Control of Respiration Flashcards
What is diffusing capacity?
Diffusion=(Change in PressureAreaSurface)/(distance*sqrt(MW))
What is the equation for DLco?
DLco=(Va60)/((Pb-47)T)*Ln(FACOi/FACOe)
Va=alveolar volume
Pb=barometric pressure
47=water pressure at 37 degrees celsius
T=breath hold time
FACOi=fractional conccnetration of alveolar CO at start of breath hold
FACOe= fractional concentration of alveolar CO expired at the end of breath hold
What is the equation fro Va?
Va=Vi/(FECH4/FiCH4)
FiCH4=fractional concentration of inspired CH4
FECH4=fractional concentration of expired CH4
VI=inspired volume at STPD
What is the equation for Dl?
D/change in pressure
What are type I cells in the aortic and carotid bodies?
type I cells are glomus
What are type II cells in aortic and carotid bodies?
type II cells are sheath cells
where are the central chemoceptors located?
located in brainstem, including the ventral medullary surface, near the nucleus tractus solilatrus and near the locus ceruleus
In respiratory distress, sternocleidomastoid muscles are contracting what ishappening ot the abdomen?
sternocleidomastoid muscles contracting; abdomen move inwards. Keep rib cage elevated and allow for ventilation
What is the diaphragm used for?
quite tidal breathing
What senses high PaCO2?
both central and peripheral chemoreceptors
What senses a low PaO2?
sensed by peripheral chemoreceptors
Low PaO2 plus high PaCO2?
increases ventilation by increasing the depth and frequency of breathign. Effectively, acessory muscles are recruited.
What are the accessory breathing muscles?
sternocleidomastoids, scalenes, and the abdominus recti
What are the inputs to the brainstem, other than peripheral and central chemoreceptors?
focus on input to the brainstem. Mechanoreceptors in the nose, in the lungs, feedback from hypothalamus and important voluntary control
Small airways collapse leading to incomplete aveolar emptying in what?
COPD or other obstructive lng disease
What is the consequence of chronically elevated PaCO2?
PaCO2 rises leads to compensatory HCO3. Increase pH
consequentially respiratory drive decreases
chronic hypercapnia such as occurs in COPD, respiratory drive is not maintained by CO2 anymore but rather b PaO2
In a pt with chronic hypercapnia what is respiratory drive maintained by?
bc of chronic hypercapnia
respiratory drive not maintained by CO2 but rather by PaO2
What is the 2nd reason why too much O2 bad for severe COPD other than PaO2 repressing respiratory drive?
pt with alveolar damage from COPD blod gets diverted away from bad portion of lung, when you give thm lots of O2 blood flow was diverted away is now vasodilated. V/q mismatch and has worsened hypercapnia
In COPD when blood is divereted away from bad portion fo lung what is this called?
hypoxic vasoconstriction
What is a thrid mechanism that makes O2 bad for COPD?
hemoglobin normally acts as a buffer for carbon dioxide
but in COPD pts with 100% oxygen because binding sites are all taken up
haldane effect CO2 cant be bufered leads to an increase of PaCO2
What is the haldane effect?
buffering of CO2 by hemoglobin during gas exchange
What happens to abdomen when diaphragm is fatigued or not working?
paradoxical abdominal breathingg
What is maximum expiratory pressure less than 60 cm H20 predicts what?
weak cough
What is maximum inspiratory pressure less than 30 % predict?
respiratory failure
What is vital capacity less than 55% predict?
respiratory failure
In brainstem you should be aware of 2 large groups of neurons
first located in medulla are the dorsal and ventral respiratory group of neurons.
What group is responsible for quite breathing?
dorsal group
What group of neurons has 6 divisions and are ultimately responsible for breathing during exercise and responible for not so quite breathin, responsible for both inspiration and expiratory changes?
medulla is the ventral respiratory group
What does the pontine group inhibit what?
central pattern generator
What is the function of the pontine group?
function is to limit inspiration. created using a ramped signal and this group of neurons act to shut off inspiration.
What nervous group is used to limit inspiration
pontine group
If the central pattern generator is damaged in a medullary stroke what hapens to breathing?
becomes ataxic; amplitude and frequency are both altered
What is the result of a pontine stroke it results in what sorta breathing?
apneustic breathing, long period of inspiration followed by a burst of expiration
What is lastly medication such as opiates and barbs have on central pattern generator?
inhibitory effect, on central pattern generator
central pattern generator function is inhibited by morphine and so the effectors do not receive the signal to increase ventilation
What is primary alveolar hypoventilation?
ondine’s curse; all autonomic functions leading to a respiratory drive are gone. pt has to Remember to breathe
What is polysomnography used for?
useful for OSA and periodic limb movment disorder determination
What can we learn from a sleep study?
sleep disordered breathing
-evaluation and treatment
movement disorder of sleep
parasomnias
What is sleep diary used for?
quantifying sleep and assessing patterns of sleep
