Hyperinflation is associated with reduced strength and efficiency of the respiratory muscles in asthmatic and normal subjects

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.

Six-minute walk test and respiratory muscle strength in patients with uncontrolled severe asthma: a pilot study

OBJECTIVE:

To evaluate respiratory muscle strength and six-minute walk test (6MWT) variables in patients with uncontrolled severe asthma (UCSA).

METHODS:

This was a cross-sectional study involving UCSA patients followed at a university hospital. The patients underwent 6MWT, spirometry, and measurements of respiratory muscle strength, as well as completing the Asthma Control Test (ACT). The Mann-Whitney test was used in order to analyze 6MWT variables, whereas the Kruskal-Wallis test was used to determine whether there was an association between the use of oral corticosteroids and respiratory muscle strength.

RESULTS:

We included 25 patients. Mean FEV₁ was 58.8 ± 21.8% of predicted, and mean ACT score was 14.0 ± 3.9 points. No significant difference was found between the median six-minute walk distance recorded for the UCSA patients and that predicted for healthy Brazilians (512 m and 534 m, respectively; p = 0.14). During the 6MWT, there was no significant drop in SpO₂. Mean MIP and MEP were normal (72.9 ± 15.2% and 67.6 ± 22.2%, respectively). Comparing the patients treated with at least four courses of oral corticosteroids per year and those treated with three or fewer, we found no significant differences in MIP (p = 0.15) or MEP (p = 0.45).

CONCLUSIONS:

Our findings suggest that UCSA patients are similar to normal subjects in terms of 6MWT variables and respiratory muscle strength. The use of oral corticosteroids has no apparent impact on respiratory muscle strength.

Role of maximal inspiratory presure in the evaluetion of respiratory muscle strength in asthmatics - Systematic review

Asthma is a chronic illness of the airways that can reduce respiratory muscle strength due to the resulting hyperinflation or treatment with corticosteroids. One of the ways to evaluate this respiratory muscular weakness is the Maximal Inspiratory Pressure (PImax).

METHODS

A systematic review of the databases PUBMED/MEDLINE, LILACS and SCIELO was carried through, using the key words: Asthma, respiratory muscle and muscle strength.

RESULTS

Fifty were found and six articles that evaluated the PImax in asthmatics, from these, thirty were excluded, making a total of twenty six articles.

FINAL CONSIDERATIONS

Through the present revision we show the effectiveness of PImax in evaluating respiratory muscle strength in asthmatics. More studies are needed, however, fot better understanding of the asthmatic individual. Rev Port Pneumol 2010; XVI (3): 463-470.

Is there an association between postural balance and pulmonary function in adults with asthma?

OBJECTIVE

Asthma may cause systemic repercussions due to its severity and the effects of treatment. Our objective was to compare posture, balance, functional capacity, and quality of life (QOL) according to the severity of disease, as assessed by pulmonary function levels.

METHOD

This cross-sectional study evaluated fifty individuals with asthma. We compared two groups of adult individuals who were divided according to the median of the forced expiratory volume in one second (FEV1) as follows: group A  =  FEV1>74% predicted; group B  =  FEV1<74% predicted. All patients underwent the following tests: spirometry, whole-body plethysmography, diffusing capacity for carbon monoxide (DLco), respiratory muscle strength, posture assessment, stabilometry, six-minute walking distance (6MWD), and QOL.

RESULTS

All pulmonary function variables exhibited statistically significant differences between the two groups, except for the DLco. The maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and 6MWD were lower in group B. The maximal mediolateral velocity and the mediolateral displacement were significantly different, while the postural changes and QOL were similar between the groups.

CONCLUSIONS

In adult individuals with asthma, the pulmonary function is associated with balance control in the mediolateral direction but does not influence the postural changes or QOL.