Heartbeat-signal detecting device

A heartbeat-signal detecting device for detecting a heartbeat signal of a living body, said heartbeat-signal detecting device comprising:

• a gas-flow sensor configured to detect a flow rate of exhalation and inhalation passing through a trachea of the living body in a state in which an artificial respirator is not provided;
• a gas-flow calculation controlling portion configured to output a cyclic respiration signal that reflects a respiratory motion of the living body, based on a signal outputted from said gas-flow sensor;
• a waveform analysis controlling portion configured to extract, from the cyclic respiration signal outputted from said gas-flow calculation controlling portion, a plurality of frequency components which are in synchronization with a pulse of a heart of the living body superimposed on the cyclic respiration signal, and to output a heartbeat signal representing a heartbeat waveform of the living body, from the plurality of frequency components;
• and
• a heartbeat-signal evaluation controlling portion configured to evaluate a functional abnormality or an anatomic abnormality of the heart, based on the heartbeat signal analyzed by said waveform analysis controlling portion, wherein
• said gas-flow sensor is further configured to detect a flow speed of a gas passing through a tube, based on a change of an electric resistance of a heater element that is heated by electricity supplied thereto, the electric resistance being changed depending on the flow speed, said heater element being constituted by an electric resistance element whose electric resistance is changed depending on a temperature, said heater element being provided on an inner surface of a circuit substrate film which is disposed in said tube and which is spaced apart from said tube a predetermined space.