ARDS Flashcards
What does ARDS stand for?
Acute Respiratory Distress Syndrome
What are some other common terms for ARDS?
Wet lung; post traumatic lung
What is ARDS?
Severe, acute onset and progessive alveolar and capillary damage
What is the mortality rate for ARDS?
35-60%. It is very high unless intervene happens promptly
What happens if a pt does not receive treatment within minutes
They will lose all respiratory function and die
What occurs to the alveolar?
There is diffuse alveolar damage (“rubbery appearance”)
List the etiology of ARDS.
- Aspiration
- near drowning, inhaling water
- aspiration of gastric contents - Drugs, toxins, therapeutic agents
- drugs (cocaine & heroin if inhaled)
- Caught in fire, inhaling excessive amounts of smoke
- breathing high concentrations of oxygen
- radiation - Infections - septicemia
- Trauma and shock
- burns
- fat embolism
- chest trauma - Disseminated intravascular coagulation
- Multiple blood transfusions
Explain the pathology of ARDS
Trauma to the lung tissue and cells cells that make up the lung wall results in increased capillary permeability
- Increased cap permeability results in an influx of inflammatory cells, plasma proteins, and exudate form the capillaries into the interstitial space and then into the alveoli. Cells entering target injured cells (elastic/epithelial cells), creating cellular debris. Pulmonary edema occurs as there is fluid inside the alveoli, compliance is compromised and the expansion of the alveoli is limited. Activated neutrophils release a variety of products that damage the alveolar cells. Damage to T2 alveolar cells results in inability to produce surfactant. The damaged cells release free radicals causing oxidative damage and inflammatory cells release proteases that break down protein structures of the lung also causing damage = injury to the capillaries and alveoli. With a buildup of cellular debris and exudate that is rich in protein a thick “membrane” forms and lines the alveoli referred to as the hyaline membrane.
What do the inflammatory cells include?
Platelets, neutrophils, macrophages
What happens with decreased surfactant in ARDS
it causes the surface tension within the alveoli to decrease and widespread atelectasis throughout all of the alveoli in the lungs
Why does hyaline refer to?
glossy, hard appearance/structure
Is the hyaline membrane an anatomic membrane?
No, it develops d/t influx of cells etc
What is significant about the hyaline membranes lining?
It is impervious meaning that nothing can move across it so gaseous exchange cannot occur -> profound hypoxia
Explain what would happen if gases could move across the hyaline membrane.
The diffusion distance would be to large for effective gas exchange
What do you end up with in ARDS?
Diffuse consolidation
Manifestations of ARDs
- acute respiratory distress
- tachypnea (response to hypoxia; compensatory)
- tachycardia (compensatory)
- dyspnea
- profound hypoxemia
- lung consolidation
What is lung consolidation?
solidification of exudate and inflammatory debris (seen on chest xray)
What are some complications that can arise from ARDS
- Pulmonary HTN
- Early respiratory alkalosis
- Late metabolic acidosis
- Multi-organ failure
Why does pulmonary HTN occur as a complication?
Compensatory vasoconstriction d/t hypoxemia
Why does early respiratory alkalosis occur as a complication?
Occurs with tachypnea as excess CO2 is exhales, decreases the ability to form carbonic acid, increasing pH
Why does late metabolic acidosis occur as a complication?
Tachypnea causes an increase in the workload of respiratory muscles, increases their demand for ATP with decrease gas exchange. O2 is in a low supply to complement the ETC, so aneorobic metabolism occurs. (Glycolysis which produces an excess of lactic acid) Build up of lactic acid results in acidosis (it is metabolic bc it is a fixed acid)
Why does multi-organ failure occur as a complication? Which organs in particular are impacted?
D/t widespread hypoxemia
- Brain, heart, kidney, liver
Treatment for ARDS?
- STAT detection and intervention which is not always possible
- Respiratory support (O2 if gas exchange is not completely impaired; mechanical ventilator for more advanced resp support)
- address any underlying cause
- deal/manage the complications
