B4.058 - Acute Lung Injury and Respiratory Distress Syndrome

Question 1

Answer 1

cardiogenic pulmonary edema

microhemorrhages –> hemosiderin-containing macrophages in thealveoli

“heart cells”

if prolonged, numerous hemosiderin laden macrphages nad fibrosis make brwon induration

Question 2

Answer 2

B. Hemodynamic pulmonary edema

Question 3

Answer 3

RDS gross appearance

congested, atelectatic lung (like liver)

usually sink in water

Question 4

Answer 4

DAD fibrosis

Question 5

what is ARDS

Answer 5

clinical syndrome characterized by the rapid onset of severe life threatening respiratory insufficiency, cyanosis, and severe arterial hypoxemia that is refractory to oxygen therapy. Chest radiographs show diffues aveolar infilatrates. May progress to extrapulmonary multisystem organ failure.

Question 6

Answer 6

pulmonary hypoplasia

Question 7

managemenf of RDS

Answer 7

assess lung maturity using amniotic fluid phospholipids

prevent labor

induce maturity with corticosteroids

surfactant replacement therapy

oxygenation/ventilation

Question 8

Answer 8

immature lung

Question 9

histo manifestation of ALI and ARDS

Answer 9

DAD

diffuse alveolar damage

Question 10

Answer 10

lamellar bodies (precursor of surfactant) within a type 2 pneumocyte

Question 11

pulmonary hypoplasia

Answer 11

another cause of acute respiratory distress in infants, due to poorly developed lungs

Question 12

causes of ARDS

Answer 12

diffuse pulmonary infections (viral, mycoplasma, miliary TB, pneumocystis

gastric aspiration

sepsis

trauma (incl. head injury)

Question 13

causes of pulmonary edema

Answer 13

hemodynaminc - cadiogenic

microvascular injury - direct increase in vasc permeability

undetermined origin - head injury, HAPE

Question 14

Answer 14

cardiogenic pulmonary edema

Question 15

resolution of ARDS/DAD

Answer 15

resorption of the exudate and dead cell removal by macrophages

macrophages also discharge fibrogenic cytokines (TGFbeta and PDGF) –> fibroblastic proliferation and collagen deposition –> alveolar wall fibrosis

Epithelial cell repopulation from proliferation fo bronchilar stem cells

endothelial repopulation from proliferation of undamaged capillaries

Question 16

other causes of respiratory distress syndrome in neonate

Answer 16

Question 17

pathogenesis of ARDS

Answer 17

endothelial activation

pneumocyte injury –> sensed by resident alveolar macrophages –> secrete mediators TNF –> endothelium

Circulating mediators activate pulmonary endothelium (severe tissue injury or sepsise)

endothlelial cells expresss increased adhesion molecules, procoagulant proteins and chemokines.

Question 18

management of DAD

Answer 18

treat underlying cause and supportive care. average mortaility is 40%

Question 19

potential complications of acute lung injury in adults

Answer 19

air leaks

unresolved fibrosis

superinfection

can be fatal

Question 20

Answer 20

renal abnormalities seen with pulmonary hypoplasia due to oligohydramnios

Question 21

Answer 21

pulmonar edema - cardiogenic

Question 22

retinopathy of prematurity phases

Answer 22

1 - hyperoxic phase, marked reduction of VEGF, endothelial cell apoptosis

2 - comparatively hypoxic room air, retinal vessel proliferatiol (neovascularization)

Question 23

pathophys of RDS

Answer 23

prematurity means reduced surfactant –> incfased ST –> atelectasis –> uneven perfusion and hypoventilation –> hypoxemia and CO2 retention –> acidosis, pulm vasoconstriction –> pulm hypoperfusion –> ednothelial and epithelial damage –> leaky plasma –> hyaline mebrane

Question 24

commonest cause fo respiratory distress in infants

Answer 24

RDS lack of surfactant in immature lungs

Question 25

Answer 25

organization phase of ARDS/DAD

Question 26

describe the adhesion and migration of neutrophils in ARDS

Answer 26

neutrophils degraulate --\> inflammatory mediators, including proteases, reactive oxygen species, and cytokines. Macrophage migration inhibitory factor (MIF) helsp to sustain proinflammatory reponse --\>increase recruitement of leukocytes --\> more endothelial injury and local thrombosis

Question 27

what is acute lung injury

Answer 27

concardiogenic pulmonary edema abrupt onset of significant hypoxemia nad diffuse pulmonary infiltrates in the absesce of cardiac failure **ARDS** is severe **ALI** inflammation associated increase in pulmonary vascular permeability and epithelial and endothelial cell death

Question 28

histo of RDS

Answer 28

presence of hyaline membranes in peripheral airspaces

Question 29

CXR for RDS

Answer 29

ground glass opacification

Question 30

what reparative changes happen after 48 hrs in RDS

Answer 30

alveolar epithelium growsn under hyaline membrane may detach into airspace partial digestion or phagocytosis by macrophages

Question 31

signs of cardiogenic pulmonary edema

Answer 31

perivascular and isterstitial fluid accumulation, particularly in theinterlobular septa, responsible for Kerleys B lines on x ray progressive edematous widening of alveolar septa accumulation of edema fluid in alveolar spaces --\> wet, heavy lungs with frothy blood tinged fluid

Question 32

pathogenensis of intraalveolar fluid and hyaline membranes in ARDS

Answer 32

endothelial damage --\> pulmonary capillaries leaky --\> interstitial and itraaveolar edema necrosis of type 2 alveolar pneumocytes leads to surfactant abnormailities --\> comprominsing alveolar gas exchange protein rich edema fluid and debris from dead alveolar epthelial cells organize int hyaline membranes

Question 33

what is wide spread pulmonary edema from microvascular injury

Answer 33

significant contributor to ARDS

Question 34

causes of hemodynaic pulonary edema

Answer 34

increased hydrostatic pressure - left sided heart failure, volume overload, pulm vein obsturction decreased oncotic pressure - low protein states, hypoalbuminemia, renal disease lymphatic obstruction

Question 35

bronchopulmonary dysplasia

Answer 35

potentially reversible abnormality in avleolar septation --\> fewer, larger alveoli --\> reduction in surface area available for gas exchange dysregulation of pulmonary vasculature superimposed effects of hyperoxia, hyperventilation, prematurity, inflammation, vascular maldevelopment

Question 36

causes of pulmonary edema from microvascular injury

Answer 36

infections inhaled gases liquid aspiration drugs and chemicals shock trauma radiation transfusion related

Question 37

Answer 37

normal mature alveoli

Question 38

what are hyaline membranes

Answer 38

debris consisting of damaged cells, exudative necrosis, leaked protein lining the alveolar sacs

Question 39

Answer 39

hyaline membrane disease hyaline membrane is composed of fibrin and necrotic cells within peripheral airspaces

Question 40

Answer 40

DAD - fibrosis

Question 41

role of surfactant in initial respiration

Answer 41

first brewth of life needs high inspiratory pressures to expand lungs, in subsequent breaths it requries much less in surfactant deficiency each breath takes as much effort as the first because the lungs collapse with additional breath

Question 42

pulmonary edema anatomic compartment pathogenesis pathphys histo

Answer 42

anatomic compartment - alveolar-capillary interface pathogenesis - **hemodynamic** disturbances or **injury to the the alveolar septa** leading to extravasation of fluid pathophys - decreased diffusing capacity and compliance histo - **congestion** of alveolar capillaries and **fluid filled aveoli**

Question 43

what is persistent fetal circulation

Answer 43

PDA foramen ovale

Question 44

pulmonary edema

Answer 44

increase in insterstitial fluid which then accumulates within the alveolar sacs

Question 45

what kinds of inhalants can cause ARDS

Answer 45

oxygen in high concentrations

Question 46

pathogenesis of pulmonary edema form microvascular injury

Answer 46

alveolar septa affected damage to vascular endo/epithelium with secondary vascular injury inflammatory exudate --\> interstitial space --\> alveoli (severe)

Question 47

increased risk of transient tachypnea of the newborn

Answer 47

C section diabetic mother

Question 48

what produces surfactant

Answer 48

T2 pneumocytes lecithin, phosphatidyl, glycerol are components of surfactant

Question 49

summarize ARDS effects of epithelial and endothelial injury

Answer 49

Question 50

neonatal respiratory distress syndrome

Answer 50

observed worldwide in premature infants of all racial and ethnic groups lack of surfactant and lung immaturity

Question 51

complications of bronchopulmonary dysplasia

Answer 51

severe disease requires prolonged mechanical ventilation, may develop pulmonary hypertension and cor pulmonale

Question 52

pathogenic factors of RDS

Answer 52

insulin (moms diabetic) and congenital surfacatnt deficiency lead to decreaseds surfactant - baby senses high blood sugar and increases insulin production which negatively affects surfactant production glucocorticoids lead to increased surfactant - this is why labor instead of C section is protective, it puts stress on the body which increases endogenous steroid release which helps produce surfactant. C sections do not cause endogenous steroid release

Question 53

Answer 53

full term lung

Question 54

Answer 54

diaphragmantic hernia seen with pulmonary hypoplasia due to chest wall abnormalities

Question 55

typical clinical scenario of RDS

Answer 55

preterm, male infant, maternal diabetes, delivered by C section labored breathing and cyanosis fine rales, flaring nostrils, increased RR

Question 56

potential complications of neonatal RDS

Answer 56

air leaks complications of oxygen therapy - bronchopulmonary dysplasia, retrolental fibroplasia PDA intraventricular hemorrhage necrotizing enterocolitis

Question 57

what is acute interstitial pneumonia

Answer 57

ALI/DAD of unknown etiology rare, usually older usually follows upper respiratory tract like illness

Question 58

a male infant born at 28 weeks to a diabetic mother develops severe respiratory difficulty 30 minutes after birth. Most likely Dx\>

Answer 58

RDS of the neonate

Question 59

what is transient tachypnea of the newborn

Answer 59

pulmonary edema resulting from delayed resoption and clearance of fetal aveolar fluid shortly after deliveryin full term or late preterm babies

Question 60

Answer 60

DAD hyaline membranes