High Quality Content by WIKIPEDIA articles! Biphasic cuirass ventilation (BCV) is a method of ventilation which requires the patient to wear an upper body shell or cuirass, so named after the body armor worn by medieval soldiers. The ventilation is biphasic because the cuirass is attached to a pump which actively controls both the inspiratory and expiratory phases of the respiratory cycle. This method has also been described as `Negative Pressure Ventilation` (NPV), `External Chest Wall Oscillation` (ECWO), `External Chest Wall Compression` (ECWC) and `External High Frequency Oscillation` (EHFO). BCV may be considered a refinement of the iron lung ventilator. Biphasic cuirass ventilation was developed by the late Dr Zamir Hayek, a pioneer in the field of assisted ventilation. Some of Dr Hayek`s previous inventions include the Hayek Oscillator, an early form of the technology.