# Calculating Pplateau with HAMILTON-C1/T1/MR1 ventilators

14.07.2017
Author: Simon Franz, Reviewer: Matthias Näf, Thomas Sperling, Kaouther Saihi, Ralph Teuber

Even if the idea of a “safe” plateau pressure is already being questioned, it is still standard of care to use it for tailoring lung-protective ventilation in acute respiratory distress (ARDS) patients1. This gives rise to a common question asked by users of HAMILTON-C1/T1/MR1 ventilators: How can I measure/calculate Pplateau with my device?

Due to the valveless pneumatics in the HAMILTON-C1/T1/MR1 ventilators, it is not possible to obtain the Pplateau by performing an inspiratory hold maneuver.

Nevertheless, Pplateau is still available as a monitoring parameter:

HAMILTON-C1/T1/MR1 SW < v2.2.0 HAMILTON-C1/T1/MR1 SW > v2.2.0
End-inspiratory pressure always displayed as Pplateau.
Please consider that if an end-inspiratory flow is present,
the Pplateau displayed is higher than the actual Pplateau.
Pplateau is only displayed if the end-inspiratory flow is close to zero.
The Pplateau displayed can still be higher than the actual Pplateau.

A possible workaround for calculating Pplateau in situations where the end-inspiratory flow is not close to zero or the pressure measured end-inspiratory seems inaccurate:

• Calculate driving pressure
Driving pressure (P) = VTE/Cstat

• Calculate Pplateau
Pplateau = P + PEEP

This calculation is dependent on an accurate Cstat measurement, which means there is no significant patient effort occurring. Pinsp should be at least ~10cmH20.

Example
VTE: 450ml; Cstat: 50 ml/cm; H20 PEEP: 8cmH20

Pplateau = 17 cmH2O
P = 9 cmH2O

Another benefit is that you get the P as a side product of your calculations. P is strongly associated with survival in ADRS patients and may therefore be the more interesting parameter2 .

Relevant devices: HAMILTON-C1/T1/MR1 (all software versions)

References:

1. Loring, S. H. & Weiss, J. W. (2007). Plateau Pressures in the ARDSnet Protocol: Cause of Injury or Indication of Disease? American Journal of Respiratory and Critical Care Medicine, 176(1), 99b-100.
2. Amato, M. B. P., Meade, M. O., Slutsky, A. S., Brochard, L., Costa, E. L. V., Schoenfeld, D. A., Stewart, T. E., Briel, M., Talmor, D., Mercat, A., Richard, J.-C. M., Carvalho, C. R. R., Brower, R. G. (2015). Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med, 372(8), 747-755.