2.9 Ventilation Modes: “Alphabet Soup”
One of the toughest challenges when explaining modes of ventilation is the terminology and the common practice of using acronyms to describe modes and parameters. When it comes to the mode of ventilation used, it can often feel like you are reading random letters from a bowl of alphabet soup!
Where things become really complicated is that every company that manufactures ventilators has slightly different names for all of their modes. When a mode is created, the manufacturer patents the specific name used. Once the patent allows for another company to utilize the intellectual principle used in that mode, other manufacturers create their own version of the mode with a slightly different name. This results in the same mode having sometimes upwards of 5 or 6 different names. For example, Volume Control can be VC, VCV, ACVC, or CMV-VC—just to name a few of the countless variations.
Try to look past the alphabet soup and identify the mode by what parameters are being set. Most modes use the same principles in their breath delivery. Examine the settings that a practitioner would set, and then classify the type of mode you are working with:
- Is the mode control or spontaneous?
- If the mode is control, is it pressure control or volume control?
Don’t worry if that sounds difficult—you’re about to learn more about how to develop this skill. If you can identify the mode accurately, short-forms and acronyms won’t confuse or overwhelm you. You can then apply the general knowledge from this book to any mode of ventilation you are exposed to—even adjunct or special modes not covered in this book—and have a better grasp of how to use it.
Ten maxims for understanding ventilation modes have been described. These maxims may help put some order in the alphabet soup described above.
| The 10 Maxims for Understanding Ventilation Modes Classification | |
| 1. | A breath is described as one cycle of inspiration and expiration. With inspiratory time describing the interval from when airflow begins to move into the lungs, to when airflow changes direction at the start of expiration. |
| 2. | A breath is assisted if the ventilator provides some or all the work |
| 3. | The ventilator provides assisted breaths by using either volume control (VC) or pressure control (PC), based on the equation of motion. |
| 4. | Breaths are classified based on phase variables (trigger and cycle) |
| 5. | Trigger and cycle variables can be either patient or ventilator initiated |
| 6. | Breaths are classified as mandatory or spontaneous based on phase variables |
| 7. | There are three basic breath sequences: continuous mandatory ventilation (CMV), intermittent mandatory ventilation (IMV) and continuous spontaneous ventilation (CSV). |
| 8. | There are five basic ventilatory patterns: VC-CMV, VC-IMV, PC-CMV, PC-IMV, and PC-CSV. |
| 9. | Within each ventilatory pattern there are several types that can be distinguished by their targeting schemes (example: dual, Servo, adaptive) |
| 10. | A mode of ventilation is classified according to its control variable, breath sequence and targeting scheme. |
| Data Source: Chatburn et al., 2014. | |
“Ventilation Modes: ‘Alphabet Soup'” from Basic Principles of Mechanical Ventilation by Melody Bishop, © Sault College is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
