LETTER
Positive-Pressure Ventilation in Amyotrophic Lateral Sclerosis
Marcia Bio, MD, and
John R. Bach, MD
1 April 1998 | Volume 128 Issue 7 | Pages 601-602
TO THE EDITOR:
Although Aboussouan and colleagues [1] reaffirm that assisting the ventilation of patients with amyotrophic lateral sclerosis can prolong survival, even their patients who "tolerated" nocturnal nasal positive-pressure ventilation survived only 15 months. Most untreated patients with this disease die of CO2 narcosis or inability to clear airway secretions [2]. However, patients for whom assisted peak cough flows greater than 160 L/min can be generated (that is, patients with less bulbar involvement) and who are equipped and trained in using assisted coughing, mechanical insufflation-exsufflation, and up to 24-hour non-invasive positive-pressure ventilation as needed can have prolonged survival without tracheostomy [3]. In contrast, those with assisted peak cough flows less than 160 L/min will require tracheostomy [3].
Aboussouan and colleagues prevented neither daytime hypoventilation with a mouth piece or nasal positive-pressure ventilation nor respiratory failure from bronchial mucus plugging. They noted that mechanical insufflation-exsufflation was used but did not describe how or when this procedure was done. This procedure is generally not effective when severe bulbar dysfunction results in assisted cough flows less than 160 L/min [4]. Furthermore, the tidal volumes used by the authors were insufficient to compensate for air leakage in this open system, and bulbar function assessment was based on an arbitrary scale rather than on peak cough flow [3, 4]. Thus, the authors underestimated the potential of noninvasive aids to prolong survival. Because we maintain alveolar ventilation around the clock and create effective cough flows, some of our patients with amyotrophic lateral sclerosis have required 24-hour ventilatory support for many years but have never undergone intubation, tracheostomy, or even hospitalization [3]. We recommend that all who are interested in this strategy read more on the subject [5].
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Author and Article Information
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University of Medicine and Dentistry of New Jersey Medical School; Newark, NJ 07103
1. Aboussouan LS, Khan SU, Meeker DP, Stelmach K, Mitsumoto H. Effect of noninvasive positive-pressure ventilation on survival in amyotrophic lateral sclerosis. Ann Intern Med. 1997; 127:450-3.
2. Bach JR, Pansit R, Ballanger F, Kulessa R, Ishikawa Y. Neuromuscular ventilatory insufficiency: the effect of home mechanical ventilator use vs. oxygen therapy on pneumonia and hospitalization rates. Am J Phys Med Rehabil. [In press].
3. Bach JR. Amyotrophic lateral sclerosis: predictors for prolongation of life by noninvasive respiratory aids. Arch Phys Med Rehab. 1995; 76:828-31.
4. Bach JR, Saporito LR. Criteria for extubation and tracheostomy tube removal for patients with ventilatory failure: a different approach to weaning. Chest. 1996; 110:1566-71.
5. Bach JR, ed. Pulmonary Rehabilitation: The Obstructive and Paralytic Conditions. Philadelphia: Hanley & Belfus; 1996.
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