Lec 14 ARDS Flashcards
What characterizes ARDS?
- PaO2/FiO2 < 200
- hypoxemia
- bilateral lung infiltrates
- no left atrial HTN
What characterizes acute lung injury [ALI]?
Pao2/FIO@ < 300
less severe hypoxemia
What is most important cause of ARDS?
sepsis
What are some things that cause ARDS?
sepsis pneumonia aspiration pancreatitis trauma burn trasnfusion
What is incidence of acute lung injury? ARDS?
acute lung injury = 80 / 10,000
ARDS = 59 / 10,000
What do you see on pathology in ARDS?
diffuse alveolar damage [DAD}
failure of alveolar capillary membrane and flooding of alveolar airspaces with proteinaceous fluid
oxygen derived free radicals cause microvascular injury and multi-organ failure
What inflammatory cytokines involved in development of ARDS?
TNF-alpha
IL-1
IL-8
What happens to surfactant in ARDS?
have depletion of surfactant –> atelectasis, gas exchange disturbance and decreased pulmonary compliance
What happens to microcirculation in ARDS?
altered NO and cytokine induced activation of coagulation cascade
What happens to fibroblasts in late phase ARDS?
fibroblasts proliferate
What is VILI?
ventilator induced lung injury = caused by us; we give positive airways pressure ventilation
since ARDS is patchy –> there are patches of normal lung that get injured by the ventilation
cause barotrauma and volutrauma –> cytokines released
What is history of ARDS?
edema phase = 1st 2 days –> alveolar capillary basement membrane broken down; proteinacious fluid exudes into alveolar space
hyaline membranes organizing = starts day 2; peaks day 4 and declines by day 7
fibroblast proliferation = starts day 7 –> leads to interstitial fibrosis
What is exudative vs proliferative phase of ARDS?
exudative = 1st week; have edema + hyaline membranes
proliferative = 2nd week; have interstitial inflammation + fibrosis due to fibroblast proliferation
What is triad for ARDS diagnosis?
bilateral lung infiltration
hypoxemia
no LA hypertension
What does imaging tell you in ARDS?
- necessary for diagnosis to see bilateral lung infiltrate
- tells you nothing about the stage
What is treatment for ARDS?
treat underlying cause [sepsis, pneumonia, etc]
due low tidal volume ventilation to avoid VILI
What is the only ARDS treatment with known mortality benefit?
low tidal volume ventilation
What is mortality of ARDS?
28-42%
How does ARDS mortality differ with diagnosis?
worse prognosis if sepsis related compared to trauma/transfusion related
What are predictors of ARDS mortality?
- advanced age
- sepsis
- degree of other organ dysfunction
- co-morbidities
What happens to lung function after ARDS?
- survivors can have persistent restrictive impaired lung function
What are some non=pulmonary sequelae in ARDS?
- muscle wasting
- polyneuropathy
- neurocognitive impairment
- depression
- anxiety
- PTSD
What happens in neonatal respiratory distress syndrome?
- happens in premature babies < 37 wks
- have lack of surfactant –> rapid shallow breathing, flaring, retraction, cyanosis within minutes of birth
- ground glass on chest xray
What are findings in neonatal RDS?
- hypoxemia, hypercapnea
- ground glass on chest xray
Who is most at risk for neonatal RDS?
- premature babies
- mother with diabetes
How do you prevent neonatal RDS?
steroids to induce surfactant production between 24-34 wks of pregnany
What is treatment for neonatal RDS?
- CPAP
- vent support
- minimize O2 tox
- artificial surfactant
What is clinical course of neonatal RDS?
worse over 2-4 days then improved
