What type of asynchrony can you see? #2

07.06.2022
Author: Jorge Correia Crespo, Reviewer: Munir Karjaghli, Thomas Reimer

Is this a) a flow asynchrony, b) an ineffective effort, c) early cycling, or c) auto-triggering?

(1) Decrease in expiratory flow or increase in inspiratory flow; (2) Ventilatory support not delivered

Answer: Ineffective effort 

The patient’s effort fails to trigger the ventilator. This is indicated on the flow waveform by an abrupt change in the steepness of the waveform (1) (a decrease in expiratory flow or an increase in inspiratory flow) that is not followed by ventilatory support (2).

How to recognize it:

Expiratory flow does not decelerate straight down to 0 l/min, but shows a positive deflection instead.

Depending on when the effort starts, it is also possible that the patient does not achieve positive flow values and stays in the negative range. 72% of health care professionals that we surveyed use waveform analysis to monitor and recognize asynchronies1. See the list of possible causes and solutions below.

Common possible causes:

  • Trigger threshold set too high
  • Pressure support too high
  • Set frequency and/or inspiratory time too high (in controlled modes)
  • Tidal volume set too high
  • Presence of Auto-PEEP
  • Low respiratory drive
  • Weak inspiratory efforts (maybe due to a low respiratory drive and/or sedation)
  • Sedation

Solution:

Evaluate the patient’s respiratory drive and correct as needed. Assess the patient for over-sedation and reduce the rate of sedative infusion. Determine whether the patient is receiving too much assistance; adjust pressure-support ventilation to reduce tidal volume if necessary.

Reference: Result of internal survey conducted online from May 27 - June 23, 2019 with 155 voluntary participants worldwide (respiratory therapists, physicians, nurses, biomed/technician/engineer, paramedics, other). 

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Date of Printing: 30.06.2022
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.
Date of Printing: 30.06.2022
Disclaimer:
The content of this Knowledge Base is intended for informational purposes only. Medin Medical AG provides no warranty with respect to the information contained in this Knowledge Base and reliance on any part of this information is solely at your own risk. For detailed instructions on operating your Medin Medical device, please refer to the official Medin Medical Operator’s Manual for the respective device.