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HFOV - SensorMedics 3100A

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SensorMedics Front Panel

Sensor Medics Front Panel

Diagram displaying set up of SensorMedics circuit

Sensor Medics circuit

Equipment required for administration of HFOV using SensorMedics Oscillator

  • SensorMedics oscillator 
  • SensorMedics oscillator circuit
    - flexible breathing circuit 
    - humidifier dry line 
    - 3100A/bellows/water trap 
    - 3 x diaphragm cap set
  • F & P MR850 Humidifyer
  • Humidifier Base
    - electrical temperature probe adaptor 
    - heater wire
  • Blue T piece and O2 analyser
  • Water for injection 1000ml bag
  • In line suction apparatus
    - green = size 6 French 
    - cream = size 7 french 
    - blue = size 8 French
  • Temperature Connector
  • Nitric Scavenging
    - scavenger unit - white plastic 
    - blue scavenging tubing 
    - white connector 
    - suction tubing 
    - suction inner 
    - green leur lock adaptor 
    - Sim's connector

Oscillator set up

Where possible the SensorMedics Oscillator should be assembled and checked ready for use

  1. Assemble the SensorMedics circuit as per diagram above,  taking care not to fracture the bellows from the water trap. Always insert and remove water trap clip first, supporting circuit throughout. Ensure it is placed as straight as possible.
  2. Then install the bellows membrane ensuring all 4 machine clamps are rotated to keep the bellows clamped in place. If it's not centred correctly the 4 machine clamps will not turn correctly, so you may need to realign bellows if this happens.
  3. Open up the flexible breathing circuit and humidifier dry line. Ensure that all connections are tight. Some connections are deliberately assembled only finger tight and must be firmly secured. Straighten the circuit and inspect heater wire assembly to be certain that there are no kinks or knots in the wire.
  4. Place the flexible breathing circuit tubing over the bellows; you may need to ensure at least ¾ of the tubing goes on.
  5. Apply your set of 3 Diaphragm Caps onto the disc slots. Before you apply check that all the membranes inside the diaphragm cap are intact e.g. no tears in them.
  6. The flexible breathing circuit you applied in step 4 has a white pressure line that needs to be connected to the white airway pressure connector. Screw this into place initially turning the line anticlockwise prior to applying, this will allow the tubing to remain unkinked.
  7. Before connecting the green control line you must apply the scavenging unit. Apply white plastic scavenging connector with blue tubing connected to it around the diaphragm cap, and then you can apply your green control line to the 1st diaphragm cap on the left. Screw this into place initially turning the line anticlockwise prior to applying, this will allow the tubing to remain unkinked.
  8. Apply the Blue limit line to the diaphragm cap on the right. Screw this into place initially turning the line anticlockwise prior to applying, this will allow the tubing to remain unkinded.
  9. Apply the red dump valve line to the furtherest away diaphragm cap. Screw this into place initially turning the line anticlockwise prior to applying, this will allow the tubing to remain unkinked.
  10. Put the humidifier base insitu.
  11. On the humidifier base place the blue T piece so the oxygen analyser can be plugged into it. Then connect your oxygen analyser. Ensure your oxygen analyser is fully charged and calibrated.
  12. Place the humidifier dry line tubing onto the blue T piece, remove an extra plastic connector on the end to allow it to fit on the top correctly. Connect the other end of the humidifier dry line to the back of the oscillator where it reads "Outlet to Humidifier".
  13. Place the bias flow tube onto the humidifier base, remove the elbow connector and put the temperature connector in its place. Make sure the rubber locking mechanism is in place on the top of the temperature connector.
    Connect up the temperature wires. Be certain that the temperature probe is fully inserted into the probe port so that the probe tip is in the middle of the temperature connector probe port. The other temperature probe needs to be inserted in the middle of the flexible breathing circuit tubing. It will sit at the point just above where the temperature wire inside the flexible breathing circuit finishes. This will allow accurate measurement of the humidifier temperature.
  14. Connect the heater wire.
  15. Put suction inner in place. Connect the blue scavenging tubing into the largest open slot. Connect suction tubing to suction inner. Cut the suction tubing to approx 30cm and insert sim's adaptor into the end of the watertrap, then connect the other end of the sim's to the Green Luer lock adaptor. Screw the Green Luer lock adaptor into the bottom of the water trap. (Refer Suction Set-up picture) Draw a black line on the water trap 2cm from the bottom.
  16. Inline suction cannot be applied until the Oscillator gets attached to the patients ETT. Work out what size inline suction you will require.(Refer In-line suction policy)
  17. Now you are ready to plug your air and oxygen into the wall inlets. Connect yellow scavenging tubing into the scavenger at the back of the ponta ensuring the scavenger is turned on. Turn scavenger on even if no is nitric running, as this will assist with removing rain out in the tubing.
  18. Connect power plug to an Uninterrupted Power Supply.

HFOV7lg HFOV10lg HFOV11lg

Start-up and initiating HFOV SensorMedics Oscillator

Initiating HFOV is the responsibility of the medical staff.

  1. Perform circuit calibration:
    Ensure stopper is inserted in patient Y connection (N.B. a lung is not used).
  2. Turn Bias gas flow to 20 LPM. Switch machine on.
  3. Turn Mean Pressure Limit to max
  4. Turn Mean Pressure Adjust to max
  5. Depress and hold reset. Observe PAW display for a reading of 39-43cm H2O. Adjust bias gas flow slightly to achieve this if necessary.
  6. An inability to achieve this PAW means a leak in the circuit.
    (Refer to troubleshooting below)
  7. Initiating treatment:
    - Turn Bias gas flow back to 15 LPM
    - Set frequency (Hz) to 8-15 as per medical order
    - Our default setting is 10Hz
    - Check Inspiratory-time is 33%
    - Set power on 2.
  8. Determine treatment MAP. Rotate the mean pressure limit anti-clockwise to set PAW (MAP) to limit 5cm above treatment setting. Be aware if the infant later requires higher MAP levels, the limit may have to be increased.
  9. Rotate Mean Pressure Adjust control anti-clockwise to set treatment MAP.
    Note: These dials are sensitive to major adjustments.
  10. If a very high MAP is required, the Bias gas flow may have to be increased to 20 LPM.
  11. Set pressure alarms 2cm above and 3cm below set PAW.
  12. Check inspired O2 level on O2 blender to the side of oscillator.
  13. Turn humidifier on.
  14. Press 'start' to commence HFOV on infant. Medical staff to adjust amplitude while observing chest movement.
  15. Adjust Piston Control to keep the piston in a central position. This will ensure both lungs are being oscillated equally.
  16. Nitric oxide may be administered in this circuit (see Nitric Oxide Protocol). Connect scavenging tubing to the back of the ponta and turn scavenger button on.

Set up of suction unit for scavenging

HFOV3lg     HFOV8lgScavenger 3

N.B When initially setting up, a black mark will need to be drawn 2cm from the bottom of the water trap to ensure the water isn't emptied past that line. This acts as a visual indicator to ensure that the drainage stopcock has been closed, and provides a more efficient seal in the circuit.

Troubleshooting: SensorMedics Oscillator Ventilator

Follow the steps below if the SensorMedics Oscillator fails to calibrate to 39-43cm H2O, or for other technical difficulties.

  1. Check the water trap is closed.
  2. Check Bias Gas Flow is on 20 LPM. Increase Bias Flow slightly.
  3. Remove and check the limit, control and dump cap/diaphragm valves (see diagram below). Replace valves if circuit still fails to calibrate.
  4. Observe mean pressure display and adjust Patient Circuit Calibration Screw (pictured below), on left hand side of oscillator, until you get a reading of 39-43cm H2O. If calibration is still not being met, replace with a new circuit.
  5. If there has been a disconnection, press and hold reset, watch the rise in MAP to set set level, then press start/stop to recommence oscillations.
  6. Battery low: has no audible alarm, means there is no electrical power to battery that supplies amplitude/power dial. The HFOV will still work.


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Document Control

  • Date last published: 17 August 2018
  • Document type: Clinical Guideline
  • Services responsible: Neonatology
  • Owner: Newborn Services Clinical Practice Committee
  • Editor: Sarah Bellhouse