Respiratory Adaptations

Question 1

If a pt is using a mix of fuels what will the RQ be?

Answer 1

0.8 (assume this number if nothing is said about their diet)

Question 2

If a patient is receiving IV glucose, what will the RQ be?

Answer 2

1.0

Question 3

If a pt is hypoglycemic or a diabetic and relying on FA metabolism, what RQ will be used?

Answer 3

0.7

Question 4

How is a decreased in V/Q ratio produced?

Answer 4

By either decreasing ventilation or increasing blood flow (without altering the other variable) as well as not blowing enough CO2 to get rid of the CO2 we produced

Question 5

How can you increase the V/Q ratio?

Answer 5

Increase ventilation (bring in more O2, blow off more CO2) or decrease perfusion

Question 6

What are two mechanisms the body has to normalize V/Q ratios?

Answer 6

Hypoxic vasoconstriction and bronchoconstriction

Question 7

Describe hypoxic vasoconstriction

Answer 7

Occurs in cases of low V/Q
Cause the blood coming into the area to be directed to other parts of the lung
Decreasing perfusion of the hypoxic area will raise the V/Q ratio and bring arterial blood gases closer to expected values

Question 8

Describe bronchoconstriction

Answer 8

Occurs in cases of high V/Q
Bronchi will constrict slightly to increase resistance and decrease the amount of ventilation coming into an area that is not well perfused
This limits the amount of alveolar dead space that occurs and minimizes the wasted work that occurs with alveolar dead space

Question 9

What is hypoxia?

Answer 9

Inadequate oxygen available for use by the tissues

Question 10

What is anoxia?

Answer 10

Refers to the total absence of oxygen being delivered to the tissue

Question 11

What is hypoxemia?

Answer 11

The proper term for low oxygen content in the blood

Question 12

What is hypoxic hypoxia?

Answer 12

PaO2 is below normal bc either the PAO2 is reduced (e.g. environmental reasons such as altitude) or the blood is unable to equilibrate fully with the alveolar air (e.g. as would occur in lung diseases with diffusion impairments such as emphysema or fibrosis)

Question 13

What is anemic hypoxia?

Answer 13

The lungs are in perfect working condition in this form but the oxygen carrying capacity of the blood has been reduced
Can be produced by CO bc it binds to Hb with high affinity preventing O2 from binding and reduces the oxygen carrying capacity of the blood
Tissues do not get sufficient oxygen to maintain their metabolic needs bc the blood is not carrying it

Question 14

What is circulatory hypoxia?

Answer 14

The lungs work just fine and the blood can carry sufficient oxygen
However the tissue is not receiving sufficient oxygen because the heart cannot pump the blood to the tissues (or the arteries leading to the tissue have been blocked by clots, etc)

Question 15

Which disease state can lead to circulatory hypoxia?

Answer 15

Sickle cell anemia as the cells sickle in the blood vessels and block them
It also produces anemic hypoxia as the sickle blood cells are removed from circulation

Question 16

What is histotoxic hypoxia?

Answer 16

Cells have been poisoned
No problem getting the O2 to the tissue (lungs, blood and circulatory system work fine)
The tissue is unable to use the O2

Question 17

What can lead to histotoxic hypoxia?

Answer 17

Cyanide leads to this form of hypoxia by poisoning the systems that utilize O2 to create energy and preventing them from using the oxygen
Cells experience a lack of oxygen and are affected as if there was too little/no oxygen available

Question 18

What does resetting the central chemoreceptors mean?

Answer 18

During disease states such as emphysema/COPD decreased CO2 levels will decrease the drive to breathe and cause O2 levels to fall
Neurons in the body will be in favor of maintaining oxygen levels at the expense of PaCO2 value
They will accept the lowered PaCO2 as normal
The composition of CSF is going to compensate for the altered CO2 by bringing the pH back to the normal value

Question 19

During conditions of chronic hypocapnia, how will the CSF adjust pH back to normal?

Answer 19

By the addition of more H+ or less HCO3 by the cells of the choroid plexus
HCO3 is moved to the blood and then removed by the kidneys

Question 20

What occurs during chronic hypercapnia?

Answer 20

Lung disease progresses to retaining more CO2 in addition to hypoxia
Leads to respiratory acidosis
Chemoreceptors stimulate more breathing
However neurons dont function well in the acidic pH meaning the CSF will need to adjust the pH

Question 21

How does the CSF adjust pH during conditions of chronic hypercapnia?

Answer 21

The cells of the choroid plexus will add more HCO3 to the CSF
The H ion created is moved back to the blood for elimination by the kidneys

Question 22

What happens to barometric pressure with increasing altitude?

Answer 22

Barometric pressure decreases although FIO2 remains the same at 21%

Question 23

What is the acute response to a change in altitude?

Answer 23

Immediate response to hypoxia
Increase in alveolar ventilation and increase in PaO2
Decreasing PaCO2 causing increased firing of peripheral and central chemoreceptors
Occurs within minutes to hours

Question 24

What is acclimatization?

Answer 24

Long term changes that occurs over several days or weeks (assuming you remain at the same altitude for a period of time) due to the chronic hypoxia/hypocapnia

Question 25

What changes occur during acclimatization?

Answer 25

Cells of choroid plexus pump more H or less HCO3 to bring pH back to normal (from being basic) —> peripheral chemoreceptors drive ventilation and central chemoreceptors maintain a low PaCO2
The hypoxia will cause an increased release of erythropoietin to increase RBC production, Hb content of the blood and oxygen carrying capacity
Cells increase the number and size of the mitochondria and express more enzymes required for anaerobic glycolysis

Question 26

What are sx of altitude sickness?

Answer 26

HA, irritability, insomnia, dyspnea, nausea and vomiting

Usually last a week and are self limiting

Question 27

What are the two types of edema that can occur with altitude sickness?

Answer 27

Cerebral and pulmonary edema

Question 28

Describe the cerebral edema that can occur during altitude sickness

Answer 28

Cerebral vasculature will dilate in response to hypoxia producing an increase in perfusion pressure and therefore increased filtration
Increased filtration from cerebral capillaries leads to mild cerebral edema
This edema can become severe and life threatening

Question 29

Describe the pulmonary edema that can occur with altitude sickness

Answer 29

It is the result of increased pulmonary vascular permeability
Pulmonary HTN is also present but LA pressure is normal
The HTN is the result of hypoxic vasoconstriction throughout the lung which increases the work load on the RV

Question 30

Pulmonary edema with altitude sickness is more likely to develop in which individuals?

Answer 30

Individuals who rapidly ascend to elevations greater than 2500m and then do heavy physical labor during the first few days of arriving
Or people who live at high altitude, come down to sea level for several weeks and then come back to high altitude

Question 31

What happens to barometric pressure as we move below sea level?

Answer 31

Barometric pressure increases

Question 32

For every 10m below the water surface (sea water) the barometric pressure will increase by how much?

Answer 32

1atm

Question 33

How do you calculate total barometric pressure?

Answer 33

Pressure due to water + pressure due to air
Ex. Descending to 40m, 4 atm + 1atm = 5atm

always add the 1atm of atm pressure on top of the water

Question 34

What are the results of oxygen toxicity?

Answer 34

Irritation of the tracheobronchial tree, nasal congestion, sore throat, coughing, muscle twitching, tinnitus, dizziness, convulsions and death
Occurs during hyperbaric conditions due to production of ROS

Question 35

Hyperbaric oxygen is useful in treating which conditions?

Answer 35

CO poisoning, injuries resulting in or related to decreased perfusion, etc

Question 36

If given for prolonged periods supplemental oxygen at 1atm of pressure can have severe side effects particularly in infants. These severe side effects include what?

Answer 36

The development of bronchopulmonary dysplasia (abnormal lung growth, particularly the presence of lung cysts and densities) and retrolentil fibroplasia (retinopathy of prematurity)

Question 37

Why is nitrogen problematic at increased barometric pressures?

Answer 37

More of it dissolves in the plasma and starts to exert effects such as nitrogen narcosis
At higher concentrations it exerts an effect similar to alcohol on the CNS which can cause serious problems when you are submerged underwater (reports of divers dying bc they removed their scuba apparatus while underwater)

Question 38

What can happen if a diver ascends rapidly?

Answer 38

Nitrogen leaves the dissolved state in the plasma and becomes a gas while still in the bodily fluids/BVs
The resulting bubbles block circulation and are very painful producing the bends or decompression sickness

Question 39

What are sx of decompression sickness or the bends?

Answer 39

Severe pain (esp in the joints) and neurologic sx such as paresthesia, itching and in extreme cases paralysis 
Usually appear within 30mins of surfacing

Question 40

What tx can be used for decompression sickness or the beds?

Answer 40

Tx in a hyperbaric chamber can be used to force the gas back into solution and then control the rate of decompression to allow the dissolved gas to be exhaled

Question 41

Decompression sickness can result from any what?

Answer 41

Rapid decompression (ex. Losing cabin pressure in a plane at very high altitude will have the same effect)

Question 42

Describe how an air embolus can form during the ascent from diving

Answer 42

During ascent the glottis must remain open so that the expanding air can leave the lungs
If air is not allowed to leave it will go to the blood
If a diver panic and rapidly ascends with a closed glottis the pulmonary Vs may rupture and air can enter the bloodstream creating an air embolus
Can be fatal