Back

Bedside tip - How to diagnose and avoid ineffective efforts

Create PDF
08.07.2019
Author: David Grooms, Reviewer: Jean-Michel Arnal

An ineffective effort is defined as a patient effort that is unable to trigger the delivery of a mechanical breath.

​The most common causes are:

  • Trigger threshold set too high
  • Pressure support too high
  • Set frequency and/or inspiratory time too high (in controlled/assisted modes)
  • Tidal volume set too high
  • Presence of AutoPEEP
  • Low respiratory drive
  • Weak inspiratory effort
  • Sedation

 Several waveform characteristics can assist in the diagnosis (see Figure 1):

  • The pressure/time scalar waveform will show a decrease in baseline airway pressure not followed by ventilator support
  • The flow/time scalar waveform will reveal an abrupt change in the steepness of the waveform (decrease in expiratory flow or increase in inspiratory flow not followed by ventilator support)
  • The esophageal pressure/time scalar waveform will display a decrease in pleural pressure not followed by ventilator support
Figure 1: Waveform characteristics indicating an ineffective effort

 

 

 

 

 

 

 

 

 

Resolution

The most practical adjustments that can be made on the ventilator to reduce ineffective efforts are as follows:

  • Minimize AutoPEEP by reducing minute ventilation
  • Reduce pressure support and/or tidal volume
  • Adjust the expiratory trigger sensitivity (ETS) to make it more sensitive to the patient's activity (Figures 2 and 3)
Figure 2: Ineffective effort with ETS set at 25%

 

 

 

 

 

 

 

 

 

 

Figure 3: ETS increased to 50% at the red line, resulting in elimination of ineffective efforts

 

 

 

 

 

 

 

 

 

Related Articles

Ineffective effort, trigger threshold, waveforms, autoPEEP, pressure support, expiratory trigger sensitivity, ETS
Back

Date of Printing: 29.11.2020
Disclaimer:
The content of this newsletter is for informational purposes only and is not intended to be a substitute for professional training or for standard treatment guidelines in your facility. Any recommendations made in this newsletter with respect to clinical practice or the use of specific products, technology or therapies represent the personal opinion of the author only, and may not be considered as official recommendations made by Hamilton Medical AG. Hamilton Medical AG provides no warranty with respect to the information contained in this newsletter and reliance on any part of this information is solely at your own risk.