MCRT-Lung volume and capacities

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After performing a multi-breath Nitrogen washout on a patient you observe the following tracing. What is the result of the tracing?

Leak

When should you suspect poor effort by the patient when comparing the SVC and FVC?

When the FVC is larger than the SVC

In the normal patient, how should the FVC and SVC compare

They should be the same

When performing measurements with the body-box and Helium dilution tests you notice that the results are higher on the results from the body-box. What would account for this difference?

Body-box measures the traped gases. Helium dilution does not.

List 4 measurements commonly made with the body-box

FRC TLC TGV RV RV/TLC% Raw

Once the FRC has been determined how are the RV and TLC calculated?

FRC - ERV = RV RV + VC = TLC

When should the patient be 'switched in' to start the nitrogen washout test?

at FRC

Why does the nitrogen washout test not require a CO2 absorber?

open circuit, no rebreathing

How long should it take the normal patient to washout during the nitrogen washout test?

3 minutes

Briefly describe how to perform the nitrogen washout procedure.

1. Have the patient breath 100% O2 and measure the %N2 exhaled. 2. Switch-in occurs at FRC 3. Test ends when %N2 is < 1% or 7 minutes

What 3 measurements are determined during the nitrogen washout procedure?

1. FRC 2. RV 3. TLC

What would explain why a Helium dilution test never equilibrates and the [He] falls to zero?

leak

Briefly describe how to perfom the Helium dilution test on a typical patient

1. Switch-in occurs at FRC. 2. O2 must be added because of consumption 3. Test ends when [He] change < 0.2% in 30 second interval or after 7 minutes 4. Rebreathing requires CO2 and H2O absorbers (closed circuit)

What three (3) volumes/capacities can be measured/calculated with the Helium dilution test?

FRC RV TLC

______________ is the only capacity/flowrate used to identify restriction

Vital Capacity

What are the 3 volumes measured during the SVC test? and what are there typical values?

1. Vt 0.5 L 2. IRV 3.1 L 3. ERV 1.2 L

Given: ERV = 1400 mlTLC = 6200 mlVt = 600 mlIC = 3700 mlCalculate; IRV & VC

IRV = 3700 - 600 = 3100 VC = TLC - RV = 6200 - 1100 = 5100

Given: ERV = 1400 mlTLC = 6200 mlVt = 600 mlIC = 3700 mlCalculate; FRC & RV

FRC = 6200 - 3700 = 2500 RV= 2500 - 1400 = 1100

Briefly describe the principle of the multi-breath, open circuit, nitrogen washout test

washes out the nitrogen in the lungs by having the patient breath 100% oxygen for several minutes

_________ Volume of air remaining in the lungs at tidal volume end-expirtaory level

FRC

_________ Maximum amount of air the can be exhaled after maximun inhaltion

_________ Volume of air in the lungs after maximum inhalation

TLC

_________ Maximum amount of air that can be inhaled from tidal volume end-expiratory level

_________ Volume of air remaining in the lungs after maximum exhalation

___________ Maximum amount of air that can be exhaled below the tidal volume end expiratory level.

ERV

The results of a Helium dilution test show an equilibrium time of 7 minutes with an increase in FRC value, this is most likely due to;

the patient has obstructive lung disease

You notice that you have entered information on a female instead of a male. What results of % predicted would change which you switch the computer over to a male?

FVC

Which of the following is best for meauring Raw?

plethysmography

Which of the following parameters are NOT used to calculate the predicted normals for an individual?

weight

A FVC that is reduced and a SVC that is normal would indicate

obstructive disorder

A patient with a FEV-1/FVC of greater than 35% would be consistent with;

obstructive disorder

Which of the following would be consistent with a pure restrictive lung disorder?

decreased VC, increased FEV-1

Which of the following is measured by the Plethysmograph?

TGV

In a healthy subjects who have no lung disease, a graph of N2 washout curve appear ______ when displayed on a semilogrhythmic graph

straight line

The FEF(25%-75%) is depends on which of the following?

FVC

Which of the following are characteristics of obstructive lung disease when measured values are compared to predicted normals?

The FRC is increased The RV is increased The RV/TLC is increased

A patient has the following results from a pulmonary function test:SVC---4.35FRC---3.40ERV---1.20IRV---2.65Vt ---0.50The residual volume would be:

Choose the answer2.2 L 0.25 L 2.90 3.15

A patient has the following results from a pulmonary function test:SVC---4.35FRC---3.40ERV---1.20IRV---2.65Vt ---0.50The total lung capacity would be:

Choose the answer7.75 L 6.05 L 6.55 L 7.25 L

A patient has the following lung volumes:-------Measured-------%PredictedSVC------2.95-------------71%FRC------1.85-------------67%RV-------1.03-------------75%TLC------3.98-------------67%The intrepretation would most likely state:

(Choose the answer)normal lung volumes hyperinflation restrictive pattern or process mixed obstructive and restrictive pattern or process

Which of the following correctly describes the measurement of FRC by the nitrogen washout method?

The test is continued until alveolar N2 is 1%. Some N2 is released from the blood/tissue

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Created by:

Stan Middleton on 2009-05-14