Measuring Peak Inspiratory Flow in Patients with Chronic Obstructive Pulmonary Disease

Changes in Peak Inspiratory Flow After Acute Bronchodilation: An Observational Study of Patients with Stable Chronic Obstructive Pulmonary Disease

Introduction: Identifying factors influencing peak inspiratory flow (PIF) is essential for aerosol drug delivery in stable patients with chronic obstructive pulmonary disease. While a minimum PIF for dry powder inhalers (DPIs) is established, acute bronchodilator (BD) effects on PIF remain unknown. Materials and Methods: An inspiratory flow meter (In-Check™ DIAL) was used to measure PIF in stable patients during a 24-week observational cross-sectional study. Additionally, bronchodilator responsiveness (BDR) was determined using the In-Check DIAL device and spirometry. Patients received four puffs of albuterol, and pre- and post-BD PIF, forced expiratory volume in one second (FEV1), and forced vital capacity were measured. Sixty-three patients completed acute BDR data collection from July 31, 2019, to November 9, 2021. Primary endpoints were pre- and post-BD spirometry and PIF. Statistical analyses included PIF correlations with FEV1. BD change was assessed according to inhaler resistance and sex (subgroup analysis). Results: Median patient age was 64.8 years, 85.7% were non-Hispanic White, and 57.1% were female. The median increase in absolute PIF (In-Check DIAL) was 5.0 L/min, and the % PIF change was 8.9%. With albuterol, 57.1% experienced a PIF BD change >5.0%, whereas 49.2% experienced a change >10.0%. Similarly, 55.6% experienced an FEV1 BD change >5.0% and 28.6% had a >10.0% FEV1 BD change with albuterol. PIF was weakly correlated with FEV1 BD change (absolute; % PIF; r = 0.28 [p = 0.02]; r = 0.21 [p = 0.11]). Pre- and post-BD median PIF were 75.5 and 83.5 L/min for low-to-medium-resistance DPI and 45.0 and 52.0 L/min for high-resistance, respectively. The median increases in pre- and post-BD PIF were 9.0 L/min in males and 4.5 L/min in females. In contrast to when using the In-Check DIAL device, we observed no consistent bronchodilatory effects on PIF measured by spirometry. Conclusions: Using the In-Check DIAL device, ∼50% of patients experienced >10% PIF increase after acute BD, potentially enhancing medication lung deposition. Further research is required to understand PIF's impact on medication delivery. ClinicalTrials.gov Identifier: NCT04168775.

Effect on Physical Position of Peak Inspiratory Flow in Stable COPD: An Observational Study

Background

We examined the effect of physical position on peak inspiratory flow (PIF) in patients with chronic obstructive pulmonary disease (COPD) using dry-powder inhalers (DPIs) with low‑medium internal resistance (R2) and/or high internal resistance (R5).

Methods

This prospective study in stable, ambulatory patients with spirometry-confirmed COPD evaluated the effect of 3 physical positions on maximal PIF achieved. Participants had PIFs of 30-90L/min (R5) or 60-90L/min (R2 DPIs) using the In-Check™ DIAL. PIF was measured in triplicate randomly in 3 positions that patients might be in while using their inhaler (standing, sitting, and semi-upright [supine position with the head of the bed at 45°, neck flexed forward]) against prescribed DPI resistance (R2/R5/both). Correlations between PIF and percentage decline in PIF between positions and differences in participant characteristics with >10% versus ≤10% PIF decline standing to semi-upright were calculated.

Results

A total of 76 participants (mean age, 65.2 years) had positional measurements; 59% reported seated DPI use at home. The mean (standard deviation) PIF standing, sitting, and semi-upright was 80.7 (13.4), 77.8 (14.3), and 74.0 (14.5) L/min, respectively, for R2 and 51.1 (9.52), 48.6 (9.84), and 45.8 (7.69) L/min, respectively, for R5 DPIs. PIF semi-upright was significantly lower than sitting and standing (R2; P < 0.0001) and standing (R5; P= 0.002). Approximately half of the participants had >10% decline in PIF from standing to semi-upright. Patient characteristics exceeding the 0.10 absolute standardized difference threshold with the decline in PIF for both the R2 and R5 DPIs were waist-to-hip ratio, modified Medical Research Council dyspnea score, and postbronchodilator percentage predicted forced vital capacity and PIF by spirometry.

Conclusions

PIF was significantly affected by physical position regardless of DPI resistance. PIF was highest when standing and lowest when semi-upright. We recommend that patients with COPD stand while using an R2 or R5 DPI. Where unfeasible, the position should be sitting rather than semi-upright. ClinicalTrials.gov identifier NCT04168775.

Utility of peak inspiratory flow measurement for dry powder inhaler use in chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Every type of dry powder inhaler (DPI) device has its own intrinsic resistance. A patient's inspiratory effort produces a pressure drop that determines the inspiratory flow, depending on the inhaler's specific internal resistance. Optimal peak inspiratory flow (PIF) is needed for effective release of dry powder, disaggregation of drug-carrier agglomerates, and optimal deposition of respirable drug particles, particularly generation of a high fine-particle fraction to reach the small airways of the lungs. However, standardized recommendations for PIF measurements are lacking and instructions appeared vague in many instances.

RECENT FINDINGS

Suboptimal PIFs are common in outpatient chronic obstructive pulmonary disease (COPD) patients and during acute exacerbations of COPD, and are associated with increased healthcare resource utilization. There is significant variation in the results of studies which is in part related to different definitions of optimal flow rates, and considerable variation in how PIF is measured in clinical and real-life studies.

SUMMARY

Standardization of technique will facilitate comparisons among studies. Specific recommendations for PIF measurement have been proposed to standardize the process and better ensure accurate and reliable PIF values in clinical trials and clinical practice. Clinicians can then select and personalize the most appropriate inhaler for their patients and help them achieve the optimal PIF needed for effective drug dispersion.

Consideration and Assessment of Patient Factors When Selecting an Inhaled Delivery System in COPD

Because guidelines and strategies for pharmacologic treatment of COPD focus on specific classes of inhaled medications, there is an unmet need for information to guide health care professionals for selecting an inhaled medication delivery system that matches the unique characteristics of individual patients. This article provides guidance for selecting an inhaled medication delivery system based on three "key" patient factors: cognitive function, manual dexterity/strength, and peak inspiratory flow. In addition, information is provided about specific tests to assess these patient factors. Cognitive impairment with an estimated prevalence of 25% among patients with COPD adversely affects patients' ability to correctly use a handheld device. To our knowledge, the prevalence of impaired manual dexterity/strength has not been reported in those with COPD. However, 79% of patients with COPD have reported one or more physical impediments that could influence their ability to manipulate an inhaler device. The measurement of peak inspiratory flow against the simulated resistance (PIFr) of a dry powder inhaler establishes whether the patient has the inhalation ability for creating optimal turbulent energy within the device. A suboptimal PIFr for low to medium-high resistance dry powder inhalers has been reported in 19% to 84% of stable outpatients with COPD. Health care professionals should consider cognitive function, manual dexterity/strength, and PIFr in their patients with COPD when prescribing inhaled pharmacotherapy. Impairments in these patient factors are common among those with COPD and can affect the individual's competency and effectiveness of using inhaled medications delivered by handheld devices.

Current Perspectives of Pharmacotherapies for COPD

Pharmacotherapies and avoidance of environmental/inhaled toxins are core to managing COPD. Compared to the drugs available 50 years ago, there has been substantial progress with COPD pharmacotherapies, but gaps in adherence and inhaler use persist. Personalizing inhaled pharmacotherapies is now possible with digital technologies by objectively documenting adherence and guiding inhaler technique. Another means to improve existing pharmacotherapies is through phenotyping and biomarkers. This is especially important considering the heterogeneity of the disease COPD. Blood eosinophils are now a recommended biomarker to guide use of inhaled corticosteroids and biologics in COPD. On the near horizon, we will see new inhaled medications as dual phosphodiesterase inhibitors, drugs to treat basic protein abnormalities as in alpha-1 antitrypsin deficiency that could have remarkable benefits, and biologic drugs targeting specific cell/mediator types in the COPD population. Characterization of COPD phenotypes, as asthma/COPD overlap and comorbid heart disease are vital to understand how to optimize pharmacotherapies. Importantly, we must determine how to optimize current medications; otherwise, we will repeat the same mistakes with new medications. But as we know so well, as we peel one layer of complexity, we encounter many more questions, all the while dedicated to limiting the burden of COPD.

Application of PLGA as a Biodegradable and Biocompatible Polymer for Pulmonary Delivery of Drugs

Pulmonary administration of biodegradable polymeric formulation is beneficial in the treatment of various respiratory diseases. For respiratory delivery, the polymer must be non-toxic, biodegradable, biocompatible, and stable. Poly D, L-lactic-co-glycolic acid (PLGA) is a widely used polymer for inhalable formulations because of its attractive mechanical and processing characteristics which give great opportunities to pharmaceutical industries to formulate novel inhalable products. PLGA has many pharmaceutical applications and its biocompatible nature produces non-toxic degradation products. The degradation of PLGA takes place through the non-enzymatic hydrolytic breakdown of ester bonds to produce free lactic acid and glycolic acid. The biodegradation products of PLGA are eliminated in the form of carbon dioxide (CO₂) and water (H₂O) by the Krebs cycle. The biocompatible properties of PLGA are investigated in various in vivo and in vitro studies. The high structural integrity of PLGA particles provides better stability, excellent drug loading, and sustained drug release. This review provides detailed information about PLGA as an inhalable grade polymer, its synthesis, advantages, physicochemical properties, biodegradability, and biocompatible characteristics. The important formulation aspects that must be considered during the manufacturing of inhalable PLGA formulations and the toxicity of PLGA in the lungs are also discussed in this paper. Additionally, a thorough overview is given on the application of PLGA as a particulate carrier in the treatment of major respiratory diseases, such as cystic fibrosis, lung cancer, tuberculosis, asthma, and pulmonary hypertension.

A review of upper airway physiology relevant to the delivery and deposition of inhalation aerosols

Developing effective oral inhaled drug delivery treatment strategies for respiratory diseases necessitates a thorough knowledge of the respiratory system physiology, such as the differences in the airway channel's structure and geometry in health and diseases, their surface properties, and mechanisms that maintain their patency. While respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma and their implications on the lower airways have been the core focus of most of the current research, the role of the upper airway in these diseases is less known, especially in the context of inhaled drug delivery. This is despite the fact that the upper airway is the passageway for inhaled drugs to be delivered to the lower airways, and their replicas are indispensable in current standards, such as the cascade impactor experiments for testing inhaled drug delivery technology. This review provides an overview of upper airway collapsibility and their mechanical properties, the effects of age and gender on upper airway geometry, and surface properties. The review also discusses how COPD and asthma affect the upper airway and the typical inhalation flow characteristics exhibited by the patients with these diseases.

Impact of Sex on Proper Use of Inhaler Devices in Asthma and COPD: A Systematic Review and Meta-Analysis

Despite females being more often affected by asthma than males and the prevalence of COPD rising in females, conflicting evidence exists as to whether sex may modulate the correct inhaler technique. The aim of this study was to assess the impact of sex on the proper use of inhaler devices in asthma and COPD. A pairwise meta-analysis was performed on studies enrolling adult males and females with asthma or COPD and reporting data of patients making at least one error by inhaler device type (DPI, MDI, and SMI). The data of 6,571 patients with asthma or COPD were extracted from 12 studies. A moderate quality of evidence (GRADE +++) indicated that sex may influence the correct use of inhaler device in both asthma and COPD. The critical error rate was higher in females with asthma (OR 1.31, 95%CI 1.14−1.50) and COPD (OR 1.80, 95%CI 1.22−2.67) using DPI vs. males (p < 0.01). In addition, the use of SMI in COPD was associated with a greater rate of critical errors in females vs. males (OR 5.36, 95%CI 1.48−19.32; p < 0.05). No significant difference resulted for MDI. In conclusion, choosing the right inhaler device in agreement with sex may optimize the pharmacological treatment of asthma and COPD.

Dry powder inhalers of antitubercular drugs

Despite advancements in the medical and pharmaceutical fields, tuberculosis remains a major health problem globally. Patients do not widely accept the conventional approach to treating tuberculosis (TB) due to prolonged treatment periods with multiple high doses of drugs and associated side effects. A pulmonary route is a non-invasive approach to delivering drugs, hormones, nucleic acid, steroids, proteins, and peptides directly to the lungs, improving the efficacy of the treatment and consequently decreasing the adverse effect of the treatment. This route has been successfully developed for the treatment of various respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), tuberculosis (TB), lung cancer, and other pulmonary infections. The major approaches of inhalation delivery systems include nebulizers, metered-dose inhalers (MDIs), and dry powder inhalers (DPIs). However, dry powder inhalers (DPIs) are more advantageous due to their stability and ability to deliver a high dose of the drug to the lungs. The present review analyzes the modern therapeutic approach of inhaled dry powders, with a special focus on novel drug delivery system (NDDS) based DPIs for the treatment of TB. The article also discussed the challenges of preparing inhalable dry powder formulations for the treatment of TB. The clinical development of inhalable anti-TB drugs is also reviewed.

Relationship between Peak Inspiratory Flow and Patient and Disease Characteristics in Individuals with COPD—A Systematic Scoping Review

Optimal delivery of medication via dry powder inhalers, the most commonly prescribed inhaler type, is dependent on a patient achieving a minimum level of inspiratory flow during inhalation. However, measurement of peak inspiratory flow (PIF) against the simulated resistance of a dry powder inhaler is not frequently performed in clinical practice due to time or equipment limitations. Therefore, defining which patient characteristics are associated with lower PIF is critically important to help clinicians optimize their inhaler choice through a more personalized approach to prescribing. The objective of this scoping review was to systematically evaluate patient and disease characteristics determining PIF in patients with chronic obstructive pulmonary disease (COPD). Medline, Cochrane and Embase databases were systematically searched for relevant studies on PIF in patients with COPD published in English between January 2000 and May 2021. The quality of evidence was assessed using a modified Grading of Recommendations Assessment, Development and Evaluation checklist. Of 3382 citations retrieved, 35 publications were included in the review (nine scored as high quality, 13 as moderate, nine as low, and four as very low). Factors correlating with PIF in >70% of papers included both patient characteristics (lower PIF correlated with increased age, female gender, shorter height, decreased handgrip and inspiratory muscle strength, and certain comorbidities) and disease characteristics (lower PIF correlated with markers of lung hyperinflation, lower peak expiratory flow [PEF] and increased disease severity). Other factors correlating with adequate/optimal or improved PIF included education/counseling and exercise/inspiratory muscle training; impaired physical function and errors in inhalation technique/non-adherence were associated with low/suboptimal PIF. In conclusion, clinicians should measure PIF against the simulated resistance of a particular device wherever possible. However, as this often cannot be done due to lack of resources or time, the patient and disease characteristics that influence PIF, as identified in this review, can help clinicians to choose the most appropriate inhaler type for their patients.