Nice description, iluvivt! yes indeed optimal placement is to have the tip in the lower 3rd of the svc, however it being pulled back 3 cm can still be in the svc, just not the lower third. Every pt's anatomy is different, and you'll need to verify the patient isn't receiving a vesicant or irritating drug; tpn can be written for peripheral concentrations. One more thing, just ask your IVT team what the protocol is for your institution, and again check with the md for need for cxr to verify placement.