Upper and Lower Respiratory Problems Flashcards
inspiration
diaphragm contracts drawing air into lungs, as volume increases, velocity decreases –> settling of dust in lungs
exhalation
lungs passively return to pre-inspiratory volume
conductive airways
not involved in gas exchange
acinar airways
main area of gas exchange
pulmonary ____ receives entire blood volume of ____ heart
artery, right
mean pulmonary pressure =
20cm H2O, low which allows better prefusion and improved exchange of gas
___ holds deoxygenated blood
arteries
___ holds oxygenated blood
veins
capillaries have a thin wall and are easily damaged –> leakage of RBCs & plasma into alveoli. what are 2 causes of capillary damage?
- pulmonary overinflation
- pulmonary hypertension
alveoli, “300 million bubbles”, are UNSTABLE and will collapse due to surface tension. what mixes with fluid lining alveoli to increase stability?
surfactant
gas exchange is rapid and efficient, each RBC spends __ second in capillary network
3/4
name 2 airway defenses
- mucocilary elevator
- alveolar macrophages
*tidal volume
volume of air inspired/expired with normal breath (10mL/kg), Vt=Vd (dead space ventilation) + Va (alveolar ventilation)
inspiratory reserve volume
amt above resting inhalation
expiratory reserve volume
exhale maximally pushing all the air out that you can
residual volume
air that can’t be exhaled due to dead space
total lung capacity
includes residual, expiratory reserve, resting tidal, and inspiratory reserve, that is all the air your lungs could hold, the maximum volume
vital capacity
this s what we use functionally, it doesn’t include residual b/c you can’t move that air
*minute ventilation
total amt new air moved into respiratory passages each minute, Vm=RR (for 1 minute)*Vt
in regards to dead space ventilation, what % of air breathed in is being used for gas exchange in a dog?
35%
in regards to dead space ventilation, what % of air breathed in is being used for gas exchange in a horse/cow?
50%
____ dead space must be considered in anesthetized patient
apparatus (ET tubes & respirator tubes)
*functional residual capacity
volume of air remaining in lungs after exhalation, measure indirectly
*what is the volume of alveolar air replaced with each breath?
~1/7th total alveolar air
decreased fractional residual capacity & tidal volume –>
HYPOXIA
hypoxia
abnormally low partial pressures O2 in tissues
what causes hypoxia?
low O2 delivery to tissues due to anemia (decreased oxygen to tissues) or poor circulation (shock)
hypoxia –>
anaerobic metabolism & .:. decreased CO2
hypoxemia
low partial pressure O2 in arterial blood, *PaO2
**List 5 reasons why a patient will have hypoxemia
- hypoventilation
- ventilation-perfusion mismatch
- anatomic shunt
- diffusion impairment
- low FiO2 (fractional inspired oxygen)
hypoventilation
ventilation inadequate for gas exchange
hypoventilation –>
hypercarbia (increased PaCO2), *PaCO2 > 45mmHg
*with hypoventilation there is an ______ relationship between Va & PaCO2
inverse
list 4 causes of hypoventilation
- decreased RR
- decreased tidal volume
- increased metabolic rate
- hyperthermia
perfusion is ____ in zone 1
absent
perfusion is ____ in zone 2
sporadic
perfusion is ____ in zone 3
constant
with great perfusion and an obstructed alveoli you will see
decreased O2 and slightly increased CO2
*with ventilation perfusion mismatch, you want it to essentially be __, you want perfusion & ventilation to be ____
1, equal
V/Q inequality impairs exchange of all gases, ____ will be the most effected, ____ exchange impaired but can be corrected with ____
oxygen, CO2, increased ventilation
in a V/Q mismatch you will see ___ A-a gradient & ___ PaO2
high (A-a gradient > 30mmHg), low (PaO2
anatomical shunt
extreme V/Q mismatch, abnormal vascular connection btwn small pulmonary artery & vein, venous blood mixes w/ arterial blood, deoxygenated blood goes back into the body, this is an example of normal ventilation but no perfusion
why won’t oxygen supplementation improve the oxygen status for a patient with an anatomic shunt?
patient is ventilating fine and can take in oxygen from the air but it can’t get blood to the alveoli to exchange that oxygen
is hypoxemia more severe with R to L or L to R shunts? why?
R to L shunt SEVERE HYPOXEMIA b/c R is going to be deoxygenated and will bring all that deoxygenated blood back to the body
how does a R to L shunt develop?
pressure increases in RV & PA –> pulmonary hypertension –> RV & PA pressure increase LV & aorta
diffusion rate is proportional to
area, partial pressure difference, & solubility of gas (CO2»_space;» O2)
diffusion rate is inversely proportional to
tissue thickness & molecular weight
list 3 causes of diffusion impairment
- pulmonary fibrosis
- decreased RBC transit time through alveolar capillaries
- thickening of blood-gas interface (smoke inhalation & pneumonia)
low partial pressure of inspired oxygen (altitude sickness) is due to
higher altitudes result in lower atmospheric pressure, all other things being equal
PaO2 @ sea level =
150mmHg
PaO2 @ 5,000ft above sea level =
124mmHg
