Optimizing Inhalation Therapy in the Aspect of Peak Inhalation Flow Rate in Patients With Chronic Obstructive Pulmonary Disease or Asthma

Jian-lan Hua; Xiao-fen Ye; Chun-ling Du; Ning Xie; Jie-qing Zhang; Man Li; Jing Zhang


BMC Pulm Med. 2021;21(302) 

In This Article

Abstract and Introduction


Background: Pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) are commonly used drug-delivering devices for patients with chronic airway diseases. Appropriate peak inhalation flow rate (PIFR) and inhaler technique is essential for effective therapy. We aimed at optimizing inhalation therapy through the analysis of PIFRs in patients with chronic obstructive pulmonary disease (COPD) or asthma as well as the effect of technique training using In-Check DIAL® to help patients to achieve their optimal inspiratory flow rates.

Methods: The study continuously enrolled patients who were diagnosed as COPD or asthma from respiratory clinics. PIFRs were described and analyzed between the newly-diagnosed and follow-up patients, and the stable and acute exacerbation patients, respectively. Every participant was trained inhaler technique using In-Check DIAL®. PIFRs before and after training was compared by self-control analysis.

Results: Among a total of 209 patients, the average age was 56.9 years. For DPIs users, 10.8% patients had a PIFR < 30 L/min and 44.1% patients had a PIFR≥ 60 L/min before technique training. After technique training, scarcely patient (1.5%) had a PIFR < 30 L/min, and 60.5% patients had a PIFR≥ 60 L/min. The patient's average PIFR increased by 5.6L/min after training. The increase in PIFR before and after training was significant (p < 0.001) for most patients, but no significant variation was found in patients with acute exacerbation (p = 0.822).

Conclusions: A considerable number of patients with COPD or asthma were not able to achieve the minimum or optimal PIFR for DPIs. Inhaler training can increase patients' PIFRs and improve their ability to use DPIs.

Trail Registration: The study has registered in chictr.org.cn (ChiCTR1900024707) and been approved by the Ethics Committee of Zhongshan Hospital of Fudan University (B2019-142).


Chronic respiratory diseases, especially Chronic obstructive pulmonary disease (COPD) and asthma, are common diseases worldwide with leading mortality and morbidity. In China, the prevalence of COPD in patients over 40 years old was 8.2–13.7%.[1,2] COPD has accounted for 1.6% of all hospital admissions and ranked as the fourth leading cause of death in urban areas and the third leading cause of death in rural areas worldwide.[3] COPD has been a heavy burden for China, with a direct medical cost of $72 to $3565 per capita per year accounting for 40% of the average family's total income.[4] In the recent epidemiological studies, the overall prevalence of asthma in China ranged from 1.2 to 5.8%, while 4.2% among adults.[5,6]

Inhalation therapies, including inhaled corticosteroid (ICS), long-acting β2 agonists (LABA) and long-acting muscarinic antagonists (LAMA), play an important role for the treatment and management of both COPD and asthma.[7] Inhalers typically used for inhalation therapy are sorted into three types based on their respective technical characteristics and particle properties: pressurized metered dose inhaler (pMDI), dry powder inhalers (DPIs), soft mist inhalers (SMI). pMDIs do not require the patients' peak inhalation flow rate (PIFR) to reach a certain value, but drug delivery using pMDIs is highly dependent on the patient's inhaler technique.[8] Failure to coordinate or synchronize actuation with inhalation leading to suboptimal lung deposition are commonplace reported in previous studies.[9] In comparison, DPIs are essentially breath-actuated and easier to use correctly than pMDIs, but demand patients to generate a sufficient inspiratory flow to release the powder and break up the powder packets into respirable particles (less than 5 μm in diameter).[10]

Recently, PIFR has been believed as a measure to assess patients' capacity to use DPIs.[11] DPIs approved for treatment of COPD and Asthma include the HandiHaler, Turbuhaler, Aerolizer, Accuhaler/Diskus, Breezhaler, Genuair/Pressair, etc. The recommended technique for patients when using DPIs is 'a fast and hard inhalation'. Due to the difference in the internal resistance of devices, the level of resistance that the patient needs to overcome when using different DPIs varies. For example, using DPIs with high resistance like Turbuhaler and HandiHaler require more inspiratory effort than using those with low resistance like Breezhaler. Patients using DPIs need to achieve a minimum inhalation rate for the effective clinical response or ideally an optimal rate for the best response. Given previous studies, it is generally considered that PIFR less than 30 L/min is insufficient for the use of DPIs.[12] PIFR of at least 60L/min achieved by patients can bring about optimal drug delivery through DPIs.[13] Unlike DPIs, the technical essential for patients when using pMDI is 'a slow and deep inhalation', which requires that the patient's PIFR should be less than 90 L/min.[14] However, observational studies demonstrate that 19% of patients with stable COPD or asthma[15] and 32% to 47% of in-patients prior to discharge after recovering from exacerbation suffered a suboptimal PIFR (less than 60L/min).[16] Moreover, the PIFRs of 12% of elder Turbuhaler users were even lower than the minimum effective rate (30 L/min).[17] If patients' inspiratory flow rate does not match DPIs, the insufficient PIFR associating with the dose of inhaled drugs poorly deposited in lung will result in unsatisfied efficacy and potentially poor prognosis.[18,19] Overall, PIFR is an important consideration for physicians to choose an appropriate inhaler for patients.

Appropriate technique for the usage of inhalers is quite important for the efficacy of inhalation therapy that improper technique is significantly associated with uncontrolled symptoms and increased exacerbation rate.[20] For patients using DPIs and pMDIs, the most critical and common technique errors are inappropriate inspiratory maneuver and poorly synchronized hand actuation with inhalation, respectively.[21] Several reports have revealed that up to 70%-80% of patients made at least 1 inhalation technique error when using DPIs, and 86%-87% of patients when using pMDIs.[22,23] Especially, patients using Turbuhaler are most likely to make mistakes.[24] Therefore, enhancing patients' inhaler technique through teaching and training may contribute to improving prognosis and decreasing medical expenditure.

In the current study, we aimed to investigate the PIFRs of patients with COPD or asthma, factors that affect PIFRs and the effect of inhaler technique training on optimizing patients' PIFRs before inhalation therapy. Through this study, the optimized inhalation therapy based on PIFR should be guided both in selection of the most acceptable inhaler for patients and in training to improve inhaler technique.