Santos EJF dos, Nunes MMJC, Cardoso DFB, Apóstolo JLA, Queirós PJP, Rodrigues MA. Effectiveness of heparin versus 0.9% saline solution in maintaining the permeability of central venous catheters: a systematic review . Rev. Esc. Enferm. USP. 2015;49(6):995-1003. doi:10.1590/S0080-623420150000600017