Comparison of three cough-augmentation techniques in neuromuscular patients: mechanical insufflation combined with manually assisted cough, insufflation-exsufflation alone and insufflation-exsufflation combined with manually assisted cough.

BACKGROUND: Mechanical insufflation-exsufflation (MI-E), more commonly known as 'cough assist therapy', is a method which produces inspiratory and expiratory assistance to improve cough performances. However, other alternatives or combinations are possible. OBJECTIVE: The objective was to compare the effects of mechanical insufflation combined with manually assisted coughing (MAC), insufflation-exsufflation alone and insufflation-exsufflation combined with MAC in neuromuscular patients requiring cough assistance. METHODS: Eighteen neuromuscular patients with severe respiratory muscle dysfunction and peak cough flow (PCF) lower than 3 liters/s or maximal expiratory pressure (MEP) lower than +45 cm H2O were studied. Patients were studied under three cough-assisted conditions, which were used in random order: insufflation by intermittent positive-pressure breathing (IPPB) combined with MAC, MI-E and MI-E + MAC. RESULTS: Overall, PCF was higher with IPPB + MAC than with MI-E + MAC or MI-E alone. Among the 12 patients who had higher PCF values with IPPB + MAC than with the two other techniques, 9 exhibited mask pressure swings during MI-E exsufflation, with a transient positive-pressure value due to the expiratory flow produced by the combined patient cough effort and MAC. Each of these 9 patients had higher PCF values (>5 liters/s) than did the other 9 patients when using IPPB + MAC. CONCLUSION: Our results indicate that adding the MI-E device to MAC is unhelpful in patients whose PCF with an insufflation technique and MAC exceeds 5 liters/s. This is because the expiratory flow produced by the patient's effort and MAC transitorily exceeds the vacuum capacity of the MI-E device, which therefore becomes a transient load against the PCF.

Comparison of Two Cough-Augmentation Techniques Delivered by a Home Ventilator in Subjects With Neuromuscular Disease.

BACKGROUND: Breath-stacking, which consists of taking 2 or more consecutive ventilator insufflations without exhaling, is a noninvasive and inexpensive cough-assistance technique for patients with neuromuscular disease. Volumetric cough mode (VCM) is a recently introduced ventilator mode consisting of a programmable intermittent deep breath equal to a set percentage of the baseline tidal volume. Here, our objective was to compare VCM to breath-stacking during volume-control continuous mandatory ventilation in subjects on long-term noninvasive mechanical ventilation at home. METHODS: We included 20 subjects with neuromuscular disease causing severe respiratory muscle dysfunction with a cough peak flow (CPF) < 270 L/min or maximum expiratory pressure < 45 cm H2O. Each subject tested breath-stacking and VCM in random order. RESULTS: CPF increased with both techniques but was higher with VCM than with breath-stacking in 16 subjects. In 17 subjects, CPF was highest with the technique that produced the greatest inspiratory capacity. CONCLUSION: Our results indicate that both breath-stacking and VCM are useful cough-augmentation techniques. Displaying insufflated volumes on the ventilator screen is a simple and accessible method for selecting the most efficient cough-augmentation technique delivered by a home ventilator.