acute respirtaory distress syndrome
TRANSCRIPT
ACUTE RESPIRTAORY DISTRESS SYNDROME
ACUTE RESPIRATORY DISTRESS SYNDROME
• Define ARDS (Primary & Secondary)• Stages of ARDS• Lung Protective Ventilation• Prone Position / ECMO
ACUTE RESPIRATORY DISTRESS SYNDROME
Acute Respiratory Distress Syndrome (ARDS) is defined as a:
“syndrome of acute and persistent lung inflammation with increased vascular permeability” (Hansen-Fletcher et al)
ACUTE RESPIRATORY DISTRESS SYNDROME
Clinically, ARDS is characterized by:
• acute onset (< 48 hours)• bilateral infiltrates• PaO2/FiO2 ratio
<300mmHg• No evidence of cardiac
causes
ACUTE RESPIRATORY DISTRESS SYNDROME
ARDS can be caused by direct injury to the lungs (primary) or indirect injury (secondary)
ACUTE RESPIRATORY DISTRESS SYNDROME
PneumoniaPulmonary ContusionsAspirationInhalation Injuries
ACUTE RESPIRATORY DISTRESS SYNDROME
SepsisBurnsOverdosesBlood TransfusionsFat Embolisms
ACUTE RESPIRATORY DISTRESS SYNDROME
Lung injury creates an immune & inflammatory response. The alveolus fill with protein-rich edema, WBC, RBC while the hyaline membrane thickens.
This causes:
• ↓PaO2• ↓Compliance• ↑PaCO2• Respiratory Failure
ACUTE RESPIRATORY DISTRESS SYNDROME
ARDS Mild ARDS
Moderate ARDS
Severe ARDS
ARDS can be mild (200-
300mmHg), moderate
(<200mmHg), or se
vere
(<100mmHg)
ACUTE RESPIRATORY DISTRESS SYNDROME
• Slow restoration of lung function
Recovery Stage
• 7—21 days• Alteration of lung
tissue• Poor Compliance• Decreased Edema
Proliferative Stage
• 0-7 days• Edema (peaks
048hrs)• Inflammation
Exudative Stage
Furthermore, ARDS has three stages:
ACUTE RESPIRATORY DISTRESS SYNDROME
Unfortunately, some patient can develop with pulmonary fibrosis.
ACUTE RESPIRATORY DISTRESS SYNDROME
ARDS
Direct ARDS
Indirect ARDS
Mild ARDS
Moderate ARDS
Severe ARDS
Lets review:
ARDS is classified by its cause: direct or indirect lung injury.
Its severity: mild, moderate and severe.
Its stages: exudative, proliferative and recovery.
ACUTE RESPIRATORY DISTRESS SYNDROME
ARDS
Mechanical Ventilation
Ventilator Associated Lung Injury
Immune & Inflammatory
Response
Worsening ARDS
Cycle of Injury: Mechanical ventilation can worsen ARDS and cause long-term disability (ie: pulmonary fibrosis)
ARDS patient frequently require mechanical ventilation.
How can this be a problem?
ACUTE RESPIRATORY DISTRESS SYNDROME
How can mechanical ventilation worsen ARDS?
Barotrauma: too much pressure (>35mmHg)
Atelectotrauma: collapse and expansion of the alveoli
Volutrauma: too much tidal volume
ACUTE RESPIRATORY DISTRESS SYNDROME
Lung Protective Ventilation
Small Tidal Volumes (VT)
High Respiratory
Rate
Minimize Airway Pressures (PIP &
PLT)
Adequate PEEP
Lung protective ventilation attempts to prevent volutrauma, barotrauma and atelectotrauma with:
ACUTE RESPIRATORY DISTRESS SYNDROME
Small tidal volume & high respiratory rate
Adequate PEEP
PEAK Pressure <35-40
ACUTE RESPIRATORY DISTRESS SYNDROME
PaO2<60mmHg PaCO2>80mmHgPH <7.1 Peak >45cmH20
What if lung protective ventilation fails?
ACUTE RESPIRATORY DISTRESS SYNDROME
Lung Protective Ventilation
Prone Positio
n
ECMO
Rescue Therapy: • Prone Position• VV-ECMO
ACUTE RESPIRATORY DISTRESS SYNDROME
The Prone Position:
• Improves perfusion to the lungs → Better V:Q matching• The diaphragm drops and the heart shift forward → Improved compliance• Improved lung recruitment • Lung Protective• Indicated:
• Moderate to Severe ARDS• Early (<48hours)• Duration: 12 – 16 hours
ACUTE RESPIRATORY DISTRESS SYNDROME
VV-ECMO:
• Provides oxygenation and removal of CO2• Allows the lung to rest (breaking the cycle of lung injury)• Blood movement is facilitated by an external pump• Indicated:
• Early (<7days)• Severe ARDS
ACUTE RESPIRATORY DISTRESS SYNDROME
In review:
• The prone position may be beneficial early (<48hours) in moderate to severe ARDS
• VV-ECMO may be indicated in severe ARDS when conventional therapy has failed.
ACUTE RESPIRATORY DISTRESS SYNDROME
(1) Hansen-Flaschen, J., Siegel, M. (2009). Acute respiratory distress syndrome: definition; epidemiology; diagnosis; and etiology. Up to Date
(2) NIH-NHLBI ARDS Network (www.ards.net)
(3) Fessler, H., Talmor, D. (2010). Should prone position be routinely used for lung protective during mechanical ventilation?. Respiratory Care. 55(1); 89-98
(4) Capital District Health Authority, Prone Positioning/Proning. #CC45-075
(5) Guerin, C., Reignier, J., Richard, JC., Beuret, P., Gacouin, A., Boulain, T., Mercier, E., Badet, M., Mercat, A., Budin, O., Clavel, M., Chatellier, D., Jbar, S., Rosselli, S., Mancebo, J., Sirodot, M., Hilbert, G., Bengler, C., Richecoeur, J., Gainner, M., Bayle, F., Boudin, G., Laery, V., Girard, R., Baboi, L., Ayzac, L.(2016). Prone position in severe acute respiratory distress syndrome. New England Journal of Medicine, 368, 2159-2168
Extras:Acute Respiratory Distress Syndrome:https://www.youtube.com/watch?v=cVCvYxVxSt4
Lung Protective Ventilation:https://www.youtube.com/watch?v=5hdpBRMdZ9M