Phonocardiographic recording from the trachea: use of a special endotracheal tube

In this report we present a novel method of phonocardiography based on the capture of heart sounds from the cuff of a modified endotracheal tube (ETT). The ETT cuff is connected to a special leak-free microphone using a three-way valve after ETT cuff inflation to around 20 mm Hg pressure. An audio amplifier amplifies the signal from the microphone to a level suitable for recording.