Respiratory muscle mechanics during diaphragmatic breathing

Noteworthy among breathing training techniques is so-called diaphragmatic breathing. In spite of the technique's name, however, little is known of the functional characteristics of this ventilatory method. OBJECTIVE: To assess the mechanics of respiratory muscles, particularly diaphragm muscles, during diaphragmatic breathing in patients with severe chronic obstructive pulmonary disease (COPD). METHODS: Ventilatory pattern and respiratory pressures (abdominal [Pga], intrathoracic [Pes] and transdiaphragmatic [Pdi]) were studied in 10 patients with severe COPD in stable phase (age 69 ± 6 years, FEV1 33 ± 12% ref) at baseline and during deep breathing with spontaneous muscle recruitment (SMR) and during breathing training. Measurements were taken with the patient seated and in supine decubitus position. RESULTS: In seated position ventilatory pattern was similar with SMR and during breathing training. Mean Pdi during airflow, however, was greater during breathing training than with SMR (34.8 ± 8.0 and 29.3 ± 9.3 cmH2O, respectively, p < 0.05) for similar levels of Pes. Mechanical effectiveness of the diaphragm expressed as Vt/Pdi) was less during breathing training, however (36.1 ± 10.4 and 49.5 ± 15.8 cc/cmH2O, p < 0.05), with no changes in overall efficacy of respiratory muscles (Vt/Pes). In supine decubitus position, ventilatory patterns of SMR and breathing training were similar, although Vt and T1 were slightly higher in the latter (1,065 ± 305 vs. 1,211 ± 314 cc, p < 0.01; and 2.76 ± 1.32 vs. 3.07 ± 1.23 sec, p < 0.05). Pdi was also higher during breathing training (29.7 ± 10.2 and 38.0 ± 10.5 cmH2O, p < 0.05), although accompanied in this case by a higher Pes (21.2 ± 7.5 to 26.4 ± 8.4 cmH2O, p < 0.005). In supine decubitus position, the effectiveness of both diaphragm muscles and respiratory muscles overall was similar for both ventilatory modes. CONCLUSIONS: Breathing training truly involves greater use of the diaphragm, both in seated and supine decubitus positions. Breathing training does not provide greater ventilatory efficacy than SMR, however, in COPD patients.