Chest
Volume 101, Issue 1, January 1992, Pages 75-78
Journal home page for Chest

Clinical Investigations
The Pattern of Respiratory Muscle Recruitment during Pursed-Lip Breathing

https://doi.org/10.1378/chest.101.1.75Get rights and content

Data from the present study indicate a change in the pattern of chest wall muscle recruitment and improved ventilation with pursed-lip breathing (PLB) in COPD. Pursed lip breathing led to increased rib cage and accessory muscle recruitment during inspiration and expiration, increased abdominal muscle recruitment during expiration, decreased duty cycle of the inspiratory muscles and respiratory rate, and improved SaO2. In addition, PLB resulted in no change in pressure across the diaphragm and a less fatiguing breathing pattern of the diaphragm. Changes in chest wall muscle recruitment and respiratory temporal parameters concomitant with the increased SaO2 indicate a mechanism of improving ventilation with PLB while protecting the diaphragm from fatigue in COPD. Alterations in the pattern of respiratory muscle recruitment with PLB may be associated also with the amelioration of dyspnea. Further investigation is necessary to explore the relationship between the pattern of respiratory muscle recruitment during PLB and dyspnea.

(Chest 1992; 101:75-78)

Section snippets

MATERIALS AND METHODS

Thirteen patients with stable severe COPD participated in this clinical investigation. Informed consent was obtained from each subject. Pulmonary function tests were performed prior to the experimental trials (Collins DSII Plus spirometer 1167).

The pattern of respiratory muscle recruitment and pulmonary function tests were measured. Two minute trials of two breathing conditions, baseline tidal breathing (TB) and PLB, were carried out while subjects were seated in an upright position at rest.

RESULTS

Thirteen male patients (mean age, 61 ±6 yr) with moderately severe and severe COPD (mean FEV1 = 1.05 ±0.44 L/s) participated in the study.

Their characteristics (mean ± SD) are shown in the following tabulation:

No. of subjects13
Gendermale
Age, yr63 ± 7
FEV1, L1.05 ± 0.44
FEV1, percent of predicted37 ± 12
FVC, L2.3 ± 0.9
FVC, percent of predicted57 ± 16
Maximal inspiratory pressure (MIP), cm H2O66 ± 31
Pdimax, cm H2O72.6 ± 20.3

When compared with baseline TB, PLB resulted in statistically

DISCUSSION

Several changes in the pattern of respiratory muscle recruitment were observed with PLB. When compared with TB, PLB led to increases in inspiratory rib cage and accessory muscle recruitment and reductions in diaphragm recruitment during inspiration; overall Pdi did not change. There were also increases in expiratory rib cage and abdominal muscle recruitment with PLB. Duty cycle of the inspiratory muscles and the RR were decreased from TB with PLB. Also, during PLB the pattern of diaphragm

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Supported in part by NCNR and NIH F32 NR06339.

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