Limits of effective cough-augmentation techniques in patients with neuromuscular disease.
BACKGROUND
Manual and mechanical cough-augmentation techniques can improve peak cough flow (PCF) in patients with respiratory insufficiency caused by neuromuscular disease.


METHODS
We studied cough-augmentation techniques in 179 clinically stable patients with various neuromuscular diseases. We measured vital capacity (VC), maximum expiratory pressure (MEP), and PCF, with and without 3 cough-augmentation techniques: manually assisted cough (MAC); breath-stacking (in a subgroup of 60 patients receiving noninvasive mechanical ventilation); and breath-stacking in combination with MAC (also in the 60-patient subgroup). We analyzed the data with the receiver operating characteristic (ROC), to predict the lower limits (assisted PCF > or = 180 L/min) and upper limits (assisted PCF < unassisted PCF) of effectiveness of the 3 cough-augmentation techniques.


RESULTS
The lower limit of effective assisted cough with MAC, breath-stacking, and breath-stacking plus MAC was best predicted by VC > 1,030 mL (ROC 0.86, P < .001), VC > 558 mL (ROC 0.92, P < .001), and VC > 340 mL (ROC 0.90, P < .001). The upper limit of effective MAC was best predicted by MEP > 34 cm H(2)O (ROC 0.89, P < .001), whereas the ROC prediction of the upper limit of effective cough with breath-stacking and with breath-stacking plus MAC was not better than random. With each of the cough-augmentation techniques the benefits decreased linearly with increasing MEP and VC (P < .001). Compared to MAC and breath-stacking alone, breath-stacking plus MAC best improved unassisted PCF (P < .001).


CONCLUSIONS
In clinically stable patients with neuromuscular diseases, the effectiveness of cough-augmentation techniques can be predicted with measurements of maximum respiratory capacity. Patients with VC > 340 mL and MEP < 34 cm H(2)O would optimally benefit from the combination of breath-stacking plus manually assisted cough to improve PCF to > 180 L/min.
Toussaint
Michel
M
Ziekenhuis Inkendaal, Inkendaalstraat 1, B-1602 Vlezenbeek, Brussels, Belgium. michel.toussaint@inkendaal.be
Boitano
Louis J
LJ
Gathot
Vincent
V
Steens
Marc
M
Soudon
Philippe
P
D000328:Adult; D003371:Cough; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009468:Neuromuscular Diseases / Q000503:physiopathology*; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D011312:Pressure; D011446:Prospective Studies; D012372:ROC Curve; D012132:Respiratory Muscles / Q000503:physiopathology*; D012138:Respiratory Therapy / Q000379:methods*; D016896:Treatment Outcome; D014797:Vital Capacity / Q000502:physiology