ventilators Flashcards
how is the servo 900 ventilator driven and controlled?
pneumatically driven
electronically controlled
give examples of flow generator ventilators…
Penlon Nuffield 200 or oxylog 1000
which ventilator uses a minute volume divider? how does this work?
Manley
FGF is split between 2 bellows
larger bellow empties into patient during inspiration to give TV
(during this time the smaller bellow is filling)
during expiration, the smaller bellow fills into the larger bellow (also fills with more FGF from ventilator)
once the small bellow is full - expiration begins - hence small bellow determines RR
what is meant by method of cycling?
This is the parameter that determines when inspiration switches to expiration. most ventilators are time cycled. After a certain time has elapsed in inspiration, expiration begins.
older methods used volume/ pressure cycling. i.e. once a certain volume had been delivered in inspiration, expiration would start.
how do modern ventilator functioning differ from old fashioned ones?
modern - uses electronically controlled pistons and bellows
old ones - pneumatically controlled valves and bellows e.g. bag in a bottle ventilator and minute volume divider.
what is the difference between BiPAP/ BPAP and BIPAP?
BiPAP/ BPAP - bilevel positive pressure ventilation, non invasive ventilation, 2 levels of pressure one for inspiration and one for expiration. for COPD/ HF
BIPAP - bi PHASIC positive pressure ventilation, invasive ventilation. 2 levels of pressure and spontaneous ventilation is encouraged throughout each level. for ARDS.
what is meant by a closed loop system?
Ultimate ventilator would take in info about patients respiratory efforts, flows, tidal volumes, airway pressures, oxygenation and CO2 removal to set the most appropriate setting. This will adapt to suit the patient in real time
what is control mandatory ventilation and assist mandatory ventilation?
CMV - complete replacement of breathing e.g. IPPV
AMV - patients respiratory efforts trigger support - PSV
what does the trigger mean on PSV?
the amount of flow the patient has to generate for ventilator to detect and trigger and then pressure to be delivered by ventilator
e.g. 1L/min - more sensitive than if set at 4L/min
what is VC -AF mode on ventilator?
volume is set and achieved
however flow is regulated to achieve this slowly to reduce pressures.
flow pattern isnt square like in VC
less barotrauma.
what is pendelluft?
transient gas flows at the end of inspiration.
this occurs because different lung units take different times to fill.
hence at end of inspiration, if there is a pause, it gives time for the gas to fill these additional alveoli/ conducting airways, pressure will as a result drop (volume is spread over a larger space)
what is P plataeu pressure? how does this differ from PIP in healthy individuals and as TV increases?
the pressure after air has distributed after an inspiratory pause (due to pendelluft)
In healthy individuals the difference between PIP and Pplat is small and as TV increases, the difference should increase proportionally.
how is Pplat/ PIP used in diagnosis of airway disease?
The difference between Pplat and PIP can be used for diagnosis of lung disease.
In conditions with increased airway resistance (e.g. bronchospasm), an increase in PIP is seen without an increase in Pplat.
Conversely, in conditions that give decreased pulmonary compliance (e.g. pulmonary oedema, pleural effusions and ascities) both PIP and Pplat increase proportionally
what is the safe limit for P plat in ventilation?
should not go above 30cmH20 pressure
what ventilators are found in emergency setting?
manual bag mask valve device
oxylog
jet ventilators
pneumatically driven and portable - manley/ nuffield
VR1
ParaPAC
VentiPac
