ARDS SEMINAR

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Slide 1:

9/19/2011 1 ACUTE RESPIRATORY DISTRESS SYNDROME

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PRESENTER : 2 Dr. Radha Madhavi Dr. Rakesh Chintalapudi 9/19/2011 MODERATER :

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Acute Respiratory Distress Syndrome Adult Respiratory Distress Syndrome New Born Respiratory Distress Syndrome ? ? ? ? 9/19/2011 3

A R D S :

9/19/2011 4 A R D S Term first introduced in 1967 Synonyms Shock lung Da Nang Lung Traumatic wet lung

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Definition 9/19/2011 5

The 1994 North American-European Consensus Conference (NAECC) criteria: :

The 1994 North American-European Consensus Conference (NAECC) criteria: 9/19/2011 6 Onset - Acute and persistent Radiographic Criteria - Bilateral Pulmonary infiltrates consistent with the presence of edema.

(NAECC) criteria: :

(NAECC) criteria: Oxygenation criteria - Impaired oxygenation regardless of the PEEP concentration, with a Pao 2 / Fio 2 ratio  300 torr (40 kPa) for ALI and  200 torr (27 kPa) for ARDS . 9/19/2011 7

(NAECC) criteria: :

(NAECC) criteria: 9/19/2011 8 Exclusion Criteria - Clinical evidence of Left Atrial Hypertension or a Pulmonary - artery catheter Occlusion Pressure > 18 mm Hg .

Aetiology :

9/19/2011 9 Aetiology

Direct Insult :

Aspiration Pneumonia Pneumonia Direct Insult C O M M O N 9/19/2011 10

Direct Insult :

Inhalation Injury Pulmonary contusions Fat Emboli Near Drowning Reperfusion Injury Direct Insult L E S S C O M M O N 9/19/2011 11

Indirect Insult :

Indirect Insult Sepsis Severe Trauma Shock C O M M O N 9/19/2011 12

Indirect Insult :

Indirect Insult Acute Pancreatitis Cardio Pul. Bypass T R A L I D I C Burns Head Injury Drug Over dosage L E S S C O M M O N 9/19/2011 13

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P athophysiology 9/19/2011 14

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9/19/2011 15 Basic Insult is Damage to Lung Lung Unit – the Alveoli

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9/19/2011 16 NORMAL ALVEOLUS

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9/19/2011 17 INJURED ALVEOLUS

Phases Of ARDS :

Acute - Exudative , inflammatory : capillary congestion, neutrophil aggregation, capillary endothelial swelling, epithelial injury; hyaline membranes by 72 hours (0 - 3 days) 9/19/2011 18 Phases Of ARDS

Phases Of ARDS :

Sub-acute - proliferative: proliferation of type II pneumocytes (abnormal lamellar bodies with decreased surfactant) , fibroblasts intra-alveolar, widening of septae (4 - 10 days) 9/19/2011 19 Phases Of ARDS

Phases Of ARDS :

Chronic - fibrosing alveolitis : remodeling by collagenous tissue, arterial thickening, obliteration of pre-capillary vessels; cystic lesions ( > 10 days) 9/19/2011 20 Phases Of ARDS

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Overall Picture 9/19/2011 21 Increased pulmonary shunt. Increased dead space ventilation. Reduced pulmonary compliance. Increased work of breathing. Hypoxemia Hypoxemia

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Overall Picture 9/19/2011 22 Respiratory failure requiring mechanical ventilation.

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9/19/2011 23 Diagnosis Plasma BNP (< 100 pg/ml) 2 D Echo Pulm . artery Cath.

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9/19/2011 24 Diagnosis Pulmonary edema, Diffuse alveolar hemorrhage Acute interstitial pneumonia Idiopathic acute eosinophilic Pneumonia

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9/19/2011 25 Ex udative phase Diagnosis

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9/19/2011 26 F ibrotic phase Diagnosis

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Therapy

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9/19/2011 28 Ventilatory Strategy Non Ventilatory Strategy Supportive Measures

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9/19/2011 29 “Lung Protective Strategy” The NIH A R D S NET Recommendations Ventilatory Strategy 816

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9/19/2011 30 Ventilatory-based Strategies in the Management of ARDS/ALI Two powerful Bombs Two poor Victims PRESSURE VOLUME

Modes :

Modes 9/19/2011 31 Both Volume cycled ventilation (VCV) and Pressure controlled ventilation (PCV) modes can be used with lung protective strategy depending upon whether it is more important to control airway pressures or to control tidal volume .

Modes :

Modes 9/19/2011 32 However, choosing appropriate ventilatory goals (VT and airway pressure) is far more important than the particular mode. In general, fully supported modes of ventilation (e.g. A/C) are favored over partially-supported modes ( SIMV + PSV OR SIMV only) particularly early in the course of the disease.

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Low Tidal volume Strategy (6-8 ml/kg predicted body weight) Plateau pressure ≤ 30 cm H2O 9/19/2011 33

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Open Lung Concept with alveolar recruitment with P C V High PEEP Strategy : Prevention of VILI : 9/19/2011 34

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Recruitment Maneuvers : Ventilation In Prone Position : 9/19/2011 35

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FiO2 < 0.6 I R P C V H F O V A P R Ventilation 9/19/2011 36

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9/19/2011 37 The open lung concept is physiologically based on the Law of Laplace. Adhering to the principles of the open lung concept, pressure controlled ventilation may improve patient out come during Mechanical Ventilation Open Lung Concept P = 2T/R

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9/19/2011 38 What is Open Lung Concept ? Poiseuille's P = 2T/R Alveolar stability The degree of this surfactant damage will determine the amount of pressure needed to expand alveoli from closed to open .

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Open Lung Concept 9/19/2011 39 Normally aerated Poorly aerated Consolidated areas Hyper inflated areas

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9/19/2011 40

Open Lung Concept:

Open Lung Concept This combines low tidal volume Optimally applied PEEP to maximize alveolar recruitment and aims to mitigate alveolar over-distension and cyclic Atlectasis. The goal of the open lung concept procedure is to recruit alveoli and maintain them open with the least changes in pressure to minimize alveolar shear forces 9/19/2011 41

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Elevate PEEP to stay away from zone of derecruitment Lower VT to stay away from over distension zone (P plat < 30cm) Increase rate if higher MV is needed (but use permissive hypercapnia) pH >7.25 Eliminate added mechanical dead space (could increase Vd / Vt ratio with lower Vt’s . 9/19/2011 42

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9/19/2011 43 CYCLICAL ATELECTASIS A – alveoli derecruitment B – optimal recruitment inflation C – alveolar over distension D – optimal inflation Optimal Volume Optimal PEEP C B A D

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Driving pressure = P plat – PEEP Goal – keep DP as low as possible Lower Vts & Higher PEEPs Keeps you out of zone A (derecruitment) and zone C ( over distension) - prevent VILI 9/19/2011 44

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9/19/2011 45

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9/19/2011 46 CYCLICAL ATELECTASIS A – alveoli derecruitment B – optimal recruitment inflation C – alveolar over distension D – optimal inflation Optimal Volume Optimal PEEP C B A D

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9/19/2011 47

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Predicted Body Weight 9/19/2011 48 Ideal Body Weight Calculating Predicted Body Weight Male = 50 + 2.3 (height in inches - 60) Male = 50 + 0.91(height in cm - 152.4) Female = 45.5 + 2.3 (height in inches - 60) Female = 45.5 + 0.91 (height in cm - 152.4)

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9/19/2011 49 What is Barotrauma ? Excess PP >50 mmHg can lead to air leaks Pneumothorax , Pneumomediastinum, SC Emphysema, Pneuopericardium

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Gas Extravasation Barotrauma

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9/19/2011 51 What is Volutrauma ? Damage to the lung (Alveoli) caused by Over distension by a Mechanical Ventilator set for an excessively high tidal Volume ( ?)

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9/19/2011 52 What is Atelectrauma ? Low lung volume surfactant is squeezed out leading to alveolar collapse, repeated collapse and reopening leads to a shear stress particularly early in the course of lung injury.

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Recognized mechanisms of Airspace Injury 9/19/2011 53 “Shear” Airway Trauma Stretch

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9/19/2011 54 What is Biotrauma ? Inflammatory products are released secondary to mechanical factors lead to MODS.

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9/19/2011 55 Volutrauma Atelectrauama Barotrauama Biotrauma Ayyoraama

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9/19/2011 56 Healthy Lung Areas V A L I V I L I (Heterogeneous distribution Of disease pattern )

Link between ALI & MOSF :

9/19/2011 57 Link between ALI & MOSF

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9/19/2011 58 Place on Pressure Control Raise Peak Inspiratory pressure to 40 -60 cmH2O 10 breaths Minimal Adjust peak Inspiratory Pressure to lowest Pressure without loss of recruitment Titrate ventilator P I P and Mean Inspiratory pressure to the smallest Possible difference I : E Ratio 1 : 1 or 2 : 1 PEEP 10 – 20 cm Keep PEEP in range of 10 – 20 cm

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9/19/2011 59 Recruitment Maneuvers Sustained high airway pressure with the goal to open collapsed lung tissue, after which PEEP is applied sufficient to keep the lungs open. CPAP 40 cm H2 2O for 40 seconds Intermittent Sighs

Still Confusing :

9/19/2011 60 S till Confusing How Much ? So Let’s Review

Tidal Volume :

9/19/2011 61 Tidal Volume How Much ? 6 to 8ml/ pbw WHAT IS THE LIMIT ! Pplat: plateau or pause pressure of 30 to 35

P E E P :

P E E P 9/19/2011 62 Recruits alveoli by opening them Improves compliance and oxygenation Decreases shunt fraction and work of breathing GOAL SpO2 88 to 92% FiO2 40 to 60% SpO2 90% at FiO2: 60% PEEP is applied in 2 to 4cm increments 5to 24cm of H2o

How much P E E P :

How much P E E P 9/19/2011 63 PEEP/FIO2 Relation - Double the FIO2 value to know the required PEEP level and if the chest wall compliance is low then add 4 to PEEP. Example - If FIO2 is 0.8 PEEP required is 8x2=16 , if the chest wall compliance is low then add 4 to PEEP i.e. 16+4=20 FiO2 .30 .40 .40 .50 .50 .60 .70 .70 .70 .80 .90 .90 .90 1.0 PEEP 5 5 8 8 10 10 10 12 14 14 14 16 18 18-24

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9/19/2011 64 High Frequency Oscillation : A Whole Lotta Shakin ’ Goin ’ On

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H F O V Rapid rate Low tidal volume Maintain open lung Minimal volume swings 9/19/2011 65

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H F O V Uses mean airway pressure ( mPaw ) to open lung alveoli (decrease intrapulmonary shunt) which ventilates above derecruitment zone on P-V curve (set 3-5 cm above previous mPaw ) Uses small tidal volumes which ventilates below the over distension zone on P-V curve (set between 85-95 amplitudes) 66

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H F O V Uses high respiratory rates of 180 –300 bpm (set between 3-7 hertz) Goal to use enough m Paw to keep Fi0 2 <0.60 and utilize permissive hypercapnia (Ph > 7.20) 67

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Why - H O F V Delivers small pressure swings at the alveolar level preventing Barotrauma 9/19/2011 68 Delivers small tidal volumes at the alveolar level preventing Volutrauma

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Why - H O F V Delivers a high level of continuous airway pressure preventing Atelectrauma 9/19/2011 69 Allows the use of lower levels of FiO2 preventing oxygen toxicity

High Frequency Oscillatory Ventilation:

9/19/2011 70 High Frequency Oscillatory Ventilation

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9/19/2011 71 High Frequency Oscillatory Ventilation

High Frequency Transtracheal Ventilation:

9/19/2011 72 High Frequency Transtracheal Ventilation Infra Glottic Supra Glottic

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9/19/2011 73 Liquid Ventilation With Per fluorocarbons

Liquid Ventilation :

Liquid Ventilation Perfluorocarbon have excellent oxygen and carbon dioxide carrying capacity (50 ml O 2 /dl and 160-210 ml CO 2 /dl, respectively). They are clear, odorless, inert fluids which are immiscible in aqueous and most other solutions 2 types of techniques : TLV -- PLV TOTAL LIQUID VENTILATION PARTIAL LIQUID VENTILATION 9/19/2011 74

Liquid Ventilation :

Liquid Ventilation There are six perfluorocarbon gases Tetrafluoromethane Hexafluoroethane Octafluoropropane 9/19/2011 75 Perflurocyclobutane Perfluoro - iso -butane Perfluoro-n-butane

Liquid Ventilation :

Liquid Ventilation Virtually all the other commercially available perfluorocarbon are liquids (the exception being perfluorocyclohexane, which sublimes at 51 C. Liquid breathing Eye surgery Imaging Artificial blood Decompression sickness 9/19/2011 76

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Partial Liquid Ventilation 9/19/2011 77 Relevance

Liquid Ventilation :

Liquid Ventilation 9/19/2011 78 Surface Tension lowered

Non – Ventilatory Strategies in A R D S / ALI :

9/19/2011 79 Non – Ventilatory Strategies in A R D S / ALI

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9/19/2011 80 Fluid & Hemodynamic Management Inhaled Nitric Oxide Prone Position Steroids Other Drug Therapy

Prone Positioning :

9/19/2011 81 Prone Positioning Limits the expansion of Cephalic & parasternal Lung regions Relieves the Cardiac & abdominal compression exerted on the lower lobes

PRONE :

9/19/2011 82 PRONE

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9/19/2011 83 Makes regional ventilation/perfusion ratios and chest Elastance more uniform Facilitates drainage of Secretions Potentiates the beneficial effect of recruitment Maneuvers .

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9/19/2011 84 Prone Positioning Relieves Lung Compression by the Heart

:

Absolute Contra Indications : Burns or open wounds on the face or ventral body surface Spinal instability Pelvic fractures Life-threatening circulatory shock Increased intracranial pressure 9/19/2011 85 Prone Positioning

Main complications :

9/19/2011 86 Main complications Facial and periorbital edema Pressure sores displacement of the endotracheal tube, Airway Obstruction Hypotension Arrhythmias Vomitings

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9/19/2011 87 Corticosteroid Therapy in ARDS: Better late than E arly & never?

A R D S :

9/19/2011 88 A R D S Do not lessen the incidence of ARDS among patients at high risk Do not reverse lung injury in patients with early ARDS/worse recovery Have no effect on mortality/even increase mortality ratesignificantly increase the incidence of infectious complications. High dose corticosteroids in early ARDS

Corticosteroids :

9/19/2011 89 Corticosteroids Aggressive search for and treatment of Infectious complications is necessary Appropriate time window for corticosteroid administration between early acute injury and established post aggressive fibrosis .

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9/19/2011 90 Supportive Measures

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Nutritional Care Deep Vein Thrombosis Prophylaxis General Condition -Bed Sores prevention Indwelling Invasive Lines - Care 9/19/2011 91

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9/19/2011 92 Take Home Message

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9/19/2011 93 Take Home Message

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94 9/19/2011 www.ards.org www.ardsnet.org www.ardsusa.org Luck favors Hard work THANK YOU

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