Mechanical insufflation-exsufflation. Comparison of peak expiratory flows with manually assisted and unassisted coughing techniques.

Pulmonary complications are major causes of morbidity and mortality for patients with severe expiratory muscle weakness. The purpose of this study was to compare peak cough expiratory flows (PCEFs) during unassisted and assisted coughing and review the long-term use of mechanical insufflation-exsufflation (MI-E) for 46 neuromuscular ventilator users. These individuals used noninvasive methods of ventilatory support for a mean of 21.1 h/d for 17.3 +/- 15.5 years. They relied on manually assisted coughing and/or MI-E during periods of productive airway secretion. They reported a mean of 0.7 +/- 1.2 cases of pneumonia and other serious pulmonary complications and 2.8 +/- 5.6 hospitalizations during the 16.4-year period and no complications of MI-E. A sample of 21 of these patients with a mean forced vital capacity of 490 +/- 370 ml had a mean maximum insufflation capacity (MIC) achieved by a combination of air stacking of ventilator insufflations and glossopharyngeal breathing of 1,670 +/- 540 ml. The PCEFs for this sample were: following an unassisted inspiration, 1.81 +/- 1.03 L/s; following a MIC maneuver, 3.37 +/- 1.07 L/s; with manual assistance by abdominal compression following a MIC maneuver, 4.27 +/- 1.29 L/s; and with MI-E, 7.47 +/- 1.02 L/s. Each PCEF was significantly greater than the preceding, respectively (p < 0.01). We conclude that manually assisted coughing and MI-E are effective and safe methods for facilitating airway secretion clearance for neuromuscular ventilator users who would otherwise be managed by endotracheal suctioning. Severely decreased MIC, but not necessarily vital capacity, is an indication for tracheostomy.