Respiratory Flashcards
When in embryonic developpement is survival possible?
At 25 weeks
How does breathing in utero work?
Aspiration and expulsion of amniotic fluid
How does breathing change at birth?
Fluid gets replaced by air and have a decrease in pulmonary vasular resistance
What is pulmonary hypoplasia?
Poorly developped bronchial tree with abnormal histology
Usually involves the right lung
Associated with congenital diaphragmatic hernia
Bilateral renal agenesis
What are brochogenic cysts?
Abnormal budding of the foregut and dilatation of terminal large bronchi
Show up as discrete, round, sharply defined air filled densities on CXR
What are type 1 cells (pneumocytes)?
97% of aleveolar surfaces
Line the alveoli
Squamous, thin for gas diffusion
What are the type 2 cells (penumocytes)
Secrete pulmonary surfactant
Decrease in alvelor surface tension
Component of pulmonary surfactant?
Complex mix of lecitins and dipalmitoylphospahtidylcholine
Club cells?
Non ciliated, low columnar/cuboidal with secretory granules
Causes of neonatal respiratory distress syndrome?
Screening test?
Symptoms?
Surfactant deficiency
Increase in surface tension
Alveolar collapse
Screening test: fetal lung maturity lecithin-spingomyelin (L/S) ratio in amnitoic fluid
> 2 is healthy
<1.5 is predictive of NRDS
Presistantly low O2 tension
Risk factors of neonatal respiratory distress syndrome?
Treatement?
Prematurity
Maternal diabetes
C-section delivery
Decrease release of fetal glucocorticoids
Treatement:
Maternal steroids before birth
Artificial surfactant for infant
Supplemental O2 (note can result in retinopathy of prematurity, intraventricular hemorrhage, bronchopulmonary dysplasia
What are conduction zone of respiratory tree?
Large airways: nose, pharynz, trachea and bronchi
Small airways: bronchioles that divide to terminal bronchioles
Function: warms, humidifies and filters air but doesnt participare in gas exchange
Has pseudostratified ciliated columnar cells that make up epithelium of bronchus
What are respiratory zones of the respiratory tree?
Lung parenchycma (bronchioles, alveolar ducts and alveoli)
Participate in gas exchange
Mostly cuboidal cells in respiratory bronchioles
Describe anatomy of the lungs?
right lung has three lobes
left lung has 2 lobes
Why right lung more common for inhaled foreign body?
Right mainstem bronchus is wider and more vertical then the left
where will a peanut go if aspirated in upright vs supine?
Upright enters the inferior segment of the right infereor lobe
Supine: enter the superior segment of the right inferior lobe
why does the left lung only have 2 lobes?
That space is occupied by the heart
What are diaphragm structures that perforate?
At T8 (the IVC) at T10 esophagus and vagus At T12: aorta thoracic duct Azygous vein
What nerves innervate the diapghgram?
Phrenic nerve
where is pain from the diaphgram referred?
Shoulder
or Trapezius ridge
What nerves keep the daipggram alive
C3
C4
C10
where does cartoid bifucate?
Trachea?
Abdominal aorta?
Carotid: C4
Trachea: T4
Abdominal aorta: L4
Inspiratory reserve volume?
Air that can still be breathed in after normal inspiration
Tidal volume?
Air that moves into lung with each quiet inspiration
Expiratory reserve volume?
Air that can still be breathed out after normal expiration
Residual volume?
Air in lung after maximal expiration (cannot be measured on spirometry)
Inspiratory capacity?
Inspiratory revserve volume + tidal volume
Functional residual capacity?
Residual volume + expiratory reserve volume
Can’t be measured by spirometry
Vital capacity?
Tidal volume+ inspiratory reserve volume + expired residual volume
Total lung capacity?
Inspiratory reserve volume + tidal volume+ expiratory reserve volume + residual volume
what is the dead space
Physiologic dead space is equivalent to anatomic dead space in normal lung
Is greater when there is V/Q defects
what is pathologic dead space
Part of respiratory zone becomes unable to perform gas exchange (ventilated but not perfused)
Calculation for dead space?
Vd = Vt X ( PaCO2- PECp2)/ (PaCO2)
Vt is tidal volume
PaCos arterial co2
PEco2: expired air PCO2
Definition of minute ventilation?
Total volume of gas entering lungs per minute
Ve = VT X RR
Definition of alveolar ventilation?
Volume of gas per unit of time that reaches the alveoli
Va = (Vt-Vd) xRR
What is elastic recoil?
tendency for lungs to collapse inward and the chest to spring outward
What happens to elastic recoil at the functional residual capacity?
Inward pull of the lungs is balanced bu the outward pull of the chest wall
Systemic pressure is atmosphereic
What is the airway and alveolar pressure at functional residual capacity?
Airway and alveolar pressure are 0
intrapleural pressure is negative
what is the lung compliance?
Change in volume for a change in pressure:
Delta V/ delta P
High compliance means the lungs are easier to fill
when is lung compliance decreased?
Pulmonary fibrosis
Pneumonia
Pulmonary edema
when is lung compliance increased?
Increased in emphysema
Normal aging
Surfactant increases compliance
what is hysteresis?
Lung inflation curve follows a different curve then lung deflation curve (due to need to overcome surface tension)
what are the component of hemoglobin?
2 alpha and 2 beta unies
What are the forms of hemoglobin?
T (deoxygenated)
R elaxed and oxygenated
what does fetal Hb affintiy for O2?
Has a higher affinity for O2 then aduld
what factors shift the dissocation curve to the right (increase O2 unloading)
Increase CL Increase H+ Increase CO2 Increase 2,3 BPG Increase temperature
Methemoglbin?
Oxidixed form of Hb
Does not bind to O2 but has an increased affinity for cyanide
Iron in Hb is reduced state
Presents as chocolate cholored blood
Mehemoglobinemia is induced by nitrates followed by thiosulfates
Can be treated with methmoglobinemia, methylene blue and vitamin C
How do nitrates cause methmeglobin?
either from dietary intake or polluted/high altitude H20
and benzocaine
Due to oxidation of Fe 2+ to Fe 3+
Fe 2+ is what binds to O2
what is carboxyhemoglobin?
Form of CO that binds to O2
Cause a decrease in binding capacity with a left shift in oxy-hemoglobin dissoaciation curve
Decrease in unloading of O2 in the tissues
CO binds competitively to HB and with 200X greater then O2
Treat with 100% O2 and hyperbaric O2
characteristics of the oxygen-hemoglobin curbe?
Sigmoidal shape
Has higher affinity for each susequent O2 molecule that is bound
Myoglobin is monomeric and does not show positive cooperatively
What happens when the curve shifts right?
decrease in affinity for Hb and O2 (facilitates unloading of O2 into the tissue)
What is a shift to the left?
Decrease in O2 unloading (renal hypoxia) increase in EPO synthesis
How is the fetal curve shifted?
Has a higher affinity for O2 then the adult Hb so the curve is shifted to the left
How is the oxygen content of blood measured?
o2 content = 1.32 X Hb X Sao2 + 0.003 x PaO2
What happens when there is anemia?
Decrease in Hb leads to decrease in O2
No change in O2 saturation and PaO2
O2 delivery to tissue = cardiac output X O2 content of blood
What happens during CO poisoning?
Hb: concentration is notmal
Decrease in O2 saturation because the CO competes with the O2
Dissolved O2 is normal
The total O2 content remains normal
What happens during anemia?
Hb concentration is decreased
% of O2 saturation of Hb is normal
Dissolved paO2 is notmal
The total O2 content is decreased
What happens during polycythemia?
The Hb concentration is incresed
The % of O2 saturation of Hb is normal
Dissolved PaO2 is normal
The total O2 content is increased
Pulmonary circulation, reaction to decrease PaO2?
Hypoxic vasocontritction
Shifts blood from poorly ventilated regions of the lung
Decrease in PaO2 due to perfusion limitation-O2?
Gas equilibriates along the length of the capillary
Diffusion can only be icnreased if blood flow increases
Decrease in PaO2 due to diffusion limited-O2
Emphysema, fibrosis, CO
Gas does not equilibriate by the time it reaches the capillary