Airflow, Lung Volumes And Flow Volume Curves

Measurements of airflow and lung volumes allow differentiation of obstructive and restrictive ventilatory impairment, the assessment of the severity and the success of therapy. The measurement results are usually expressed as an absolute flow rates and volumes (actual) and as relative percentages of the target values ??that were determined to a large population pulmonary Healthy. Parameters that go into the determination of the reference values ??are age, gender, ethnicity, and body size. Clinical Calculator: PFT predictive values ??for girls MultiCalc clinical calculator: PFT predictive values ??for boys MultiCalc clinical calculator: Adjusted PFT predictive values ??for women MultiCalc clinical calculator: Adjusted PFT predictive values ??for men MultiCalc airflow Quantitative measurement of inspiratory and expiratory flow by means forced spirometry. In order to eliminate nasal breathing nose clips are used. To determine the expiratory flow is allowed to breathe the patient a maximum, wherein the lips have to completely enclose the mouthpiece, and then if possible strong and completely exhale into a measuring apparatus, the exhaled volume (forced vital capacity [FVC]) and exhaled in the first second volume (forced volume in one second [FEV1] -. Normal spirogram) records. (Ed. Note. D .: Unlike in North America is recommended to use the nichtforcierten, measured after slow maximum ex- and inspiration vital capacity [IVC] in Germany.) Most devices currently used only measure airflow and integrate time to the expiratory estimate volume. For the record, the inspiratory flow and volume are allowed to breathe the patient maximum and then forced breathe. This breathing maneuvers allow different measurements. The FVC is the maximum amount of air that can be forced to breathe maximum inhalation of the patient. The FEV1 is the best to be reproduced parameters and for diagnosis and monitoring obstructive respiratory diseases particularly useful (eg., Asthma, COPD). FEV1 and FVC help distinguish between obstructive and restrictive lung diseases. A normal FEV1 makes an irreversible obstructive pulmonary disease unlikely during normal FVC makes a restrictive disease unlikely. Normal spirogram. FEF25-75% = forced expiratory flow during exhalation of 25-75% of the FVC; FEV1 = expiratory volume in the first second of forced vital capacity maneuver; FVC = forced vital capacity (the maximum amount of air forced by the maximum inspiration may be exhaled). The forced expiratory flow averaged over the period in which 25-75% of FVC exhaled, may be a more sensitive parameter for the obstruction of small airways than FEV1, but it is difficult to reproduce. The expiratory peak flow (PEF) corresponding to the largest occurring respiratory flow during exhalation. This variable is primarily for domestic monitoring of asthmatics and determination of daily variations in flow rates. Clinical Calculator: prediction of peak expiratory flow (PEF) The validity of the measurements depends on the cooperation of the patient, which can often be improved by a good guide during the breathing maneuvers. Acceptable spirograms show a good initial curve (z. B. a fast and strong beginning of exhalation), the absence of cough, a smooth curve, and no premature discontinuation of expiration (z. B. expiration of at least 6 seconds without volume change last in the Second). Reproducible measurements differ by a maximum of 5%, or 150 ml of other measurements. Results that do not meet these minimum criteria of acceptance should be interpreted with caution. The lung volume lung volumes (Normal lung volume.) Are determined by spirometry or by measuring the functional residual capacity (FRC). Normal lung volume. ERV = expiratory reserve volume; FRC = functional residual capacity; IC = inspiratory capacity; IRV = inspiratory reserve volume; RV = residual volume; TLC = total lung capacity; VC = vital capacity; VT = tidal volume. FRC = RV + ERV; IC = VT + IRV; VC = VT + IRV + ERV. Clinical calculator: lung volume Multicalc FRC is measured using a gas dilution technique or a plethysmograph (which is more accurate in patients with a narrowing of the airways and entrapped air). To the gas dilution techniques include nitrogen dilution helium dilution In the method of nitrogen dilution of the patient breathes to the end of a normal breath, then inhaled through a spirometer 100% of the O2. The measurement is stopped when the nitrogen concentration in the exhaled air 0th The collected volume of abgeatmetem nitrogen corresponds to 81% of the initial FRC. In the helium dilution method allowed to breathe the patient to the FRC and then connects it to a closed system containing known volumes of helium and O2. The helium concentration is measured so long until it is large in the input and exhalation equal, indicating the equilibration with the gas volume of the lungs, which can then be calculated from the change of the occurred helium dilution. In these two methods, the FRC may be too low, as only the lung volume is measured, which is involved in the exchange with the upper respiratory tract. In patients with severe respiratory disorders a significant amount air can be trapped in the lower respiratory tract and little or no part in the ventilation. The body plethysmography uses Boyle’s Law to measure the compressed gas volume in the thorax and is more accurate than the gas dilution methods. The patient sits in an airtight chamber and attempts made by the FRC to inhale from a closed mouthpiece. By the expansion of the thoracic walls of the pressure in the closed chamber increases. From the known volume and pressure of the chamber before and the pressure after the Einatmungsmanöver can be the change in volume of the chamber charge, which must correspond to the change in lung volume. If the FRC known, some other lung volumes can be determined or calculated by spirometry (lung volume Normal.) Below. Normally, the FRC corresponds to about 40% of the total lung capacity (TLC). Flow volume curve in contrast to spirogram in which the flow is shown (in liters) over time (in s), in a volume of flow curve (flow volume curves.) Is (in l / s) over the course of the change in lung volume during the flow rate (in liters) recorded the maximum inspiration from the full expiration out (residual volume [RV]) and during maximal exhalation from the complete inspiration layer (TLC). The main advantage of flow volume curves is that it can be seen whether the flow is appropriate to the appropriate volume. For example, the flow in the area of ??smaller lung volumes is usually lower because the elastic restoring forces are lower here. Patients with pulmonary fibrosis have smaller lung volumes, and the river seems to have slowed down with them, when measured alone. If the flow, however, as a function of the lung volume, it is apparent that due to the typically increased elastic restoring forces of the flow in these patients is actually higher than in healthy lungs. Flow volume curves. (A) Normal. The inspiratory limb of the loop is symmetrical, and convex. The expiratory limb is linear. The current at the center of the inspiratory capacity and the current at the center of the expiratory capacity are often measured and compared. Because a dynamic compression of the airway occurs during exhalation, the maximum inspiratory flow at 50% of the forced vital capacity is (MIF 50% FVC) greater than the maximum expiratory flow at 50% FVC (MEF 50% FVC). (B) obstructive disorder (z. B. emphysema, asthma). Although any air flow is reduced, outweighs the expiratory extension and MEF 16 mg / ml of this diagnosis. PC20 values ??between 1 and 16 mg / ml are inconclusive. For the diagnosis of exercise-induced bronchoconstriction a physical exercise test can be done, but which is less sensitive than the methacholine provocation test for the diagnosis of non-specific bronchial hyperreactivity. The patient performs on a treadmill or bicycle ergometer over 6-8 min a constant power at which to achieve 80% of the desired value of the maximum heart rate. FEV1 and FVC or VC from exposure as well as 5, 15 and 30 min thereafter measured. In an exercise-induced bronchospasm the FEV1 or FVC ? 15% is reduced according to load. “Eucapnic voluntary hyperventilation (EVH)” can also be used for diagnosis of exercise-induced bronchoconstriction and is the method that is recognized by the International Olympic Committee. EVH includes hyperventilation a gas mixture of 5% CO2 and 21% O2 at 85% of maximum voluntary ventilation for 6 min. FEV1 is then measured at certain time intervals after the test. As with other provocation tests too, the drop in FEV1 that is diagnostic for the exercise-induced bronchospasm, Restrictive depending Labor.Obstruktive disorders ventilation disorders are characterized by a decreased lung volume varies, a TLC esp. <80% of the setpoint. The severity of the disease depends on the restriction of TLC (The severity of obstructive and restrictive lung disease *). Limitations of the lung volumes cause a drop of the flow rate (limited flow volume FEV1 curves. B). The river in relation to lung volume, however, is accelerated so that the ratio FEV1 / FVC is normal or increased. Restrictive defects caused by the following: loss of lung volume (. Eg Lobectomie) abnormalities of the structures that the lung surrounded (. Eg Pleuralstörung, kyphosis, obesity) weakness of the inspiratory muscles (. Eg neuromuscular disorders) abnormalities lung parenchyma (z. B. pulmonary fibrosis) the common feature of all these diseases is a restricted elasticity (compliance) of the lung and / or the chest wall.

Health Life Media Team

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