Presentation on theme: "HFOV Presented by SAYU ABRAHAM"— Presentation transcript:
1 HFOV Presented by SAYU ABRAHAM SLE5000HFOVPresented bySAYU ABRAHAM
2 High Frequency Ventilation Defined by FDA as a ventilator that delivers more than 150 breaths/min.Delivers a small tidal volume, usually less than or equal to anatomical dead space volume.While HFV’s are frequently described by their delivery method, they are usually classified by their exhalation mechanism (active or passive).
4 HFV Gas ExchangeHenderson first published his findings in 1915, assessing dead space relationship in ventilation.He stated, “there may easily be a gaseous exchange sufficient to support life even when Vt is considerably less than dead space.”
5 High Frequency Ventilation Types of HFV’s Approved for use in both Neonates and PediatricsSLE HFOVSensorMedics 3100A HFOVBird Volumetric Diffusive HFPPVTypes of HFV’s Approved for use in Neonates OnlyBunnell Life Pulse HFJVInfrasonics Infant Star (discontinued) HFFI
6 SLE5000 Electrically powered, electronically controlled Conventional and HFOV ventilatorPaw of mbarDelta P from 4 – 180 mbarFrequency of HzI:E Ratio 1:1Active exhalation
10 Pulmonary Injury Sequence of the neonatal patient: Absence of SurfactantAtelactasisTidal BreathingHigh Distending PressuresAirway Stretch / DistortionCellular Membrane DisruptionEdema / Hyaline Membrane FormationHigher FIO2 , Volumes, PressuresVolutrauma, Barotrauma, BiotraumaPIE, BPD
11 Pulmonary Injury Sequence If we cannot prevent the injury sequence , then the target goal is to interrupt the sequence of events.High Frequency Oscillation does not reverse injury, but will interrupt the progression of injury.
12 Ventilator Induced Lung Injury BarotraumaAir leaking into pleural spaceAir leaking into interstitial space (PIE)Tearing at Bronchio-Alveolar Junction as lung is recruited and allowed to collapseMost occurs in dependent lung zones (transition zone)
14 Ventilator Induced Lung Injury Stretch InjuryAlters capillary transmural pressuresChanges in transmural pressure causes breaks in capillary endo and epitheliumIncreases leak of proteinacious materialPromotes Atelectasis
15 Ventilator Induced Lung Injury VolutraumaCaused by cycling of the lung (change in surface area), independent of pressure requiredAlters Surfactant functionPromotes AtelectasisIncreases capillary leak of proteinacious materialDreyfuss,D ARRD 1988;137:1159
16 Ventilator Induced Lung Injury Premature baboon modelCoalson J. Univ Texas San Antonio
17 Ventilator Induced Lung Injury Premature baboon modelCoalson J. Univ Texas San Antonio
18 Pulmonary Injury Sequence There are two injury zones during mechanical ventilationLow Lung Volume Ventilation tears adhesive surfacesHigh Lung Volume Ventilation over-distends, resulting in “Volutrauma”The difficulty is finding the “Sweet Spot”Froese AB, Crit Care Med 1997; 25:906
19 Ventilator Induced Lung Injury HFOV with Surfactant as Compared to CMV with Surfactant in the Premature PrimateHFOV resulted inLess Radiographic InjuryLess Oxygenation InjuryLess Alveolar Proteinaceous DebrisJackson C AJRCCM 1994; 150:534
21 Theory of OperationOxygenation is primarily controlled by the Mean Airway Pressure (Paw) and the FiO2Ventilation is primarily determined by the stroke volume (Delta-P) and the frequency of the ventilator.
24 Principles of the SLE5000 HFOV “Super-CPAP” systemto maintain lung volume
25 Optimized Lung Volume Strategy: Increase Lung Volume above critical opening pressure to the Optimum and keep it there in Inspiration and Expiration.Benefits: - homogenous gas distribution- reduced regional atelectasis- maximized gas exchange area and pulmonary blood flow- better matching of ventilation/perfusion- reduction of intrapulmonary shunting- reduced Oxygen exposure
26 Optimized Lung Volume Strategy: Decrease Tidal Volumes to less or equal to dead space and increase frequency.Benefits: - enhanced gas exchange due to combined gas transport mechanisms- no excessive volume swings- reduced regional over-inflation and stretching- reduced Volutrauma
27 OxygenationThe Paw is used to inflate the lung and optimize the alveolar surface area for gas exchange.Paw = Lung Volume
38 Mechanisms of HFOV Gas Exchange There are six mechanisms of gas exchange during HFOVConvective VentilationAsymmetrical Velocity ProfilesTaylor DispersionPendeluftMolecular DiffusionCardiogenic Mixing
39 Practical preparation Avoid leak around the E.T tubeTc PO2,CO2,Pulse oxymeter and invasive blood pressure monitoringBaseline CXROptimize blood pressure and perfusion(volume replacement and inotropes)Muscle relaxant/sedationReusable low compliance circuits must be used
40 NURSING CAREPerform through suction before connecting to the oscillator.Assess patient upon commencement of HFOV.Monitor vital signs, chest wiggle must be evaluated upon initiation and followed closely thereafter. If chest wiggle diminishes it may be ETtube moved or obstructed. Chest wiggle on one side indicates patient developed pneumothorax,thus chest wiggle assessment should be performed after repositioning.Auscultation the chest by putting in standby mode.A closed suction should be used. It is not necessary to disconnect the patient to suction as this will potentially derecruit lung volumes.The point at which the ET tube is cut and secured at lips should be initially noted this measurement is reference.
41 Continued……… Evaluation of lung expansion on CXR Check capillary refill, skin color and temperatureComparing central and peripheral pulsesMonitoring of ECG TracingFrequent CXR’s blood gases in initial stabilization periodOptimal lung volume for oxygenation is 8-9 rib inflationBlood pressure and perfusion should be optimized prior to HFOV,any volume replacement should be completed and inotropes commenced if necessary
42 Continued………Muscle relaxants are not indicated since spontaneous respiratory effort will be a clinical indicator of adequacy of ventilationSedation with opiates is often indicatedTHANKYOU