Lung inflation by glossopharyngeal breathing and "air stacking" in Duchenne muscular dystrophy

Objective: To compare the use of glossopharyngeal breathing (GPB) and air stacking to increase lung volumes and cough peak flows (CPF), and GPB to increase ventilator-free breathing ability (VFBA), for patients with Duchenne muscular dystrophy. Design: A case series of all referred patients with declining vital capacity NO. Seventy-eight patients underwent training in and monitoring of the efficacy of air stacking (retaining consecutively delivered volumes of air delivered via manual resuscitator and held by glottic closure) to maximum insufflation capacity (MIC). GPB also was demonstrated to all 78 patients, and 32 were formally trained and prescribed GPB as their VCs decreased below 400 ml. To be successful, the MIC or GPB maximum single-breath capacity (GPmaxSBC) had to exceed VC. Improvements in VFBA were determined by requiring fewer ventilator-assisted breaths per minute. CPFs were measured by peak flow meter. Results: Seventy-four (94.9%) of the patients could air stack (MIC > VC), and, thus far, 21 (27%) are able to GPB. Fifteen could GPB sufficiently to delay onset of daytime ventilator use and, later, to require 1.9 fewer ventilator assisted breaths per minute. For the 47 patients with multiple data points, as VC deteriorated from 1080 +/- 870 to 1001 +/- 785 ml, MIC increased from 1592 +/- 887 to 1838 +/- 774 ml. For 21 patients, GPmaxSBC significantly exceeded VC (824 +/- 584 vs. 244 +/- 151 ml, respectively, P < 0.001). The ability to increase lung volume by air stacking (MIC) was better retained than was the ability to increase lung volume by GPB (GPmaxSBC). Air stacking also permitted assisted CPF to exceed unassisted CPF 289 +/- 91 and 164 +/- 76 liters/m, respectively (P < 0.001). Conclusions: GPB and air stacking can increase lung volumes and, thereby, cough flows. GPB also can be used in many cases to delay and decrease daytime ventilator use.