Respiratory Disease Flashcards

1
Q

A normal breath volume is AKA?

A

Tidal volume

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2
Q

The remaining gas in the lung after normal expiration is AKA

A

Functional residual capacity

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3
Q

What is the maximum expiratory volume after a maximum inspiration?

A

Vital capacity

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4
Q

What is the remaining gas n the lung after MAX expiration?

A

Residual volume

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5
Q

By Ficks law of diffusion, diffusion rate is proportional to??

A

Tissue area
Partial pressure difference
Solubility of gas in tissue

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6
Q

By Ficks law of diffusion, diffusion rate is inversely proportional to??

A

Tissue thickness and square root of molecular weight

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7
Q

T/F: CO2 diffuses mor rapidly than O2

A

True 20x faster

  • higher solubility
  • similar molecular weight
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8
Q

What is the definition of hypoxemia?

A

PaO2 <60mmHg

SpO2 90%

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9
Q

What are the 5 causes of hypoxemia?

A
Hypoventialion 
Anatomic R to L shunt 
Low inspired O2
Diffusion impairment 
Ventilation-perfusion mismatch
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10
Q

How is hypoventilation defined?

A

High PaCO2 >40mmHg

Will result in hypoxemia if breathing room air (FiO2 0.21)

Not at 100% oxygen (FiO2 1)

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11
Q

At 100% oxygen, PaO2 should be??

A

500mmHg

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12
Q

What is an anatomic R->L shunt?

A

Blood entering arterial system without going through ventilated area of lung (eg PDA)

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13
Q

T/F: there are some normal small R->L anatomic shunts

A

True

  • bronchial artery
  • coronary enough blood (thesbeian veins)
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14
Q

Under what conditions can you have a low inspired FiO2?

A

High altitude

Anesthesia —> delivery of hypoxic gas mixture (rare)

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15
Q

What are examples of diffusion impairment ? How common is this in vet species?

A

Thickened blood-gas barrier

Rare in vet sp.

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16
Q

What is V/Q mismatch? What are causes?

A
V= ventilation 
Q= perfusion 

When these are not equal can lead to hypoxia

V/Q = 0 —> perfusion occurs without ventilation (eg atelectasis )

V/Q = infinity —> ventilation without perfusion (eg pulmonary thromboembolism)

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17
Q

What is hypoxic pulmonary vasoconstriction (HPV)?

A

Normal physiological mechanism to match V:Q

Alveolar hypoxia —> vasoconstriction of small pulmonary arteries

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18
Q

How do anesthetic drugs affect hypoxic pulmonary vasoconstriction??

A

Decreased reflex

—> increased V:Q mismatch
—> decrease PaO2:FiO2

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19
Q

What ways can oxygenation be assessed?

A

Alveolar arterial O2 gradient

PaO2: FiO2

20
Q

What is normal PaO2 at normal room air?

A

FiO2 is 0.21 or 21%

PaO2 = 100mmHg

21
Q

What is the alveolar-arterial gradient ?

A

Difference between PAO2 (in alveoli) and PaO2 (arterial)

22
Q

The alveolar -arterial O2 gradient should be??

A

Less than 10-15mmHg

23
Q

If the A-a gradient is >15mmHg, what does this mean?

A

Oxygenation problem

—> controls for hypoventilation

24
Q

What is the most common cause of a <500mmHg PaO2 if giving 100% oxygen?

A

V:Q mismatch

25
What is the only way to accurately evaluate oxygenation?
Arterial blood gas SpO2 requires huge change in PaO2 before it registers and change is saturation
26
What is CaO2? What is the major determinant of this value?
Content of oxygen in blood Hemoglobin concentration
27
T/F: CaO2 and cardiac output determines O2 deliver to tissues
True
28
T/F: an anemic patient may have an normal PaO2 but marked tissue hypoxia
True
29
an anemic patient may have an normal PaO2 but marked tissue hypoxia. How can this be resolved?
Must increase [H] - rbc - synthetic Hb (eg oxyglobin)
30
What factors affect ventilation ?
``` PaCO2 **main determinant** Arterial pH PaO2 Pulmonary airway stretch receptors Body temp Stress, anxiety, pain ```
31
What anesthetic dugs have minimal respiratory depression?
Benzo Phenothiazines A2 agonsit Opioid
32
What anesthetic drugs can cause significant respiratory depression ?
Propofol, etomidate, alfaxalone > ketamine Volatile anesthetic Drug combos
33
What is the role of IPPV?
Decrease PaCO2 May increase PaO2 if resolving areas of atelectasis (improve V/Q matching)
34
What is peak inspiratory pressure?
Pressure achieved at end of inspiration
35
What is PEEP?
Pressure maintained in airway to prevent alveolar collapse -positive end-expiratory pressure
36
How much pressure do we give with IPPV?
Close popoff | <20cmH2O
37
When is a mechanical ventilator required?
Equine gas anesthesia Small animals if open thorax, using NMBD or with increased ICP
38
What are disadvantages of IPPV?
Normal inspiration —> contraction of breathing mm—> decreased intrathoracic pressure —> airflow down pressure gradient to alveoli =>PPV is not physiologically normal - decrease BP (decrease preload and increased afterload) - pulmonary damage (volutrauma or pneumothorax)
39
What are the types of respiratory dysfuntion?
Airway obstruction Pulmonary dysfunction > pneumonia, edema, contusions Extrapulmonary dysfunction > effusions, pneumothorax, d-hernia, flail chest
40
T/F: light sedation is indicated in dypneic animals
True Decrease anxiety and work of breathing -> butorphanol +/- benzo or low dose ace
41
What do you do with animals that have pleural effusions and pneumothorax?
Thoracocentesis ASAP
42
What can quickly reverse life-threatening hypoxemia secondary to hypoventilation ??
Anesthesia with IPPV - > laryngeal paralysis - > upper airway obstruction - > paralysis
43
How do you anesthetize a bulldog?
``` Monitor closely after premed Preoxygenate Rapid sequence infusion Small ETTtube Recover in sternal Prolong extubation ``` Monitor until alert and awake
44
How do you treat hypoxemia during anesthesia?
Resolve any airway obstruction Position in sternal if possible while away Position lateral with good lung up Increase PIP Consider bronchodilator PEEP
45
What is re-expansion pulmonary edema and how is it done?
Lung expansion after chronic compression (eg D hernia or pleural effusion) Keep PIP low during IPPV
46
Why is hypoxemia so common with equine colic?
Severe V/Q mismatch | Distended abdomen, hoisting, dorsal recumbency, decreased CO/poor pulmonary perfusion, pain
47
How do you treat hypoxemia during equine colic?
``` Start IPPV asap High PIP PEEP Bronchodilator Tilt table headup ``` Improve cardiac output Balance positive pressure ventilation with maintaining BP and CO O2 deliver dependent on CaO2 and CO