acute lung injury
DESCRIPTION
injuri paru akutTRANSCRIPT
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Acute Lung InjuryandARDS
Andreas CredeEmergency Medicine Registrar
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OverviewIntroductionDefinitionPathophysiologyTreatmentNew StuffReferences
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Introduction1st described 1967 (Ashbaugh et al)Incidence 1.5 -7.5/ 100000 population28 day mortality 25 30%1Diagnosis clinical
- DefinitionAcute onset (
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Risk FactorsAlcoholismGenetic predisposition
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CausesDirect Injury1PneumoniaAspirationDrowningAmniotic fluid and fat embolismAlveolar haemorrhageSmoke, toxic gas inhalationReperfusion (incl rapid drainage pleural effusion)Unilateral lung re-implantation
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CausesIndirect Injury1Severe SepsisMassive transfusionShockPancreatitisSalicylate/ narcotic overdoseAnaphylaxisCardiopulmonary bypass
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DifferentialLVFFluid overloadMitral stenosisLymphangitis carcinomatosisInterstitial lung disease1
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Respiratory Failure
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HistologicallyExudative Phase3 Neutrophilic InfiltrateAlveolar HaemorrhageProteinaceous Pulmonary OedemaCytokines (TNF, IL1,8) Inflammation Oxidative Stress and Protease Activity Surfactant ActivityAtelectasis
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HistologicallyElastase- induced capillary and alveolar damage3 Alveolar flooding Fluid clearanceCapillary thrombosis Anticoagulant proteins Procoagulant proteins (Tissue Factor) Anti- fibrinolytic Protein (Plasminogen Activator Inhibitor)
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Post Acute PhaseFibroproliferative Phase3Variable time periodFibrosisChronic InflammationNeovascularisationResolution3Improvement of hypoxaemiaImproved dead space and lung complianceResolution radiographic abnormalitiesCan take up to 1 yearResidual restrictive or obstructive picture
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Long TermChronic Respiratory DiseaseMuscle FatigueMuscle WastingWeakness
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TreatmentVentilationFluid ManagementSteroidsOther Stuff
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VentilationTidal VolumesPEEPPositioningWeaning Protocols
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Tidal VolumeRecommended 4-6ml/kg4High tidal volumes4Overdistention of alveoliLocal inflammatory response resulting in systemic inflammationTNF, IL6, IL10,
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Tidal Volume4Low tidal volume ventilationWeight Predicted not actualPlateau Pressure 30cm H2OResp Rate Titrated to pH 7.3-7.45PEEP and FiO2 Adjusted to maintain saturationLow tidal volume may result in hypercarbiaARMA (Respiratory Management in ALI/ARDS Trial)NaHCO3 infusions/ hyperventilation to maintain pH
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Tidal VolumesSame sedation strategiesNo duration of ventilationHigh frequency oscillatory ventilation shown no benefit over low tidal volume ventilation 30 day mortality not statistically significant (37% vs 52%, p=0.10)Earlier recovery from hypoxiaOnly ventilation strategy shown to reduce mortality (40% - 31%)4
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PEEP Recommendation: lowest PEEP/ FiO2 to maintain saturationRecruits collapsed alveoliIn dependant regionsOver-distends in non-dependant regions Repetitive opening/ closing of alveoli: airway damageEndothelial/ epithelial stretch injury with subsequent capillary injurySimilar cytokine response as tidal volume
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PEEP
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PEEPALVEOLI Trial4Higher PEEP = improved oxygenationIn hospital mortality equal btw high and low PEEPTime on ventilator similarDuration non- pulmonary organ failure equal
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PEEPAdverse effects of PEEP Cardiac outputVolutrauma Lung water High VA/Q Dead space Endothelial permeability Epithelial permeability Bronchial blood flow
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Fessler, ARRD 1993
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PEEP + Lung PerfusionPermutt, JAP 1961
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PEEPSome EndpointsBest PaO2Lowest ShuntBest O2 deliveryBest lung perfusionPlateau Pressure 30cm H2OOptimise aeration on CTPressure/ volume curve becomes concave
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PositioningProne positioning1,4Redistribution of blood & ventilation to least affected areas of lungSecretion clearanceShifts mediastinum anteriorly assists recruitment of atelectatic areas? reduce lung injuryReduced lung compression by abdominal contents
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Supine Ventilation 40% lung volume under lung, especially patients with large hearts
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Prone Ventilation
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Effect of Blood Flow in Prone Positioning7Percent Flow25500SupineDorsalVentral
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PositioningProne position4Transient improvement PaO2/FiO2No improvement: survival/ time on ventilator/ time in ICURole:High FiO2High plateau pressures
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Weaning ProtocolsReduce duration of mechanical ventilation vs patients managed by IMV protocol4Daily spontaneous breathing trial430-120 mins unassisted ventilation4 Criteria before commencementSome reversal of underlying causePEEP 8cm H2O/ FiO2 50%Haemodynamic stabilityAbility to initiate inspiratory effort
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Fluid Management
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Fluid ManagementFluid movement regulated by:Starling equationVessel wallAbility to filter fluidSelective permeability to proteins
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Fluid Management
- Fluid ManagementStudy of conservative vs liberal fluid management560 day mortality: 25.5 vs 28.4% p=0.301st 28 days ventilator free: 14.6 vs 12.1 p
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SteroidsTheoretical use to inflammatory response associated with ARDS62006 study6No 60 day mortality (28.6% vs 29.2% p= 0.10)Use of steroids 14+ days post onset: mortality need for vasopressors ventilator and shock free days neuromuscular weaknessShort term improvement in oxygenation
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Other stuffExtracorporeal membrane oxygenationImprovement in oygenationNo long term survivalVasodilatorsImproved oygenationNo long term survivalKetoconazolePentoxyfillineNutritional modificationAntioxidantsSurfactantB2 stimulants1
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Emergency Department SummaryPREVENT!Low tidal volume ventilationRestrict PEEPRestrict Fluids (if possible)Initiate Weaning ProtocolSupine Ventilation
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ConclusionMany theoretical therapiesOnly proven strategy to improve survival is low tidal volume ventilationTherapies to reduce number of days needing scarce resources valuable in our setting
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Thank You
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References1. Wheeler, A.P. and Bernard, G.R. 2007,Acute Lung Injury and the Acute Respiratory Distress Syndrome: A Clinical Review. Lancet; 369: 1553652. The Acute Respiratory Distress Syndrome Network. 2000, Ventilation With Lower Tidal Volumes as Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute Respiratory Distress Syndrome. N Engl J Med; 342:1301-083 Plantadosi, C.A and Schwartz, D.A. 2004, The Acute Respiratory Distress Syndrome. Ann Intern Med; 141:460-470.4. Girard, T>D> and Bernard,G.R. 2007, Mechanical Ventilation in ARDS: A State-of-the-Art Review. Chest; 131;921-9295. The National Heart, Lung and Blood Institue Acute Respiratory Distress Syndrome Clinical Trials Network. 2006, Comparison of Two Fluid-Management Strategies in Acute Lung Injury. N Engl J Med; 354:2564-756. The National Heart, Lung and Blood Institue Acute Respiratory Distress Syndrome Clinical Trials Network. 2006, Efficacy and Safety of Corticosteroids for Persistent Acute Respiratory Distress Syndrome. N Engl J Med; 354:1671-847. www.slideshare.net