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FHB - Pulmonary & Renal - Exam 2 > Pulmonary 3 > Flashcards

Pulmonary 3 Flashcards

1
Q

What are the two major air flow determinants at a given pressure gradient?

A
  1. Pattern of Gas Flow

2. Resistance to air flow by Airways

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2
Q

What is the equation for laminar flow?

Turbulent flow?

A

V(flow) =
(Pressure r^4pi) / 8Ln

Reynolds Number

R= densityDiameterVelocity/ viscosity

Anything LESS than 2000 = laminar
greater than 2000 = TURBULENT

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3
Q

Where is airflow most turbulent? Where does it become laminar? Where does diffusion occur?

A
  1. In the TRACHEA: largest diameter and velocity is high
  2. Higher Airway becomes laminar
  3. Diffusion occurs in the RESPIRATORY ZONE –> slow velocity
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4
Q

Where is the highest resistance found? Why does this not follow the usually rules of resistance = 1/r^4 (aka smaller vessels have greater resistance)?

A
  1. in Generation 4
    (highest in zones 1-6)
  2. Due to the BRANCHING the system is in PARALLEL so the short length & frequent branching area has HIGHEST resistance = TURBULENT FLOW
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5
Q

What is the resistance in the Respiratory zone where the alveoli reside? Where is true laminar found?

A

Resistance in the Respiratory Zone is
LOW

  • True laminar is found in the VERY SMALL
    BRONCHIOLES
  • zones 10-16!!

Large airways = TURBULENT FLOW
then turns into Laminar
in RESPIRATORY ZONE
- FLOWS VIA DIFFUSION

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6
Q

How is conductance related to resistance?

What happens to conductance and Airway Resistance (AWR) during:

  1. Lung Volume increases
  2. Sympathetic Stimulation via B2 agonists
A

C= 1/R

  1. Conductance Increase
  2. AWR DECREASES

For BOTH!
- when you expand the lung, the diameter of the airways is enlarged so resistance is decreased

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7
Q

How do the following affect resistance and thus conductance?

  1. Vagal Stimulation
  2. Edema
  3. Viral INfection
A

ALL INCREASE AWR

  • so conductance decreases
  • vagal stimulation causes smooth muscle in the airway to CONTRACT
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8
Q

What is FVC? FEV1?

How is this ratio expressed? What is a NORMAL value of this ratio?

A

FVC = forced vital Capacity
-breating at tidal volume & ask patient to take a full inspiration & forced expiration
(FVC = IRV+VT+ERV)

FEV1 = forced expiratory volume in 1 s

FEV1/FVC
- usually around 75% is NORMAL

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9
Q

What is FEV1 a measure of? What does a smaller FEV1 signify? What is a clinical case of a smaller FEV1?

A

Airway resistance!

  • smaller FEV1 means INCREASED resistance to expiratory airflow!
  • ASTHMA! = trapping air in lungs
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10
Q

If the FEV1/FVC ratio is less than 75% what does this mean? Greater than 75?

A
  1. OBSTRUCTIVE disease

2. Normal if OVER 75%

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11
Q

What is different about PEFR and PIFR in a flow volume loop?

A
  1. PEFR occurs EARLY

2. Flow rates for PEFR decrease as they approach RV due to expiratory flow limitation

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12
Q

What is PEFR and PIFR? What values are they on a Flow-Volume loop (aka which is most positive, most negative)

A

PEFR = Peak Expiratory FLow Rate (9.5l/sec)

PIFR = Peak Inspiratory Flow Rate (-10 L.sec)

PIFR = NEGATIVE
PEFR = POSTIVE
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13
Q

What happens to the following during INSIRATION as lung volume increases:
(increase/decrease)

  1. Force of inspiratory muscle
  2. Lung Recoil Pressure
  3. Airway Resistance
  4. Max Inspiratory Flow
A
  1. Force of inspiratory muscle DECREASES
  2. Lung recoil pressure INCREASES
  3. Resistance DECREASES
  4. Max Inspiratory flow occurs HALFWAY between TLC and RV
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14
Q

What is Expiratory Flow limitation? How is this represented on a Flow-VOlume loop?

A
  • due to the dynamic compression of airways

once the pressure gradient is reduced and the pressure outside is greater than the pressure inside = EXPIRATORY FLOW LIMITATION

slow decline towards RV!

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15
Q

The following describes Expiratory Flow rates at High Volumes or Low volumes?

  1. Effort Independent
  2. Flow Limited
A

LOWER LUNG VOLUMES

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16
Q

When is expiratory flow EFFORT DEPENDENT?

A

At HIGH volumes

17
Q

1.What happens at the Equal Pressure Point?

When is this altered?

2.When is airflow resistance highest?

A
  1. Airflow becomes INDEPENDENT of total driving pressure
    - in normal lungs, this usually occurs at an area of cartilage so that the airway is not compressed
    - It is altered in DISEASE (obstruction) leading to premature airway closing (air trapping)
  2. Airflow resistance is greater during EXHALATION
18
Q

When is FEV1 reduced? When is FVC reduced?

A
  1. OBSTRUCTIVE lung disease in Asthma, COPD

2. FVC reduced in RESTRICTIVE lung diseases aka fibrosis

19
Q

In restrictive disease, what is usually normal?

A

FEV1/FVC since only FVC is decreasing (total ratio becomes greater than 75%)

20
Q

When using Albuterol (B2 Agonist) what happens to FEV1/FVC?

A

FEV1/FVC ratio becomes NORMAL!

w/o albuterol, the FEV1 is very low since this is an OBSTRUCTIVE disease

21
Q

In obstructive lung disease how is flow affected? In restrictive? What is different in restrictive lung disease?

A

Obstructive - flow is SIGNIFICANTLY reduced

Restrictive - flow rates appear normal, but vital CAPACITY is reduced

(max amount of air that can be expired with max inhalation)

22
Q

How are the following changed in OBSTRUCTIVE disorders:

  1. FEV1/FVC
  2. FEV1
  3. FVC
  4. TLC
  5. RV
A
  1. FEV1/FVC-decreased
  2. FEV1 - Decreased
  3. FVC - decreased/normal
  4. TLC - normal or increased
  5. RV - normal or increased
23
Q

How are the following changed in RESTRICTIVE disorders:

  1. FEV1/FVC
  2. FEV1
  3. FVC
  4. TLC
  5. RV
A
  1. FEV1/FVC - normal/increased
  2. FEV1 - Decreased/Normal/ or increased
  3. FVC - DECREASED
  4. TLC - DECREASED
  5. RV - DECREASED
24
Q

What are the 2 main components of respiratory work? (TOTAL WORK)

A
  1. Elastic Work

2. Work to Overcome Airflow Resistance

25
Q

What is Elastic Work?(3 types)

What is it proportional to?

A
  1. Work to overcome Elastic Recoil of lungs
  2. To Expand Thoracic Cage
  3. Work to Dispace abdominal organs

Proportional to TIDAL VOLUME

26
Q

What is non elastic work? What is this proportional to?

A

Work to overcome airflow resistance

Proportional to BREATHING FREQUENCY

27
Q

When is work increased? (4)

A
  1. Pulmonary compliance is reduced
  2. Airway resistance is increased
  3. Elastic recoil is decreased
  4. Exercise, however total energy is also increased,
    proportion remains at ~5%
28
Q

What type of increased work are the following:

  1. Pulmonary Fibrosis
  2. COPD

How does breathing change in both of this conditions?

A
  1. Fibrosis = Increased elastic Work
    - breathing is shallow & rapid
  2. Increased Flow Resistive Work = breathing becomes slow & deep
29
Q

What is the Equal Pressure Point? When is this point closer to the alveolus?

A

Pressure inside =Pressure outside

During COPD equal pressure point is closer so the flow is reduced

30
Q

How is dynamic compression determined? What does it limit & when specifically? (expiration/inspiration)

A
  1. Determined by Alveolar - Pleural Pressure (PA - Ppl)

2. Limits the AIRFLOW during FORCED EXPIRATION

31
Q

When is work of breathing MINIMAL?

A

Normal Tidal Volume Ventilation

32
Q

How do patients with lung disease minimize work of breathing?

A

Change the breathing patterns & frequency

FHB - Pulmonary & Renal - Exam 2 (21 decks)

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