Ruppel Chapter 4 Flashcards

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Questions and Answers

What should the reservoir bag in a closed circuit CO2 rebreathing response test contain?

50% O2, 50% CO2

21% O2

7% CO2 in O2 (correct)

100% CO2

What is the alveolar volume (VA) if the patient has a respiratory dead space of 0.3 L (BTPS) and is breathing at a rate of 22 bpm with a tidal volume (VT) of 0.7 L (BTPS)?

8.8L

What is the subject's tidal volume (Vt) if VE is 7.6 L/min and RR is 18 bpm?

0.42L

Which of the following can be measured noninvasively to calculate the Vd/Vt ratio?

Both A and B (C) Signup and view all the answers

Which measurement confirms the diagnosis of hypoventilation?

PAco2 of 48 mm Hg and pH of 7.29 (B) Signup and view all the answers

What is P100 in respiratory measurements?

Pressure developed during the first 100 msec of an occluded breath Signup and view all the answers

To calculate respiratory dead space (Vd), which measurements are required?

VT, PaCO2, and PECO2 (D) Signup and view all the answers

How can hyperventilation be defined?

PaCO2 less than 35 mm Hg and pH greater than 7.45 (C) Signup and view all the answers

Which parameter should be measured to assess the adequacy of the output of the respiratory centers?

P100 (C) Signup and view all the answers

Which test requires a variable CO2 scrubbing device in the breathing circuit?

Closed-circuit O2 response (D) Signup and view all the answers

What color do sodium hydroxide crystals change to when they are fully depleted?

Violet Signup and view all the answers

Calculate the subject's alveolar volume if tidal breathing is measured at 720 ml, with a RR of 12 and a dead space of 150 ml.

7.60 L Signup and view all the answers

Which statement best describes the measurement P100 or P0.1?

Pressure measured at 100 msec during a CO2 response test (A) Signup and view all the answers

Which concentrations should the rebreathing bag be filled with before a CO2 response test?

Oxygen 93%, CO2 7% (A) Signup and view all the answers

What formula can be used to estimate dead space?

1 ml per pound of ideal body weight Signup and view all the answers

Calculate the subject's VE given the following parameters: Temp 25 C, BTPS correction factor: 1.011, Pb: 750, Volume expired: 27L.

5.56L Signup and view all the answers

What is the subject's tidal volume (Vt) given the following parameters: Volume expired 27L, RR 12?

463 ml Signup and view all the answers

Calculate the subject's Vd/Vt% given: Temp 25 C, Volume expired 27L, FeCO2 33, RR 12, pH 7.38, PCO2 44, PO2 71.

25% Signup and view all the answers

What is the subject's VA given: Temp 25 C, Volume expired 27L, FeCO2 33, RR 12, pH 7.38, PCO2 44, PO2 71?

4.17 L/min Signup and view all the answers

What is the calculated Vd/Vt ratio given the variables: PeCO2 38, RR 15, PaCO2 42, Ve 7.8 L, Temp 19 C, BTPS conversion 1.111?

9.6% Signup and view all the answers

Study Notes

Closed Circuit CO2 Rebreathing Test

Reservoir bag should contain 7% CO2 in O2 for the test setup.
A variable CO2 scrubbing device is necessary in the breathing circuit for closed-circuit O2 response tests.

Respiratory Measurements

Patient's respiratory dead space calculated at 0.3 L (BTPS), with a tidal volume (VT) of 0.7 L (BTPS) and a breathing rate of 22 bpm yields an alveolar ventilation (VA) of 8.8 L.
In a COPD patient, effective tidal volume (VT) can be calculated using minute ventilation (VE) and respiratory rate (RR); example yields a VT of 0.42 L.
Alveolar volume from tidal breathing of 720 ml and dead space of 150 ml results in an alveolar volume of 7.60 L.

Vd/Vt Ratio Calculation

Noninvasive measurement of Vd/Vt ratio requires mixed expired PCO2 and PETCO2.
Vd/Vt ratio estimation can mathematically illustrate the efficiency of ventilation; calculated from the formula VD/VT=(PaCO2-PeCO2)/PaCO2.

Hypoventilation Indicators

Confirmed hypoventilation with a PAco2 of 48 mm Hg and a pH of 7.29.

Hyperventilation Criteria

Defined by a PaCO2 less than 35 mm Hg, accompanied by a pH greater than 7.45.

P100 Measurement

P100 (or P0.1) signifies the pressure developed during the first 100 milliseconds of an occluded breath in response testing.

Use of Sodium Hydroxide Crystals

Sodium hydroxide crystals (sodasorb) used for CO2 scrubbing change color to violet when fully depleted.

VE and VT Calculations

Subject's VE (minute ventilation) calculation requires BTPS correction factor; example results in 5.56 L.
For the subject’s tidal volume (VT), a volume expired of 27L at a rate of 12 breaths per minute computes to 463 ml.
Vd/Vt % calculated for the same subject is 25%.
VA measurement for the same conditions results in 4.17 L/min.

Estimating Dead Space

Dead space can be estimated at approximately 1 ml per pound of ideal body weight for patients.

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Test your knowledge with these flashcards from Ruppel Chapter 4. This quiz covers essential respiratory concepts and calculations related to CO2 rebreathing and dead space measurements. Perfect for students preparing for exams in respiratory physiology.