1. The document describes the structure and function of the lungs and trachea. It discusses key anatomical features like the trachea, bronchi, bronchopulmonary segments, blood supply, lymphatic drainage, and gas exchange in the lungs. 2. It also provides information on measuring lung volumes using spirometry and includes two sample patient cases - one with normal pulmonary function and one with moderate airflow obstruction. 3. The cases demonstrate how to interpret spirometry results and determine the presence, severity, and differential diagnosis of any lung abnormalities.

1. Structure and Function
of the lungs
Cardiothoracic Department
University Hospital of South Manchester
Dr Marco Nardini

4. Trachea
• 1.5 cm below the vocal cord and is not fixed to
surrounding tissues
• 12 cm length
• Internal diameter 2.3 cm laterally. 1.8cm
anteroposteriorly
• 18 to 22 cartilaginous rings, the cricoid is the only
one complete
• Important relationships
• Blood supply is lateral and segmental

8. Lungs
• The Bronchopulmonary segments are division
of each lobe that contain anatomically
separate arterial, venous and bronchial
supplies.
• 10 segments on the right
• 8 segments on the left
• The blood supply of the lung is twofold
• Lymphatic drainage usually affect ipsilateral
lymph nodes

9. •In the lung 80% of its volume
is air
•10% is blood
•10% is solid tissue
•Alveoli make up 50% of the
entire volume
Lungs

15. http://www.thoracic-anesthesia.com/?page_id=2

21. Fick’s law of diffusion through a tissue sheet

22. Ventilation

23. Diffusion

24. Gas exchange

25. Volumes

26. Volumes & flow rates

27. Measuring lung volumes with a spirometer

28. Pre-Bronchodilator (BD) Post- BD
Test Actual Predicted % Predicted % Change
FVC (L) 4.39 4.32 102 -1
FEV1 (L) 3.20 3.37 95 7
FEV1/FVC
(%)
73 78 8
FRC (L) 3.17 3.25 98
ERV (L) 0.63 0.93 68
RV (L) 2.54 2.32 109
TLC (L) 6.86 6.09 113
DLCO*
uncorr
25.69 31.28 82
DLCO corr 26.14 31.28 84
*DLCO is measured in ml/min/mmHg
Case 1
A 65 year-old man undergoes pulmonary function testing as part of a routine health-
screening test.
He has no pulmonary complaints.
He is a lifelong non-smoker and had a prior history of asbestos exposure while serving
in the Navy.
His pulmonary function test results are as follows:

29. 1. Describe the pattern of abnormality, if one is present.
2. Grade the severity of the abnormality.
3. Generate a differential diagnosis for the observed
abnormality.
Case 1
Case 1 Interpretation
This case demonstrates an example of normal pulmonary function tests. The FVC and the
FEV1 are 102% and 95% of predicted, respectively, values well above the lower limit of
normal and the FEV1/FVC ratio is greater than the predicted value minus 8. The flow-
volume loop also corresponds quite nicely to the predicted values for this patient
(darkened circles). Based on this normal spirometry pattern, you would conclude that
there is no evidence of air-flow obstruction. The patient also has normal total lung
capacity, indicating that there is no evidence of restriction, and a normal diffusing capacity
for carbon monoxide, indicating that the alveolar-capillary surface area for gas exchange is
normal. There is no bronchodilator response.

30. Pre-Bronchodilator (BD) Post- BD
Test Actual Predicted %
Predicted
Actual % Change
FVC (L) 3.19 4.22 76 4.00 25
FEV1 (L) 2.18 3.39 64 2.83 30
FEV1/FVC
(%)
68 80 71 4
Case 2
A 54 year-old man presents to his primary
care provider with dyspnea and a cough.
He is a non-smoker with no relevant
occupational exposures.
His flow volume loops is as follows:

31. Case 2 Interpretation
The FVC and FEV1 are both below the lower limit of normal
(defined as 80% of the predicted value for the patient). In addition,
the FEV1/FVC ratio is only 0.68, less than the lower limit of normal
of the predicted value minus 8 (80-8 = 72) for this male patient. A
low FEV1 and FVC with a decreased FEV1/FVC ratio is consistent
with a diagnosis of air-flow obstruction. With an FEV1 of 64%
predicted this would be classified as “moderate” airflow
obstruction.
In addition, the FVC improves by 0.81 L (25% increase) and the
FEV1 improves by 0.65L (30% increase) following administration of
a bronchodilator so this patient would qualify as having a
bronchodilator response (defined as a 12% and 200 ml increase in
either the FEV1 or FVC).
The flow volume loop also shows several abnormalities consistent
with obstructive lung disease. The peak expiratory flow rate is
lower than the predicted peak expiratory flow and the curve has
the characteristic scooped out appearance typically seen in airflow
obstruction.