Biphasic cuirass ventilation (BCV) improves ventilation by delivering intermittent or constant negative pressure to the thorax. It has been demonstrated that BCV improves lung function in a number of respiratory failures. The patient’s chest and upper abdomen are enclosed in a domed plastic shell called a cuirass, which is attached to an external pump. Because Cuirass ventilators are made to exert equal pressure across the thorax, the lungs can expand evenly and there will be consistent ventilation. BCV alternates between negative and positive phases, in contrast to traditional positive pressure ventilation (PPV). While diseases of the neuromuscular and chest wall systems are rare in isolation, they constitute a significant category of illnesses that can result in chronic ventilatory failure. Negative pressure ventilation is an alternative to positive pressure procedures, which are typically employed in conjunction with nose and face masks. Careful selection of patients is required, especially in the presence of progressive neuromuscular disorders such as motor neurone disease.