Respiratory Flashcards
3 factors (pathophys) leading to RDS
decrease lung volume
decrease FRC
decrease compliance
A chest x-ray may show hyperinflation, prominent perihilar vascular markings, edema of interlobar septae, or fluid in the fissures. What is diagnosis?
TTN
Adenosine leads to increased or decreased apnea?
leads to increased apnea
caffeine competitive antagonist for adenosine, and less apnea when caffeine is used
airway resistance is comprised of what 3 components?
Chest wall resistance (25%), airway resistance (55%), lung tissue resistance (20%)
At what embryological stage would CDH occur?
Before 10th week
due to failure of pleuro-peritoneal closure
At what embryonic stag is lung considered viable?
Cannicular
Does airway resistance increase or decrease with postnatal age?
Increases
does high or low PcO2 lead to increase IVH risk?
both do
name 5 ways caffeine helps
decreases hypoxic depression of breathing
decreases periodic breathing
improves CO2 sensitivity
increased diaphragmatic activity
increases minute ventilation
How is oxygen content determined?
can be calculated by adding amount of O2 bound to hgB ot the amount of dissolved O2 in blood
(1.34 ml O2/ghb x hgb (g/dl) x 02 sat ) + (.002 x paO2)
How is surfactant synthesized?
Predominantly Choline incorporation pathway, induced by steroids, cAMP or beta agonists
Meconium aspiration releases which chemical vasoconstrictors?
endothelin-1, thromboxane A2 and prostaglandin E2
Name 3 physical factors of lung development
Lung Fluid: Promotes growth through chronic stretch (due to pressure)
Fetal breathing (increased pressure when coupled from upper airway contractions)
Peristaltic airway contractions (pressure on distal buds)
name 5 things that can cause pulmonary hypoplasia
Renal agenesis
urinary outlet obstruction
loss of amniotic fluid (PPROM)
CDH
Large pleural effusions
name some factors associated with delayed lung maturation
Diabetes, Rh isoimmunoization with hydrops, 2nd born twin, c-section
mediated by insulin, androgens, and transforming growth factors
New BPD vs old BPD
new BPD interferes with luing development
old BPD is caused by direct injury to lungs
new BPD have decrease in alveolar septation, and microvascular development
(arrest of pulmonary alveolarization, with increased alveolar deimateres and fewer alveoli)
pressure controlled ventilation what happens when compliance increases?
Tidal volume increases, PIP, stays same
Volume targeted ventilation what happens when compliance increases
pressure drops (PIP), and TV stays same
What abnormalities might you see in Pseudoglandular phase of lung development, if something is amiss?
BRANCHING ABNORMALITIES OF LUNG
bronchogenic cysts
CDH
Congenital lobar emphysema
Cystic adenomatoid malformations
what are 5 variables that impact distribution of surfactant
- gravity (position of lung)
- volume of instillation
- Speed of instillation
- Surfactant type and properties
- Fluid volume in lung
what are benefits of permissive hypercapnia?
need for less MV
less lung injury
direct protective effect of lung
neuroprotection
ensures maximal respiratory drive
less danger of hypocapnia
What are the hydrophilic surfactant proteins
Sp-A Tubular Myelin
sp-D Surfactant lipid homeostasis (host defense)
What are the hydrophobic Surfactant proteins?
SP-B Type II surface tension reduction
SP-C tension reduction film stability
What information does the alveolar-arterial (A-a) gradient provide?
provides information about whether the lungs are transferring oxygen from atmosphere to pulmonary circulation.
the larger the A-a gradient, the poorer O2 transfer
What is a pulmonary artery sling?
anomalous origin of the left pulmonary artery from right pulmonary artery
LPA supplies left lung goes posterior to trachea, and anterior to esophagus
LPA aberration compresses distal trachea, and right mainstem bronchus
What is ABCA 3 Transporter?
ATP Binding cassette protein that helps with transport of lipids
Autosomal recessive,
30-40% of all refractory acute respiratory failure
abnormal accumulation of lamellar bodies in type 2 cells, and inablity to transport to surface
what is hyperoxia test?
determining if low O2 sats are due to Cardiac or Respiratory reasons
if paO2 >100, it’s respiratory
What is physiological deadspace, and how can it be calculated?
Anatomical dead space (gas in conducting areas of respiratory system) does not come into contact with alveoli +
Alveolar dead space (air contacting alveoli without blood flow in adjacent pulmonary capillaries)
can be calculated by Bohr equation
What is the Haldane effect
Decrease in hgb Saturation
enhances removal of CO2 from oxygen
increased Hgb Saturation decreases its ability to carry CO2
promotes dissociation of CO2 from hgb in oxygen rich capillaries of lungs
What is the most sensitive test for evaluating phrenic nerve injury?
ultrasound
What respiratory measurements are increased in neonates compared to adults
Respiratory Rate
Residual Volume
Minute Ventilation
Alveolar Ventilation [(TV - dead space) x RR]
Where do majority of CDH take place?
They occur posteriorly and are a result of the failure of pleuroperitoneal membrane closure in utero.
Why is MCT formula recommended for patients with chyolothorax?
if lymphatic vasculature has been injured, the lymphatic vessels are not necessary for absorption of MCT
How does iNO work
increases soluble guanlyate cyclase, which increases cyclic GMP
What do you see in all patients with Congenital Lobar emphysema?
hyperinflation of affected lung segment
Best way to position infant with PIE
on affected side lateral decubtius, allows unaffected lung to oxygenate
Reciprocal of time constant is equal to what in flow volume curve on vent?
slope of exhalation
What is reciprocal of compliance?
elastance?
What is reciprocal of conductance?
resistance
How is resistance represented on flow volume curve?
Resistance is represented by the distance from the slope of the curve to the outer portion of the loop
When resistance to flow is increased, the distance will increase and the loop will become wider
Which aortic arch derivates stick, of the 6?
3, 4, 6
pulmonary structures arise from 6th arch
Do antenatal steroids improve alevorization?
No, but they do increase surface area
and they do increase surfactant production
Time constant measures what?
resistance x compliance
time required for inflation for deflation by 63%
Embryologically where do lungs derive from
from ventral bud of esophagus
Type I pneumocytes differ from Type 2 pneumocytes how
Type 1 cover alveolar surface, help in gas exchange,
Type 2 mainily in alveolar lining (only 10% of surface), and play role in surfactant metabolism
Boyle’s Law
P1V1 = P2V2
as pressure of a gas decreases, the volume in that space increases
Chemoreceptors on medulla respond to what kind of changes?
Changes in CO2, increase in H
There are no O2 sensors in medulla
Peripheral chemoreceptors are located where?
carotid and aortic bodies
they responde to decrease in PaO2, and increase in PaC02
Alveolar Ventilation equation
Va= (Tidal volume- dead space) x RR
Va/Q >1
(the ____________ effect)
excessive ventilation and blood from that area in lung will have high PaO2 and low PaCO2
dead space effect
Va/Q <1
(the __________ effect)
some gas exchange, but lower than normal PaO2 and higher PaCo2
(shunt effect)
What kind of blood is intrapulmonary shunt
any blood that goes through systemic circulation without going through ventilated lung region.
What is anatomic dead space?
areas of lung, not involved in gas exchange
What is physiologic dead space?
WASTED VENTILATION
anatomic deadspace + alveolar dead space
What does the Bohr equation measure?
Physiologic dead space
Bohr equation
[Arterial CO2- Expired CO2/(Arterial CO2) ] x tV
Poiseuille’s law
length x viscosity /radius to 4th power
bronchoconstriction increases or decreases dead space?
decreases
What is equation for elastance?
inverse of compliance
change in pressure/ Change in volume
hypoxemia vs hypoxia
hypoxemia is low O2 in blood (not necessarily reflective of O2 sat)
hypoxia is low O2 in tissues
What does A-a gradient measure?
how well lugs are transferring O2 from atmosphere to pulmonary circulation?
Calculation of A-a gradient
Equation for O2 Delivery
Cardiac Output x O2 content
Fick Principle
O2 consumption in blood is difference between O2 delivered to tissues (arterial blood) and blood returning form tissues (venous blood)
O2 consumption equation
VO= 1.34 x (hgb) (arterial O2 sat - venous O2 sat)
If O2 delivery is decreased to tissue, how will body compensate?
Increase O2 extraction (less venous O2)
Recruiting more capillaries
What is Haldane effect
Changes im CO2 binding to Hb based on amount of O2
Haldane effect on tissues
O2 is removed from Hb, thus greater amount of CO2 can bind to Hb
Haldane effect on lungs
binding of O2 to hb in alveolar capillaries increases CO2 unloading from capillary to alveoli.
Co2 elimination is dependent on
Alveolar minute ventilation (Resistance, compliance, time constant)
Diffusion across alveolar capillary membrane ( distane between alveoli and capillaries)
What decreases if you increase PEEP
TV will decrease, but if you increase PIP by same TV remains same
TV decreases because you reduce pressure gradient
which manipulation of vent parameter will increase O2 and decrease PcO2
increasing flow
Benefits of VV ECMO?
spares carotid artery
lower risk of arterial emboli
Benefits of VA Ecmo
provides respiratory and cardiac support
can use femoral vessels
HFJV requires ________ time for gas to get OUT of lungs?
MORE
HFOV requires __________ time for gas to get IN to lungs
MORE
Why are majority of infants asymptomatic with pneumomediastinum?
because air is seldom under tension
What causes a pulmonary hemorrhage
acute increase in capillary hydrostatic pressure
(From L to R shunting of PDA, or vasoconstriction from illness)
How to manage pulmonary hemorrhage
increase PEEP, to impede pulmonary blood flow
What is more worrisome, inspiratory stridor, biphasic stridor or Expiratory Stridor?
Expiratory stridor
(region narrows during expiration)
Tracheomalacia, tracheal stenosis
Vascular rings, mediastinal mass
How do you diagnose vascular ring?
barium swallow (might show indentation in esophagus)
LHR < 1.0 good or bad prognosis in CDH
bad
How do you distinguish between Pneumothoraces and Congenital Lobar emphysema on xray?
both have hyperinflated lobe and mediastinal shift, but in CLE, lung markings will extend to the periphery
Most affected lob in Congenital Lobar Emphysema
left upper lobe > right middle lone> right upper lobe
How do CPAMs differ from bronchopulmonary sequestrations?
blood supply from pulmonary circulation
CPAMS also have communication with tracheo-broncial tree
What types of CPAM have most favorable prognosis
Types 1 and 4
(2 and 3 usually associated with other morbidities, syndromes TEF etc)
What leads to lymphagneictasia?
failure of lymphatic vessel regression at 20 weeks gestation, or lymphatic obstruction
Is Extralobar or intralobar sequestration more common in neonates?
extralobar, but overall intralbor more common in general population
where are majority of extralobar sequestrations located?
mainly left side between lower lobe and diaphragm
Prognosis of Alveolar-capillary dysplasia
poor, respiratory failure in first 48 hours
Pulmonary veins are misaligned, and inadequate vascularization of alveoli with decreased number of capillaries adjacent to alveoli
Alveolar-capillary dysplasia
What does Guanyl Cyclase do?
with NO increases cyclic GMP
In what CHD legion might you see WPW
Ebstein’s anomaly
What happens when there is an increase in resistance (either CLD»_space;» or RDS) without a concomitant decrease in compliance, what happens to time constant?
time constant increases and takes longer for lung to empty
If a ventilator does not allow for sufficient time for expiration what happens
lungs will have long time constant, and gas trapping occurs
Where are most intrapulmonary sequestrations located?
posterior basal segment, mainly in left lung
blood supply by anomalous usually from aorta
What is immediate goal in treatment of of hyperammonemia?
to remove ammonia
hemodialysis
allso
IV sodium benzoate and sodium phenylacetate will remove glycine and glutamate from body
In Methemglobinemia what happens to Hgb?
Iron changes from ferrous (reduced) state to ferric (oxidized) state, decreasing ability of hemoglobin to bind O2.
What happens during an intrathoracic obstruction?
(kind of sound)
Region narrows during expiration, expiratory stridor
tracheomalacia, tracheal stenosis, external compression (vascular ring)
What happens during laryngeal obstruction?
(kind of sound)
region is fixed in size, larynx is narrowest part of airway, so this is the most common type of stridor
layrngomalacia, vocal cord paralysis
With surfactant surface tension is greater in expiration or inspiration?
Lowest at expiration, highest at inspiration
What are side effects of therapeutic hypothermia?
platelet dysfunction, decreased surfactant, pulmonary hypertension, vasoconstriction
