Ventilatory Support Hypoxaemic - (2a) Flashcards
What is hypoxaemic respiratory failure?
Inadequate transfer of 02 into blood, inadequate 02 transport, Extraction/utilisation problems
What can cause Inadequate transfer of 02 into blood?
Problems with perfusion. - eg emboli
Inadequate fresh air reaching gas exchange area
Reduced SA for gas exchange
Diffusion problems
What could cause inadequate O2 transport?
Hb
Inadequate circulation
What is a diffusion problem?
Gas is going in but can’t diffuse across into capillaries
What needs to be resolved to increase PaO2?
Increased diffusion
Or Increased surface area (FRC
Medical treatments to increase diffusion
Oxygen therapy ( To Increase F1O2, Increased PastmosO2 -(atmospheric pressure))
What are medical methods to increase surface area (FRC)?
PEEP
CPAP
What can a ventilator deliver? What can be done if that is not high enough?
F1O2 0.21 - 1.0
For patients requiring high F102, its more appropriate to use strategies such as high PEEP or other support modalities if available ( eg HFOV, NO, ECMO)
What could a hyperbaric oxygen chamber be used for
The bends
Elite athletes
Severe wounds
What is a normal dose of PEEP?
5-7.5 cm
If gas diffusion problem, up to 15 cm PEEP.
What is CPAP?
Continuous positive airway pressure
Pressure positive at the mouth during both inspiration and expiration
Used for spontaneous breaths
What is PEEP?
Positive end expiratory pressure
Pressure may be negative during inspiration
Usually used in relation to ventilator breaths
What are the three things that can be supported when breathing?
Volume
Flow
Pressure
What is different about the pressure graph for CPAP?
Don’t come back down to atmospheric pressure. Come back to whatever has been dialled in.
What does positive airway pressure on expiration do?
Reduces alveolar emptying which increases alveolar size (inc. FRC) thus increasing gas exchange surface area
Re expand collapsed alveoli (recruitment) therefor increases number of alveoli participating in gas exchange
