AP II Unit 4 Flashcards
Describe the basics of the FEF 25-75 test
It’s the same information as the FEV1/FVC test, you just ignore the first 25% and last 25% and focus on the middle 50%. The idea is that if there is going to be variability in the test it is most likely to show up during this portion of the FVC measurement
What specifically is the FEF 25-75 supposed to be sensitive to?
Small/medium airway obstruction
Per lecture, what is the most sensitive PFT to changes and why?
Closing capacity test; because it measures airway collapse without forceful expiration
What is the “ballpark” desirable range for the FEF 25-75 in an asthmatic?
500 - 1000 cc/second
What change would occur to lung volumes if the lung had less inward recoil?
The chest wall still has the same opposing recoil and is now greater than the lungs inward recoil, lung volume would expand (volume would increase)
What happens to lung volumes as you lose/gain elastance?
Less elastance = less recoil opposing the chest wall = higher lung volumes (think obstructive lung disease)
More elastance = more recoil opposing the chest wall = lower lung volumes (think restrictive lung disease)
How does supine vs standing affect chest recoil?
Upright = more outwards chest recoil
Supine = less outwards chest recoil (this contributes to lower FRC when supine)
What happens to lung volumes after you give a paralytic?
The diaphragm loses all tone and relaxes, this allows the diaphragm to creep upwards and reduce lung volume
What controls our rate/depth of breathing?
The medulla
What is the main element of blood/CSF that central chemoreceptors are concerned with?
Protons
What is the main component of the blood that peripheral chemoreceptors are concerned with?
Oxygen
What is the normal arterial/CSF pH and concentration CO2?
Arterial = 7.4 pH and PCO2 of 40
CSF = 7.31 pH and PCO2 of 50
Exactly where would you expect to find central chemoreceptors?
The antro-lateral medulla
What fraction of blood gas management is performed by the central and peripheral chemoreceptors?
Central = 85%
Peripheral = 15%
What houses peripheral chemoreceptors? Where would you find them?
Bodies, 2 pairs are at the bifurcation of the internal/external carotids and 3-5 are in the region of the aorta
What transmits information from the carotid and aortic chemoreceptors?
Carotid = Glossopharyngeal nerve (CN IX)
Aortic = Vagus nerve (CN X)
At what PO2 do peripheral chemoreceptors begin to rapidly fire?
less than 60 mmHg of PO2
What are the 2 primary ways the body can respond to changes in blood gas CO2?
By modifying ventilation or respiratory rate
If the body wants to increase respiration, what is the most effective change to make?
Increase tidal volume before increasing RR (increasing Vt doesn’t increase dead space ventilation, whereas an increase in RR will increase dead space ventilation)
Per lecture, what is a non-pharmacologic method to reduce BP?
Hyperventilate = blow off CO2 = less metabolic byproducts in circulation, BP should decrease
What is the relationship of CO2 to iCal?
As you blow off CO2, less protons occupy albumin, as they leave albumin this leaves room for the Ca++ to occupy sites on albumin and plasma iCal should decrease which slows down HR or reduce CO
Why do infants not handle changes to blood gases?
Their respiratory systems haven’t fully developed and the brainstem isn’t able to fully respond to blood gas changes
What are the pulmonary pleural layers?
Visceral = attached to the lung tissue
Parietal = attached to the chest wall
How does each layer of the intercostals affect breathing?
External = help with inspiration
Internal = help with expiration