This document provides information and guidelines for using the Sensormedics 3100A High Frequency Oscillatory Ventilator. It indicates the ventilator is used for neonatal respiratory support between 24-43 weeks gestation weighing 0.54-4.6kg. The document outlines initial settings for frequency, inspiratory time, power, mean airway pressure and guidelines for calibration, treatment initiation, patient management, suctioning, and weaning from the ventilator.

1. Sensor Medics 3100 A
High Frequency Oscillatory
Ventilation (HFOV)
Allelieh Javier Capistrano, RTRP
Pediatric Respiratory Therapist
Section of Pulmonary Medicine
Philippine Children’s Medical Center

2. The Sensormedics 3100A Oscillatory Ventilator is indicated
for ventilatory support and treatment of respiratory failure
and barotrauma in neonates who weigh between .540 and
4600 kilograms and who are between 24 and 43 weeks
gestational age.

3. Indications
Neonatal Respiratory Distress Syndrome
Persistent Pulmonary Hypertension
Meconium Aspiration Syndrome
Congenital Diaphragmatic Hernia
Neonatal Lung Hypoplasia
Neonatal Air Leak Syndrome

4. Goals
Improve and maintain oxygenation
Eliminate CO2 retention
Create less lung injury

5. Adverse Effects
The adverse effects associated with high frequency
oscillatory ventilation can be divided into three
categories:
1. Pulmonary Barotrauma
2. Cardiovascular Effects
3. Removal of natural defense mechanisms with
intubation

6. Equipment
One high-output humidifier with temperature feedback circuit.
One disposable breathing circuit with heated wire.
One manual water-feed system.
One Oxygen/ Air Blender with 50 psi connections
One Oxygen line with 50 psi connection (to drive bias gas flow)
One Air line with 50 psi connection (to connect to the air cooling inlet)

7. Procedure

8. Perform circuit calibration:
1.Insert stopper into the patient Y connection.
2. Turn Bias gas flow to 20 LPM.
3. Turn on the power.
4. Adjust Mean Pressure Limit to max.
5. Turn Mean Pressure Adjust to max.
6. Depress and hold reset.
7. Observe MAP display for a reading of 39-43 cm H2O.
8. Adjust bias gas flow slightly to achieve this pressure if
necessary.
Failure to achieve this MAP indicates a leak in the
circuit.

9.  Ventilator performance checkout:
 1. Set “Bias Flow” to 20 lpm.
 2. Turn power on, oscillator off.
 3. Set “Mean Pressure Limit” to maximum.
 4. Adjust MAP to 19-21 cmH2O.
 5. Set “Frequency” to 15 Hz.
 6. Set “I-time” to 33%.
 7. Turn oscillator on.
 8. Turn “Power” to 6.00.
 9. Center the piston.
 10. Check the amplitude values against the graph on tip of the ventilator. If the
values are in range, the ventilator is ready for placement.
 11. Fill out the ventilator log sheet and place in the logbook. Fill out the blue
sticker and place on the ventilator

10. Initiating treatment:
1. Set Frequency (Hz) to desired rate.
2. Check that Inspiratory Time (I.T.) is set at 33%, unless otherwise
directed by physician.
3. Adjust the Power knob to desired level.
4. Once the physician has determined starting MAP, decrease the Bias
flow rate to ~15L/min
5. Adjust the Mean Pressure Limit knob in a counter-clockwise fashion
to a pressure of 18-22 cmH2O

11. 6. Using the Mean Pressure Adjust knob set the MAP to the
desired setting.
7. Set pressure alarms 4 cm H2O above and below the set MAP.
8. Check inspired FiO2 levels from the Air/ Oxygen blender on
the side of the oscillator using a calibrated oxygen analyzer.
9. Press start to begin HFOV once connected to the patient’s
endotracheal tube.
10. Adjust Piston Control to keep piston in a central position
11. Turn humidifier on and set in the invasive humidification
mode.

12. Troubleshooting during circuit calibration:
1. Check that the water trap is closed.
2. Check that Bias Gas Flow is on 20 LPM. Increase Bias
Flow slightly.
3. Remove and check the limit, control, and dump
cap/diaphragm valves. Replace valves if circuit still fails
to calibrate.
4. Replace circuit if it cannot be calibrated to 39-43 cm
H2O.
5. If there has been a disconnection, push reset/power
and hold until oscillations resume.

13. Controls
 Bias Flow
0–40 liters per minute (LPM) Continuous, 15-turn control.
 Mean Pressure Adjust
Approximately 3–45 cmH2O minimum range; Bias Flow dependent.
 Mean Pressure Limit
Approximately 10–45 cmH2O mean proximal airway pressure.
 Power
At 100% power, ΔP >90 cmH20 max amplitude of proximal airway pressure.
 Frequency-Hz
3–15 Hz oscillator frequency.

14.  % Inspiratory Time
30–50% of oscillatory cycle.
 Start/Stop
Oscillator enable/disable.
 Set Max awP Alarm Thumbwheel
0–49 cmH2O mean airway pressure.
 45 –Sec Silence
Inhibits audible alarm function for 45 seconds (±5 seconds).
 Reset
Resets awP >50 cmH2O and <20% of “Set Max awP” alarms if
condition has been corrected; always resets power failure alarm.
 Pressure Measurement
Range: –130 to +130 cmH2O airway pressure.
Pressure Limit 20 psig.

15. Alarms
Safety Alarms
Audible and visual indicators, machine intervention.
 awP >50 cmH2O
Indicators activated, oscillator stopped, and dump valve opened
when limit exceeded.
 awP >20% of “Set Max awP”
Indicators activated, oscillator stopped, and dump valve opened
when limit exceeded.

16. Warning Alarms
Audible and visual indicators, operator intervention.
 Set Max awP exceeded
Indicators activated when set limit exceeded.
 Set Max awP
Thumbwheel switch marked in cmH2O.
 Set Min awP
Thumbwheel switch marked in cmH2O.
 Alarm (audible)
3khz modulated tone.
 AC Power
Visual indication of AC power applied (I/0).

17. INITIAL SETTINGS
FREQUENCY
 term infants10 Hz (600 BPM)
 premature infants 15 Hz (900 BPM) (< 2.5 kg).
children between 6-10 kg, 8 Hz,
children > 10 kg, 6 Hz

18. INITIAL SETTING
INSPIRATORY TIME (I.T.)
Set initially at 33% (e.g. 22 milliseconds at 15 Hz, 41
milliseconds at 8 Hz, 55 milliseconds at 6 Hz).
1) Warning - The percent of I.T. should never be
increased because it will lead to air trapping and
fulminant barotrauma. Total I.T. should only be
increased by decreasing frequency, thus leaving the I:E
ratio constant. I.T. can be decreased to 30% to heal air-leaks.
2) I:E ratio: ≈ 1:2 for 3-15 Hz at 33% I.T.

19. INITIAL SETTINGS
POWER
the volume of gas generated by each high frequency
wave. Range (1.0 - 10.0).
Maximum true volume of gas generated by the piston is
365 cc.
Maximum amplitude or volume delivered is highly
variable and depends on the following factors:
circuit tubing (compliance, length and diameter),
humidifier (resistance and compliance - water level),
ET tube diameter and length (FLOW is directly
proportional to r4/l,
where r = radius of airway and l = length of airway), the patient's airways and compliance.

20. 1) Set the POWER initially at if weight is:
 <2.0 kg 2.5
 < 2.5 kg 3.0
 2.5 - 4.0 kg 4.0
 4.0 - 5.0 kg 5.0
 < 10 kg 6.0
 > 20 kg 7.0

21. MAP
Oxygenation on HFOV is directly proportional to MAP,
which is similar to CMV, however with the SensorMedics
HFOV the MAP is generated by PEEP. Thus during
HFOV: MAP = PEEP.
1. Initial MAP Settings:
a) Neonates - Initial MAP should be 2-4 cm above the
MAP on CMV.
b) Infants/Children - Initial MAP should be 4-8 cm above
the MAP on CMV.
c) If starting immediately on HFOV 15-18 cm in
infants/children.

22. Patient Management during HFOV
Step Action
1 Positioning:
The Oscillator should be placed at the head of the
patient’s bed.
The brakes should be on at all times.

23. Patient Repositioning:
Patients should be individually assessed for frequency of
repositioning.
 When patient is stable, patients should be repositioned
every 2-4 hours. Repositioning is to be done only at
physician direction.
A respiratory therapist will be present for all major
repositioning of the infant
Avoid disconnection during repositioning.
Caution: Inadvertent disconnection from HFOV can
cause alveolar collapse and loss of lung volume.

24. Suctioning:
In-line suction catheters will be used on patients during
HFOV in order to maintain MAP.
Suction is done on an as needed basis only, unless
otherwise directed by the physician.

25. WEANING
OXYGENATION
Once oxygenation is adequate and the patient is ready
to be weaned follow these steps:
1) First only wean FiO2 until < 0.50-0.60 unless hyper-inflated.
2) Once FiO2 < 0.50-0.60 or hyper-inflated, decrease
MAP by 1 cm Q4-8h; if OXYGENATION is lost during
weaning then increase MAP by 3-4 cm to restore lung
volumes and begin weaning again, but proceed more
slowly with decreases in MAP.
3) Minimal MAP ≈ 8-16 cm with FiO2 < 0.40-0.50, at this
point one can convert to CMV or remain on HFOV while
the patient continues to heal and grow (e.g., 8-12 cm <
2.5 kg, 13-16 cm > 2.5 kg).

26. References Sensormedic High Frequency
Oscillatory Ventilator Operating Manual.
Whitaker, K., Comprehensive Perinatal and
Pediatric Respiratory Care,
Delmar, Albany, New York, 2001.