Hypercarbia and Hypoxemia
What happens to our cells if we don’t get enough O 2 ?
Cannot make ATP
What happens to our cells if we don’t remove CO 2 ?
CO2 is not bad by itself but can combine with H2O in the blood makes carbonic acid change in pH can cause structure changes in proteins if 3D structure can lead to loss in function.
Why is P I O mmHg if atmospheric PO 2 is 160 mmHg?
Why is P I O mmHg if atmospheric PO 2 is 160 mmHg? Saturation with H 2 O in the lung space decreases the PO 2
Causes of Hypoxemia
Causes of Hypoxemia 1. Diffusion Impairment 2. V/Q Abnormalities 3. Shunt 4. Hypoventilation
Diffusion impairment. VO 2 = K x A x (P A O 2 – P a O 2 )/T
Diffusion impairment. VO 2 = K x A x (P A O 2 – P cap O 2 )/T How does the rate of transport change with: -Increased thickness, ie. with fibrosis? -Decreased surface area, ie pneumonia? -Decreased P cap O 2, less O 2 in the capillary blood?
Diffusion impairment. VO 2 = K x A x (P A O 2 – P cap O 2 )/T How does the rate of transport change with: -Increased thickness, ie. with fibrosis? Slow -Decreased surface area, ie pneumonia? Slow -Decreased P cap O 2, less O 2 in the capillary blood? fast, increased diffusion
V/Q Abnormalities 0 Upper parts of the lung receive more/less blood supply than the lower parts (gravity). 0 Upper parts of the lung also receive more/ less of the tidal volume.
V/Q Abnormalities 0 Upper parts of the lung receive more/less blood supply than the lower parts (gravity). 0 Upper parts of the lung also receive more/ less of the tidal volume.
V/Q Abnormalities 0 The result is that the upper parts of the lung receive relatively more/less ventilation than they do blood flow, while the lower parts of the lung receive relatively more/less ventilation than they do blood flow.
V/Q Abnormalities 0 The result is that the upper parts of the lung receive relatively more/less ventilation than they do blood flow, while the lower parts of the lung receive relatively more/less ventilation than they do blood flow.
Shunt Definition: Let’s take a short cut! But is it a good short cut?
Shunt Definition: When blood passes from the right heart to the left heart without becoming oxygenated?
Shunt Which causes blood to go from the right to left heart without going through the lungs? A. Foreign object (ie. Peanut) B. Bronchial circulation C. Pneumonia or abundant pus D. Foramen Ovale
Shunt Which causes blood to go from the right to left heart without going through the lungs? A. Foreign object (ie. Peanut) B. Bronchial circulation C. Pneumonia or abundant pus D. Foramen Ovale
Shunt Bronchial circulation- only goes through the larger airways and does not reach the alveolar region Foramen Ovale- system established in utero that may not close when the baby is born
Shunt What happens with these two? Foreign object (ie. Peanut) Pneumonia or abundant pus
Shunt What happens with these two? Foreign object (ie. Peanut) Pneumonia or abundant pus Blood goes through the lungs but does not come into contact with the gas exchange region.
Does hypoventilation cause hypoxemia or hypercarbia?
BOTH!!
Hypoventilation What things can cause hypoventilations?
Hypoventilation What things can cause hypoventilations? 1. Problems with nerves 2. Problems with muscles 3. Drugs that suppress resp. drive (morphine) 4. Problems with central resp. drive (CCHS, Ondine’s)
Hypercarbia In addition to hypoventilation, Think ALVEOLAR VENTILATION Think DEAD SPACE
How to calculate alveolar ventilation?
V A = (V T ‑ V D ) x f
What happens when you increase dead space? V A = (V T ‑ V D ) x f
What happens when you increase dead space? V A = (V T ‑ V D ) x f Incr. dead space decrease alveolar ventilation increase P a CO 2 = hypercarbia if above 40 mmHg
Dead Space Name 3 things that cause changes in dead space.
Equipment -Snorkel -Gas Mask -Ventilator
Deep Vein Thrombosis How does DVT cause dead space?
Deep Vein Thrombosis How does DVT cause dead space? Sedentary blood clot travels to lung embolus creates dead space decreased gas exchange air in and out is unchanged
Air can get in but gas exchange surface is destroyed.