APEX Respiratory Physiology Flashcards
Where does dead space end?
Terminal bronchioles
Next is respiratory bronchioles, which is where gas exchange begins
Muscles of expiration
“I let the air out of my TIRE”
internal intercostals
Rectus abdominis
external oblique/ internal oblique
Traverse abdominis
Muscles of inspiration
Diaphragm
External intercostals
Sternocleidomastoid
Scalene muscles
Primary determinant of CO2 elimination
Alveolar ventilation- more important than MV (Ve) bc it includes dead space
Alveolar ventilation formula
Vt-Vd x rr
What increases PaCO2/ETCO2 gradient?
Things that increase deadspace
PPV
Hypotension- decreased BP decreases ETCO2
Atropine- bronchodilator
Normal Vd?
33%
Define physiologic Vd
anatomical Vd + alveolar Vd
Anatomical vs alveolar Vd
Body part is confined to conducting airways
alveoli has ventilation but no perfusion
Things that change dead space
I- old age, copd, hotn, atropine, decreased co
D- ETT, LMA, Trach
The base of the lung has more / less what in compared to the apex in the sitting position
More blood, more CO2,
Less PO2, Less Vq ratio
The most compliant part of the lung
Base
V/Q= infiniti cause
Dead space
Does HPV minimize shunt or dead space?
Shunt!
Theres no shunting since theres no blood flow
It could be said that it increases Vd bc the air has to travel further for VQ
VQ=0 means
Shunt
The tendency of an alveolus to want to collapse is indirectly proportional to ____
Surface tension
The tendency of an alveoli collapse is directly proportional to ______
Radius
VQ ratio in Zone 1, does zone 1 always occur? how does lung combat this zone?
infinity / 0
Zero blood flow
Does not occur in normal lung
To combat, bronchioles constrict
Zone 2 VQ ratio
1/1=1
Zone 3 VQ ratio
0 / infinity
Although, zone 3 is good, most zone 3 is just “shunt-like” bc the Q is higher than V
Anatomical shunts
Thesbian veins (drain L heart)
Bronchiolar veins (drain bronchial blood)
Pleural veins (drain bronchial blood)
Zone 4 lung
Too much fluid, not enough removal by lymph
Fluid overload, pulmonary edema, Mitral stenosis,
Aa gradient can be altered, meaning?
Can be increased
Can not be decreased, just stays “normal”
Hypoxemia define
PaO2 <80mmHg
Things that increase Aa gradient
VQ mismatch (too much V, COPD, embolism)
Older age
Shunt (Pneomonia, atelectasis, alveoli cant touch blood!)
Diffusion impairment- Same as shunt! (Emphysema, ILD, Fibrosis)
Aa gradient formula
PAO2-PaO2
Normal range is <15mmHg
IRV, ERV, Vt, IC, FRC, RV, TLC
What cant spirometery measure?
RV, FRC, TLC, CC, CV
What inreases/ reduces FRC?
Age- Old people can sigh long af bc high FRC
Sighs recruit alveoli
COPD traps air in FRC
Prone- thats why we do it
PEEP adds air to FRC
—–
Obesity/ pregnancy- no space left over!
GA, light anesthesia, NMB- decreased muscles
Supine- thats why we only prone under emergency
CV, things that increase CV
The volume above RV where small airways begin to collapse, a bad thing! want it to be small
COPD
LV failure
Obesity/ pregnancy
Surgery
Extremes of age
Closing capacity (CC) formula
CV + RV
Absolute volume of gas in lungs when collapse begins
How does CC ratio to FRC
FRC should be higher
If CC higher, more shunts
DO2 definition and formula
Delivery of O2
CaO2 x CO x 10
CaO2 definition and formula
Arterial oxygen content (AOC)
(1.34 x hgb x SaO2) + (PaO2 x 0.003)
VO2 meaning and range
Consumption of Oxygen
250ml/min
Increase vs decrease P50
Decrease is actually a L shit- HALDANE HOLDS O2- holding stronger to O2
Haldane is about CO2, not O2
HGB F hypocarbia, carboxyhemoglobin, decreased CO, decreased 2,3 DPG (which is also in banked blood) decreased H ions- alkalosis, low Fio2 (gonna hold because its scarce)
Increase is a R shift- BOHR BYE O2- letting go of O2 easily
Bohr is about O2 not CO2
Acidosis, hypercarbia, increased 2,3 DPG (caused by hypoxia which tells body let go of O2!), hyperthermia, high fio2 (can let it go easily)
Glucose ATP ratio
1:38
1 glucose converts to 38 ATPs
What is the biggest ATP producer? lesser ones?
electron transport- 34 ATPs
Krebs- 2
Glycolysis- 2
The hamburger shift
Pertaining to CO2 production and elimination
main character- Cl-
For every molecule of HCO3 that leaves the RBC, a Cl is transported in
Hypercarbia effects on O2 demand
Other effects of Hypercarbia
Increases it! too much CO2 in blood
Hypoxemia
Hyperkalemia
Salicylates effect on minute ventilation
Increase!
“Aspirin makes you breathe!”
Pacemaker for breathing
Dorsal Respiratory center in the medulla
Although, new evidence says pre-botzinger complex in VRG
Door cell- door opens for breathing
CO2 Ventilatory response curve
Opposite of Bohr haldane
L shift- prompts breathing
R shift- stops the prompt to breathe
Pacemaker for expiration
Ventral respiratory center in the medulla
What inhibits the respiratory pacemaker?
Pneumotaxic center in the upper pons
What stimulates the respiratory pacemaker?
Apneustic center in the lower pons
What does the DRC respond to ?
pH of the CSH
PaCO2
Although, stimulated by hypoxemia and hypercarbia, and is depressed by PROFOUND hypoxemia and hypercarbia
Can CO2 cross BBB? (CCR)
Yes, but H can’t
What does the central chemoreceptor respond to?
H+, although h cant pass bbb, so when co2 diffuses across, it combines with h2o to form h and hco3
Peripheral chemoreceptor location and purpose
Carotid arteries, transverse aortic arch
monitor for hypoxemia PaO2<60mmHg (hypoxic ventilatory response)
How does the peripheral chemoreceptors respond to hypoxemia
Raises RMP, opens CA channels, AP is sent down Herings nerve to CN9 to increase ventilation
Things that impair hypoxic ventilatory response
Endarectomy cuts the limbs of the nerves
Low anesthetic gases 0.1MAC
Volatile anesthetics
What prevents over inflation of the lung (reflex, nerve, etc.?)
Hering-Breuer Reflex
J receptors
Hyperventilate, i cause ventilation o_o (side eye)
Agents that causes shunt/ prevent HPV
DES prevents HPV
TIVA agents will not increase shunts
Vasodilators like dobutamine, CCB will
Vasoconstrictors will cause fast BF and cause shunt
How do the stupid lungs respond to zone 3?
HPV to prevent shunt
Sepsis effect on P50
Right shift, take the O2! although it wont
Whats another way to say increase dead space?
increase paco2 etco2 gradient
Does hemorrhage effect Vd?
Yes, increases , adds more pathways in the body
What drugs increase shunting?
Des, SNP
VO2 formula
250ml/min
3.5ml/kg/min
EMLA cream and oxyhemoglobin curve
Shifts to the left
EMLA turns into methemoglobin which is a left shift