Pulmonary function

Question 1

What is the normal total minute ventilation?

Describe the generations of bronchioles

Answer 1

It is qual to the product of the respiratory rate and the tidal volume. It is approximately 6L/min

23 generations in total
1-16 conducting
17-23 respiratory zones with the 23rd being a single alveoli

1-4 are cartilaginous and 5-23 membranous

ALL HAVE SMOOTH MUSCLE EXCEPT 23RD

Question 2

What does a pneumotachograph do?

Answer 2

Measures flow of air, converts to volume

At alveoli, flow is so slow that large fluctuations in breathing don’t really have an effect

Question 3

Consider pulmonary function testing. What is spirometry ?

Answer 3

Spirometry measures the total amount of air you can breathe out from your lungs and how fast you can blow it out.

Considers gender, age, heigh, race (as in predicted value). Above 80% similarity is good

If FEV/FVC<0.7 =obstruction
Reversible obstruction shows positive response to albuterol (BRONCHODILATOR RESPONSE)

Question 4

Consider pulmonary function testing. What is peak expiratory flow rate ?

Answer 4

Uses a spirometer or home device

Useful for asthmatics as they assess response to treatment and can identify exacerbations

Question 5

Consider pulmonary function testing. What does the methacholine test indicate?

Answer 5

Methacholine causes bronchoconstriction. Those with pre-existing hyperreactive airways such as asthmatics will react to lower doses

A positive result means FEV1 decreased by 20%
It indicates hyper reactive airways

Question 6

Describe flow rate loops

Answer 6

There is an effort dependent phase in which the bigger the effort, the bigger the flow rate

The effort independent phase is opposite. Airway resistance causes a decreased pressure from alveoli to mouth. When Ppl= Pairway, compression starts. This is called the Equal pressure point (EPP). The bronchioles reopen when Pairway builds up enough to overcome Ppl Cartilage-free bronchioles act as starling resistors.

Question 7

Consider pulmonary function testing. What is body plethysmography ?

Answer 7

Measures patients breathing at their comfortable level

P1V1=P2V2
where P1=AlvP (pressure at mouth) at FRC, V1: FRC
P2: AlvP during inspiratory effort, against closed shutter
V2: FRC change in volume of the box

Question 8

Consider pulmonary function testing. What is helium dilation technique ?

Answer 8

Decreased lung volumes can be caused by 1. pleural disease, 2. chest wall disease, 3. weakness which is focal or global, nerve or muscular

Hyperinflation= increased TLC which could be due to decreased elastic recoil of lungs

Air tapping= increased RV

Question 9

Consider pulmonary function testing. Describe the diffusing capacity test ?

Answer 9

Measure by seeing how much CO breathed in

Amount of diffusion= inspired CO-expired CO

Question 10

Outline which diseases ay cause reduced capacity

Answer 10

Pulmonary
Emphysema, lung infiltration, lobectomy

Cardiovascular/haemotological disease
Pulmonary hypertension,low CO, pulmonary oedema, anaemia

High CO, Pulmonary haemorrhage, polycythaemia