Chest
Clinical InvestigationsVariation in Maximum Inspiratory and Expiratory Pressure after Application of Inspiratory Loads in Patients with COPD
Section snippets
PURPOSE
The purpose of this study was to evaluate the possible variation of the maximum inspiratory and expiratory pressures after the application of inspiratory loads generating 65 percent of MIP in patients with stable COPD.
Sample
The study was conducted on eight male patients with COPD in stable phase, that is, the patients had not shown any symptoms of acute relapse in a period of at least two months prior to the study. The average age was 60.57 ± 7.59 years, the height was 162.14 ± 10.43 cm, and the weight was 65 ± 9.7 kg. The patients did not have any other type of cardiorespiratory, endocrine, neuromuscular, or hepatic illness. We explained the protocol to be followed and all patients gave their consent. Various
RESULTS
It can be seen in Table 1 that there is evidence that the patients suffered a moderate obstruction of air flow and the volumes are increased. Three of the patients had a Dco of less than 80 percent due to clinical and radiologic signs of pulmonary emphysema.19 The average TLIM of the sample was 3.7 ± 1.96 minutes. The anthropometric measurements were normal.
Table 2 shows the MIP and the MEP of the patients at the basal stage, on exhaustion, and at 10, 20, and 30 minutes following exhaustion.
DISCUSSION
The studies that have been performed on respiratory muscle endurance are based on the capacity of the respiratory muscles to sustain and generate high levels of pressure. The most common test consists of generating a pressure against a given resistive inspiratory load.1, 2, 3, 20 In our study, we used the Nickerson, Keens and Kelsen methods,3, 4, 21 that consist of breathing through a constant threshold load equivalent to 65 percent of the MIR This pressure lies within the range of critical
CONCLUSIONS
On the basis of foregoing results, it may be said that the MIP decreases in the patients with COPD after the application of inspiratory loads equivalent to 65 percent of MIP The drop in MIP begins to take place at the end of the test and becomes significant ten minutes after exhaustion, without returning to its basal value even beyond 30 minutes after the end of the test. The MEP does not vary with respect to the value obtained at rest.
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1998, Respiration
Supported by grant FISS88.
Manuscript received April 6; revision accepted August 31.