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24 A&P II > Lecture 18: FEV₁/FVC Tests (Exam III) > Flashcards

Lecture 18: FEV₁/FVC Tests (Exam III) Flashcards

1
Q

What is the Bohr Equation?

A

VDCO₂ / VT = (PACO₂ - PĒCO₂) ÷ PACO₂

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2
Q

What is the Bohr equation used to find?

A

Total Dead Space

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3
Q

Give an example of a Bohr equation with numbers.

A

VTotalDS / VT = (40mmHg - 28mmHg) ÷ 40mmHg

0.3 = VTotalDS ÷ 500mL

VTotalDS = 150mL

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4
Q

How would one find alveolar dead space?

A

VAlveolarDS = VTotalDS - VAnatomicDS

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5
Q

How can anatomical dead space be estimated?

A

1mL of deadspace per 1lb of body weight

(Ex. 200lbs = 200mL anatomic deadspace)

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6
Q

A 100kg patient presents with a PĒCO₂ of 25mmHg, a VT of 600mls, and a PaCO₂ of 42mmHg. What would the estimated alveolar dead space of this patient be?

A

VA = ?
VT = 600mls
VAnatomic = 220mls (100kg x 2.2 = 220lbs)

VD ÷ 600mls = (42 - 25) ÷ 42
VD = 242.86mls

VA = 22.86mls (242.86mls - 220mls)

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7
Q

If there is no shunting present then PACO₂ should = ____________.

A

PaCO₂

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8
Q

If ĒCO₂ (mixed expired CO₂) is lower than expected, what conclusion could one likely draw?

A

There is increased dead space.

likely VAlveolarD

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9
Q

What would you expect from the flow-volume loop depicted below?

A

Normal

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10
Q

What would you expect from the flow-volume loop depicted below?

A

Restrictive Disease

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11
Q

What would you expect from the flow-volume loop depicted below?

A

Obstructive Disease

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12
Q

What would you expect from the flow-volume loop depicted below?

A

Fixed Obstruction (Ex. ETT)

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13
Q

What would you expect from the flow-volume loop depicted below?

A

Variable Extrathoracic Obstruction

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14
Q

What would you expect from the flow-volume loop depicted below?

A

Variable Intrathoracic Obstruction

Peaked beginning likely due to emphysema

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15
Q

What is FEV₁ ?

A

% of VC expired in 1 second

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16
Q

What is an ideal FEV₁ assuming VC = 4.5L?

A

FEV₁ = 3.6L

17
Q

What is FEF25-75% ?

A

Slope of line from once 25% of air has been expired to 75% of air expired.

18
Q

What would a gradually sloped FEF25-75% (such as the one below) indicate?

A

Obstructive disease

19
Q

What would a steep sloped FEF25-75% (such as the one below) indicate?

A

Normal

20
Q

FEV₁ could largely be considered an indicator of _____ airway health, whereas FEF25-75% would be more indicative of ______ airway health.

A

large; small

FEV₁ = large airways
FEF25-75% = small airways.

21
Q

What is the Vital Capacity of the patient from the graph below?

A

VC = 3.75L (ish)

22
Q

What is the FEV₁ of the patient from the graph below?

A

FEV₁ ≈ 1.5L

23
Q

What is the FEV₁/FVC of the patient from the graph below?

A

FEV₁ = 1.5
FVC = 3.75

1.5 ÷ 3.75 = 40%

24
Q

What is a normal FEV₁/FVC ?

A

80%

25
Q

What is the FEV₁ of the black line below?

A

3.6L

26
Q

What is the FEV₁ of the blue line below?

A

1.5L

27
Q

The two graphs below would be indicative of what?

A

FEV₁ / FVC = 3.8 ÷ 5 = 76%

Normal Physiology

28
Q

The two graphs below would be indicative of what?

A

FEV₁ / FVC = 2.5 ÷ 3 = 83%

Restrictive Disease

29
Q

The two graphs below would be indicative of what?

A

FEV₁ / FVC = 1.5 ÷ 3.5 = 43%

Obstructive Disease

30
Q

What FEV₁ / FVC would be considered pathologic?

A

< 70%

31
Q

Calculate the FEV₁ / FVC of the green line below.

What is this indicative of?

A

VC = 5 - 1.5 = 3.5
FEV₁ = 3

FEV₁ / FVC = 3÷3.5 ≈ 86%

Normal or Restrictive disease

32
Q

Calculate the FEV₁ / FVC of the red line below.

What is this indicative of?

A

VC = 5 - 0 = 5L
FEV₁ = 4L

FEV₁ / FVC = 4÷5 ≈ 80%

Normal

33
Q

What is abnormal about the flow-volume loop below?

A

Normal breathing should be closer to FRC

34
Q

What is the formula for Total Respiratory System Compliance?

A
  • CRS = Total Compliance of the Respiratory System
  • CL = Compliance of the tissue.
  • CCW = Compliance of the chest wall (i.e. ribs).
35
Q

What two factors oppose negative pressure exerted by PIP ?

A
  • PER (Tissues resistance to stretching)
  • CCW (ribcage resistance to expansion)
36
Q

What is the compliance of the respiratory system at FRC? (Total system compliance)

A

0.1 L/cmH₂O

37
Q

Solve for Respiratory System Compliance.

A
  • CL = 0.2
  • CCW = 0.2
  • x = CRS

(1÷x) = (1÷0.2) + (1÷0.2)
↓
(1÷0.1) = (1÷0.2) + (1÷0.2)
↓
CTotalCompliance(RS) = 0.1L / cmH₂O

38
Q

How will body positioning affect ventilation at FRC?

A
  • Upright: ribs assist ventilation
  • Supine: ribs impede ventilation.
39
Q

If a lung was completely blocked off, what would occur to compliance?

A

Compliance would be cut in ½.

24 A&P II (24 decks)

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