ADVANCED PATHOPHYSIOLOGY EXAM 4
2026 CLINICAL REASONING QUESTION
BANK AND STEP BY STEP EXPLANATIONS
◉ ventilation
Answer: ability to clear CO2
◉ oxygenation
Answer: the process of delivering oxygen to the blood
◉ causes for CO2 increase
Answer: -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
Answer: alveolar volume x RR
◉ hypoxemia normal P (A-a) O2
(15-20)
Answer: -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)
Answer: 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
Answer: V/Q mismatch
Shunt
,Diffusion Defect
◉ V/Q mismatch
Answer: 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
Answer: 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
Answer: 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
Answer: pressure that is required to overcome the resistance to gas
flow through the airway during prespiration
◉ clinical conditions that increase airway resistance
Answer: COPD
mechanical obstruction
infection
asthma, bronchospasm
◉ work of breathing - compliance
Answer: 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?
Answer: 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?
2026 CLINICAL REASONING QUESTION
BANK AND STEP BY STEP EXPLANATIONS
◉ ventilation
Answer: ability to clear CO2
◉ oxygenation
Answer: the process of delivering oxygen to the blood
◉ causes for CO2 increase
Answer: -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
Answer: alveolar volume x RR
◉ hypoxemia normal P (A-a) O2
(15-20)
Answer: -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)
Answer: 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
Answer: V/Q mismatch
Shunt
,Diffusion Defect
◉ V/Q mismatch
Answer: 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
Answer: 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
Answer: 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
Answer: pressure that is required to overcome the resistance to gas
flow through the airway during prespiration
◉ clinical conditions that increase airway resistance
Answer: COPD
mechanical obstruction
infection
asthma, bronchospasm
◉ work of breathing - compliance
Answer: 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?
Answer: 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?
