Pulmonary Physiology and Pulmonary Function Tests Flashcards

1
Q

Four major factors that determine alveolar gas composition

A
  1. Inspired gas composition
  2. Mixed venous gas composition
  3. Alveolar ventilation
  4. Alveolar perfusion
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2
Q

Most frequently used objective tool to assess teh mechanical characteristics of the lung

A

FVC

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3
Q

Maximum volume expired after maximal inspiration

A

Vital capacity

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4
Q

Volume in lungs after maximal inspiration

A

Total Lung Capacity

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5
Q

Volume remaining in lungs after maximal exhalation

A

Residual volume

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6
Q

Volume in lungs at end of normal exhalation

A

Functional residual capacity (FRC)

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7
Q

Volume of spontaneous breath

A

Tidal volume (TV)

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8
Q

Maximum volume inspired from resting end expiratory position to total lung capacity

A

Inspiratory capacity

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9
Q

Volume expired from spontaneous end expiratory position

A

Expiratory reserve volume

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10
Q

Volume that can still be inspired from a spontaneous end inspiratory position

A

Inspiratory reserve volume

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11
Q

PFT technique most commonly used

A

Forced Expiratory Vital Capacity Maneuver

  • Maximal inhalation followed by rapid and completed exhalation
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12
Q

FVC may be decreased due to what

A
  • Intrinsic lung disease
  • Pleural disease
  • Chest wall restriction
  • Respiratory muscle dysfunction
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13
Q

FEV1 decreased in what setting

A

Airway obstruction or restrictive disease

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14
Q

Normal range (FEV1/FVC ratio)

A

75-85%

  • Decreased with age
  • Increased in children (90%)
    • Children have higher flow rates for their size
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15
Q

Low FEV1 with normal FEV1/FVC ratio

A

Restrictive lung disease process

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16
Q

Low FEV1 and decreased FEV1/FVC ratio

A

Obstructive lung disease process

17
Q

Test performed where patient is asked to breathe as hard and fast as possible for 10-15 seconds and result is extrapolated to 60 seconds and reported in L/min

A

Maximal Voluntary Ventilation (MVV)

  • Low MVV occurs in both obstructive and restrictive lung disease
  • Very nonspecific test
  • Useful to estimate patient’s ability to undergo major pulmonary resection
18
Q

Estimates transfer of CO across alvelolar capillary membrane

A

DLCO

  • Impacted by:
    • Area of alveolar capillary membrane
    • Thickness of capillary membrane
    • Driving pressure for each gas being transferred
19
Q

Positive response to bronchodilators during PFT testing

A
  • 12% or 200 ml increase in FEV1 or FVC
20
Q

Important elements of Preoperative Pulmonary Assessment

A
  • Preop PFTs
  • ABG (room air)
    • resting hypercapnea (pCO2 > 50) high-risk for periop morbidity
  • Predicted Postop PFTs
    • multiply preop value of test by fraction of functional segments that remain postoperatively
    • quantitative radiographic assessment: V/Q scan or CT
  • Maximal Oxygen Consumption During Exercise (VO2max)
21
Q

Best method to determine the risk of perioperative morbidity and complications following major lung resection

A

Maximal Oxygen Consumption During Exercise (VO2max)

  • Prohibitive for lung resection: < 10 ml/kg/min
  • High-risk for lung resection: 10-15 ml/kg/min
22
Q

Prohibitive and High-Risk results for Predicted Postoperative PFT testing

A
  • Prohibitive:
    • ppoFEV1 < 20%
    • ppoDLCO < 20%
  • High-Risk
    • ppoFEV1 < 40%
    • pproDLCO < 40%
23
Q

Preopeative values considered high-risk or prohibitive for pulmonary resection

A
  • ppoFEV1 < 0.8L or < 40% predicted
  • ppoDLCO < 40%
  • FVC < 1.5 L or < 30% predicted
  • FEV1/FVC ratio < 50%
  • resting pO2 < 45 mmHg
  • resting pCO2 > 50 mmHg
  • VO2max < 10 ml/kg/min
  • unable to climb 1 fight of stairs
  • resting O2 saturation < 90% or desaturation >4% during exercise
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