Respiratory

Question 1

A-a Gradient Equation =

Answer 1

A= [FiO2 x (elevation - barometric pressure) - (PaCO2/Respiratory Quotient)

Question 2

Definition of A-a Gradient

Answer 2

The difference between the calculated Alveolar PaO2 and the measured Arterial PaO2.

Question 3

Normal A-a Gradient value

Answer 3

Less than 15 mm Hg

Question 4

True or false: The A-a gradient is beneficial as a one-off value.

Answer 4

False: It’s the most useful when used for trending.

Question 5

Using the P:F ratio, what would an expected arterial PaO2 be on a patient breathing 100% oxygen?

Answer 5

PaO2= ~500 mm Hg

Question 6

Define the P:F ratio

Answer 6

PaO2:FiO2 ratio is the arterial PaO2 should = ~5x the FiO2

Question 7

Define the 120 rule

Answer 7

Essentially PaO2 + PaCO2 should be equal to or greater than 120 in an animal with normal pulmonary function. It’s an easier version of the A-a gradient.

Question 8

Define a V/Q mismatch.

Answer 8

Blood that has traveled through the lungs without becoming properly oxygenated resulting in venous admixture.

Question 9

What are some causes of a low V/Q?

Answer 9

Pneumonia, PTE, pulmonary edema, asthma

Question 10

What would cause no
V/Q?

Answer 10

Atalectasis, severe pleural effusion, collapsed alveoli

Question 11

When can the 120 rule be applied?

Answer 11

It only applies to patients breathing room air at sea level.

Question 12

What is the function of PEEP (Positive end expiratory pressure) in regards to ventilation?

Answer 12

PEEP maintains positive pressure in the airway during exhalation to prevent the lungs from emptying completely.

Question 13

How can PEEP be beneficial to a patient requiring ventilation assistance?

Answer 13

PEEP can increase the oxygenating efficiency of diseased lungs by recruiting previously collapsed alveoli.

Question 14

What would the appropriate PEEP setting be on a ventilator for a patient who has healthy lungs?

Answer 14

0-5 cm of H2O

Question 15

What would be an appropriate initial PEEP setting for a ventilator patient with lung disease?

Answer 15

5-8 cm of H2O

Question 16

What is the function of PIP (Positive Inspiratory Pressure) in regards to ventilation?

Answer 16

PIP is the maximum pressure generated during inhalation.

Question 17

How does your PEEP setting on the ventilator affect your PIP setting?

Answer 17

The PEEP setting will affect the inspiratory pressure as an additional amount of pressure. Essentially, whatever your PEEP setting is, it must be factored in to your PIP setting.

Question 18

If your PEEP setting is at 5cm of H2O and you want your total PIP to be 20 cm of H2O, what should your PIP setting be?

Answer 18

15cm of H2O

Question 19

How can your PEEP setting affect venous return?

Answer 19

High PEEP settings maintain elevated intrathoracic pressure during exhalation and can therefore decrease venous return.

Question 20

What are 3 indications for mechanical ventilation?

Answer 20

Severe hypoxemia despite oxygen supplementation, severe hypoventilation, excessive respiratory effort with impending fatigue.

Question 21

True or false: venous blood gas values can be used to diagnose hypoxemia.

Answer 21

False. Only arterial blood gas can be used.

Question 22

True or false: venous PaCO2 can be used to diagnose hypoventilation in hemodinamically stable patients.

Answer 22

True.

Question 23

True or false: diseased lungs need higher PEEP and PIP setting, but lower tidal volume settings.

Answer 23

True

Question 24

Lung compliance is variable, how compliant would you expect a healthy animals lungs to be in regards to tidal volume?

Answer 24

Healthy lungs are significantly more compliant and can handle a higher tidal volume.

Question 25

If you have a ventilator patient who is consistently hypoxemic, what are some things you can do to trouble shoot?

Answer 25

Increase the FiO2, change the patient to sternal recumbency, increase the PEEP/PIP/Tidal volume if the patient has compliance.

Question 26

If you have a ventilator patient who is consistently hypercapneic what can you change to trouble shoot?

Answer 26

Assess ET tube, ensure there’s adequate expiratory time, increase the tidal volume and/or respiratory rate.

Question 27

What is a normal by product of the metabolism of oxygen that can lead to oxygen toxicity if excess accumulation occurs?

Answer 27

Reactive oxygen and nitrogen species AKA RONS.

Question 28

How do RONS cause oxidative injury?

Answer 28

They damage lipids, nucleic acids and proteins resulting in cellular injury.

Question 29

What are the 3 predominant systems affected by oxygen toxicity?

Answer 29

Respiratory, Central Nervous, and Cardiovascular.

Question 30

True or false: an A-a gradient calculation of 10 mm Hg is indicative of adequate ventilation. Why?

Answer 30

False. The A-a gradient indicates oxygenation not ventilation.

Question 31

Hypoxemia is defined as what?

Answer 31

A PaO2 of less than 80% or an arterial hemoglobin saturation of less than 95%.

Question 32

True or false: cyanosis is an early indicator of hypoxemia.

Answer 32

False. It is a late sign of hypoxemia.

Question 33

Name at least three methods to asses the severity of hypoxemia.

Answer 33

Physical exam, A-a gradient, P/F ratio, S/F ratio, oxygenation index, oxygen saturation index.

Question 34

What are the three causes of hypoxemia?

Answer 34

Low inspired O2 concentration, hypoventilation, venous admixture.

Question 35

Name at least two causes of venous admixture.

Answer 35

Low ventilation-perfusion regions, small airway and alveolar collapse, diffusion defects, anatomical right-to-left shunts.

Question 36

Define hyper and hypoventilation.

Answer 36

Hyperventilation is a PaCO2 of less than 30-35 mm Hg, hypoventilation is a PaCO2 of greater than 40-45mm Hg.

Question 37

What is minute ventilation and how is it measured?

Answer 37

It is the total volume of gas exhaled per minute. Respiratory rate x tidal volume

Question 38

What portion of tidal volume does not participate in gas exchange?

Answer 38

Dead space

Question 39

What is the gold standard method of measuring PaCO2 levels?

Answer 39

Arterial blood gas analysis

Question 40

What airway disease is almost exclusively limited to small breed dogs?

Answer 40

Tracheal collapse

Question 41

True or false: pulmonary hypertension is the defining characteristic of a specific disease. Why?

Answer 41

False. It is a pathophysiologic state that can be present in a broad spectrum of diseases.

Question 42

Name at least two diseases that can cause secondary pulmonary hypertension.

Answer 42

Pulmonary arterial hypertension, left sided heart disease, respiratory disease, hypoxia, pulmonary thrombus or thromboembolism, parasitic disease, multifactorial or unclear etiologies.

Question 43

What type of edema is ARDS categorized as?

Answer 43

Increased permeability edema