HFV - HFOV SAMANTHA DURHAM & RAJBEER SINGH

What is HFV and types of HFV?  High frequency jet ventilation  high frequency oscillatory ventilation,  high frequency percussive ventilation,  high frequency positive pressure ventilation

What is HFOV? A rapid rate and low tidal volume form of mechanical ventilation High rates can be between 3-15 Hz (cycles per second) up to 900 breaths per minute for adults Tidal volumes are less than dead space so HFOV relies on alternative methods of gas exchange to promote removal of CO2 from the lung Uses a constant distending pressure (mean airway pressure) with pressure oscillations around the mean pressure Maintains adequate alveolar recruitment Active inspiration and active expiration

Describe history of HFOV? Devolped by Lunkenheimer Animal Trials Used successfully in neonates and then Pediatrics The 3100A High Frequency Oscillation Ventilator was first approved for use in 1991 and is the only HFV approved for early intervention in the treatment of neonatal respiratory failure FDA approval of Pediatrics, and 2001 for adults

Mechanisms of gas transport and gas exchange Convection Turbulence Bulk Convection Convection- Diffusion Pendelluft Asymmetric velocity (inspiratory and expiratory) Diffusion Collateral Ventilation Cardiogenic Mixing

Indications and Contraindications Indications Immature lungs or surfactant deficiency Premature neonates with hyaline membrane disease Meconium Aspiration Syndrome ARDS Diaphragmatic Hernia PPHN Bronchopulmonary fistula Contraindications Severe airflow obstruction Intracranial hypertension

Initial Settings Optimal lung volume strategy (aim to maximise recruitment of alveoli). Set MAP 2-3 cmH 2 O above the MAP on conventional ventilation ↑ MAP in 1-2 cmH 2 O steps until oxygenation improves Set frequency to 10 Hz Consider recruitment manoeuvres after discussion with consultant Low volume strategy (aim to minimise lung trauma) Set MAP equal to the MAP on conventional ventilation Set frequency to 10 Hz Adjust amplitude to get an adequate chest wall vibration. Initial settings on HFOV

Adjustments Poor OxygenationOver OxygenationUnder VentilationOver Ventilation Increase FiO 2 Decrease FiO 2 Increase AmplitudeDecrease Amplitude Increase MAP* (1-2cmH 2 O) Decrease MAP (1-2cmH 2 O) Decrease Frequency** (1-2Hz) if Amplitude Maximal Increase Frequency** (1-2Hz) if Amplitude Minimal

Parameters  Flow >8  MAP >20  Amplitude >  I : E  Frequency – 5-20  FiO2  Tidal Volume

Suctioning ● Indicated for ● diminished Chest wall movement ● Elevated Co2 or worsening oxygenation ● ET obstruction ● Visible or audible secretions in the airway ● Always press the STOP button, and suction quickly. ● C/I – ● avoid 1 st 24 hours

Weaning ● Reduce FiO2 <40% before weaning MAP ● Reduce MAP (1-2 cm H2O when chest radiograph shows evidence of over inflation ● Frequency amplitude in 2-4 cm H2O increments ● Discontinue weaning when MAP 8-10 and amplitude 20-25

Important Considerations Perform thorough suction before connecting to the oscillator Closed system suction catheter Avoid disconnection from the ventilator Check for changes in pitch/rhythm of delivered breaths Check chest wiggle Always humidify gases Obtain blood gases and CXR 2 hours after HFOV commencement and at least daily

Complications Hypotension Pneumothorax Endotracheal tube obstruction Intraventricular hemorrhage (high MAP)

Which ventilators utilize HFOV? CareFusion 3100A- for neonates and pediatrics less than 35 kg 3100B - for adults and children weighing more than 35 kg

SLE2000 Infant Ventilator by SLE

● Acutronic FABIAN ● o8_4PEUDT4 o8_4PEUDT4

Babylog 8000 by Drager

Which ventilators utilize HFOV? Infant Star 950 by Soma Technology

Positive and negatives regarding it? Positive 1. Used for lung protective ventilation - HFOV is more lung protective than the best application of conventional ventilation a. supports gas exchange with small Vt b. improved alveolar recruitment c. decreased inflammation 2.Used for severe hypoxemia

Negative 1. There is not strong evidence a. There are only a few studies on HFOV on its effect on alveolar inflammation b. HFOV was used as a “rescue therapy” in “failed conventional ventilation,” despite “rescue” a high percentage of patients died 2.Cost a. Expensive equipment and costs to train b. hard to justify from an economic standpoint 3.Need for sedation and paralysis a. Paralysis can cause ICU acquired muscle weakness b. Sedation may delay weaning 3. Safety a. increased occlusion of pulmonary arterial pressure b. decreased stroke volume c. risk of pneumothorax d. risk of barotrauma

What does research say in terms of effectiveness?  A randomized control study concluded that high-frequency oscillation is a safe and effective mode of ventilation for the treatment of acute respiratory distress syndrome in adults.  HFOV was used as a rescue therapy in very sick patients with refractory hypoxemia, and improvement in oxygenation was observed after 24 hours of this technique. HFOV is a reasonable alternative when a protective lung strategy could not be achieved on conventional ventilation.  High frequency oscillatory ventilation was associated with better early oxygenation and shorter hospital stay compared to synchronized intermittent mandatory ventilation in preterm neonates with hyaline membrane disease  Compared with CV, the use of HFOV in ARDS was not associated with a significant reduction in mortality. But the physiologic parameters of patients in HFOV group were better than those in the CV group.

Question ● ABG ● pH = 7.26 ● CO2 = 64 ● O2 = 60 ● HCO2 = 28 1)Interpret the ABG 2) What changes would you make on the HFOV?

Questions ● What is the difference between the Carefusion 3100A and 3100B? ● What are some disease treated with HFOV? ● 1Hz = how many bpm.

Questions ● What does MAP have an effect on? ● What does Delta P (amplitude) have an effect on? ● What is PPHN?

References ● Donn, S. (2012). High Frequency Oscillatory Ventilation. In Manual of neonatal respiratory care (3rd ed.). New York: Springer. ● Fessler, H, MD (2007). Does high frequency ventilation offer benefits over conventional ventilation in adult patients with acute respiratory distress syndrome? ● Jonathan M. Klein, MD, Management Strategies with High Frequency Oscillatory Ventilation (HFOV) in Neonates Using the SensorMedics 3100A High Frequency Oscillatory Ventilator, 2015 ● ● Pillow, Jane J PhD. (2005). High frequency oscillatory ventilation: Mechanism of gas exchange and lung mechanics. ● S. P. Stawicki, MD, Munish Goyal, MD, and Babak Sarani, MD, FACS, High-Frequency Oscillatory Ventilation (HFOV) and Airway Pressure Release Ventilation (APRV): A Practical Guidem, Jurnal of Intensive Care mediicin ● Stephen Derdak, Sangeeta Mehta, Thomas E. Stewart, Terry Smith, Mark Rogers, Timothy G. Buchman, Brian Carlin, Stuart Lowson, John Granton, and the Multicenter Oscillatory Ventilation for Acute Respiratory Distress Syndrome Trial (MOAT) Study Investigators High-Frequency Oscillatory Ventilation for Acute Respiratory Distress Syndrome in Adults A Randomized, Controlled Trial, ATS Journal ● Javier D Finkielman 1, Ognjen Gajic 2, J Christopher Farmer 2, Bekele Afessa 2 and Rolf D Hubmayr 2* The initial Mayo Clinic experience using high-frequency oscillatory ventilation for adult patients: a retrospective study, BMC ● SN SINGH, GK MALIK, GP PRASHANTH, ANITA SINGH ANDMALA KUMARHigh Frequency Oscillatory Ventilation versus Synchronized Intermittent Mandatory Ventilation in Preterm Neonates with Hyaline Membrane Disease: A Randomized Controlled Trial, Inidan Pediatrics, 2012 ● Wang H, Sun T, Wan Y, Kan QThe effects of high frequency oscillation ventilation on patients with acute respiratory distress syndrome: a Meta-analysis and sequential analysis of trial], Europe PubMed 2015 Wang HSun TWan YKan Q