The Battle Continues:
Saline vs Heparin

Flushes are used with intravenous lines for a few reasons. If intravenous fluids are no longer needed but the IV line may be needed for medication administration, that IV line is “capped off” or “hep-locked”. In order to make sure that the line remains unobstructed, it is flushed on a regular basis. This flushing prevents clots from forming and the line from occluding off. It also prevents bacteria from building up and infection from setting in. Flushes are also used when two medications should not be given together. Often a flush is inserted in between medications in order to prevent the medications from mixing.

In adults, IV lines are changed about every three days in order to prevent the above from happening. However in sick newborns who are hospitalized, they have few usable veins.

In addition, repeated attempts at IV insertion break the skin barrier and predisposes these neonates to infection in the skin such as staphylococcus which can be life threatening to the neonates. In order to decrease these complications, intravenous lines (peripheral and central) are often left in until complications arise.

Heparin has long been used in patients (newborn through adult) because it is an anticoagulant. It is delivered either intermittently or continuously to prevent thrombus formation and consequently prolong catheter patency. But the down side of heparin has been noted for a long time even at low doses. Some of those adverse effects have included; bleeding complications due to dosing error, intraventricular hemorrhage in preterm infants and heparin induced thrombocytopenia.

The practice of using saline flushes instead of heparin flushes can be traced back to over 15 years ago. Many studies have called for the reconsideration of the routine of using heparin flushes. The American Society of Hospital Pharmacists has supported the use of normal saline flushes instead of heparin since 1994 .

One study in particular looked at three hundred and sixty children with 599 central venous catheters (CVC’s) . They found that heparin flushes affords no advantages in terms of reducing occlusion rates. Another study looked specifically at neonates in a newborn intensive care unit tertiary care hospital . The purpose of their study was to determine the effects of saline and heparin on the duration of intravenous lock, and the incidence of IV infiltration in neonates. Their results found no statistical or clinical difference between the three groups for duration of IV or for incidence of complications. So they concluded that the use of heparin in IV lock solutions did not affect the duration of IV locks or the incidence in neonates.

References:
American Society of Hospital Pharmacists. ASHP therapeutic position statement on the institutional use of 0.9% sodium chloride injection to maintain patency of peripheral indwelling intermittent infusion devices. AM J Pharm. 1994; 51:1572-1574.

Schilling S; Doellman D; Hutchinson N; Jacobs BR. The impact of needless connector device design on central venous catheter occlusion in children: a prospective, controlled trial. JPEN 2006 Mar – Apr; 30(2): 85-90.

Heilskov J; Kleiber C; Johnson K; Miller J. A randomized trial of heparin and saline in maintaining intravenous locks in neonates. J Soc Pediatr Nurses, 1998 Jul-Sep3(3): 111-6.