Optimizing Performance of Respiratory Airflow Resistance Measurements

Body plethysmographic study of specific airway resistance in a sample of healthy adults

“…A number of studies have described the usefulness of sRaw evaluations, 2,13,29,30 which can be also used in poorly cooperative subjects such as patients with Down syndrome (i.e. cognitive incapacity) or neuromuscular diseases, or subjects failing to cooperate for any other reason.…”

“…Another important measurement is that of the airways resistance (Raw), which is the ratio between alveolar pressure and airflow obtained during quiet breathing. Raw can be measured in several ways; however, plethysmography is considered the ‘gold standard’ for measuring airway resistance 2,3 . Nevertheless, there are other methods less utilized.…”

“…The ‘oesophageal balloon technique’, which measures airway and lung tissue resistance, is uncomfortable and particularly unsuitable for repeated or protracted measurements; in addition, its variance is very high 4 . The ‘forced oscillation technique’ (FOT) measures the total thoracic resistance (airway, lung tissue and chest wall resistance), but it does not provide information about flow, nor does it distinguish between restrictive and obstructive changes, or intra‐ and extra‐pulmonary disorders 2,4 . The ‘interruption method’ (Rint) is used less frequently, and it also measures a component of extra‐pulmonary resistance and is less reproducible and sensitive than other methods 4–7 …”

“…Although FEV 1 and Raw measurements generally agree, under low‐flow conditions, these two parameters do not provide the same information and may differ. Rather, they are complementary, as Raw is sometimes more sensitive to variation in airway calibre 2 . Furthermore, Raw plethysmographic measurement, the most commonly used system to measure the airway resistance, is not affected by a deep inspiration, thus making this assessment very useful in patients presenting with bronchoconstriction 8 …”

Metabolic Acidosis Improves Airway Conductance in Patients with Asthma

“…However, they give no data of reproducibility on specific Raw nor on specific Gaw when corrections are made for thoracic gas volumes. Airflow resistance measurements, including specific airway conductance, were recently updated (14). However, we are not aware of any recent literature on reproducibility data in modern, computer-assisted body plethysmography.…”