Friday, March 13, 2009

What is t-Low?: APRV terminology

The t-Low sets the time interval for the low pressure/CPAP phase (p-Low).
  • Allows for intermittent release in airway pressure, providing paCO2 removal.
  • Partially unloads the patients work of breathing associated with pure CPAP breathing.
  • The name "t-Low" is used in both Draeger and Hamilton ventilators. 
note- t-Low should not be considered "expiratory time" as the patient may exhale throughout the entire inspiratory phase. 

On the Servo-i ventilator "T-PEEP" is the t-Low setting when using Bi-Vent to mimic APRV.

t-Low on the Draeger, Evita 4 ventilator. 

When using Bi-Level on the PB 840 there is no setting to set the low pressure interval. The operator must change frequency & "TH" to set a t-Low. This can become problematic when trying to precisely set a t-Low interval.