Transcript Slide 1
The bird IPPB machine • The Bird is pneumatically powered & controlled. • it can be triggered [1] by negative pressure [2] by time or [3] manually. • It is pressure limited, changing the breath as pressures rise • It is pressure or time-cycled off Ambient chamber Sensitivity control Gas inlet From 50 psig Pressure chamber Pressure control Nebulizer drive line Main flow drive line • • • • • A flow rate control B ceramic switch C restricted orifice for entrainment D nebulizer drive line to in-line SVN E exhalation valve [mushroom valve] left This is a simplified picture of the ceramic switch and what makes it move to start or end a breath. On the left side of the screen is the AMBIENT CHAMBER [see the hole toward the outside?] On the right side of the screen see the PRESSURE CHAMBER, [see the outlet going to the patient circuit?] In A you see that the diaphragm is mid-line, the ceramic switch is closed. No air moves In both the AMBIENT CHAMBER and in the PRESSURE CHAMBER, there is no extra pressure, both chambers are at zero [ 1 atmosphere]. There is no gas flow and the ceramic switch is closed. This negative pressure pulls the clutch plate toward the magnet in the PRESSURE CHAMBER & when it gets close enough, the magnet pulls the clutch plate closer. The diaphragm moves toward the patient, to open the ceramic switch. Gas flows into the PRESSURE CHAMBER, into the circuit and into the patient’s lungs. In C, the diaphragm stays toward the magnet As long as the pressure in the PRESSURE CHAMBER is lower Than the magnet force in the AMBIENT CHAMBER …the breath continues We can control how deep a breath the patient takes by altering the positive pressure needed to overcome the magnet that will stop the breath As the patient’s lung fills with gas, the pressure builds up in the lung, then in the circuit and finally in the PRESSURE CHAMBER Once high enough, the positive pressure in the PRESSURE CHAMBER pushed the diaphragm toward the AMBIENT CHAMBER and flow stops--- the breath has stopped. On inspiration ceramic switch is open, gas flows to the patient whose lung fill On exhalation: the ceramic switch is closed, gas stops flowing and the patient exhales into the exhalation valve On inspiration, the gas flows from the top into the Pressure chamber, into the circuit. At the same time, the exhalation valve is closed by the same pressure As long as there is pressure building up in the pressure chamber, the exhalation valve is closed. Gas can move only into the lung On exhalation phase: the pressure drops in the pressure chamber and the exhalation valve is open to the atmosphere so that the patient exhales into the atmosphere The ceramic switch is closed and there Is no gas flow into any chamber. Air mix: entrainment devices During inspiration, 02 from the ceramic switch moves into the line that powers the entrainment device. The flow goes through the restricted orifice decreasing lateral wall pressure in the ambient chamber so that it pulls air from the ambient chamber into the gas flow going to the pressure chamber. What do you suppose happens to the Fi02 and to the total flow down the main flow drive line as the pressure rises inside the pressure chamber?