PFT's

Question 1

what are PFTs used for?

Answer 1

-screen for presence of pulmonary disease
-pre-operative assessment
-assessment - weaning from ventilation
-evaluation of treatment
-evaluation of disease progression
-to see effects of exercise on lung function

Question 2

what 3 broad categories do PFTs put lung disease into?

Answer 2

-obstructive eg COPD, asthma, bronchiectasis, CF
-restrictive eg IPF, pregnancy, motor neuron disease
-pulmonary disease vascular disease eg pulmonary hypertension

Question 3

what do PFTS assess?

Answer 3

-airways
-parenchyma
-pulmonary vasculature
-thoracic pump
-neural control of ventilation

Question 4

what are different types of PFTs and what do they diagnose?

Answer 4

-spirometry - diagnosis of obstructive lung disease
-lung volumes - restrictive
-diffusing capacity of CO - pulmonary vascular tissue

Question 5

what are examples of contraindications for PFTs?

Answer 5

-nausea/ vomiting
-recent abdominal, thoracic or eye surgery
-recent pneumothorax
-chest or abdominal pain
-stress incontinence
-dementia or confused state

Question 6

what info do you need before you do a PFT procedure?

Answer 6

-position of person - feet on floor
-age, height, weight and gender
-medication use
-lab conditions eg atm and temperature

Question 7

what is the FVC?

Answer 7

-forced vital capacity
-forced maximal exhalation following a max inhalation
-normal patients - 4-6 secs to fully exhale, but with a severe obstruction, it could take up to 15 seconds +

Question 8

what is FEV1?

Answer 8

the volume of expired air over the 1st second of an FVC manoeuvre

Question 9

what is the normal ratio of FEV1/FVC?

Answer 9

greater than 70%

Question 10

what does less than 70% in a fev1/fvc ratio indicate?

Answer 10

suggests airflow limitation with an obstructive pattern
EG COPD

Question 11

do restrictive diseases have a high or low FEV1/FVC ratio?

Answer 11

they often produce a normal or high FEV1/FVC ratio

Question 12

what are the values of FEV1/FVC ratio for mild, moderate, severe and very severe COPD

Answer 12

1. mild = less than 70%
2. moderate -between 50-80%
3. severe - between 30-50%
4. very severe -30-50% + chronic resp failure

Question 13

what is the FEF?

Answer 13

average flow rate of middle 50% of forced vital captacity
-reduced in medium and small airway disease eg COPD

Question 14

what is peak expiratory flow rate?

Answer 14

-maximal expiratory flow rate
-used to monitor airway obstruction and therapy response

Question 15

what is DLCO?

Answer 15

-diffusing capacity for carbon monoxide
-these values represent the ability of the lung to transfer gas from the inhaled air into the blood and acts as a marker of the extent of lung damage
-used to measure the gas exchange ability of the lungs

Question 16

what is the value of a normal DLCO?

Answer 16

-75% of predicted, up to 140%

Question 17

what is an example of a condition in which DLCO is reduced?

Answer 17

-emphysema

Question 18

what are conditions where DLCO is raised?

Answer 18

-exercise prior to test
-asthma
-polycthaemia
-mild left sided heart failure

Question 19

what are the main characteristics of obstructive lung disease?

Answer 19

-reduced flows - FEV1/FVC
-some volumes may increase - FRC
-upper airway - flow rates in initial 25%, FVC will be reduced
-small airway - flow rates in after FVC will be reduced

Question 20

what are characteristics of restrictive lung disease?

Answer 20

-flow rates are preserved
-reduced lung volumes and capacities (less than 80%) predicted
-fev1 normal or reduced
-fev1/fvc is normal or a little high

Question 21

would different lung volumes such as FEV1/FVC, FEV1, FVC and DLCO be increased or decreased in COPD?

Answer 21

• FEV1/FVC = decreased
  -FEV1= decreased
  -FVC = decreased
  -DLCO = decreased