Lung Volumes and Capacities Quiz

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Questions and Answers

What is the difference between vital capacity (VC) and total lung capacity (TLC)?

Vital capacity (VC) is the maximum amount of air that can be exhaled after a full inspiration, while total lung capacity (TLC) is the maximum amount of air that the lungs can hold.

Describe the relationship between tidal volume (TV) and inspiratory reserve volume (IRV).

Tidal volume (TV) is the normal amount of air inhaled during relaxed breathing, while inspiratory reserve volume (IRV) is the additional air that can be forcibly inhaled on top of the tidal volume.

What lung volumes contribute to the functional residual capacity (FRC)? Briefly explain their roles.

Functional residual capacity (FRC) is composed of the expiratory reserve volume (ERV) and residual volume (RV). ERV is the additional air that can be forcibly exhaled after a normal breath, while RV is the air remaining in the lungs even after maximum exhalation.

Explain the significance of residual volume (RV) in terms of lung function.

Residual volume (RV) ensures that the lungs remain partially inflated even after a full exhalation, preventing collapse and maintaining a minimal level of gas exchange. Signup and view all the answers

If a person's inspiratory capacity (IC) is 3,000 mL, and their tidal volume (TV) is 500 mL, what is their inspiratory reserve volume (IRV)?

2,500 mL. IC = TV + IRV, so IRV = IC - TV = 3,000 mL - 500 mL = 2,500 mL. Signup and view all the answers

A person's vital capacity (VC) is 4,500 mL and their expiratory reserve volume (ERV) is 1,000 mL. Calculate their inspiratory reserve volume (IRV).

3,500 mL. VC = TV + IRV + ERV. We know TV is 500 mL. So, 4,500 mL = 500 mL + IRV + 1,000 mL, which means IRV = 3,500 mL. Signup and view all the answers

How does the functional residual capacity (FRC) differ from the residual volume (RV)?

FRC is the total volume of air remaining in the lungs after a normal expiration, while RV is the air remaining in the lungs even after a maximum exhalation. FRC includes both RV and expiratory reserve volume (ERV). Signup and view all the answers

What is the significance of understanding lung volumes and capacities in terms of respiratory health?

Lung volumes and capacities provide valuable information about lung function and can indicate potential respiratory issues. They are used to diagnose diseases, monitor treatment progress, and assess overall respiratory health. Signup and view all the answers

What are the three indirect techniques used to measure lung volumes?

Helium dilution, nitrogen washout, and body plethysmography. Signup and view all the answers

Why is residual volume (RV) not directly measurable using spirometry?

Because RV cannot be exhaled. Signup and view all the answers

What is the assumption made in the Helium dilution technique regarding the patient's initial Helium concentration?

The patient is assumed to have no Helium in their lungs at the beginning of the test. Signup and view all the answers

Describe the process of Helium dilution in the context of measuring lung volumes.

A known volume and concentration of Helium is introduced to the patient's lungs, and its dilution is measured as it mixes with the patient's lung volume. Signup and view all the answers

What is the significance of the equilibration time in the Helium dilution technique?

The equilibration time indicates the distribution of ventilation in the patient's lungs. Signup and view all the answers

What volume is the patient usually connected to the breathing circuit at in the Helium dilution technique?

The resting expiratory level of the FRC (functional residual capacity). Signup and view all the answers

What does the nitrogen washout technique assume about the nitrogen concentration in the patient's lungs?

It assumes that nitrogen concentration in the lungs is 78%, in equilibrium with the atmosphere, before the test begins. Signup and view all the answers

Describe the process of nitrogen washout in the context of lung volume measurement.

The patient inhales 100% oxygen, which replaces the nitrogen in their lungs, and the amount of nitrogen exhaled is measured. Signup and view all the answers

Why does the nitrogen washout technique use a non-breathing or open circuit?

Because the patient inhales 100% oxygen and exhales the nitrogen mixture. Signup and view all the answers

What is the difference in the measurement approach between the Helium dilution and nitrogen washout technique?

Helium dilution uses a closed, rebreathing circuit, where Helium is introduced and its dilution is measured. Nitrogen washout uses an open circuit, where the patient exhales the nitrogen replaced by oxygen. Signup and view all the answers

Explain the relationship between cabinet volume and thoracic volume during the panting maneuver.

During the panting maneuver, a decrease in cabinet volume leads to an increase in thoracic volume. This is due to the pressure changes within the chamber, as described by Boyle's law. Signup and view all the answers

What specific measurement is used to calculate the total compressible volume (TCV) in the panting maneuver?

The simplified equation used to calculate TCV during panting is: TCV = PB X V/P, where PB represents barometric pressure, V is the volume change, and P is the pressure change. Signup and view all the answers

What is the primary principle behind the plethysmography technique for measuring lung volumes and capacities?

The plethysmography technique relies on Boyle's law, which states that the product of pressure and volume remains constant for a given mass of gas at a constant temperature. Signup and view all the answers

Describe the specific gases considered in the plethysmography technique when determining lung volumes and capacities.

The plethysmography technique measures the volume of all compressible gases in the thorax, including gas trapped in the airways, behind airway instructions, or in the pleural space. Signup and view all the answers

Outline the steps involved in measuring total gas volume (TGV) using the plethysmography technique.

The patient sits in the chamber and breathes normally through a mouthpiece until they reach their functional residual capacity (FRC). The shutter is then closed at the end of an expiration for 2-3 seconds to allow for measurements. Signup and view all the answers

Explain the relationship between carbon monoxide (CO) and oxygen (O2) regarding their molecular weights and solubility coefficients.

CO and O2 have similar molecular weights and solubility coefficients, meaning they have comparable characteristics in terms of their size and ability to dissolve in fluids. Signup and view all the answers

Describe the interaction between carbon monoxide (CO) and hemoglobin (Hb) in the bloodstream.

CO chemically combines with hemoglobin (Hb) in a similar way to oxygen, but it has a much higher affinity for Hb, leading to a stronger binding. Signup and view all the answers

How does the high affinity of carbon monoxide (CO) for hemoglobin (Hb) influence its diffusion into pulmonary blood?

Due to its high affinity for Hb, CO diffuses rapidly into the pulmonary blood, effectively displacing oxygen from Hb molecules. Signup and view all the answers

Identify at least two lung volumes or capacities that are likely to be increased in cases of obstructive lung disease.

Obstructive lung disease can result in an increased total lung capacity (TLC) and functional residual capacity (FRC). Signup and view all the answers

Explain how CO's high affinity for Hb affects its binding to Hb compared to oxygen.

The high affinity of CO for Hb means that it binds to Hb more readily and strongly than oxygen. This leads to a higher concentration of CO bound to Hb, reducing the oxygen-carrying capacity of the blood. Signup and view all the answers

Explain how the single-breath technique for measuring diffusing capacity works.

The single-breath technique, also known as the modified Krogh method, involves the patient exhaling completely to residual volume (RV) and then rapidly inhaling to total lung capacity (TLC) a volume of air containing a small concentration of carbon monoxide (CO) and helium (He). The patient holds their breath for 10 seconds and then exhales rapidly at least 1 liter of the gas mixture. The diffusing capacity (DLCO) is calculated based on the concentration of CO in the expired air and the partial pressure of CO in the alveoli. Signup and view all the answers

What are the factors that influence the diffusion of gases in the lungs?

The diffusion of gases in the lungs is affected by factors such as the volume of gas transferred into the lungs, the partial pressure of the gas in the alveolus (P1), and the partial pressure of the gas in the capillary (P2). Signup and view all the answers

Why is CO used as the transfer gas when measuring the diffusing capacity of the lung (DLCO)?

Carbon monoxide (CO) is used as the transfer gas in DLCO measurement because it is similar to oxygen (O2) in important ways, such as the way it binds to hemoglobin and its tendency to diffuse across the alveolar-capillary membrane. This makes it a reliable indicator of the overall lung diffusing capacity. Signup and view all the answers

What are the different techniques used to measure diffusing capacity (DLCO)?

The three main techniques used to measure diffusing capacity are the single-breath technique (DLCO-SB), the steady-state technique, and rebreathing techniques. Signup and view all the answers

How is the diffusing capacity of the lung (DLCO) expressed?

The diffusing capacity of the lung (DLCO) is typically expressed in milliliters per minute per millimeter of mercury (ml/min/mmHg) under standard temperature and pressure dry (STPD) conditions. Signup and view all the answers

What is the formula for calculating DLCO?

The formula for calculating DLCO = VCO/PACO, where VCO is the volume of carbon monoxide transferred and PACO is the partial pressure of CO in the alveoli. Signup and view all the answers

How can the diffusing capacity of the lung (DLCO) be affected by various lung diseases?

DLCO can be affected by various lung diseases, including restrictive lung diseases, obstructive lung diseases, and acute and chronic lung diseases. It is often decreased in restrictive lung diseases due to reduced lung volume and surface area for gas exchange. In obstructive lung diseases, DLCO can be decreased due to airflow obstruction and thickening of the alveolar-capillary membrane, which reduces diffusion efficiency. Signup and view all the answers

What are some factors that can affect the reliability of a DLCO test?

Factors that can affect the reliability of a DLCO test include the repeatability of the test, the time allowed between tests (at least 4 minutes), the patient's ability to cooperate and follow instructions, and the equipment used for the test. Signup and view all the answers

What are the main characteristics of restrictive lung diseases?

Restrictive lung diseases are characterized by a decreased lung volume, which limits the amount of air that can be inhaled and exhaled. This typically results in a decreased total lung capacity (TLC) and inspiratory capacity (IC). Signup and view all the answers

What is the difference between single-breath DLCO (DLCO-SB) and multi-breath DLCO?

The single-breath DLCO (DLCO-SB), also known as the modified Krogh method, involves a single breath hold, while multi-breath DLCO involves multiple breaths. In multi-breath DLCO, the patient breathes a mixture of gases for several minutes, allowing for a steady-state measurement of diffusing capacity. Signup and view all the answers

Explain the difference between the Steady-State Technique and the Rebreathing Technique for measuring DLCO.

The Steady-State Technique measures DLCO while the subject is breathing normally, collecting exhaled air over two minutes. The Rebreathing Technique involves a specific gas mixture being rebreathed until equilibrium is reached, then the exhalation washes out the mixture for analysis. Both techniques involve different approaches to measuring the diffusion capacity of the lung (DLCO). Signup and view all the answers

What is the importance of having a reproducible result in DLCO measurement?

Reproducibility is crucial for ensuring reliable and accurate DLCO measurements. Consistency in results allows for meaningful comparisons over time and between different individuals, aiding in diagnosis and monitoring of lung health. Signup and view all the answers

Describe the criteria for an acceptable DLCO test.

An acceptable DLCO test is reproducible to within 10% or 3 ml CO ml/min/mmHg, whichever is greater. Signup and view all the answers

Why is a gas mixture containing 0.1% CO used in the Steady-State Technique?

The gas mixture with 0.1% CO allows for a safe and measurable amount of carbon monoxide to be inhaled during the test. It enables accurate measurement of the subject's diffusion capacity of the lung without posing significant health risks. Signup and view all the answers

What is the role of the Douglas bag in the Steady-State Technique?

The Douglas bag is used to collect the exhaled air of the subject during the last two minutes of steady-state breathing. This collected air is then sampled for analysis of the CO concentration. Signup and view all the answers

What does the formula for DLCO-SS, "DLCO-SS= VCO (STPD)/ PACO", represent?

The formula represents the calculation of the diffusion capacity of the lung at steady-state (DLCO-SS) using the volume of carbon monoxide absorbed at standard temperature and pressure (VCO) divided by the partial pressure of carbon monoxide in the alveolar air (PACO). Signup and view all the answers

Explain the purpose of the 'washout' phase in the Washout-Sampling Technique.

The washout phase involves the subject inhaling regular air after rebreathing the gas mixture. This process washes out the mixture from the lungs, allowing for a more accurate analysis of the carbon monoxide and helium concentrations in the exhaled air. Signup and view all the answers

Flashcards

Residual Volume (RV)

The volume of air remaining in the lungs after exhaling.

Total Lung Capacity (TLC)

The maximum volume of air the lungs can hold, about 6,000 mL.