ARDS LECTURE

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ACUTE RESPIRATORY DISTRESS SYNDROME : 

ACUTE RESPIRATORY DISTRESS SYNDROME DR. JAYAKUMAR. R. M.D., ASST. PROFESSOR, DEPT. OF PULMONARY MEDICINE, CHETTINAD HOSPITAL & RESEARCH INSTITUTE

ACUTE RESPIRATORY DISTRESS SYNDROME : 

ACUTE RESPIRATORY DISTRESS SYNDROME Synonyms: Non-Cardiogenic pulmonary edema Adult hyaline membrane disease Capillary leak syndrome Stiff lung syndrome Shock lung

DEFINITION : 

DEFINITION ACUTE LUNG INJURY (ALI): A syndrome of inflammation and increased permeability that is associated with a constellation of clinical, radiologic, and physiologic abnormalities that cannot be explained by, but may co-exist with, left atrial or pulmonary hypertension. ARDS: Severe form of ALI

CRITERIA FOR ALI & ARDS : 

CRITERIA FOR ALI & ARDS

ARDS causes : 

ARDS causes Direct Lung Injury: Aspiration of gastric contents Diffuse pulmonary infections (bacterial, viral, fungal) Pulmonary contusion Near drowning Inhalation injury Reperfusion pulmonary edema after lung transplant Radiation

ARDS causes : 

ARDS causes Indirect lung injury: Sepsis Severe trauma w/ shock hypoperfusion Acute pancreatitis Severe burns TRALI (Transfusion related acute lung injury) Cardiopulmonary bypass Anaphylaxis Lymph reticular malignancy

ARDS - PATHOGENESIS : 

ARDS - PATHOGENESIS Insult (direct or indirect) Activation of inflammatory cells & mediators Damage to alveolar capillary membrane Increased permeability of alveolar capillary membrane Influx of protein rich edema fluid and inflammatory cells into air spaces Dysfunction of surfactant

PATHOLOGICAL STAGES OF ARDS : 

PATHOLOGICAL STAGES OF ARDS Exudative (acute) phase (0- 4 days) Proliferative phase (4- 8 days) Fibrotic phase ( >8 days) Recovery

PHYSIOLOGICAL ABNORMALITIES : 

PHYSIOLOGICAL ABNORMALITIES Decreased ventilation Impaired diffusion Reduced perfusion

CLINICAL FEATURES – symptoms : 

CLINICAL FEATURES – symptoms Precipitating insult is usually evident Early (24 – 48hrs) - cough, breathlessness, fatigue Late (after 48hrs) - due to worsening hypoxemia - agitation, anxiety, confusion

CLINICAL FEATURES – signs : 

CLINICAL FEATURES – signs Dyspnoea Tachypnoea Tachycardia Restlessness Cyanosis even with supplemental oxygen ( refractory hypoxemia)

Differential diagnosis : 

Differential diagnosis Cardiogenic pulmonary edema Diffuse alveolar hemorrhage Acute pulmonary embolism Acute eosinophilic pneumonia Hypersensitivity pneumonitis Pulmonary alveolar protienosis Sarcoidosis Leukemic infiltration Drug induced pulmonary edema

Investigations : 

Investigations Chest x-ray & CT thorax: bilateral diffuse alveolar infiltrates more on the peripheral lung fields. R/O Cardiogenic edema if there is * cardiomegaly * pulmonary artery dilatation * bat’s wing perihilar distribution * responding to diuretics

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Ards

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Cardiogenic pulmonary edema

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NEONATAL RESPIRATORY DISTRESS SYNDROME

INVESTIGATIONS : 

INVESTIGATIONS Arterial blood gas analysis: PaO2 range 55 – 60 mm of Hg Initially respiratory alkalosis later mixed acidosis Routine CBC, urea, creatinine, Na, K Echocardiogram to R/O Cardiogenic cause. PAWP < 18mm of Hg  ALI / ARDS Bronchoscopy ( CCF,DAH,AEP)

ASSESSMENT OF SEVERITY : 

ASSESSMENT OF SEVERITY Murray lung injury score: - Chest x-ray - Hypoxemia - PEEP - Compliance Score 0  no lung injury o.1 – 2.5  mild to moderate lung injury > 2.5  severe lung injury

POOR PROGNOSIS FACTORS : 

POOR PROGNOSIS FACTORS Advanced age Male sex Extra pulmonary organ dysfunction Sepsis HIV Alcoholism Active malignancy Organ transplantation

Treatment of ALI/ARDS : 

Treatment of ALI/ARDS

Complications (ACUTE) : 

Complications (ACUTE) ACUTE RESPIRATORY FAILURE VENTILATOR ASSO PNEUMONIA VENTILATOR ASSO LUNG INJURY (VALI) DVT AND PULMONARY EMBOLISM PRESSURE SORES

Complications (CHRONIC) : 

Complications (CHRONIC) REDUCED EXERCISE CAPACITY DECREASED QUALITY OF LIFE POST TRAUMATIC STRESS DISORDER (depression, anxiety, decreased memory & concentration) Rarely acquired cystic lung disease may develop

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Thank you