Diluted venous blood appears arterial: implications for central venous cannulation
Ho AM., Chung DC., Tay BA., Yu LM., Yeo P.
IMPLICATIONS: There is always a danger of arterial puncture during central venous access. One can usually identify an inadvertent arterial puncture when the aspirated blood is bright red. This sign is removed if one were to put saline in the aspirating syringe, as dusky venous blood turns bright red on dilution.