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8.3 – Ventilator

Medical Ventilators

Figure 8.3.1 An image of a Nellcor Puritan Bennett 760

Terminology:

  • Ventilation is movement of air in and out of lungs and is pulmonary specific
  • Respiration is wider context of breathing, or combination of respiratory and cardiovascular system for gas exchange.

Types of Ventilators:

  • Positive pressure ventilator: create pressure gradient by adding positive pressure to airway.
  • Negative pressure ventilator: expose the surface of the chest wall to sub-atmospheric pressure during inspiration; The expiration occurs when the pressure around the chest wall becomes atmospheric
  • Fluidic ventilators
  • Pediatric ventilators
8.3.2 The top row schematics shows positive (left side) and negative (right side) pressure ventilator. The bottom row shows two images of a negative pressure medical ventilators from Hayek Medical (https://hayekmedical.com/)

Positive ventilator (CC BY-SA 4.0 DEED)

8.3.3 This schematic shows a positive medical ventilator is connected to a patient. Also this schematic labeling six different parts of a medical ventilation system.

 

Closed Positive ventilator (CC0 1.0 DEED)

https://commons.m.wikimedia.org/w/index.php?search=ventilator&title=Special:MediaSearch&type=image

8.3.4 An animated diagram illustrating a simplified schematic of a closed-system ventilator (also known as respirator) where a CO2 filter recycles air to reduce waste and an outflow valve controlled by the ventilator releases pressure that builds up as more and more fresh air is added to the closed system. The fresh gas flow is an optimized mix so they can control the oxygen ratio, eliminate particulates, etc. This type usually used in our anesthesia ventilator because the anesthesia gas is expensive, so all the gases (air, oxygen, anesthesia gas, etc.) are kept constrained in the tubing and re-breathed.

 

Modes of Ventilators:

  • Negative end-expiratory pressure (NEEP): it is a sub-atmospheric pressure that develops at the airway at the end of expiration.
  • Positive end-expiratory pressure (PEEP): it is a pressure applied at the end of expiration to maintain alveolar recruitment. The airway pressure is kept positive and is not allowed to return to the atmospheric pressure.
  • Continuous positive airway pressure (CPAP): it is a positive pressure applied to the airway in inspiration and expiration.
  • Continuous-flow ventilation (CFV): it is a constant flow ventilation and maintains normal gas exchange.

 

Attributes

  • Figure 8.3.1: An image of a Nellcor Puritan Bennett 760. Credit to S. Ghoreyshi, licensed under CC BY 4.0

License

Icon for the Creative Commons Attribution-NonCommercial 4.0 International License

Biomedical Instrument Troubleshooting Copyright © by Brendan Chapman, Soheil Ghoreyshi, Centennial College is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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