Peripheral intravenous cannulation. A Peripheral intravenous cannulation. A. Apply gentle pressure over the catheter with a gloved finger to prevent hemorrhage from the catheter hub. B. Blood samples may be withdrawn from the cannula via a syringe or vacuum tubes. C. Intravenous infusion tubing is attached to the catheter. D. A saline (heparin) lock is attached to the catheter. Source: Chapter 48. Venipuncture and Peripheral Intravenous Access, Emergency Medicine Procedures, 2e Citation: Reichman EF. Emergency Medicine Procedures, 2e; 2013 Available at: https://accessemergencymedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/reic2/reic2_c048f013.png&sec=45347487&BookID=683&ChapterSecID=45343687&imagename= Accessed: October 11, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved