6.2 Acute Respiratory Distress Syndrome (ARDS) Flashcards
ARDS
- Acute, inciting (violent) inflammation followed by hypoxemic respiratory failure.
- Common injuries that cause this include pneumonia, sepsis, or trauma but does not have to be a respiratory injury. These injuries lead to pulmonary infiltrates, hypoxemic respiratory failure, and associated high probability of mortality.
Fulminant - Any event which occurs suddenly, quickly and is intense to the point of lethality
Fulminant ARDS - Acute lung inflammation and diffuse alveolar-capillary injury
Acute Lung Injury (ALI)
- Less severe than ARDS
- Lets fluid, protein, etc flow into lungs
Process
- Lung injury
- Inflammation
- Pulmonary Edema
- Hypoxemia
Supine
- In this position lung tissue is more susceptible to compression by heart or abdominal viscera.
- In ARDS there is fluid filled lungs that are heavy which increases pleural pressure
- Ventral alveoli become overinflated and dorsal alveoli become further compressed
Prone Position
- Fewer differences between dorsal/ventral transpulmonary pressure
- This allows recruitment of otherwise collapsed dorsal alveoli
EDUCATION
- This is a high risk procedure
- Caregivers lack confidence
- Manual simulation training leads to good outcomes
DEVELOPMENT OF PROTOCOL
- Physician leader
- Nurse (3-4 to turn patient and another nurse to protect vascular/arterial accesses)
- Respiratory therapist (protects the ET tube and reposition head during maneuver)
Position Steps
Supine to Prone
- Each nurse position on each side of the bed
- Decide which side to turn the patient based on lines of ventilator
- Check patients hematologic status and level of sedation and move tubes as close to patient as you can
- Protect pressure sores with adhesive pads
- Move patient horizontally and move the hand on the side of rotation underneath them
- Prepare new bedsheet
- Rotate to side lying position for a short time while 1 person removes electrodes from anterior to posterior
- After this use bed sheet to pull patient into final prone position (horizontal at 180 degrees)
- Abdomen is usually not supported
- Lastly move patient to center of bed, turn patients head laterally and turn head every 2 hours
Prone to Supine
- Horizontal move (towards the direction the nose is pointing)
- Rotate to side-lying position, remove electrodes from anterior to posterior
- Complete supine position by pulling bed sheet into position
Times
Average time to recognize a code situation - 19.3 seconds
Resupinate Maneuver - 44 seconds
Time to implement CPR - 9.7 seconds
Placement of backboard - 23.2 seconds
POSITIONING
- In medical emergencies, to resupinate a patient pull the patient in the same direction the nose is pointing (The Nose Knows)
Conditions that can Cause ARDS
Causes
- Direct injury to lungs (smoking)
- Indirect injury to lungs (shock)
- Most common cause of death is non-pulmonary MODS often with sepsis and multiple trauma
Others
- Major Trauma, Sepsis
- Pneumonia
- Acute Pancreatitis
- DIC
- Metabolic Events
- Reactions to Drugs
- Burns
- Aspiration
- Cardiopulmonary Bypass
- Oxygen Toxicity
- Smoking
- Radiation
Pathologic Lung Changes
- Acute injury of alveolocapillary membrane and pulmonary edema leads to massive inflammation
- Cell injury causes increased alveolar capillary permeability which leads fluid, plasma protein and blood cells to shift from vascular component to alveoli and interstitiam. This causes edema fluid, surfactant inactivation, formation of hyaline membrane and alveolar collapse (which leads to impaired gas exchange)
Hyaline - Glassy, pink substance
- Severe inflammation that causes alveolar damage which results in pulmonary edema, which increases infiltrates (seen on x-ray) hypoxemia unresponsive to oxygen supplementation regardless of PEEP and absence of elevated left arterial pressure.
- Ventilation-Perfusion (VQ) mismatch is caused by blood going through non-functioning areas of the lungs which causes shunting which causes impaired gas exchange resulting in refractory hypoxemia.
Refractory Hypoxemia
- PaO2 < 50 with FIo2 >70% (oxygen) for >12-24 hours.
INTERVENTIONS
- INCREASE PEEP (positive end expiratory pressure)
- Use oscillating vent
- If not on a vent use inhaled vasodilators, prone position and corticosteroids
- Neuromuscular blocking agents, sedatives and analgesics may improve patient-ventilator synchronization to decrease severe hypoxemia
- Inhaled nitric oxide (endogenous vasodilator) can also help reduce VQ mismatch and improve oxygenation
Neutrophils - Accumulate early in treatment and synthesize/release a variety of inflammatory mediators
- Proteolytic Enzymes
- Toxic oxygen species
- Cause increased inflammatory response (which causes injury to capillary endothelium and alveolar endothelium)
AS DISEASE PROGRESSES
- Work of breathing becomes harder as lung stiffens and becomes more difficult to inflate
- Impaired gas exchange and profound hypoxia
Clinical Manifestations of ARDS
- Rapid onset 12-18 hours of initiating event
- Increased RR, HR
- Refractory Hypoxemia (less than 50 O2 on 70%+ supplemental O2)
- Signs of respiratory failure
- Chest X-rays show bilateral infiltrates of lung tissue without cardiac dysfunction
- Multiple Organ Failure (Kidneys, GI, CNS, CV)
- Anxiety/Restlessness
- SOB, Accessory muscle use, cough, altered LOC, Cyanosis, Crackles
- Hypotension
Diagnostic
- Physical exam shows crackles when fluid starts leaking into lungs and intercostal retractions
- CBC, BMP, CXR, CT, Plasma Brain Natriuretic Peptide (BNP), Echocardiography, Pulmonary Artery Catherization
Chest X-ray - Shows fluid in both lungs “infiltrates”
- ABSENSE OF HEART DISEASE WHICH CAN ALSO CAUSE FLUID IN LUNGS
- Worsens a few days after diagnosis before lungs start to heal
BNP
- Distinguishes ARDS from Cardiogenic Pulmonary Edema
- If BNP is not available transthoracic echocardiography may be used
Management of ARDS
- Meds, ETT, Mechanical Ventilation, Adequate Fluid Volume, Nutritional Support, Circulatory Support
PEEP - Helps function residual capacity, reverse alveolar collapse, reduce VQ imbalances, and allows lower level FIO2
Meds
- Neuromuscular blockers, vasopressors (hypotension from hypovolemia),
Nursing Management of ARDS
- Same as acute respiratory failure but with anxiety control
- Frequent position change to reverse atelectasis and facilitate removal of secretions
- Elevate HOB greater than 30 degrees to prevent ventilator associated pneumonia
- Prone position with “Stryker Frame or Roto-Prone” therapy systems to improve pulmonary gas exchange, facilitate drainage, and prevent consolidated dependent alveoli (supine position) in dorsal lung region.
RISKS OF PRONE POSITION
- Loss of airway control due to accidental extubation
- Loss of vascular access
- Facial edema and pressure ulcers
- Difficult for cardiopulmonary resuscitation
- TREAT UNDERLYING CONDITION
Ventilator Use in ARDS
- Improve oxygenation while minimizing lung damage from over pressurized lungs
PROTOCOL
- SaO2 Maintained at 88-92%
- Low Tidal Volume (4 mL/kg)
- Higher respiratory rate to compensate
- High PEEP (10-20 mmHg)
