Ventilatory Pump, Gas Exchange and Airway Clearance

Question 1

<p>Name an airway clearance problem, describe what causes it and how can it be measured?</p>

Answer 1

<p>-Asthma

- CF, Bronchitis
- Descried by the inability to clear secretions
- CT, chest film
- Breath sounds
- Xray would work; can identify pneumonia
- Can also measure secretions</p>

Question 2

<p>Name a ventilatory pump problem, describe what causes it and how can it be measured?</p>

Answer 2

<p>-Decreased compliance from increased stiffness
-Chest can’t expand properly (ie. Rib fracture)
-Pleural effusion (fluid compressing lung)
-Muscle weakness
-Measure PFTs
-Postural assessment
->A/P diameter
-flat subcostal angle
->90 degree zyphoid angle
Breathing pattern
-accessory muscle use</p>

Question 3

<p>-Name a gas exchange problem, describe what causes it and how can it be measured?</p>

Answer 3

<p>-Pulmonary embolism

- Infection (tuberculosis)
- COPD (emphysema and chronic bronchitis (affects all 3))
- alveoli continue to expand and lose elastic properties
- Measured by O2 sats, ABG (arterial blood gas)</p>

Question 4

<p>What four things must be present to qualify someone with pneumonia? </p>

Answer 4

<p>1. Inability to clear airway

2. Evidence of retained secretions, infiltrate or consolidation
3. Pathology with chronic retained secretions
4. Mediate percussion</p>

Question 5

<p>What's the difference between internal and external respiration?</p>

Answer 5

<p>EXTERNAL
-Gas moving into alveoli to diffuse across membrane into blood supply

INTERNAL
-Gas moving from blood into the cell</p>

Question 6

<p>At rest, your I:E (inspiration to expiration ratio) is 1:2, what is it during exercise?</p>

Answer 6

<p>1:1</p>

Question 7

<p>What happens with a discoordinated (paradoxical) breathing pattern?</p>

Answer 7

<p>There is a thoraco-abdominal motion occurring at an odd time.</p>

Question 8

Describe what constitutes an obstructive and restrictive pathology

Answer 8

Obstructive

• can’t get air out
• premature collapse

Restrictive

• radiation; changes to lung tissue and external tissue
• volumes and capacities have the same ratios, just the volumes shrink

Question 9

What are a few key PFT flow measures? When reduced, what pulmonary conditions do they point towards? How do you calculate them?

Answer 9

Forced Vital Capacity (FVC)
-likely restrictive when reduced
Forced Expiratory Volume in 1 second (FEV1)
-likely obstructive when reduced

Calculate normal values, then compare measures as %.

Question 10

What are MIF/MIP and MEF/MEP values?

Answer 10

MIF or MIP test the maximal inspiratory force. MEF or MEP test the maximal expiratory force.

Question 11

Ventilation occurs at the alveolar space. What is the difference between anatomical and physiological dead space? At what generation of bronchioles does respiration begin?

Answer 11

Anatomical
-space in the trachea where no gas exchange can occur

Physiological

• where air is in the alveoli, but no blood can get to the area
• happens with a PE

Respiration begins at the 16th generation.

Question 12

Why is assessing minute ventilation (Ve) useful?

Answer 12

It allows your to assess CO2 levels for either hypoventilation or hyperventilation (low levels).

Question 13

Dalton’s Law states that Pgas = Pb x Fgas, where Pb is total pressure and Fgas is the % of the total volume of the particular gas. If PO2 = 760 mHg and Fgas is 0.21 (O2), what is the normal atmospheric pressure of oxygen? What about pre-metabolic levels in the blood?

Answer 13

160 mmHg.

O2 = 100mmHg (40 mmHg after)
CO2 = 40mmHg (46 mmHg after)

Question 14

In alveolar gas exchange, O2 takes about 0.75 milliseconds to diffuse. How long does CO2 take?

Answer 14

10% of the time.

Question 15

What’s the rule of thumb for someone on 100% FiO2 as it relates to their PO2?

Answer 15

Every 10% increase means an increase of 50 mmHg.

Question 16

Ventilation and perfusion (extraction of O2 out of alveoli into blood) are only 1:1 under perfect circumstances. Which area of the lung usually has a V/Q rations >1? Why?

Answer 16

The base of the lungs because gravity holds more blood in that area.

Question 17

What are some factors decreasing SpO2 accuracy?

Answer 17

• Decreased blood flow
• Mobility or when SpO2 70-80%
• Severe anemia (not always)
• Dark pigmented skin or nail polish

Question 18

O2 dissociates from hemoglobin at different rates depending on the PaO2. The higher the PaO2, the faster O2 dissociates. What are 2 significant landmarks on the oxyhemoglobin curve for dissociation?

Answer 18

SaO2 of 90 is a PO2 of 55.
SaO2 of 70 is a PO2 of 40.

Dissociation between the two benchmarks happens in a brief moment.

Question 19

pH affects the oxyhemoglobin curve. What happens in an acute alkalosis (increased pH) and an acute acidosis (decreased pH)?

Answer 19

Alkalosis: increased affinity for O2.
Acidosis: decreased affinity for O2.

Question 20

What are the normal ABGs (Arterial Blood Gases)?

Answer 20

pH = 7.40
PaCO2 = 40 mmHg
PaO2 = 100 mmHg
HCO3 = 24 mEQ/L

Question 21

A low pH means there is an acidemia with a high pH indicating an alkalemia. How do you determine whether a respiratory or metabolic acidosis / alkalosis exists?

Answer 21

First, look at the pH. If it is low, look for an increased CO2 intake to increase acidity. If it is high, look for an increased buffering situation (like decreased O2). If HCO3 (metabolic) is not normal, this means kidney’s have started working to balance pH and it’s now chronic and fully or partially compensated. Low HCO3 = acidic.

Question 22

How large are the pH changes that occur with compensation?

Answer 22

For each 10 point change in CO2, the pH will change 0.08 in the opposite direction.

For each 10 point change in the HCO3, the pH will change 0.15 in the same direction.