In a method and device for positioning a linear array of electrodes mounted on a distal end section of an elongated flexible member in a patient's respiratory airways at the level of the patient's diaphragm, a length of the elongated flexible member pre-determined to position the linear array of electrodes at the level of the patient's diaphragm is inserted through the patient's respiratory airways. Signals representative of an electrical activity of the patient's diaphragm (EAdi) are detected through the electrodes of the linear array, a presence or absence of ECG signal components is detected in the EAdi signals, and the position of the linear array of electrodes in the patient's respiratory airways is detected in response to the presence or absence of the ECG signal components in the EAdi signals. Also, lower esophageal sphincter activity may be detected in the EAdi signals, and the position of the linear array of electrodes in the patient's respiratory airways determined in response to the detected lower esophageal sphincter. Finally, an end-expiratory occlusion of the patient's respiratory airways may be performed to verify that the electrical activity of the diaphragm coincides with a negative deflection of the patient's respiratory airways pressure again in view of determining adequate positioning of the linear array of electrodes.