Presentation on theme: "HFOV high frequency Oscillatory Ventilation"— Presentation transcript:
1 HFOV high frequency Oscillatory Ventilation Becky Varela & Jamie Wood
2 Overview High Frequency Ventilation (HFV) High Frequency Oscillatory Ventilation (HFOV) and how it worksWhen do we use HFOVBasic Parameters for HFOVHow HFOV prevents Ventilator Induced Lung Injury (VILI)
3 High Frequency Ventilation Provides augmented gas distributionBy means of numerous gas transport mechanisms.Convection, transit time, direct ventilationPendalluft effectTaylor dispersionAsymmetric velocityCardiogenic MixingMolecular diffusionCollateral Ventilation
4 Convection, Transit Time and Direct Ventilation is the transport of air flow at a constant equal velocity that is parabolic in shape.Transit Time:Airflow to the alveoli will vary in proportion to the length of the Bronchial airways.Direct Ventilation:Results from bulk air flow to alveoli that have a much shorter transit time.
5 Asynchronous Filling Taylor Dispersion Pendalluft Effect At the end of expiration:Alveoli with short time constants (fast alveoli units) are empty.Alveoli with longer time constants (slow alveoli units) are still emptyingAsynchronous filling:Gases will move from slow units to fast units because of pressure gradients between the alveoli.The relationship between:Axial velocity profile (Turbulence)the diffusion of gases in motionand the branching network of the lungs.
6 AsymmetryCardiogenic MixingAirflow moving through the airways moves in a u-shape formation. At the center of the lumen air will move at a faster velocity, than air that is closest to the wall.AsymmetryOccurs with rapid respiratory cycles. Gases (O2) at the center of the lumen will advance further into the lungs as gases (CO2) along the wall of the airway moves out towards the mouth.As the heart beats the heart provides additional peripheral mixing by exerting pressure against the lungs during contraction of the heart.This pressure promotes the movement of gas flow through the neighboring parenchymal regions.
7 Collateral Ventilation Molecular DiffusionCollateral VentilationMaintaining a constant distending pressure with HFV within the lungs along with movement of gas molecules promotes gas diffusion across the alveolar membrane, at a faster rate.Collateral ventilation increases with HFV due to connections between the alveoli(Pores of Kohn)
9 Oscillation/Frequency Hz How does it work?Small tidal volumes at high frequency are generated by low amplitude pressure oscillations. These tidal volumes that are approximately equal to dead space.High mean airway pressures (PEEP) provides distending pressure.HFOV can provide 5-15 Hz equal to (900 breaths/min.What is HFOVHFOV has all of the elements of high frequency ventilation discussed previously.Also provides a bias oscillatory gas flow used to generates positive and negative pressure fluctuations referred to as amplitudes or (Delta-P)Oscillation/Frequency HzAmplitudeMAP/PEEP
12 HFOV: 3100A Oscillator Subsystem Uses an External Air/O2 Blender1. Provides blended air/O2 and cooling to the oscillatorOscillator SubsystemUses an1.electronic control circuit called the square wave form driver2. Forward and backward linear motion provides inspiratory and expiratory gas flow.3. Provides frequent small VT in HZExternal Humidifier1. Attaches and functions with the patient’s circuit2. Capable of flows up to 40 LPMPneumatic Logic and Control SystemComprised of 4 pneumonic controls1. Bias flow2. Mean Pressure adjustments3. Mean pressure limit control4. Patient circuit calibration adjustmentPressure Monitoring System1. Safety and alarms rely on this system2. The PMS senses pressures within the patient’s circuit through the tubing that runs from the y-couplerElectronic Power SupplyMonitors:1. Alarms2. Pressures3. Function of the oscillatorPatient CircuitProvides:1. Bias flow/pressure2. Pressurized oscillations3. Pressure limiting
13 3100 A 18 3100A Interface: Bias flow knob Mean Pressure adjustment Mean Pressure LimitPower% Inspiratory TimeFrequencyStart/StopMean Airway PressureSet Max PawSet Min PawPaw >50 cm H2OPaw <20 cm H2OPower failure ButtonReset15a Battery Low15b Source Gas Low16. Oscillator Overheated17. Oscillator stoppedsecond Silence13-1448311597261012115b1615a17
14 Adjustable Parameters Amplitude:Determines the volume of gas generated by each frequency waveOscillation/ Frequency (Hz)Frequency = The Rate15 Hz =900 BPM for neonates12-14 Hz =600 BPM for termed infants8 Hz =480 BPM for children 6-10 kg6 Hz =360 BPM for children above 10 kgIT%Inspiratory Time Percentage33% IT = 22 milliseconds a 15 HzI:E: For HFOVI:E also determines the time for movement of the piston to generate another oscillatory breath.Initial I:E of 1:2 for 3-15 Hz at 33% ITMAP/PEEP:Maintains constant distending pressure in the airway15-18 cmH2OAmplitudes2.5 for3.0 for4.0 for5.0 for6.0 for7.0 forWeight: kg/mg<2.0 kg.<3.0 kg< kgkg< 10 kg>20 kg
15 Pulmonary Diseases and Disorders treated with HFOV https://www.youtube.com/watch?v=dHuXtoODHuA
17 Potential Advantages of HFOV are 1 Potential Advantages of HFOV are 1. Uniform inflation of the lung fields 2. Improves gas exchange 3. Improves lung mechanics 4. Enables stable lung inflation o Allows recruitment of alveolar space o Reduces the risk of volutrauma o Reduces risk of high peak airway pressure (PIP) o Reduces the risk of airway stretching o Improves V/Q matching 5. Reduces air leak 6. Decreases the amount of inflammatory mediators and alveolar edema 7. Prevents the development of hyaline membrane disease (HMD)
18 CMV VS HFOVDuring CMV, there are swings between the zones of injury from inspiration to expiration.During HFOV, the entire cycle operates in the “safe window” and avoids the injury zones.INJURYHFOVCMVINJURY
19 HFOV is used to prevent Ventilator Induced Lung Injury VolumePressureZone of OverdistentionSafe windowZone of Derecruitment and atelectasisGoal is to avoid injury zonesand operate in the safe window
20 Indications:When traditional ventilation failsAirleak syndromesFor patients with severely low lung complianceRefractory hypoxemiaContraindications:ICPobstructive lung diseaseincreased airway resistance (small endotracheal tube)asthmasecretionsincreased physiological dead space
21 Work Citations Page:Alves, Amanda. “High Frequency Oscillatory Ventilation HFOV; a new strategy in theTreatment of patients with Acute Respiratory Distress Syndrome and low lung compliance.” CIMC Web 13 August 2014.Birch, Pita. “Newborn Services Clinical Guideline High Frequency Oscillatory Ventilation.”Web. 14 AugustCareFusion; “3100A High frequency oscillatory ventilation; Operator’s manual.” CareFusionCorporation Savi Ranch Parkway Yorba Linda, CA Web 18 August 2014Haines, Mike. “Mechanical Ventilation: High Frequency Ventilation.” Respiratory TherapyFiles. Web. 8 August 2014.Jeng, Mei-Jy. Lee, Chen, Soong. “Neonatal air leak syndrome and the role of high-frequencyventilation.” Sci Verse Science Direct Journal of the Chinese Medical Association 75 (2012) 551e559 Web. 8 AugustProst, Allen. “High Frequency Oscillation Ventillation.avi.” Youtube.comWeb 24 AugSlee-Wijffels1, Fieke YAM. RM van der Vaart, Twisk, Markhorst, Plötz5 “High-frequencyoscillatory ventilation in children: a single-center experience of 53 cases, pp. R274” Open Access. 16 Web August