After William had blood drawn through his tunneled central venous catheter, his nurse was ready to flush with a syringe of prefilled saline (NS). William asked, “Please use saline from an IV bag, because these flushes give me a sour taste and makes me nauseous.” The nurse explained that their policy, based on the Centers for Disease Control and Prevention guidelines, was to use prefilled syringes.
What Would You Do?
Parageusia (bad oral taste) and/or nausea have been anecdotally associated with NS flush solutions, although little information has been published. A study of 10 healthy volunteers comparing prefilled NS syringes to NS drawn from an IV bag demonstrated dramatically more occurrences of parageusia with the prefilled saline (97% versus 13%, respectively). Symptoms also occurred when the volume was reduced or the catheter flushed more slowly. Analysis revealed volatile nontoxic microcontaminants that had leached from the plastic in the syringes.
A number of theories have emerged as to why some patients can “taste” their NS flushes, including position of the catheter tip, pressure gradient changes within the superior vena cava, and preservatives in the saline solution itself, although the phenomenon has been observed with preservative-free flushes.
The use of hard candy has been shown to decrease nausea and parageusia in a variety of clinical situations. William’s nurse suggested that he eat hard candy the next time his catheter needed to be flushed to see whether it decreases his symptoms.