Peak Inspiratory Flow Rate as a Prerequisite for Prescription of Inhaler Devices: A Cross-sectional Study

Inhaler therapy has become the mainstay of treatment in obstructive airway diseases. Although patients, and to a certain extent doctors also, were not initially comfortable with inhalation devices, they have now become the standard of care in chronic obstructive pulmonary disease (COPD) and asthma. However, the choice of inhaler device prescribed in different subsets of patients is still not clear. Prescription of a device depends upon age, dexterity, hand-mouth coordination, and peak inspiratory flow rates (PIFR). Prescription of wrong inhaler and wrong technique is not uncommon. In our study, 52.6% cases had prescription of wrong inhaler device, as per their PIFR. Physicians often do not consider the PIFR and the respiratory effort of the patient, while advising inhaler device. Only 43% patients with asthma had an adequate asthma control [asthma control test (ACT) > 19]. One of the main causes of a general inability to use an inhaler device properly results from the generation of an inadequate PIFR. It is more pronounced in those using dry powder inhalers (DPI), as it requires a higher effort-dependent inspiratory flow rate. PIFR of patients was divided into four groups, ≤30, 31-60, 61-90, and >90 L/minute. The required PIFR was taken as 30-60 L/minute for metered dose inhaler (MDI) and >60 L/minute for DPI. A positive correlation was noted for PIFR and advice to change the device as per the readings (p = 0.05). A positive correlation was also noted with PIFR compared to smoking/biomass use (p = 0.002). Thus, clinicians should advise inhalers as per PIFR and also continue to monitor PIFR on subsequent visits.