The Gas Flow Through the Bird Mark 7

The Gas flow through the Bird Mark 7

1. 50 psig connector to the top of the machine

2. gas moves into the area just above the ceramic switch.

3. As the patient inhales and creates a -2 pressure, the diaphragm in the ambient chamber is pulled toward the pressure chamber and the clutch plate is moved closer to the magnet until it is pulled into it-- so that the ceramic switch is pulled open

4. gas flows into the pressure chamber where it goes down the mainstream and the drive lines

5. As the preset PIP is reached in the pressure chamber, the diaphragm is pushed toward the ambient chamber’s magnet till it is captured by the magnet and the ceramic switch is pulled shut.

· The Bird Mark 7 inspiratory phrase can be pressure triggered on, or triggered on manually. If the breath rate knob is set for ventilation, this can even be time triggered on.

· In Air mix mode, it is pressure limited, because as the pressure builds up the flow rate slows down.

· It is pressure cycled off because as the PIP is reached, inspiration ends

The gas flow through the PRII

1. 50 psig connector to the back of the machine

2. Gas enters the top of the drum where it is measured on the CONTROL MONOMETER

3. the resting state of the drum is to be closed, because it has a counter-weight that is set off to the side.

4. to open the drum, initiates a breath. The drum is attached to a vane that is very close to the opening to area above the drum. Only a tiny bit of negative pressure will pull this vane toward the opening

5. the patient creates a negative pressure that will pull the vane attached to the drum just enough that the gas starts to flow from above. This flow forces the vane all the way open, the drum is rotated open and the gas fills the circuit and the drive lines to the SBN and to the mushroom valve. The breath has started

6. the SYSTEM PRESSURE MONOMETER measures the pressure below the drum which is also the circuit pressure.

7. As the gas leaves the area above the drum to enter the circuit, the control monometer’s pressure drops and the system pressure monometer rises. As the pressure gradient gets smaller, the flow rate slows down.

8. Once the flow rate is less than 1-3 lpm, the drum rolls shut as gravity takes over.

· The PR II’s inspiratory phase is pressure-triggered, and can be triggered manually by tugging on the knob on the drum, if the machine has the breath rate turned on for ventilation it can be time triggered on.

· In the air-mix mode, it is pressure-limited because as the pressure increases the flow decreases. It has a descending pressure curve

· It is flow cycled off because the rise in pressure drops the inspiratory flow to less than 1-3 lpm and the drum cannot stay open