Respiratory

Question 1

How to treat pneumomediastinum?

Answer 1

Observe. Usually resolves spontaneously

Question 2

____ is actively transported across pulmonary epithelial cells to air spaces to create fetal lung fluid. Changes to ____ secreting to move fluid out of alveolar air spaces.

Answer 2

Chloride / Sodium. 30% of FLF is absorbed PTD

Question 3

Diaphragm paralysis, the affected side has ____ movements compared to unaffected side. The _____ side is more common (_____ sign)

Answer 3

LESS movement on affected side. R side more common. Kienbock’s sign.

Question 4

Which stages of lung development have which pathologies?

Answer 4

Embryonic: TEF, tracheal stenosis, laryngeal cleft:
Pseudoglandular: CDH, bronchogenic cyst, CCAM/CPAM, congenital lobar emphysema
Canalicular: pulmonary hypoplasia
Saccular: pulmonary hypoplasia

Question 5

Difference between CCAM and bronchopulmonary sequestration?

Answer 5

CCAM: congenital cystic adenomatoid malformation. Cystic lesion occurs in developing lung. Supplied by PULMONARY circulation and connected to tracheobronchial tree

Bronchopulmonary sequestration: non-functioning lung tissue. NOT connected to tree. receives blood from systemic circulation.

Question 6

By what principles does HFOV work?

Answer 6

PAM TB
Pendelluft effect: differential movement of gas as result of diff time constraints
Asymmetric velocity of gas
Molecular diffusion: across alveolar gradients all factor in gas exchange
Taylor dispersion: parabolic movement of inspired gas that allows for increased area for diffusion
Bulk Convection: bulk axial gas flow

Question 7

How many types of surfactant are there? Which is NOT in exogenous surfactant?

Answer 7

A, B, C, D. SP-A is NOT in exogenous surfactant No clinical dz in deficiency of D. A is most abundant. B is “better” for you.

Question 8

Type I vs Type II pneumocytes? Which comes first?

Answer 8

Type II –> Type 1 pneumocytes
Type II: cuboidal, 10% of alveolar surface. Greater # of cells in alveolar lining. Important role in SURFACTANT metabolism and secretion
Type I: fried egg, tight junctions. 90% of alveolar surface. Important role in gas exchange, no gene material for surfactant.

Question 9

Surfactant is mostly comprised mainly of _____

Answer 9

Lipids. Phosphatidylcholine desaturated (50%), monosaturated (20%)

Question 10

Most common organisms associated with chorioamnionitis?

Answer 10

ureaplasma and mycoplasma

Question 11

Prenatal corticosteroids help mature fetal lung by ______? Postnatal corticosteroids help by ______?

Answer 11

Antenatal: Decreasing amount of mesenchymal tissue and increasing potential airspace volume. Arrest alveolar septation.

Postnatal: arrest alveolar septation and microvascular development

Question 12

BPD Definition (2000 NIH)

Answer 12

Mild: O2 for 28 days, RA at 36 weeks
Moderate: O2 x 28 days plus <30% O2 at 36 weeks
Severe: same, but >30% O2 and/or PPV

Question 13

New BPD pulmonary changes?

Answer 13

Consistent with ALTERED lung development. Arrest of alveolarization with increased alveolar diameters and fewer alveoli. Hyperinflation, minimal cystic emphysema. Less airway reactivity compared to “classical” BPD. Less pulmonary HTN, minimal fibrosis.

Question 14

Factors that help distribute surfactant admnistration

Answer 14

Gravity, higher volume, faster rate of administration, positive pressure to distribute, higher volumes of fetal lung fluid/edema helps distribute

Question 15

Central chemoreceptors that respond to CO2 are located on ____. Mechanoreceptors are located on ____ and respond to TV. Oxygen peripheral chemoreceptors are located on _____.

Answer 15

ventrolateral surface of medulla; airway smooth muscle; carotid and aortic bodies

Question 16

Bohr equation and measuring dead space?

Answer 16

Volume of CO2 in expired air = volume of CO2 from dead space + volume of CO2 from alveoli that are V/Q

Question 17

What is physiologic, alveolar, and anatomic dead space?

Answer 17

Anatomic: conducting airways (bronchoconsriction decreases dead space)
Alveolar: alveoli that are not involved in gas exchange with vasculature
Physiologic = anatomic + alveolar

Question 18

Fetal breathing is interrupted by?

Answer 18

Prostaglandin

Question 19

A-a gradient equation?

Answer 19

[FiO2(760-PH2O) - PaCO2/R] - PaO2
R = 0.8

Question 20

3 observations about apnea of prematurity

Answer 20

1) decreased ventilatory response to hypercarbia
2) irritation of laryngeal mucosa induces inhibition of breathing (superior laryngeal nerve)
3) Hypoxic ventilatory depression is reaction to sustained hypoxia (mediated centrally in pons by inhibitory NT like adenosine). Caffeine is competitive antagonist of adenosine

Question 21

Locations and names of sodium pumps to get fluid out of lungs

Answer 21

Apical surface: amiloride sensitive ENaC - actively transports Na from alveolar lumen into respiratory cell (dev. expressed, increase also after endogenous steroids/catecholamines of labor)

Basolateral cell membrane: Na-K-ATPase, transports Na from the respiratory cell into interstitial

Water follows via aquaporins

Question 22

How long before echo shows improvement of PH on sildenafil?

Answer 22

2 weeks

Question 23

Boyle’s Law
Charles’ Law
Dalton’s Law
Fick’s Law
Henry’s Law

Answer 23

BL: at constant temp, given V of gas varies inversely to P to which subjected
CL: warm gas expands, cool gas shrinks
DL: Total + by mixture of gases = sum of partial pressure of each gas
FL: transfer of solute by diffusion directly proportional to XS area available for diffusion
HL: at constant temp, any gas physically dissolves in liquid proportion to PP

Question 24

Choanal atresia has problem b/w which weeks of development?

Answer 24

Failure of bucconasal membrane to rupture b/w 5-6th weeks of development. Unilateral more common. Can be bony or membranous obstruction or both. Most are sporadic, most have associated malformations. More common in females.

Question 25

How many alveoli does term infant have at birth?

Answer 25

50-150 million alveoli (adults have 200-600 million)

Question 26

When have chylothorax, switch to enfaport bc

Answer 26

lymphatic vessels not required for absorption of MCT Chylothorax: transudative effusion; pH > 7.4, WBC < 1K, LDH < 200. >80% lymphocytes, TG > 110

Question 27

Corticosteroid effects prenatally can be seen on US?

Answer 27

No! Less fetal breathing and movements, HR less variability. Fetal blood flow NOT affected.

Question 28

Describe classic BPD (Pre surfactant era)

Answer 28

structural damage of normal pulmonary structures from mechanical ventilation and oxygen toxicity - airway squamous metaplasia, alveolar septal fibrosis, airway smooth muscle hypertrophy, marked inflammation

Question 29

Describe new BPD

Answer 29

disruption of normal alveolar/vascular development; diffuse alveolar/capillary hypoplasia. Significant loss of surface area for gas exchange. Airway injury, inflammation, fibrosis are milder

Question 30

What is the primary component of surfactant?

Answer 30

saturated phosphatidylcholine presents 50% of surfactant.

Question 31

Which surfactants are hydrophobic and hydrophilic? Which are more important to function

Answer 31

Surfactant B and C are hydrophobic, A/D are hydrophilic B/C - critical to optimal dynamic behavior and function of surfactant and facilitate ABSORPTION AND SPREADING of phospholipid monolayer A/D: collectins; part of host innate system A: regulate surfactant expression and uptake D: surfactant reuptake and recycling

Question 32

Describe function of surfactant B. What is the gene mutation associated?

Answer 32

critical to surfactant function, facilitates adsorption of surfactant lipids to air-liquid interface SFTPB gene on chromosome 2 MC mutation in individuals of northern european descent = frameshift mutation (121ins2)

Question 33

Who in preterm neonates benefits from iNO

Answer 33

iNO in preterm neonates studied, no diff in incidence of death or BPD Neonates BW > 1 kg, iNO decreased incidence of death or BPD from 60 to 30%

Question 34

How does caffeine act in the brain?

Answer 34

primary effects by antagonism of adenosine A1/A2 receptors in brain

Question 35

Mechanism of action of glucocorticoids

Answer 35

anti-inflammatory effect by annexin A1 synthesis —> decreased phospholipid A2 expression —> decreased production of prostaglandins, thrombaxnes, prostacyclins, leukotreienes

Question 36

What is primary reason why there is less MAS now?

Answer 36

fewer births > 41 weeks

Question 37

Incidence of intermittent hypoxia episodes during first few months of life

Answer 37

low incidence in first week —> progressive increase between 2-3 weeks, peaks at 4-5 weeks; plateau or decrease during weeks 6-10

Question 38

When does TTN resolve? When do X-ray findings show it?

Answer 38

TTN - resolves within 72 hrs - Xray findings clear after 24 hrs

Question 39

When was surfactant approved for use bye FDA? When did NIH recommend antenatal steroids?

Answer 39

surfactant: 1989 Steroids: 1994

Question 40

What is most utilized finding to see if there is PH on echo?

Answer 40

TR Jet

Question 41

Dexamethasone is _____ times more potent than hydrocortisone. Name adverse effects.

Answer 41

25-50 times adverse effects: hyperglycemia, hypertension, HOCM, growth failure, GI bleeding and perf, chronic suppression of hypothalamic-pituitary-adrenal axis, ND outcomes

Question 42

Name some mechanisms for lasix resistance

Answer 42

- Distal tubule cell hypertrophy, altered furosemide oral absorption, concomitant NSAIDS that inhibit prostaglandins, blunt response to loop diuretics, decreased delivery to thick ascending loops

Question 43

How does chorio affect lung maturation?

Answer 43

can induce lung maturation and decrease RDS, but can lead to diffuse PNA presenting as respiratory distress

Question 44

What is the NAVA Break point

Answer 44

NAVA level is at a plateau phase, PIP and TV do not increase further as result of down regulation of Edi Edi peak = measure of neural inspiratory effort or respiratory drive Edi min: measure of tonic activity of diaphragm, or effort to prevent alveolar de-recruitment at end expiration trigger: minimum increase in electrical activity from preceding baseline that will trigger ventilator NAVA level: conversion factor that converts Eni signal into proportional pressure

Question 45

What is lucinactant (surfaxin)

Answer 45

third generation surfactants that are synthetic that contain proteins capable of mimicking properties of surfactant protein B and C

Question 46

What gram stain are tracheal aspirates?

Answer 46

94% are gram negative. BAL --> 62% are pseudomonas

Question 47

Where and how is caffeine metabolized?

Answer 47

Liver via N7 demethylation process; matures with increasing GA and PMA Caffeine metabolism higher in girls In VLBW infants, caffeine clearance and Vd are lower, increasing linearly with increasing weight

Question 48

How many types of CPAM and describe them

Answer 48

5 types, typically in lower lobes. No L/R predilection. 40% of all congenital lung malformations. 0 rare: limited to upper tracheobronchial tree 1 70 %: macro-cystic (>2 cm), may have dominant single cyst or multiple cysts 2 (20%): multi cystic with size > 2 cm 3 (10%):: microcystic adenomatoid solid without cystic elements, can be associated with other anomalies and carries worse prognosis 4 (rare): hamartomatous malformation of distal acini with peripheral cysts.

Question 49

Intratracheal buesonide + surfactant compared to surfactant alone =

Answer 49

Prelim studies show intratracheal budesonide with surfactant compared with surfactant alone required lower MAP for ventilation, lower OI and PCO2 during first 24-48 hrs

Question 50

SpO2 in umbilical vein

Answer 50

Umbilical vein = O2 sat 70-75%; decreases to 60% prior to birth (same as NRP)

Question 51

Benefits of conventional lymphography, lymphoscintigraphy

Answer 51

Conventional lymphography – best anatomical details, but requires direct cannulation of lymphatic vessels Lymphoscintigraphy – feasible in neonates but lower resolution than conventional. Performed by injecting radioisotope into webs b/w neonate’s fingers and toes and may provide information on lymph vessels aplasia, hypoplasia, or dysplasia MR lymphangiography, noninvasive, is best at evaluating nodes, poor resolution for evaluation of lymph vessels

Question 52

What is inherited disorder of surfactant metabolism?

Answer 52

mutations in surfactant protein SP B, SP-C adenosine triphosphate-binding cassette member A3 (ABCA3) and NKX2-1 genes ABCA3 – variable clinical presentation – acute resp distress vs interstitial lung dz in infancy or childhood. Lamellar bodies with eccentric dense inclusionsP

Question 53

What is inositol

Answer 53

essential nutrient shown to promote surfactant maturation. Meta-analysis = significantly decreases neonatal death

Question 54

What is risk for preterm neonates with BPD developing PH?

Answer 54

25-35%

Question 55

Incidence of congenital lung abnormalities

Answer 55

1 in 10k

Question 56

Describe lung development

Answer 56

Embryonic (0-7 weeks): formation of lung bud and conducting airways (trachea, lobar, segmental/subsegmental bronchi) Pseudoglandular (7-17 weeks): branching morphogenesis with formation of 20 generations of conducting airways, terminal bronchioles, and closure of pleuroperitoneal folds. Type 22 pneumocystis are undifferentiated. Canicular (16-27 weeks): terminal branching, respiratory bronchioles with establishment of early air-blood interface, alveolar ducts, PRIMITIVE ALVEOLI. Differentiation of type II pneumocytes with emergence of lamellar bodies Saccular (26-36): Enlargement of peripheral airways, saccule formation with thinning of alveolar wall, SURFACTANT production in type II pneumocytes at 26 weeks. Alveolar: 36 weeks-2 yrs: formation of terminal alveoli, secondary inter-saccular and inter-ductal septation with exponentional increase in lung SA for gas exchange. Further thinning of alveolar wall

Question 57

How does iNO improve respiratory function

Answer 57

* Decrease V/Q mismatch secondary to decrease in PVR and pulmonary vasodilation * Decrease in lung inflammation secondary to reduction in early neutrophil accumulation * Decreased oxidant stress * Protection against surfactant dysfunction * Restoration of normal angiogenesis and parenchymal growth

Question 58

How does lung injury affect surfactant function?

Answer 58

Inactivation by environmental exposure (oxidants), degradation by LIPASES, conversion to inactive structural forms, inhibition of function by plasma protein and lipids, altered synthesis by alveolar type 2 cell secondary to circulating cytokines

Question 59

Mechanisms of central apnea

Answer 59

Preterm neonates have enhanced sensitivity of respiratory control system to inhibitory neurotransmitters such as serotonin Hypoxic ventilatory depression 2/2 increased peripheral chemoreceptor sensitivity in carotid bodies Impaired hypercapnic ventilatory response and apnea threshold only slightly below eupnea threshold Exaggerated laryngeal chemoreflex Increased amount ofa ctive sleep associated with generalized inhibition of skeletal muscle activity

Question 60

Describe central and peripheral effects of caffeine

Answer 60

Stimulate medullary respiratory centers, increase co2 sensitivity, bronchodilation, enhanced diaphragmatic function, increased MV, reduced hypoxic respiratory depression, stimulate CNS and CV, increase catecholamine secretion, enhance diuresis, antagonize prostaglandin activity

Question 61

Describe congenital lobar emphysema. What stages of lung development do problems occur?

Answer 61

Congenital lobar emphysema - also known as CL hyperinflation; overdistension of one or more lobes, potentially causing severe respiratory compromise Etiology: dysplastic cartilage formation in canalicular stage or endoluminal obstruction resulting in ball-valve effect in saccular and alveolar stages of lung development

Question 62

How does ACE activity get affected in BPD?

Answer 62

increased ACE activity —> fluid retention and increase risk of BPD

Question 63

What is CAP trial?

Answer 63

lower rates of severe retinopathy of prematurity among caffeine-treated group compared with placebo group CAP trial - improved respiratory outcomes with caffeine, decreased need for intervention for PDA, decreases in death / disability at 18 months

Question 64

Cell count for Chylothorax

Answer 64

WBC > 1000 cells (80% monos, ie lymphocytes) Protein count similar to plasma TG > 100

Question 65

What factors help with surfactant administration?

Answer 65

larger volume, faster rate, ventilator assistance, lung fluid improves distribution, positional maneuvers help

Question 66

Mechanism for meconium aspiration syndrome

Answer 66

Airways obstruction is prominent early PVR and PPHN - typically improve within 3-4 days Surfactant dysfunction - subacute and late phases of dz Chemical pneumonitis, secondary infection can occur

Question 67

the problem with INSURE

Answer 67

can alter cerebral perfusion and EEG activity

Question 68

When are trach-ed patients weaned off?

Answer 68

weaned off PPV by 5th Bday and median weaning time of 2 years

Question 69

How to dx VAP

Answer 69

dx is subjective Radiographic - new or pgoressive infiltrate, consolidation Clinically worsening gas exchange At least 3 - temp instability, leukopenia, leukocytosis, left shift, change in secretion pattern, apnea or increase in work of breathing, abnormal lung auscultation, bradycardia or tachycardia

Question 70

Who is at risk for TTN? other than CS.

Answer 70

SGA/LGA are at increased risk for TTN. Males more susceptible. Maternal hx of asthma or GDM.

Question 71

Mechanism of bubble CPAP

Answer 71

variable distending pressure due to submerged expiratory limb in water. RCT showed bcpap support was decreased by 50% for preterm neonates 24-29 weeks compared to ventilator

Question 72

What long term risk do lung transplant patients face

Answer 72

susceptible to bronchiolitis obliterates as long term morbidity (short term = infections)

Question 73

What is primary component of surfactant?

Answer 73

lipids constitute 90% of surfactant; phosphatidylcholine (mainly desaturated form dipalmitoylphosphatidylcholine) is main phospholipid responsible for lowering surface tension; represents 50% of surfactant by weight

Question 74

percentage of variance in susceptibility for BPD attributable to genetic factor alone is

Answer 74

53%