Respiratory

Question 1

What aortic arch forms the pulmonary blood vessels?

Answer 1

6th aortic arch (same as PDA)

Question 2

What is difference between preacinar and intraacinar arteries?

Answer 2

Pre-acinar: near non-respiratory bronchioles, angiogenesis, growth complete at 16wks GA
Intra-acinar: near alveoli, develops via vasculogenesis (de novo, not angiogenesis). Grows for 8-10 years

Question 3

How many alveoli does a term infant have? Adult?

Answer 3

Term: 50-150 million
Adult: 200-600 million

Question 4

What factors delay alvelolar development?

Answer 4

Antenatal steroids, supplemental oxygen, poor nutrition, mechanical ventilation

Question 5

What are the stages and weeks of lung development?

Answer 5

Embryonic (0-5 wk) - TEF, tracheal stenosis, laryngeal cleft
Pseudoglandular (5-16wk) - CDH, CCAM, bronchogenic cysts
Canalicular (16-25wk) - pulm hypo
Saccular (25-36wk) - pulm hypo
Alveolar (36+wk)

Question 6

Type I vs type II pneumocyte

Answer 6

Type I: thin/flat, gas exchange, 90% of alvelolar surface, made by type II, less cells
Type II: cuboidal, surfactant, 10% of surface but higher # of cells

Question 7

What is major cation of fetal lung fluid?

Answer 7

Chloride goes into alveoli and liquid follows. Then prior to birth Na leaves alveoli and liquid follows.

Question 8

What is the largest component of surdactant?

Answer 8

DPPC (dipalmitoyl phosphatidylcholine)

Question 9

What happens with surfactant protein A deficiency? B? C? D?

Answer 9

A: most abundant protein, some increase in RDS if deficient
B: critical, if partial def: CLD; if none, needs lung transplant
C: mild to sev sx after few months
D: no disease

Question 10

What is phosphatidylglycerol (PG)?

Answer 10

Reflects lung maturity, present after 34-35 weeks; absent in infants with RDS

Question 11

What is the L/S ratio?

Answer 11

Lecithin/sphingomyelin ratio
If >2= lung maturity
=2 at about 35 wks
Lecithin reflects lung maturity, increases w GA, sphingomyelin unrelated to lungs but decreases after 32 weeks

Question 12

What is the largest factor in respiratory resistance?

Answer 12

55% airway resistance (50% nasal)
25% chest wall
20% lung tissue (friction between lung and chest wall)

Question 13

What does time constant mean? How does it change in RDS? BPD?

Answer 13

Time constant: time is takes for lungs to empty. 63% (1), 84% (2), 95% (3)
Decreases in RDS
Increases in BPD

Question 14

How does NO work?

Answer 14

NO -> activates guanylyl cyclase -> inc cGMP -> induces vascular muscle relaxation

Question 15

Where does CCAM get blood supply? Bronchopulmonary sequestration?

Answer 15

CCAM: pulmonary blood supply

Bronchopulm sequestration: systemic blood supply (if extralobar may not need surgery, good prognosis)

Question 16

Where is CO2 monitored?

Answer 16

Chemoreceptors in medulla, sense H ion concentration in extracellular fluid. Preterm infants less sensitive

Question 17

Where is O2 monitored?

Answer 17

Peripheral chemoreceptors in carotid bodies and aortic bodies

Question 18

What is the Bohr equation?

Answer 18

Dead space V = (arterial CO2 - expired CO2)/ arterial CO2 x TV

Question 19

What is Poiseuilles law for laminar flow?

Answer 19

Flow= dP x pi x radius^4/ (8 x length x viscosity)
Laminar flow: small airways
Turbulent flow: large airways

Question 20

How does lung volume change with RDS?

Answer 20

Dead space increases, all other volumes decrease

Question 21

What lung volumes are increased in neonates compared to adults?

Answer 21

RR, alveolar and minute ventilation, residual volume

Question 22

What lung volumes are decreased in neonates compared to adults?

Answer 22

TV, TLC, VC, inspiratory capacity

Question 23

What is formula for O2 content in blood?

Answer 23

O2 content= (1.37 x Hb x O2 sat) + .003x paO2

Question 24

A - a gradient formula

Answer 24

A - a = [FiO2 x (760-47)] - (paCO2/0.8) - paO2

Question 25

O2 delivery formula

Answer 25

Amount of oxygen available to body in one minute (O2 content x cardiac output) O2 delivery= CO x [(1.34 x Hb x O2 sat) + (0.003 x paO2)]

Question 26

O2 consumption formula

Answer 26

VO2= CO x (1.34 x Hb) (arterial O2 sat - venous O2 sat)

Question 27

What is the Bohr effect?

Answer 27

As CO2 rises, decreases oxygen affinity for Hb. Allows unloading of oxygen to tissues.

Question 28

What is the Haldane effect?

Answer 28

Describes CO2 unloading, high O2 binding of Hb in alveolar capillary induces increased unloading of CO2

Question 29

What is methemoglobin?

Answer 29

Iron on hemoglobin changes from reduced (ferrous) to oxidized (ferric) and decreases ability to bind O2. paO2 normal but O2 sat low Rx: methylene blue

Question 30

OI calculation

Answer 30

OI = MAP x FiO2 / paO2 (postductal) x 100

Question 31

What benefit do antenatal steroids have on lung?

Answer 31

Increase lung surface area (even though delay alveolarization)

Question 32

How much of secreted surfactant is recycled? What is turnover time?

Answer 32

95% recycled, 10 hour turnover time

Question 33

What are glycogen lakes? Lamellar bodies?

Answer 33

Glycogen lakes : found only in immature type II pneumocytes | Lamellar bodies: sign of lung maturity

Question 34

What protein do the animal surfactants not have? What do they all have?

Answer 34

None have SP-A | All have SP-B and SP-C

Question 35

What is LaPlaces law?

Answer 35

Relationship between Pressure, surface tenton, and radius P=2T/r *linear relationship between radius and pressure

Question 36

What is the relationship between Pa (alveolar), Pv (pulm venous pres), PA (pulm art pres) in the neonatal lung?

Answer 36

Pa > Pv > PA

Question 37

What is the Fick principle?

Answer 37

Oxygen consumption | VO2= CO x 1.34xHbx(art sat - ven sat)

Question 38

Does neonate or adult have higher oxygen consumption?

Answer 38

Neonate 6-8 ml/kg/min (adult 3.2) | Term > preterm infant

Question 39

What increases oxygen consumption?

Answer 39

1. Increased caloric intake 2. Decreased body temp 3. AGA > SGA 4. Term > preterm

Question 40

What shifts oxyhemoglobin dissociation curve to left?

Answer 40

``` Low H Low CO2 Low temp Low 2,3 DPG Fetal hemoglobin ```

Question 41

What shifts oxyhemoglobin dissociation curve to right?

Answer 41

``` High acid High temp High CO2 High 2,3 DPG Adult Hb ```

Question 42

Is unilateral or bilateral vocal cord paralysis more common? If unilateral, which side?

Answer 42

Unilateral, left | Because left recurrent laryngeal nerve with longer course, more fragile

Question 43

Are most CDH syndromic? Left or right more common?

Answer 43

``` No, most nonsyndromic. But 40% with associated defects Left 85% (bilateral 1%) If syndrome: Fryns syndrome Denys-Drash Cornelia de Lange Marfan Spondylocostal dysostosis Craniofrontonadal syndrome ```

Question 44

What defects are most commonly associated with diaphragmatic hernia?

Answer 44

Heart defects Undescended testes Meckel diverticulum Unilateral kidney

Question 45

Is diaphragm paralysis more common unilateral or bilateral? If unilateral which side? Outcome?

Answer 45

Unilateral, right (if 2/2 birth trauma) Due to phrenic nerve injury Will have no retractions on affected side If birth trauma - most recover in 1 year

Question 46

What is the most common type of CCAM? Second most common?

Answer 46

1. Type 1 (50-70%) most common, defect 7-10 weeks GA. Usually single cyst, can be multiloculated. Often causes compression. 2-10cm 2. Type 2 (20-40%). With other anomalies (60%), TEF, renal agenesis, intestinal atresia, hydroceph, skeletal. Defect 3wks GA. Multiple small cysts and solid areas. 0.5-2cm. Doesnt compress.

Question 47

Where does diamox work? How does it work?

Answer 47

Proximal tubule | It is a carbonic anhydrase inhibitor, inhibits NaHCO3 reabsorption

Question 48

Where do lasix and bumex work? How?

Answer 48

Ascending loop of henle | Blocks active chloride transport. K losing

Question 49

Where does spironolactone work? How?

Answer 49

Collecting system Competitive antagonist of aldosterone K sparing

Question 50

Where does diuril work?

Answer 50

Distal tubule Inhibits NaCl reabsorption *can cause hyperbili and hyperglycemia

Question 51

How do methyxanthines work?

Answer 51

Increase cAMP and changing intraular Ca | Also inhibit central adrenergic receptor

Question 52

What are the criteria for mild, mod, severe BPD?

Answer 52

1. Mild: o2 28 days plus RA at 36 weeks or dc 2. Mod: o2 28 days and <30% Fi02 at 36 wks 3. Severe: o2 28 days and FiO2 30% or more at 36 wks, or CPAP/PPV at 36 wks.