Pulmonary Function

Laboratory Requirements The commercially available instruments are much smaller than their traditional research counterparts and are much easier to use and maintain. The cost of the instruments is in the range of $12,000 to $20,000. Laboratory space requirements are minimal: the instrument is usually mounted on an adjustable arm attached to a small table or […]

The fact that FO measures the total pulmonary system resistance, and that peripheral Raw, obtainable only through conceptual and mathematical modeling, may be masked by effects in larger airways may seriously limit the usefulness of the method. Results from the technique can be reported in several ways. Total resistance values at particular frequencies may be […]

To determine Raw, one needs to know instantaneous values for flow and the pressure that drives flow through the airways at multiple points in the breathing cycle. Body plethysmographs report the average Raw of the entire airway tree from mouth to the “average” alveolus. Plethysmographs are large and expensive, and some patients find it difficult […]

Laboratory Requirements The cost of NO analyzers is currently quite high, in the range of $20,000 to $40,000. Most analyzers were designed for monitoring the delivery of NO, so they are not designed for documentation of exhaled NO. The ideal instrument for measuring exhaled NO would be easy to calibrate and maintain, and it would […]

Given the presence of NOS in many of the cell types of the lung’ it should be no surprise that NO can be measured in exhaled air. Since the first description of NO in exhaled air’ much work has been done to characterize the source of NO and to correlate exhaled NO with various disease […]

Although the use of NEP and the plotting of the tidal FV loops are fairly easily applied techniques that advance our understanding of VE limitation in various populations without the need for more invasive studies (ie’ esophageal and gastric balloons). other factors that may contribute significantly to exercise limitation involving the pulmonary system clearly cannot […]

Although an effect similar to NEP could be obtained by asking subjects to simply augment expiration slightly during a transient breath, the NEP technique has the advantage of detecting expiratory flow limitation in patient groups that cannot easily respond to instruction. In addition’ it is possible that breathing mechanics immediately preceding the expiration may be […]

Typically, subjects are attached to a mouthpiece connected in series to a pneumotachograph and a T-tube. One side of the T-tube is open to the atmosphere, while the other side is equipped with a pneumatic valve, which allows for the subject to be rapidly switched to a negative-pressure source (eg, a vacuum). The negative-pressure source […]

When assessing flow limitation using the tidal breath method relative to the expiratory boundary of the MFVL, it remains controversial how to best define the maximal expiratory flows for comparison to the tidal FV loop. This is due to several factors, which have been shown to have varying influences on the size of the MFVL, […]

The use of the extFVL would be helpful in many patient groups in which dyspnea and exercise intolerance were noted and mechanical constraints to breathing are a possibility. In patients with normal lung function or with severe airway changes (eg, FEV1 < 30 to 40%), such an assessment is unlikely to yield significant additional insight, […]