3100B Theory of Operation and Controls

SensorMedics 3100B

Electrically powered, electronically controlled piston-diaphragm oscillator

Paw of 5 - 55 cmH2O Pressure Amplitude from

8 - 130 cmH2O Frequency of 3 - 15 Hz % Inspiratory Time 30% -

50% Flow rates from 0 - 60

LPM

Paw is created by a continuous bias flow of gas past the resistance (inflation) of the balloon on the mean airway pressure control valve.

To pressurize the patient circuit, the Reset / Power Fail button must be pressed and held until the mean airway pressure is at least 5 cmH2O

Oxygenation

The Paw is used to inflate the lung and optimize the alveolar surface area for gas exchange.

Paw = Lung Volume

Primary control of CO2 is by the stroke volume produced by the Power Setting.

Alveolar ventilation during CMV is defined as:

F x Vt Alveolar Ventilation during HFV is defined as:

F x Vt 2

Therefore, changes in volume delivery (as a function of Delta-P, Freq., or % Insp. Time) have the most significant affect on CO2 elimination

Ventilation

The % Inspiratory Time also controls the time for movement of the piston, and therefore can assist with CO2 elimination.

Increasing % Inspiratory Time will also affect lung recruitment by increasing delivered Paw.

Secondary control of PaCO2 is the set Frequency.

Frequency controls the time allowed (distance) for the piston to move. Therefore, the lower the frequency , the greater the volume displaced, and the higher the frequency , the smaller the volume displaced.

Piston Centering is automatically regulated by the instrument and requires no operator intervention.

The Start / Stop button is used to start and stop the oscillator. The oscillator may be stopped without a complete loss of mean airway pressure.

Alarms

Preset High and Low mean airway pressure alarms.

Upon activation the oscillator will stop and the circuit pressure will vent to ambient.

Activation of the high mean pressure alarm will trigger the Auto Limit System.

The Auto Limit System will open the “blue” limit valve on the circuit and vent pressure.

The valve will then repressurize to it’s normal operational state.

After resolution of the fault condition the visual alarm can be cleared by pressing the Reset / Power Fail Button

After resolution of the fault condition the visual alarm can be cleared by pressing the Reset / Power Fail Button

Activation of the low mean airway pressure alarm will only provide audible and visual alarms.The visual alarm will automatically reset after the fault condition has resolved

The source gas low alarm will provide only a visual indicator if either of the high pressure gas supplies falls below 30 psi.

The battery low alarm will provide only a visual indicator when the nine volt alarm battery needs replacement.

The oscillatory overheated alarm will provide only a visual indicator if the linear motor temperature exceeds 150 degrees Centigrade.

The oscillator stopped alarm will provide audible and visual indicators if the oscillatory amplitude is at or below 7 cmH2O and the oscillatory subsystem is energized. (as indicated by the illumination of the green LED on the start stop button)