Monitoring diaphragmatic electrical activity

A method of minimally invasive medical use of an apparatus comprising an elongated part including a catheter and/or a catheter sheath, the elongated part having a distal portion and an intermediate portion, the intermediate portion being located proximally relative to the distal portion, one or more monitoring electrodes being arranged on the intermediate portion of the elongated part, the method comprising:

• introducing the elongated part inside an inferior vena cava of a human patient, and positioning the elongated part at an operating location where the distal portion is in and/or beyond a right atrium and, at a same time, the intermediate portion is in the inferior vena cava;
• while the elongated part is at the operating location and the one or more monitoring electrodes are thereby located in the inferior vena cava, and while at the same time the distal portion is located in and/or beyond the right atrium, performing a phrenic nerve stimulation of the human patient, and by the one or more monitoring electrodes, capturing an electrical signal representing an electrical activity of a diaphragm of the human patient;
• and
• monitoring the electrical activity of the diaphragm of the human in response to the phrenic nerve stimulation.