To get the length of the tube that I'm gonna need, I measure from the tip of the nose to the earlobe and down to the xiphoid process, which is here. Then I usually mark that off with some tape.
Zundaren luzeera, neurtzen da sudurretik... belarri gingilerainoik eta gero, hemen jeisten gara, arrunt, zinta itsasgarriarekin markatzen dut.