Lung Testing

Question 1

static lung volumes

Answer 1

lung volumes during periods without air flow

Question 2

static lung volumes

Answer 2

FRC

RV

TLC

Question 3

functional residual capacity

Answer 3

volume of gas remaining in the lung as the end expiratory level

typical= 2400 mL or 2.4L

decreased with restrictive lung disease
increased with obstructive lung disease (air trapping)

Question 4

residual volume

Answer 4

volume of gas in the lungs at the end of maximum expiration

typical- 1200mL or 1.2 L

decreased with restrictive lung disease
increased with obstructive lung

Question 5

total lung capacity

Answer 5

volume of gas in the lungs following a maximum inspiration

typical= 6000mL or 6.0L

decreased with restrictive lung disease
increased with obstructive lung disease

Question 6

following methods may be used to measure static lung disease

Answer 6

1. helium dilution technique
2. nitrogen washout
3. body box
4. radiological estimation

Question 7

looking at obstructive disease with air trapping… which values would you look at

Answer 7

FRC, RV, TLC, Vtg

Question 8

Helium Dilution

Answer 8

this method uses helium in a closed system to measure FRC

rebreathing air… going to need a scrubber

start with 10% helium and room air.. rebreathe this for up to 7 minutes

“end of test” occurs ten the helium concentrations changes by less than 0.02% over a 30 second interval

Question 9

erroneously high measurements during the helium dilution

Answer 9

1. leaks
2. ruptured eardrum
3. switch-in occurred at a point before end expiration
4. failure of analyzers

Question 10

Nitrogen Washout

Answer 10

measure FRC by replacing the nitrogen in the lungs with oxygen

switch in should be at the end of normal expiration

open circuit

Question 11

Nitrogen Washout technique

Answer 11

patient breathes 100% oxygen for up to 7 minutes or until the nitrogen % is less than 1% to washout the nitrogen from the lungs

Question 12

Nitrogen Washout Results

Answer 12

normal= washout in 3 minutes

obstructive disease= may not washout completely even after 7 minutes

Question 13

troubleshooting nitrogen washout

Answer 13

if nitrogen does not drop after several minutes there is a air leak into the system

replace the o2 tank

Question 14

Body Box

Answer 14

most accurate

FRC and Vtg should be the same number
if Vtg is bigger than there is air trapping

Question 15

calculate RV/TLC x 100

Answer 15

RV divided by TLC multiple by 100%

Question 16

Body Box Technique

Answer 16

patient breathes normal for several breaths

at end expiration the shutter closes and that patient pants. at this point there is no air flow

because airflow is not present with the shutter closed, mouth pressure approx. alveolar pressure

a pressure transducer measures the pressure at the mouth which is equal to alveolar pressure when there is no airflow

Question 17

radiological estimation

Answer 17

chest xrays are taken at total lung capacity from both posterior anterior and lateral views

Question 18

Methacholine Challenge Test

Answer 18

bronchial provocation testing is performed by administering a provocative agent to a patient to detect airway hyperreactivity

the test is positive when there is a 20 % decreased in the FEV 1