Mechanically Assisted Coughing Research Articles

Oximetry and Indications for Tracheotomy for Amyotrophic Lateral Sclerosis

To explore the use of oximetry as a guide for using respiratory aids and tracheotomy in the treatment of patients with amyotrophic lateral sclerosis (ALS). A retrospective review of all ALS patients presenting to a neuromuscular disease clinic since 1996. Patients who were symptomatic for nocturnal hypoventilation were prescribed noninvasive ventilation (NIV). Patients with assisted cough peak flows of < 300 L/min were prescribed oximeters and access to mechanically assisted coughing (MAC) to prevent or reverse decreases in baseline pulse oximetric saturation (Spo(2)) levels of < 95%. The number of decreases in baseline Spo(2) that could be normalized by any combination of NIV and MAC and the duration of normalization were recorded. When the baseline was not or could not be normalized, the time to acute respiratory failure and tracheotomy or death were recorded. Twenty-five patients became dependent on NIV, including 13 patients who received NIV continuously for a mean (+/- SD) period of 19.7 +/- 16.9 months, without desaturation (group 1). For another 76 patients, the daytime baseline Spo(2) level decreased to < 95% 78 times. For 41 patients, the baseline level was corrected by NIV/MAC (group 2) for a mean duration of 11.1 +/- 8.7 months before desaturation reoccurred for 27 patients. Of the latter patients, 11 underwent tracheotomy, 14 died in < 2 months, and 2 had their condition again corrected by the addition of MAC therapy. For 35 patients, the desaturation was not or could not be normalized (group 3). Thirty-three of these 35 patients required tracheotomy or died within 2 months. The only significant difference between groups 1 and 2 and group 3 was significantly poorer glottic function in the patients in group 3. Tracheotomy or death is highly likely within 2 months of a decrease in baseline Spo(2) that cannot be corrected by NIV or MAC. The long-term use of NIV and MAC, and the avoidance of tracheotomy is dependent on glottic function rather than on inspiratory or expiratory muscle failure.

Amyotrophic Lateral Sclerosis: Prolongation of Life by Noninvasive Respiratory Aids

To describe prolongation of survival in patients with amyotrophic lateral sclerosis (ALS) by continuous noninvasive intermittent positive-pressure ventilation (NPPV) and mechanically assisted coughing (MAC) using oximetry as feedback. A retrospective review of ALS patients visiting one center from 1990 to 2000. Patients were trained in mouthpiece and nasal NPPV when symptomatic for hypoventilation, and trained in MAC with oximetry feedback when assisted peak cough flow (PCF) levels decreased to < 270 L/min. Survival was considered to be prolonged when full-time NPPV was required with limited ventilator-free breathing tolerance. Of 101 patients who met the criteria for access to NPPV and MAC, 15 have not yet used them, and 11 patients with severe bulbar muscle dysfunction died without ever successfully using them. Three patients used NPPV full-time, and oximetry and MAC episodically, but did not yet require ongoing NPPV. Eighteen used NPPV part-time for a mean (+/- SD) duration of 3.8 +/- 4.1 months. Nineteen others underwent tracheotomy after 4.7 +/- 4.5 months of receiving part-time NPPV. Sixteen patients used part-time NPPV for 17.5 +/- 13.0 months (maximum, 25 months), then full-time NPPV for 14.1 +/- 12.6 months (maximum, 40 months) before undergoing tracheotomy. Nineteen patients used part-time and full-time NPPV for 25.2 +/- 19.8 months (maximum, 114 months) and 17.5 +/- 13.3 months (maximum, 87 months), respectively, without undergoing tracheotomy. Ten of these NPPV users died once bulbar dysfunction became severe. We conclude that up to continuous use of NPPV, along with MAC when needed, can permit prolonged survival and delay the need for tracheotomy for a significant minority of ALS patients by > 1 year.