ventilators tuesday, 20 april 2004 bill mcculloch
TRANSCRIPT
![Page 1: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/1.jpg)
Ventilators
Tuesday, 20 April 2004
Bill McCulloch
![Page 2: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/2.jpg)
Types of Ventilator
Positive Pressure Ventilators Gas blown into lungs All Current Itu and Theatre Ventilators Unphysiological but practical
Negative Pressure Ventilators “Iron Lung” Cuirass (breastplate) ventilators Physiological but impractical
![Page 3: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/3.jpg)
History
Need arose from polio epidemics in 1950s and changes in anaesthetic techniques (muscle relaxants)Originally engineering challengeInflexible
![Page 4: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/4.jpg)
ClassificationMost classifications obsolete but need to be knownBased on cycling
Pressure cycling – cycles when pressure attained in system Compensates for leaks Vt changes with changes in compliance
Volume cycling – cycles when preset volume delivered Doesn’t compensate for leaks Will generally deliver preset volume (unless limit reached)
Time cycling – cycles after given time Unresponsive to leaks or compliance changes
or Inspiratory flow patterns Flow generation
High powered ventilator can deliver constant flow through inspiration – flow rate unaffected by patient characteristics
Pressure generationLow powered ventilator delivering decreasing flow through inspiration
-
![Page 5: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/5.jpg)
Anaesthetic Ventilators
Need to be capable of being attached to anaesthetic machine and scavengingLess sophisticated / flexible than itu ventilatorsNowadays , generally must be usable with circle
![Page 6: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/6.jpg)
Manley Ventilator
Minute Volume dividerVt set by operator. Rate=FGF/VtDriving Force = Fresh Gas Pressure
![Page 7: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/7.jpg)
Penlon Nuffield
Tubing from ventilator plugs into bag port on bain or circleUses “Fluid Logic” (coanda effect) Used in paediatrics (with Newton Valve)
![Page 8: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/8.jpg)
Ohmeda
Bag in bottleDriving gas blown into bottle , compressing bellows (“bag”)Bellows contain anaesthetic gas“Pneumatic bag squeezer” Controlled by electronic management of driving gas.
![Page 9: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/9.jpg)
IMV
Originally , entailed attaching a t-piece onto the inspiratory limb of a ventilatorAllowed patient access to spontaneous breathsPEEP had to be adjusted to be equal in spont & controlled circuits
![Page 10: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/10.jpg)
sIMVAllows imv within the normal breathing circuitBreathing cycle ( which will contain 1 mandatory breath) broken into 3 parts 1. Spontaneous breathing allowed 2. Spontaneous breath will trigger the
mandatory breath 3. If spontaneous breath not taken in 2 ,
mandatory breath delivered
Reduction in sIMV rate not considered useful weaning method
![Page 11: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/11.jpg)
Pressure vs volume control
Generally volume control used to initiate ventilationChanged to pressure control where lungs susceptible to damage by high pressures (ards)Volume delivered under pressure control variable
![Page 12: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/12.jpg)
Pressure Support
System for reducing work of breathingPatient inspiration spontaneous but breathes from pressurised reservoirApplied to any breathing modeGradual reduction of level of pressure support is valid means of weaning
![Page 13: Ventilators Tuesday, 20 April 2004 Bill McCulloch](https://reader036.vdocuments.us/reader036/viewer/2022083006/56649f345503460f94c523fe/html5/thumbnails/13.jpg)
BiLevel (BiPap)
2 levels of peep setPatient can breathe spontaneously at any phase of respirationChange in peep level-> change in volume within lungs