as a mechanical index of respiratory drive.

P0.1 corresponds to the drop in Paw, observed during the first 100 ms of an inspiratory effort made against the occluded airway opening.

Current ICU ventilators maximize freedom for the patient. A fast response compensates pressure drops before 100 ms, especially when the inspiratory valves remain open to guarantee free breathing at any time (biphasic concept).

  • No occlusion
  • Pressure is compensated before the first 100 ms








How can P0.1 be monitored without an occlusion maneuver?

The ventilator calculates the steepest tangent of the drop in the pressure curve during an inspiratory effort.

This is shown in the graphic as a white triangle, and describes the minimum gradient of ∆t/∆P. 





Once the minimum gradient is calculated, the value P0.1 is the extrapolation to 100 ms after pressure drops below PEEP.

Shown in the graphic as a triangle with white dotted lines, P0.1 is the pressure drop below PEEP.

In this example:
P01 = Paw (100 ms) - PEEP = -9 cmH2O




P0.1 is monitored breath-by-breath, regardless of whether flow- or pressure-triggered (HAMILTON-G5/S1 pressure trigger only). 

Relevant devices: All


Brenner, M., et al. (1990). "A New Method for Measurement of Airway Occlusion Pressure." Chest 98(2): 421-427.

P0.1, respiratory drive, pressure drop, compensation, occlusion

Date of Printing: 15.04.2021
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