Respiratory Flashcards
Fetal lung fluid plays a critical role in lung devleopment. Prior to birth, ~30% of fetal lung fluid is cleared from he alveoli and airways. Of the following, which anion/cation is actively transported across the pulmonary epithelial cells to induce fetal lung absoprtion prior to delivery?
Sodium
At 12 hours of age, a term infant devleops unequal chest wall movements during spontaneous breathing with moderate retractions on the L side and mild retractions on the right side. The R chest appears to collapse more with inspiration than the L side. What is the diagnosis?
R-sided diaphragmatic paralysis
An infant is born with a TE fistula. At what stage of lung devleopment did this occur
Embryonic; other anomalies that can occur during this phase are laryngeal clefts ,tracheal stenosis, and pulmonary sequestration
An infant is born with a CDH. At what stage of lung devleopment did this occur?
Pseudoglandular; other abnormalities include braching abnormalities of the lung, bronchogenic cysts, congenital lobar emphysema, cystic adenomatoid malformations. CDH occurs secondary to failure of the pleuro-peritoneal closure
At what stage in lung devlopment can pulmonary hyoplsia occur?
canalicular or saccular
True or false: a self inflating bag cannot reliably delivery free flow 100% O2
TRUE
What are the physiologic changes seen in a tension PTX?
decrease in PaO2, increase in HR and CVP, decrease in arterial BP and pulse pressure, and decrease in cerebral O2 delivery
What can delay alveolarization?
antenatal steroids (despite the increased benefit of increased fetal surface area), supplemental O2 (hyper and hypo O2), nutritional deficiencies, mechanical ventilation, insulin, protein kinase C,
How is NO produced in the lungs?
in the enothelial cells lining the pulmonary blood vessels, nitric oxide synthase converts L-arginine into nitric oxide; then NO is used by guanylyl cyclase to convert GTP to cGMP which relaxes smoother muscle
What receptor is involved in fetal lung fluid secretion?
NA-K-2Cl transporter and Cl channels (ClC2 and ClCN2); inhibited by Bumetanide, beta adrenergics and vasopressin
What drug inhibits ENaC channels?
amiloride
What drug inhibits Na-K-ATPase?
Ouabain
lung over inflation leads to cessation of inspiration- name the reflex
hering Breur inflation reflex, NB>adults
inhibition of the Hering Breur reflex results in extended inspiraton; causes a paradoxical increase in diaphragmatic contraction during inflation
paradoxical reflex of head; important during the first few breaths after birth
increased in ventilation rate with a/w abrupt deflation of the lungs
hering bruer deflation reflex. Occurs with PTX and ‘sighs”
What is the hallmark of new BPD?
alveolar/ capillary hypoplasia
What is the principle lipid in surfactant?
saturated phosphatidyl choline (dipalmitoylphosphatidylcholine) that makes up 50% of surfactant and is responsilbe for the formation of the lipid monolayer and thereby reduction in the surface tension.
What is the primary function of SP-B?
promotes absorption and speading of surfactant. (SP-C does this too). critical for surfactant function; type II cell functions
Infant presents with severe respiratory failure soon after birth. What surfactnant protein is deficient? What is the genetic mutation most commonly seen in individuals of Northern European desccent?
SP-B homozygote deficient (AR); SP-B is encoded by the SFTPB gene on chromosome 2. The most common mutation in Northern Europeans is the framshift mutation (121in22). It accounts for 60-70% of all sFTPB allele mutants identified to date
Name the hypdrophobic surfactant proteins
SP-B and SP-C
name the hydrophilic surfactant proteins
SP-A and SP-D
This surfactant protein helps regulate surfactant expression and uptake and is also a collectin and is part of the innate immume system; tubular myelin. The most abundant surfactant protein
SP-A
This surfactant protein regulates surfactant reuptake and recycling, is a collectin, and is part of the innate immune system; antioxidant
SP-D
Name the malformations that can happen in the lung during the embryonic phase
atresias (Laryngeal, esophageal, tracheal); bronchogenic cysts, TEF, pulmonary agenesis/aplasia, pulmonary sequestration