Comparison of the Oxygen Cost of Breathing Exercises and Spontaneous Breathing in Patients With Stable Chronic Obstructive Pulmonary Disease

Abstract

Background and Purpose. The oxygen demand of breathing exercises and the clinical implications have not been studied in detail. In this study, the oxygen cost of 3 common breathing exercises believed to reduce oxygen cost (ie, work of breathing) was compared with that of spontaneous breathing in patients with chronic obstructive pulmonary disease (COPD). Subjects. Thirty subjects with stable, moderately severe COPD participated. Methods. Oxygen consumption (V o 2 ) and respiratory rate (RR) during spontaneous breathing at rest (SB) were recorded for 10 minutes. Subjects then performed 3 breathing exercises in random order, with a rest between exercises: diaphragmatic breathing (DB), pursed-lip breathing (PLB), and a combination of DB and PLB (CB). Oxygen consumption and RR were measured. Results. Mean V o 2 (ϮSD) was lower during the breathing exercises (165.8Ϯ22.3 mL O 2 /min for DB, 164.8Ϯ20.9 mL O 2 /min for PLB, and 167.7Ϯ20.7 mL O 2 /min for CB) compared with SB (174.5Ϯ25.2 mL O 2 /min). Correspondingly, mean RR (ϮSD) was higher during SB (17.3Ϯ4.23 breaths/min), followed by DB (15.0Ϯ4.32 breaths/min), PLB (12.8Ϯ3.53 breaths/min), and CB (11.2Ϯ2.7 breaths/min). Discussion and Conclusion. Given that patients do not spontaneously adopt the breathing pattern with the least V o 2 and the lowest RR, the results suggest that determinants of the breathing pattern other than metabolic demand warrant being a primary focus in patients with COPD. [Jones AYM, Dean E, Chow CCS. Comparison of the oxygen cost of breathing exercises and spontaneous breathing in patients with stable chronic obstructive pulmonary disease. Phys Ther. 2003;83:424 -431 Due to their increased ventilatory demands, people with chronic obstructive pulmonary disease (COPD) have a higher resting oxygen consumption (V o 2 ) than do people without pulmonary disease. 1,2 This higher resting V o 2 may be explained by increased mechanical work of breathing or reduced ventilatory muscle efficiency, or both, in patients with severe COPD. 3 Mechanical work in biological systems is achieved when a force applied to a structure results in movement. The amount of work produced is the product of the force applied and the distance moved. With respect to spontaneous ventilation, the mean pressure generated by the ventilatory muscles is equivalent to the force, and the tidal volume is equivalent to the distance. Ventilatory muscle work is primarily dependent on minute ventilation, airway resistance, and lung compliance, which, in turn, determine ventilatory muscle efficiency and the pattern of breathing. 4 Efficient ventilatory muscle function is equivalent to the attainment of the requisite minute ventilation with the least energy cost.In COPD, the loss of alveolar tethering and elastic recoil contributes to increased lung compliance and impaired lung perfusion. 5 Typically, these changes result from prolonged inhalation of cigarette smoke, which irritates the airways, thus increasing mucous production and airway resistance. Over time, these pathophysiologic chan...

Effects of Diaphragmatic Breathing With and Without Pursed-Lips Breathing in Subjects With COPD

“…The breathing frequency was significantly lower during diaphragmatic breathing plus pursed-lips breathing, even in relation to each technique in isolation, although there was no difference in oxygen consumption among the 3 exercises. 5 According to these findings, a combination of these techniques seemed to be more effective than performing the exercises separately. However, to the best of our knowledge, this was the only study to evaluate the effects of the combination of the techniques for only these 2 outcomes.…”

“…3 Pulmonary rehabilitation has been shown to improve symptoms, exercise tolerance, and health-related quality of life as well as reduce hospitalizations. [2][3][4] Breathing exercises, such as diaphragmatic breathing and pursed-lips breathing, which can be performed separately or in combination, [5][6][7][8][9] have a role in managing breathlessness in patients with COPD and can also be considered for those who are unable to undertake exercise training. 1,7 These techniques aim to reduce dyspnea, improve ventilation and gas exchange, optimize chest wall motion, and reduce hyperinflation.…”

“…6,10,14,17 However, dyspnea relief remains poorly consistent, because this response is different among subjects. 6,10 With regard to the combination of these techniques (diaphragmatic breathing plus pursed-lips breathing) in subjects with COPD, Jones et al 5 reported a significant decrease in breathing frequency and oxygen consumption during the combined exercise compared with the spontaneous breathing. The breathing frequency was significantly lower during diaphragmatic breathing plus pursed-lips breathing, even in relation to each technique in isolation, although there was no difference in oxygen consumption among the 3 exercises.…”

Efficacy of breathing retraining program on bedside assessment of pulmonary function

“…Breathing Retraining Program beneit chronic mouth breathers and patients with sleep apnea and dyspnoea (Garrodl et al, 2005). Routine investigations of respiratory functions like volumes, lows, and indices of gas exchange, are non need, and they are not speci ic to diagnosis but give some information about respiratory muscle performance (Jones et al, 2003). But the respiratory muscle dysfunction can be identi ied by conventional respiratory function tests.…”

“…The ef icacy of pursed-lip breathing (PLB) and diaphragmatic breathing (DB) in the rehabilitation of people with dyspnoea remains unclear and there is no proper teaching of these breathing retraining exercises was done in routine practice (Nield et al, 2007). This study examines the usefulness of these techniques in normalizing the breathing pattern of people with dyspnoea (Jones et al, 2003). The studies included the use of PLB and DB and used outcomes that were measured at the bedside.…”