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Physiology I F2015 > 8. Pulmonary Lung Vol > Flashcards

8. Pulmonary Lung Vol Flashcards

1
Q

What is diff b/w vol + capacities?

A

Vol = directly measured; capacities = inferred from lung vol

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2
Q

What is normal TV?

A

6-8ml/kg

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3
Q

What is normal vital capacity (VC)?

A

60ml/kg +/- 20% (~10x TV)

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4
Q

What is normal RR?

A

12-20bpm for adults

30-60bpm at birth

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5
Q

To cough effectively VC has to be how much greater than TV?

A

VC > 3 x TV

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6
Q

What is TV?

A

Normal volume of air breathed in during baseline state

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7
Q

What is expiratory reserve vol (ERV)?

A

Add. vol of air forcefully expired past norm. expiration

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8
Q

What is residual volume (RV)?

A

Vol remaining after max. expiration –> vol to keep alveoli open, RV=FRC-ERV

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9
Q

What is inspiratory reserve volume (IRV)?

A

Add. vol of air that can be forcefully inhaled past norm. inspiration

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10
Q

What is vital capacity (VC)?

A

Max vol of air that can be forcibly expired after max inspiration

VC=TV+IRV+ERV

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11
Q

What is inspiratory capacity?

A

If at end of tidal vol expiration, vol of max inspiration

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12
Q

What is total lung capacity (TLC)?

A

Vol air at end of max. inspiration

TLC=FRC+TV+IRV=VC+RV

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13
Q

What is functional residual capacity (FRC)?

A

Vol air remaining after norm. passive exhalation

FRC=RV+ERV

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14
Q

What is minute ventilation?

A

Vol air exhaled per min

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15
Q

What is normal TV?

A

500ml

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16
Q

What is normal IRV?

A

3000ml

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17
Q

What is normal ERV?

A

1100ml

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18
Q

What is normal RV?

A

1200ml

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19
Q

What is normal FRC?

A

2300ml

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20
Q

What is normal TLC?

A

5800ml

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21
Q

How does pt positioning affect alveolar size?

A

Size of alveoli diff at top than bottom (upright) –> weight of lungs compressing alveoli at base. W less weight pushing against upper alveoli, expanded out more (alveolar interdependence). Top alveoli has decr. compliance b/c closer to TLC –> lesser ventilation.

22
Q

(T/F) Gravity doesn’t affect perfusion.

A

False, greater perfusion near base of lungs. HOWEVER, perfusion and ventilation have diff slopes resulting in V/Q mismatches at both extremes of apex + base.

23
Q

Describe a flow-volume loop.

A 
Full expiration near 0 on Lhand side
TLC/total inhalation on Rhand
Lower curve inhalation
Upper curve exhalation
BUT typically move only small range w/in flow-vol loop (from FRC to TLC), typically w/ most compliance
24
Q

What happens to elasticity + compliance in a sick lung?

A

Lower compliance (easier to distend) + elasticity (ability of lungs to recoil) worsens –> greater V/Q mismatches, alveoli are hyperextended

25
Q

What is FVC/FEV1

A

Forced VC is when pt asked to take biggest breath as can + as quick + hard as can blow out –> vol measured. Forced expiratory volume at 1s measured over 1s (norm=~4L)

26
Q

What is Max. Voluntary Vent (MVV)?

A

MVV (aka Maximal breathing capacity) is max vol air that can be exhaled by voluntary effort in 15s interval, then multiplied by 4 –> L/min

27
Q

What is closing capacity?

A

Vol in lungs at which airway + alveoli start to collapse. Want to stay above this or else cause atelectasis.

FRC + alveolar interdependence helps compete against this. CC typically well below FRC. HOWEVER, CC sig. increases with age while FRC barely if any. FURTHERMORE, FRC decr. based on position + esp. w anes., smoking history, and lung disease –> encourage coughing + deep breathing after GA.

28
Q

What happens as alveoli remain collapsed for longer + longer periods of time?

A

More V/Q mismatch, gas exchange prob, hypoxemia + other post-op pulm. complications

29
Q

(T/F) In young, healthy pt, a few coughs + deep breaths is not sufficient to re-expand alveoli.

A

False

30
Q

What variables affect FRC?

A
  1. Sex
  2. Body habitus (obesity adds extra weight –> blunts outward recoil of chest wall –> decrease FRC)
  3. Posture/positioning
  4. Age
  5. Lung disease
  6. Diaphragmatic tone
31
Q

Where is the dependent part of lung?

A

Lower portion of lung

32
Q

What happens when you lose diaphragmatic tone?

A

(almost imm w induction of anes even before MR) abd contents push up on lungs –> compress to smaller size –> sig. drop FRC

33
Q

What % of all pt have atelectasis under GA as result of loss of diaphragmatic tone

A

85-95%

34
Q

When pt transitions from upright to supine position, how much does FRC drop?

A

0.5-1L

35
Q

What is the relationship between FRC + age

A

FRC decreases w increasing age

36
Q

How does induction of anesthesia affect muscle tone?

A

GA causes diaphragm + chest wall muscle tone to decrease

37
Q

By what % does FRC decrease w GA?

A

10-20% drop

38
Q

How long does it take for FRC to return back to normal after GA?

A

Hours

39
Q

(T/F) Elderly pt can’t generate enough P to overcome atelectasis after GA.

A

True

40
Q

What are different types of ventilation that you can use on pts + how do they affect atelectasis?

A

Standard TV ventilation (10-20cmH2O) - ineffective
Sigh breaths (20cmH2O) - ineffective
40cmH2O - typically effective

41
Q

How does size + number change as progress down pulm. airway?

A

The size of airways decrease but number increases sig –> sig. increase in sum cross-sectional airway (many terminal bronchioles vs. trachea)

42
Q

Describe the tracheobronchial tree and how it affects ventilation.

A

Terminal bronchi have smooth muscle surrounding them –> contract + dilate. However, are very small –> greater resistance in bronchus than in trachea

43
Q

Which flow system has lowest resistance to flow?

A

Laminar flow as opposed to turbulent flow

44
Q

Which type of airway has the greatest resistance to flow?

A

Small airways, esp. those lined w secretions –> increased work of breathing. Larger airways = easier to maintain laminar flow

45
Q

What is Poiseuille’s Law?

A

Resistance is inversely related to r^4 –> small increase in radius decreases resistance sig!

46
Q

How does lung volume affect airway resistance?

A

As lung vol increase, resistance decreases sig (exponential drop). Alveolar expansion helps extend term. bronchioles

47
Q

How does airway resistance change as pt changes from upright to supine position?

A

Resistance increases, R in upright pt is close to its lowest

48
Q

Where is the greatest resistance found in pulm. airway + why?

A

Greatest R in bronchi because of smaller size compared to trachea. However, R decreases sig. as branch from bronchus to bronchioles to term. bronchioles –> sig. increase in total surface area (make up sig. portion of airflow)

49
Q

How does secretions or bronchospasm affect airway resistance?

A

Change in diameter –> sig increase in R –> increased work of breathing

50
Q

What is alveolar interdependence?

A

Tethering of alveoli to each other –> helps stent open alveoli + airway –> drops R. HOWEVER, tethering decreases w disease + destruction of alveoli

Physiology I F2015 (13 decks)

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