We are handicapped by non-access to an image intensifier/C-ARM/fluoroscopy but would still like to insert permcaths because of the high morbidity with temporary catheters. How does one determine the length of the permcath to be used (i.e. 36 or 40 cm, etc...) and more importantly the insertion length of the permcath? We have access to an ultrasound machine with a vascular probe.