[Technical aspects of mechanical insufflator-exsufflators. Construction and function of the Emerson CoughAssist].

The electromechanical insufflator-exsufflator (Emerson CoughAssist) was developed as an aid for patients with neuromuscular disorders suffering from impaired cough. The insufflator-exsufflator simulates and supports physiological cough by supporting inspiration with positive pressure and shifting this positive pressure rapidly into a negative pressure that supports exsufflation and thus bronchial clearance. Maximum pressures are +/- 60 cm H2O, pressures between 30 and 50 cm H2O are sufficient to produce assisted cough in adults with neuromuscular disease. The pressure shift from positive to negative occurs with 0.02 sec and is regulated by a magnetic valve. An anaesthetic facemask is used as interface, alternatively, a mouthpiece can be used in combination with a nose strap. It is also possible to use the insufflator-exsufflator in patients with tracheostomy. We present in this article detailed information about the technical principles and practical use of the electromechanical insufflator-exsufflator.