Detecting increasing fluid in a lung of a subject

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
• determining, at a first time, a first difference between a time of arrival of a first feature of a received electrical signal of a subject's heart beat and a time of arrival of a second feature of a received acoustic signal of a subject's heart beat;
• determining, at a second later time, a second difference between a time of arrival of the first feature of a received electrical signal of a subject's subsequent heart beat and a time of arrival of the second feature of a received acoustic signal of the subject's subsequent heart beat;
• detecting the second feature of the received acoustic signal of a subject's heart beat and subsequent heart beat by detecting a first peak following an R peak of a QRS complex of the received electrical signal;
• and
• producing a fluid detection alert indicative of increasing fluid in a lung of the subject, if the second difference is less than the first difference by more than a threshold value.

A method of detecting increasing fluid in a lung of a subject, the method comprising:

• at a first time, determining a first difference between a time of arrival of a first feature of a received electrical signal of a subject's heart beat and a time of arrival of a second feature of a received acoustic signal of the subject's heart beat;
• at a second later time, determining a second difference between a time of arrival of the first feature of a received electrical signal of a subject's subsequent heart beat and a time of arrival of the second feature of a received acoustic signal of the subject's subsequent heart beat;
• detecting the second feature of the received acoustic signal of a subject's heart beat and subsequent heart beat by detecting a first peak following an R peak of a QRS complex of the received electrical signal;
• and
• if the second difference is less than the first difference by more than a threshold value, producing a fluid detection alert.

A non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following:

• at a first time, determining a first difference between a time of arrival of a first feature of a received electrical signal of a subject's heart beat and a time of arrival of a second feature of a received acoustic signal of the subject's heart beat;
• at a second later time, determining a second difference between a time of arrival of the first feature of a received electrical signal of a subject's subsequent heart beat and a time of arrival of the second feature of a received acoustic signal of the subject's subsequent heart beat;
• detecting the second feature of the received acoustic signal of a subject's heart beat and subsequent heart beat by detecting a first peak following an R peak of a QRS complex of the received electrical signal;
• and
• if the second difference is less than the first difference by more than a threshold value, producing a fluid detection alert.