High Frequency Ventilation
OVERVIEW
High Frequency Ventilation ventilation with small tidal volumes at high frequencies
TYPES
- high-frequency positive-pressure ventilation
- high-frequency percussive ventilation
- high-frequency jet ventilation
- high-frequency oscillatory ventilation
HIGH FREQUENCY POSITIVE-PRESSURE VENTILATION
- TV 3-4mL/kg at 60-100/min
- conventional mechanical ventilator
- often used with high PEEP
- expiration is passive and relies on elastic recoil
- -> risks: gas trapping, hyperinflation and overdistension injury
HIGH-FREQUENCY PERCUSSIVE VENTILATION
- aims to combine high frequency and conventional ventilation
- conventional ventilator used + a gas driven piston at the end of the ETT
- piston generates oscillation at 3-15Hz with short expiratory times which are superimposed on conventional inspiratory-expiratory pressure waves.
- high frequency bursts generate auto-PEEP through breath stacking -> then are stopped and allow alveolar pressure to fall back to baseline.
- improves alveolar recruitment with exposing them to high peak airway pressures
HIGH FREQUENCY JET VENTILATION
- jet drive pressure augments TV
- expiration is passive and gas trapping with intrinsic PEEP can develop
- risks: trauma to upper airway, humidification and warming a problems, lung injury through shear forces
HIGH-FREQUENCY OSCILLATORY VENTILATION
- oscillating diaphragm creates pressure waves in the ventilator circuit.
- diaphragm is active in both directions -> creates inspiratory and expiratory pressure waves -> expiration is active.
- clinicians set: flow rate, mean airway pressure, frequency, inspiratory-expiratory ratio, energy applied to the oscillating diaphragm.
- see HFOV page for more details
Advantages
- decreased risk of overdistention injury
- increases mean airway pressure -> improved oxygenation and prevention of atelectrauma
- good evidence base in paediatrics and neonates
References and Links
CCC Ventilation Series
Modes: Adaptive Support Ventilation (ASV), Airway Pressure Release Ventilation (APRV), High Frequency Oscillation Ventilation (HFOV), High Frequency Ventilation (HFV), Modes of ventilation, Non-Invasive Ventilation (NIV), Spontaneous breathing and mechanical ventilation
Conditions: Acute Respiratory Distress Syndrome (ARDS), ARDS Definitions, ARDS Literature Summaries, Asthma, Bronchopleural Fistula, Burns, Oxygenation and Ventilation, COPD, Haemoptysis, Improving Oxygenation in ARDS, NIV and Asthma, NIV and the Critically Ill, Ventilator Induced Lung Injury (VILI), Volutrauma
Strategies: ARDSnet Ventilation, Open lung approach, Oxygen Saturation Targets, Protective Lung Ventilation, Recruitment manoeuvres in ARDS, Sedation pauses, Selective Lung Ventilation
Adjuncts: Adjunctive Respiratory Therapies, ECMO Overview, Heliox, Neuromuscular blockade in ARDS, Prone positioning and Mechanical Ventilation
Situations: Cuff leak, Difficulty weaning, High Airway Pressures, Post-Intubation Care, Post-intubation hypoxia
Troubleshooting: Autotriggering of the ventilator, High airway and alveolar pressures / pressure alarm, Ventilator Dyssynchrony
Investigation / Indices: A-a gradient, Capnography and waveforms, Electrical Impedance Tomography, Indices that predict difficult weaning, PaO2/FiO2 Ratio (PF), Transpulmonary pressure (TPP)
Extubation: Cuff Leak Test, Extubation Assessment in ED, Extubation Assessment in ICU, NIV for weaning, Post-Extubation Stridor, Spontaneous breathing trial, Unplanned extubation, Weaning from mechanical ventilation
Core Knowledge: Basics of Mechanical Ventilation, Driving Pressure, Dynamic pressure-volume loops, flow versus time graph, flow volume loops, Indications and complications, Intrinsic PEEP (autoPEEP), Oxygen Haemoglobin Dissociation Curve, Positive End Expiratory Pressure (PEEP), Pulmonary Mechanics, Pressure Vs Time Graph, Pressure vs Volume Loop, Setting up a ventilator, Ventilator waveform analysis, Volume vs time graph
Equipment: Capnography and CO2 Detector, Heat and Moisture Exchanger (HME), Ideal helicopter ventilator, Wet Circuit
MISC: Sedation in ICU, Ventilation literature summaries
Journal articles
- Evans E, Biro P, and Bedforth N. Jet ventilation. Contin Educ Anaesth Crit Care Pain (2007) 7 (1): 2-5 doi:10.1093/bjaceaccp/mkl061 [Cited 21 Dec 2014] Available at URL: http://ceaccp.oxfordjournals.org/content/7/1/2.full
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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