Boden H, Paliege R, Klinik fur Innere Medizin, Suhl. Gesamte Inn Med 1990 Nov 1;45(21):643-6 In 9 voluntary test persons with a sound heart, comparative examinations were carried out to discover the optimum depth of insertion by unipolar and bipolar determination of the absolute threshold and transoesophageal derivation as well as the correlation of the optimum depth of insertion with external measurements of the body. The methods mentioned to ascertain the optimum depth of insertion are equivalent concerning the bipolar arrangement of the electrodes in the oesophagus. The average effective depth of insertion can simplified be defined. A correlation of the average effective depth of insertion concerning external measurements of the body could not be found, so that the conscientious discovering of the optimum depth of insertion is a necessity for every patient. The average value found could attain an orientating importance with the primary placing of the probe concerning the average effective depth of insertion of 37 cm.