HIGH FREQUENCY OSCILLATORY VENTILATION|HFOV

 High-Frequency Oscillatory Ventilation (HFOV):Revolutionizing Respiratory Support

Introduction of HFV

High-frequency ventilation (HFV) is a type of ventilation that is utilized when conventional ventilation fails. It is a technique where the set respiratory rate greatly exceeds the normal breathing rate. In this rescue strategy, the tidal volume delivered is significantly less and can also be less than dead space ventilation.

Types of HFV

Types of HFV are

1. High-frequency oscillatory ventilation(HFOV)

2. High-frequency positive pressure ventilation(HFPPV)

3. High-frequency jet ventilation(HFJV)

4. High-frequency percussive ventilation(HFPV)

What is HFOV?

HFOV stands for High-Frequency Oscillatory Ventilation. It's a type of mechanical ventilation used in intensive care units to support patients with severe respiratory failure. HFOV delivers very small, rapid breaths at a set frequency, allowing for greater lung recruitment and oxygenation while minimizing barotrauma.

Indication of HFOV

• Ventilator-associated lung injury 

• Alveolar hemorrhage

• Large air leak with inability to keep lungs open 

• Abdominal Compartment Syndrome 

• Failure of conventional mechanical ventilation 

• Refractory hypoxemia 

• Increased intracranial pressure 

• Persistent pulmonary hypertension 

• Acute Respiratory Distress Syndrome

• Pulmonary Interstitial Emphysema 

• Meconium aspiration 

• Pulmonary hypoplasia 

• Bronchopulmonary fistulae

Contraindication of HFOV

• Obstructive airway disease

• TBI/intracranial haemorrhage

• Hemodynamic compromise

Chest wiggle factor

1. Infant-umblicus
2. Children-pubic symphysis
3. Adult-mid thigh

Settings and parameters in HFOV

The settings in hfov are

1. Bias flow

2. Mean airway pressure

3. Amplitude

4. Frequency

5. Inspiratory time

1.Bias flow

• It is also called base flow

• Its supplies oxygen and remove exhale air

• Generate the Paw

• Initial flow 20L/min

• Maximum upto 60L/min

Parameters

• premature-10-15L/min

• <1yrs-15-25L/min

• 1 to 8 yrs-15-30L/min

• >8 yrs-25-40L/min

2.Mean airway pressure

Its used to optmize lung  volume & thus improves  alveolar surfacearea for gas exchange.

1. Neonates: 8-10cmH2o

2. infants:15-20cmH2o

3.Amplitude

• Distant the diaphragm moves

• Set the Pswing around MAP

• If is too low-under ventilation

• If its too high-VILI

• Determines Vt

PARAMETERS

• wt<2-0kg-2.5

• Wt2.1-2.5kg-3.0

• Wt2.6-4.0kg-4.0

• Wt4.6-5.0kg-5.0

• Wt5.1-10kg-6.0

• wt>20kg-7.0

4.Frequency

• Measured in Hertz(HZ)

• 1HZ=1cycle/sec=60breaths/min

• Increase in amplitude=decreasein frequency

• Decrease of age/wt=increase in  frequency

• Decrease of compliance=increase in frequency

PARAMETERS

1. Preterm neonates-15HZ
2. Term neonates-12HZ
3. infant/child-10HZ
4. Older child-8HZ

5.Inspiratory time

1. Similar to conventional
2. Ratio 1:2
3. Insp time is 33%
4. Increase in time will leads to air trapping

Complication of HFOV

Irritation

1. Hypotension
2. Pneumothorax
3. ETT obstruction due to secretion
4. Intracranial hemorrhage
5. Bronchopulmonary dysplasiaNecrotizing tracheo bronchitis

Conclusion

High-Frequency Oscillatory Ventilation is a transformative technique in mechanical ventilation, offering significant advantages in lung protection and oxygenation. Its role is crucial in managing severe respiratory conditions where conventional ventilation may fall short. As healthcare technology and practices continue to advance, HFOV's application may expand, offering new hope and improved outcomes for critically ill patients.

By understanding the principles, benefits, and clinical considerations of HFOV, healthcare providers can better utilize this advanced ventilation strategy to optimize patient care and outcomes in intensive care settings.