unit 2 bird mark 7 Flashcards
Limited variable
A limit variable implies that during inspiration, a certain present value is reached and maintain until the end of inspiration
How is breath initiated in bird mark 7
The ventilator senses the patients inspiratory
Effort or sub- ambient
Cycle variable
A cycle variable describes how inspiration ends and exhalation begins and include pressure, flow, volume, or time
Pressure chamber
It on the right side of the ventilator
Has exhalation valve drive
Also has ventilator outlet
Ambient chamber
Large plastic chamber on the left
And also has gas inlet and cinder brass filter
Permanent magnet ambient chamber magnet and pressure chamber magnet function is ?
Their function is to control pressure for gas delivery and sensitivity
Sensitivity purpose
Determine the inspiratory effort require to initiate inspiration
How sensitivity works
Utilizes two opposing forces and magnetic attraction and gas pressure
Movement of vernier arm does what?
Increases or decrease magnetics attraction between clutch plate and magnet
If magnet is closed more pressure generated by patient to slide ceramic switch
If magnet far away and less pressure needed
Flow rate
Determines the inspiratory flow from the ventilator
Reduces 50 psi to safe level
And as the bigger opening the more higher flow
Air mix control
Purpose to determines pathway gas flow takes through ventilator
Functionally determines fio2 is less then or at 1.00
Also determines flow pattern square and semi-sinusoidal
Venturi operation
As pressure in chamber increases fio2 increases and back pressure decrease ambient air entrainment
At 12 cm h2o sufficient pressure chamber to close complete
End result is fio2 is around 65-90%
Flow depends upon how much air entreament
Flow is greatest early inspiration
Flow taper during late inspiration
Expiratory timer apnea control
Will initiate inspiratory for apneic patient in absense
Of inspiratory effort
Can cause a synchrony
Works using a controlled leak
Activation of apnea control opens needle valve causing leak gas from apnea cartilage into the pressure chamber
As gas leaks from cartridge a leveler arm pushes against the clutch plate on the ambient side, initiating inspiration by opening the ceramic switch
Respiratory rate determines by how fast gas leak from cartridge
Pressure control
Sets the pressure at which the ventilator will terminate inspiration
Typically inspiratory pressure from 12-30 cm h2o
operation of pressure control
movement of control determines the position of permanent magnet in relation to a metal clutch attached to a ceramic switch
if magnet is close to clutch plate the magnetic attraction is high and vice versa
when gas pressure builds up in pressure chamber which is transmitted to diaphragm which is also attached to the ceramic switch and when gas pressure attempts to push the diaphragm toward the ambient chamber then ventilator terminates breath
when the venturi completely closes the
gas flow is through nebulizer drive line and nebulizer is poet by source gas and after that Venturi closes the ventilator is gives pure 100% oxygen
air mix operation flow and flow pattern
flow ranges from 0 - 80 L/min
The flow patter is pseudo-sinussoidal
flow is high early during inspiration and tapers during the inspiratory phase
this corresponds to the change in air entrapment as back pressure increase and flow through venturi decreases
source gas flows and flow pattern
flow is from 0-50 L/min
the flow pattern is square or rectangular and flow is constant
purpose of negative pressure control on mark 8
it is used for negative end expiratory pressure
and also positive end expiratory pressure
operation of negative pressure control
functionally the control is a needle valve:
bleeds gas from the timing cat ridge which is pressurized during inspiration and is driven by separate 1/8 inch drive line
as the opening is large the flow is high and time of operation is limited to the capacity of timing cartridge which is kind small
