Advanced Pathophysiology Exam 4
Exam Latest 2022
Normal Blood Gas Values - - pH: 7.35 - 7.45
PaO2: 80 - 100 mmHg
PaCO2: 35 - 45 mmHg
ventilation - - ability to clear CO2
oxygenation - - the process of delivering ox
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Advanced Pathophysiology Exam 4
Exam Latest 2022
Normal Blood Gas Values - - pH: 7.35 - 7.45
PaO2: 80 - 100 mmHg
PaCO2: 35 - 45 mmHg
ventilation - - ability to clear CO2
oxygenation - - the process of delivering oxygen to the blood
causes for CO2 increase - - -CO2 is being produced but not being exhaled quickly
enough
-increase in CO2 by increased metabolism like fever or exercise
-PaCO2 in ABG is increased therefore pH decreases
-as CO2 accumulates, peripheral and central chemoreceptors signal brain to
increase RR
-PaCO2 is influenced by alveolar minute ventilation and CO2 production
-ventilation is influenced by alveolar minute ventilation and Co2 production
-O2 sat decreases because increased CO2 pressure keeps O2 away
alveolar minute ventilation - - alveolar volume x RR
hypoxemia normal P (A-a) O2
(15-20) - - -lungs are working fine but there is problem above airways
-altitude
-nitrogen gas poisoning
-fire smoke (O2 displacement)
Alveolar hypoventilation increased P (A-a) O2
(>20) - - not getting enough ventilation into the alveoli, reducing oxygen
-ex. OD antidepressants slowing RR
fixed with O2 and increased ventilation
causes of hypoxemia with increased P - - V/Q mismatch
Shunt
Diffusion Defect
V/Q mismatch - - areas of our lungs that are receiving ventilation are not matched
with perfused areas.
when there is high CO2, pulmonary vessels selectively vasoconstirct so blood goes
where best work is done
low ventilation but normal perfusion because of airway secretions
somewhat hypoxemic but not as severe as shunt
shunt - - extreme VQ mismatch
severe pneumonia
ARDS
when alveoli is filled with something that should not be there (fluid, blood, or
infection) or alveoli is collapsed (atelectasis) Very hypoxemic
diffusion defect - - conditions where there is a problem in O2 diffusing into the
bloodstream: like with interstitial lung disease, some sort of irritation, body tries to
restore damage, and fibroblasts lines up on the alveolar walls. other examples are
pulmonary edema, hydrostatic pressure is too great, leaking into interstitial space
work of breathing - resistance - - pressure that is required to overcome the
resistance to gas flow through the airway during prespiration
clinical conditions that increase airway resistance - - COPD
mechanical obstruction
infection
asthma, bronchospasm
work of breathing - compliance - - the ability of the lungs to expand is measured as
the lung compliance. The volume change per unit of pressure
when is more muscular effort for work of breathing is required? - - lung compliance
is decreased (ex. pulmonary edema)
chest wall compliance is decreased (spinal cord deformity or obesity)
airways are obstructed by bronchospasm of mucous plugging (asthma, bronchitis)
What 5 problems with oxygenation result in hypoxemia? - - -O2 concentration of
FiO2
-ventilation of the alveoli (hypoventilation)
-V/Q mismatch
-Diffusion Defect
-Shunt
Examples of O2 content of FiO2 as a problem with O2 delivery to the alveoli - - high
altitudes or oxygen displacement scenarios
Examples of hypoventilation as a problem with O2 delivery to the alveoli - -
unconciousness
neurolgoic, muscular or bone diseases that restrict chest expansion
COPD
Examples of VQ mismatch as a problem with diffusion of O2 from the alveoli into the
blood - - atelectasis
asthma
chronic bronchitis
pneumonia
ARDS
PE
Examples of diffusion defects as a problem with diffusion of O2 from the alveoli into
the blood - - edema
fibrosis
emphysema
examples of shunt as problem with perfusion of pulmonary capillaries - - blood flow
bypassing lungs
intracardiac defects
intrapulmonary arteriovenous malformations
DLCO - - diffusion capacity of the lung for carbon monoxide
How is DLCO measured and preformed? - - inhale CO for 10 seconds and exhale
measure how deep of breath and how much CO is left over
diffusing capacity is a measure of the gas diffusion rate at the alveolocapillary
membrane
variables that affect DLCO - - Hb
CoHb
altitude
PAO2
body position
pulmonary capillary blood volume
asthma
obesity
When is DLCO reduced - - pulmonary fibrosis
pulmonary vascular disease
restrictive lung diseases (loss of lung volume, fibrotic lung diseases)
obstructive lung diseases (especially emphysema and others with V/Q mismatch)
How does anemia cause a decrease in DLCO? - - there is less hemoglobin to pick
up the carbon monoxide
hemoglobin loves oxygen but it loves carbon monoxide more
indications for DLCO - - -to monitor parenchymal lung diseases
-evaluate pulmonary involvement in systemic diseases (RA, sarcoidosis, SLE,
systemic sclerosis)
-evaluate obstructive lung disease
-evaluate cardiovascular diseases
-quantify disability associated with interstitial lung disease
COPD - - airflow limitations associated with chronic inflammatory response in the
airway to noxious particles or gas. chronic irritant exposure recruits neutrophils
macrophages and lymphocytes to lungs resulting in progressive damage from
inflammation, oxidative stress, extracellular proteolysis apoptic and autophagic cell
death
chronic bronchitis - - inflammation and edema of the bronchials, increases size and
number of mucous glands and goblet cells in airway, smooth muscle hypertrophy
with fibrosis and narrowing airways. thick mucous can't be cleared r/t impaired cilia.
bacteria also colonized (repeat infections) "blue bloater".....
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