Measuring Lung Volumes

0.5 to 1 Hz

To relate the pressure change to the known volume and obtain the calibration factor

A sloping line equal to ΔP/ΔV, where ΔP equals the change in alveolar pressure, and ΔV equals the change in alveolar volume (VA)

<p>By noting the reciprocal change in plethysmograph volume</p> Signup and view all the answers

<p>At least three</p> Signup and view all the answers

<p>It may result in an overestimation of lung volume</p> Signup and view all the answers

<p>To note the acceptability of the maneuvers</p> Signup and view all the answers

<p>VTG = (PB /lambdaVTG) x (PBoxcal/Pmouthcal) x K</p> Signup and view all the answers

<p>Breathing frequency should be between 0.5 and 1.0 Hz</p> Signup and view all the answers

<p>It is determined by the balance of lung and chest wall recoil at relaxed end expiration</p> Signup and view all the answers

<p>Residual volume (RV)</p> Signup and view all the answers

<p>Functional residual capacity (FRC) measured with the body plethysmograph (FRCpleth)</p> Signup and view all the answers

<p>TLC = RV + IVC (inspiratory vital capacity)</p> Signup and view all the answers

<p>Single-breath N2 washout</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Expiratory reserve volume (ERV)</p> Signup and view all the answers

<p>Liters (L) or milliliters (mL) corrected to body temperature, pressure, and saturation (BTPS)</p> Signup and view all the answers

<p>To allow the air pressure in the mouth to equalize with the alveolar pressure</p> Signup and view all the answers

<p>Indirectly</p> Signup and view all the answers

<ul> <li>Multiple-breath He dilution</li> <li>Multiple-breath N2 washout</li> <li>Single-breath N2 washout</li> <li>Single-breath He (or other inert gas; e.g., neon) dilution (Calculated as part of Dlco (VA))</li> <li>Plethysmography</li> <li>Chest radiograph, Chest computerized tomography (CT), Magnetic resonance imaging (MRI)</li> </ul> Signup and view all the answers

<p>The lung volume where closed-shutter breathing is performed to calculate FRC.</p> Signup and view all the answers

<p>The expiratory reserve volume (ERV) measured immediately after the acquisition of FRC is subtracted from the FRC.</p> Signup and view all the answers

<p>The calculated value for RV is added to the “linked” inspiratory vital capacity (IVC).</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>alveolar pressure</p> Signup and view all the answers

<p>By measuring pressure changes in the plethysmograph.</p> Signup and view all the answers

<p>The patient has an unknown volume of gas in the lungs at the end of a normal expiration (i.e., at FRC). The airway is occluded momentarily at or near FRC; the patient is asked to gently breathe at a frequency be- tween 0.5 and 1.0 Hz (0.5–1.0 cycles per second), allowing the air in the chest to be gently compressed and decompressed. The breaths are shallow and should not create pressure changes &gt;10cm H2O. The closed-shutter breathing causes a change in volume and pressure. The changes in pressure are easily measured at the mouth (Pmouth) with a pressure transducer. Mouth pressure theoretically equals alveolar pressure when there is no airflow. Changes in pulmonary gas volume are estimated by measuring pressure changes in the plethysmo- graph.</p> Signup and view all the answers

<p>Pmouth is plotted on the vertical axis, and Pbox is plotted on the horizontal axis.</p> Signup and view all the answers

<p>The change in alveolar pressure. The change in alveolar volume.</p> Signup and view all the answers

<p>VTG = (PB /lambdaVTG) x (PBoxcal/Pmouthcal) x K Wherere: PB is barometric pressure minus water vapour pressure, LambdaVTG is slope of the deltaP/deltaV PBOXcal = box pressure transducer calibration factor Pmouthcal = mouth pressure transducer calibration factor K = correction factor for volume displaced by the patient</p> Signup and view all the answers

<p>From tidal breathing</p> Signup and view all the answers

<p>with the patient breathing shallow at about 1.5 to 2.5Hz (1.5–2.5 cycles per second, or 90–150 breaths/min)</p> Signup and view all the answers

<p>A minimum of three, each followed by ERV and IVC maneuvers.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<ol> <li>The shallow-breathing maneuver shows a closed loop without drift or another artifact.</li> <li>Pressure changes are within calibration ranges; the tracing does not go off-screen.</li> <li>Breathing frequency should be between 0.5 and 1.0 Hz.</li> <li>A minimum of three technically satisfactory shallow-breathing maneuvers should be recorded.</li> <li>At least three FRC pleth values that agree within 5% should be obtained.</li> <li>Reported FRCpleth is averaged from the three acceptable and repeatable panting maneuvers.</li> </ol> Signup and view all the answers

<p>False. The FRC, RV, and TLC should be reported in liters or milliliters, BTPS</p> Signup and view all the answers

<p>Unlike TLC and RV, FRC is an effort-independent maneuver determined by the balance of lung and chest wall recoil at relaxed end expiration.</p> Signup and view all the answers

<p>Indirectly, by noting the reciprocal change in plethysmograph volume.</p> Signup and view all the answers

<p>Airway resistance (Raw) is calculated as the ratio of sRaw to FRCpleth.</p> Signup and view all the answers

<p>Raw is a measure of airway obstruction and indicates the alveolar pressure needed to establish a flow rate of 1 L s−</p> Signup and view all the answers

<p>sRaw can be interpreted as the work to be performed by volume displacement to establish the flow rate of 1Litter per second</p> Signup and view all the answers

<p>Pressure generation means that a mass of air is compressed or decompressed relative to its equilibrium volume. This difference is called “shift volume”</p> Signup and view all the answers

<p>Airway resistance is the resistance to airflow within the respiratory airways. It is calculated as the ratio of the pressure difference (alveolar pressure minus mouth pressure) to the flow rate (L/s).</p> Signup and view all the answers

<p>Specific airway resistance (sRaw) is the product of airway resistance (Raw) and the lung volume (usually functional residual capacity, FRC). Mathematically, sRaw = Raw × FRC sRaw=Raw×FRC.</p> Signup and view all the answers

<p>T</p> Signup and view all the answers