HFOV

Hi guys, today at work during rounds sm1 was asked to present on the indications of High Frequency Ventilation, n she din really have all the ans n also was not sure of what Amptitute n Frequency is. N we had crit care advance dip students today n i was also trying to explain what amp n freq is, i can't really explain, so decided to do abiit of research...

Readers who r not interested or dunno what the heck i'm talking abt, pls skip the following :) hehe...

Definition

HFOV is a method of mechanical ventilation that uses fast breathing rates and tidal volumes frequently less than dead space volume.

Indications for Use

Severe respiratory failure unresponsive to conventional ventilation
Pulmonary air leaks, pulmonary interstitial emphysema, pneumothorax, bronchopleural fistulas and pneumo-pericardium.
Hypoplastic lungs, diaphragmatic hernia.
Persistent pulmonary hypertension, meconium aspiration.

Functions

Improves and maintains oxygenation
HFOV recruits alveoli and the number of open alveoli is in direct relationship to the mean airway pressure (MAP).
Eliminates CO2 retention
In conventional mechanical ventilation (CMV) the expiratory phase is passive whereas in HFV inspiration and expiration are active.
Creates less lung injury
Uses small tidal volume ventilation which may reduce lung injury and prevent over inflation of more compliant lung units
Less likely to get air-trapping because inspiratory and expiratory phrases are active.

Parameters

Hertz(Hz)
Breathing rate or frequency. 1 Hz is equal to 1 breath per second.
Commonly used frequencies are 10-15Hz (600-900 b/min) although lower frequencies of 6-8 Hz have been used.
Mean Airway Pressure(MAP)
Mean airway pressure recruits and maintains lung volume. Small adjustments can result in significant changes in lung volume. Commence treatment at an MAP 2cm H2O higher than infant was receiving on conventional ventilation.
Displayed as PAW on the SensorMedics oscillator.
To acquire appropriate MAP on the Babylog ventilator adjust CPAP/PEEP rotary knob.
Amplitude(ΔP or power)
The volume of gas per breath observed by the chest vibration or wobble.
Not a standard parameter between oscillators:
Is reflected as a % in the Drager Babylog.
The dial to adjust the amplitude value on the SensorMedics is the power dial.
At the beginning of treatment observation of chest movement is the best indicator of required amplitude.

Management

Oxygenation and ventilation are best considered separately.
PaO2: is affected by adjusting the MAP or FiO2
PaCO2: controlled by adjusting amplitude.

http://www.akhealth.co.nz/newborn/Guidelines/Respiratory/HFOV/HFOVInformation.htm