Artificial External Glottic Device for Passive Lung Insufflation

PURPOSE: For patients with neuromuscular disease, air stacking, which inflates the lungs to deep volumes, is important for many reasons. However, neuromuscular patients with severe glottic dysfunction or indwelling tracheostomy tubes cannot air stack effectively. For these patients, we developed a device that permits deep lung insufflations substituting for glottic function. MATERIALS AND METHODS: Thirty-seven patients with bulbar-innervated muscle weakness and/or tracheostomies were recruited. Twenty-three had amyotrophic lateral sclerosis, and 14 were tetraplegic patients due to cervical spinal cord injury. An artificial external glottic device (AEGD) was used to permit passive deep lung insufflation. In order to confirm the utility of AEGD, vital capacity, maximum insufflation capacity (MIC), and lung insufflation capacity (LIC) with AEGD (LICA) were measured. RESULTS: For 30 patients, MICs were initially zero. However, with the use of the AEGD, LICA was measurable for all patients. The mean LICA was 1,622.7+/-526.8 mL. Although MIC was measurable for the remaining 7 patients without utilizing the AEGD, it was significantly less than LICA, which was 1,084.3+/-259.9 mL and 1,862.9+/-248 mL, respectively (p<0.05). CONCLUSION: The AEGD permits lung insufflation by providing deeper lung volumes than possible by air stacking.

Clinical Implication of Air Stacking Exercise in Patients with Neuromuscular Diseases

OBJECTIVE: To evaluate the effect of the air stacking exercise on maximal insufflation capacity (MIC) and peak cough flow (PCF) in patients with neuromuscular diseases. METHOD: Two hundred twenty nine neuromuscular patients with vital capacity (VC) below 50% of the predicted normal value were initially evaluated for VC, MIC, PCF, and assisted PCF (APCF). After the first evaluation, these patients were instructed to carry out air stacking exercise periodically, and were re-evaluated after one year. RESULTS: Forty seven patients were capable of performing air stacking exercise on regular basis, at least twice a day for one year. Among these patients, MIC increased in 28 patients from 1345.4 ml to 1572.9 ml on average (p<0.05), while it decreased in 19 patients from 1740.0 ml to 1325.3 ml on average (p<0.05). In the increasing MIC group APCF increased from 244.6 L/min to 278.1 L/min (p<0.05). In the decreasing MIC group, every value decreased significantly. CONCLUSION: Air stacking exercise was shown to be capable of increasing MIC and APCF despite the reduction in VC and PCF in patients with neuromuscular diseases.