ARDS Flashcards
Causes of ARDS
Alveolar capillary interface becomes damaged and more permeable to intravascular fluid –alveoli fill with fluid
Sepsis Pneumonia Aspiration Trauma Massive transfusions Pancreatitis Shock states
Inflammation!!
How do we define ARDS clinically
Acute onset
Bilateral infiltrates
Severe, refractory hypoxemia PaO2/FiO2 ratio
PaO2/FiO2 ratios and severity of ards
200-300 mild
100-200 moderate
<100 severe
Refractory hypoxemia results from & leads to..
Severe V/Q mismatch & shunting of pulmonary capillary blood
Unresponsive to increasing O2 concentrations
Lungs are less compliant
Increased airway pressures must be generated.
Exudative phase changes
Inflammatory mediators • Disruption of alveolar capillary membrane • Fluid in the alveoli • V/Q mismatch • Loss of surfactant=alveolar collapse
Manifestations of Exudative phase
Tachypnea and tachycardia • Mild hypoxemia and respiratory alkalosis caused by hyperventilation • Dyspnea, tachypnea, cough, restlessness • Chest auscultation may be normal or may reveal fine, scattered crackles
Proliferative phase changes
Inflammatory mediators cross ACM = damaged alveolar and capillary epithelium = diffusion defects • V/Q worsens • Pulmonary HTN due to hypoxemic vasoconstriction=R HF • Fibrotic changes
Proliferative phase manifestations
Decreased lung compliance=increased work of breathing=tachypnea • Hypercarbia and worsening refractory hypoxemia • Diaphoresis, decreased LOC, cyanosis, and pallor • Increased peak inspiratory pressures
Fibrotic phase changes
Changes • Diffuse scarring • Worsening pulmonary HTN • Worsening V/Q mismatch, diffusion defects and shunting
Fibrotic phase manifestations
• R sided HF • Decreased BP, CO • Refractory hypoxemia • Tissue hypoxia/lactic acidosis
Diagnostic labs and testing for ARDS
• CXR – bilateral infiltrates – Ground glass appearance • Laboratory testing – ABGs – CBC with differential – Cultures – CMP
Treatment for ARDS
• Treat the Cause! • Mechanical Ventilation with PEEP • Diuresis • Antibiotics • Steroids - improve oxygenation, not survival – use is controversial • Hydration – maintain circulatory volume, decrease viscosity of secretions • Nutrition
Mechanical ventilation
– Low Tidal Volumes to reduce barotrauma
– High PEEP to aid in recruitment
– No mode proven to improve outcomes
– Requires advanced airway
Positive End Expiratory Pressure
PEEP
• Increase FRC and open up collapsed alveoli
• Higher levels of PEEP are often needed to maintain
Pa
O
2 at 60 mm Hg or greater
• High levels of PEEP can compromise venous return
•
↓ Preload, CO, and BP
Nursing O2 managment
Nursing • Optimize O2 delivery – Frequent assessment – hemodynamic and ventilatory – Keep the airways clear • Minimize O2 demand - Decrease O2 consumption – Comfort – Sedation – Pain relief – Neuromuscular blockade
