Acute Respiratory Distress Syndrome Flashcards
How is acute respiratory distress syndrome characterized?
- Clinical syndrome of a rapidly progressing state that occurs in critically ill patients (ICU)
- Three inclusion and one exclusion criteria
What are the risk factors of Acute Respiratory distress syndrome (ARDS)
- Sepsis
- Aspiration
- Lung contusion
- Toxic inhalation
- Near drowning
- Infection
- Multiple blood transfusions
How does the Berlin criteria describe ARDS
- Presentation within 1 week of clincial insult (I)
- New bilateral radiographic pulmonary opacities (I)
*not from HF, volume overload, effusion, atelectasis or nodules (E) - Ratio of partial pressure of arterial blood O2 to fractional concentration of inspired O2 is less than 300mmHg (I)
- Life threatening, acute, will eventually lead to failure
What is a normal health ratio of partial pressure of arterial blood O2 (Pao2) to fractional concentration of inspired O2 (Fio2)
> 400mmHg
What was the old term for Acute Respiratory distress syndrome
Adult respiratory distress syndrome
What is the etiology of ARDS
Systemic
*sepsis
Pulmonary
*aspiration of gastric contents
*Covid 19
What is the pathophysiology of ARDS
- Some event happens which leads to inappropriate host inflammatory response
*will be development of pulmonary edema, impaired gas exchange and possible fibrosis
What happens within the lung interstitial / alveoli during ARDS (activated neutrophils)
- Activated neutrophils leads to inflammatory cascade
*cytokines, pro coagulant molecules, oxidants, proteases, PAF, other toxic mediators
What happens within the lung interstitial / alveoli during ARDS (endothelia dysfunction)
- Endothelia dysfunction leads to tissue damage and the induction of pulmonary vasoconstriction, formation of micro vascular emboli, potential vascular remodeling, pulm HTN and eventually fibrosis
What happens to the alveolar space during ARDS
Fluid releasing from capillaries filling the alveolar space and preventing gas exchange
What is the acute stage of ARDS
Exudative stage (days 0-6)
1. Pulmonary edema with endothelial and epithelial damage
What is the subacute stage of ARDS
Fibroproliferative stage (days 7-14)
1. Edema improves
2. Epithelial repair with collagen and fibroblasts begins
What is the chronic stage of ARDS
Fibrotic stage (days 14 and later)
1. Cleared acute neutrophil infiltration but residual fibrosis remains
Will all patients with ARDS progress to the chronic stage
No
What are the S/sx of ARDS
Rapid onset of profound dyspnea (12-48 Hours) after insult
1. Labored breathing
2. Tachypnea
3. Intercostal retractions
4. Fever cough
5. Pink frothy sputum
6. Hypoxemia refractory to oxygen therapy
What will be positive on the PE
- Crackles bilaterally
- Mottling of the skin
How will ARDS show on the radiograph
- Diffuse or patchy bilateral infiltrates
- Ground glass appearance
*air bronchograms (80%)
*effusions
*will be able to see the costophrenic angles
How will ARDS show on the ABG
- hypoxemia
- hypercarbia
*possible respiratory acidosis
- hypercarbia
What is the “mild” category of ARDS according to oxygenation impairment
Pao2 / Fio2 (via ABG)
1. Ratio between 200 and 300mmHG
*mortality 27-35%
What is the “moderate” category of ARDS according to oxygenation impairment
Pao2 / Fio2 (via ABG)
1. Ratio between 100 to 200mmHG
*mortality 32-40%
What is the “severe” category of ARDS according to oxygenation impairment
Pao2 / Fio2 (via ABG)
1. Ratio less than 100mmHG
*mortality 45%
What is the DDx of ARDS
- Cardiogenic pulmonary edema
*emergent echocardiogram (use)
*berlin criteria can be used to confirm ARDS diagnosis
What is the treatment and management of ARDS
- Prone positioning and mechanical ventilation
*must provide adequate gas exchange - Identify and treat what caused it
- Meticulous supportive measures
Is there any proven prevention or prophylactic techniques for ARDS
No
How long should early prone positioning be done
- > 16 hours following 12-24 hours of ventilator stabilization
What is the pharmacological intervention of ARDS
- Careful fluid management
- Diuretics
- ATB
- Corticosteroids
*in critical hyperglycemia
What is high frequency oscillatory ventilation (HFOV) (tx of ARDS)
- Oscillatory pump will deliver very high respiratory rates
- Recommended against routine used
- For COVID 19 last ditch, salvage methods for refractory hypoexmia
What is extracorporeal membrane oxygenation (ECMO) (tx of ARDS)
- Venous-venous ECMO used to bypass the lung
- Reserved for patients with severe, refractory ARDS who have not responded to standard supportive therapies
*Will decrease 90 mortality of severe ARDS
What is the prognosis of ARDS
- Multiple organ failure
- Mortality 40 to 60%
What is the usual COD of ARDS
- Sepsis
- Multiple organ dysfunction syndrome
- Withdrawal of mechanical ventilation
Who will have a better prognosis of ARDS
- Trauma associated ARDS
- Low-tidal volume MV
Who will have a poorer prognosis of ARDS
- Sepsis
- Failure to improve within first week after diagnosis / initiation of tx
What patient population usual survives ARDS
Younger who originally have healthy pulmonary function
What is the recovery timeframe of ARDS
6 to 12 months bc of complications
1. Pneumonia
2. Pneumothorax
3. Atelectasis
4. Permanent lung injury
5. Tracheostomy placement
