Extensive research on children and adults has been conducted in the efficacy of normal saline (NS) or heparizined saline (H) as a flush solution to maintain patency (dwell time) of PIID. Fourteen pediatric studies were found that have compared NS and H flushes in terms of catheter brand and size (16 to 24 gauge), insertion site, frequency of IV usage, type of infusate, age of child, reasons for removal, and incidence of complications, such as phlebitis and pain.
Seven of eight studies support the use of NS for catheters larger than 24 gauge; dwell time was either similar to or greater than the dwell time for H. Also, the incidence of phlebitis and pain was decreased with NS in some studies. Other advantages of NS are decreased cost, compatibility with infusates, no effect on clotting time, elimination of dosage error, and less nursing time (Goode and others, 1991; LeDuc, 1997). The following is a review of eight studies that compared NS and H with a variety of catheter sizes.
Lombardi and others (1988) used a sequential, non-random design to study 74 catheter sites (34 in the NS group and 40 in the H group) in children 4 weeks to 18 years of age. They found no difference between the groups in terms of patency. Catheter gauge (20 to 24), site of placement, and medication administered did not influence the results. There was a tendency for more phlebitis to occur in the H group (13 vs 7 in NS group).
Danek and Noris (1992) randomly assigned children from birth to 18 years to receive either a NS or H flush. They studied 160 infusion devices: 40 were 22 gauge and 120 were 24 gauge. There were no significant differences in catheter longevity for either flush for 22 gauge catheters. However, in 24 gauge catheters, patency was longer with H.
In 1993, McMullen and her group studied the efficacy of NS and H in 142 subjects from birth to over 18 years with only a small percentage of young adults. They were randomly assigned to receive H or NS. Infiltration, phlebitis, and clotting were categorized as problem lines. Overall, there were no significant differences between the 2 groups regarding dwell time. Age, types and effects of medications, catheter size ranging from 18- to 24-gauge, site locations, problem lines, frequency of line usage, and comfort were considered.
However, in both the H and NS groups, IVs in older children had longer periods of patency than in young children. The shorter periods of dwell time may have been due to the difficulty in maintaining an IV in young children because of their age and development. In addition, catheter size correlated with the size of the child; smaller catheters were frequently chosen for smaller children. Lines used frequently, regardless of the flush, remained patent longer. Longer dwell times occurred in the NS group whether the medication was of the irritating or nonirritating type. When problem lines were flushed with NS, the dwell times were longer than those flushed with H. In subgroups of children three years of age and younger, the NS group had longer mean periods of patency than the H group (37.38 hours vs 28.27 hours respectively). For the total sample, no significant difference was found in pain response to the NS or H flush. However, in the subanalysis of the small number of problem lines, there was evidence that H may have contributed to discomfort, particularly when irritating antibiotics were used.
Hanrahan and her colleagues (1994) conducted an evaluation of a policy change based on a previous study, which compared H and NS flushes (Kleiber, Hanrahan, and Fagan, 1993). In the first study no significant difference was found between the two flushes in the areas of IV duration, patient age, number of flushes, site location, or complications. The incidence of pain, however, was significantly higher in the patients that received H flushes. The study resulted in a change of hospital policy from H to NS flushes.
To evaluate the policy change the researchers divided a total of 126 children over 28 days old into two groups. The randomly selected children in group I were those who had received a saline flush in the 1993 study. The children in group 2 received the saline flush after the policy change was made. The study's results showed no significant differences between the two NS groups as far as age, site locations, dwell times (60.86 hours for group I and 60.03 hours for group 11), number of flushes, number and types of medications, and sSite complications. Catheter size was not considered. The study concluded that saline is a safe and effective flush solution for maintaining IV patency in children.
Robertson (1994) compared H versus NS in 152 patients between the ages of 2 months and 18 years. During a preliminary examination of the data a significant association was found between the incidence of phlebitis and the IV administration of timentin and tobramycin. As a result the 48 children who received these antibiotics were eliminated from further analyses. Of the remaining children, no significant difference in duration of IV catheters flushed with H or NS was found. A significant difference, however, was demonstrated between blocked cannula and the age of the child. Fewer blockages were found in the larger catheters used on the older children. Where patency was not maintained or the flush was blocked, chart data revealed that numerous 0200 hour flushes had been withheld rather than wake the child. As in other studies, frequency of flushing the catheter was an important factor. Nurses reported that more children who received H flushes had a higher incidence of redness and/or pain at the catheter site. The conclusions of this study are that NS appeared to be an acceptable alternative to H for routine flushes of intermittent IV catheters.
Beecroft and others (1997) did a collaborative study of nine hospital sites. The subjects (N=451, ages birth to 13 years) were randomly assigned to receive either flush solution. Several variables were considered, including catheter size (43 % were 22 gauge and 57% were 24 gauge), catheter brand, infusate, reason for removal, and complications, including pain. The catheters were flushed every eight hours using a positive pressure technique. There was no difference in dwell time for the 22 gauge-catheters but 24 gauge ones had longer dwell times with H (see also the discussion below).
The findings of Gyr and others (1995) disagree with those of the previous studies. In their group of 53 patients ranging from 1 month to 19 years they found significantly longer patency in the H group as compared to the NS group. There were also more instances of nonpatency for 16 to 20 gauge catheters than for 22 gauge catheters. Shorter dwell times were significantly associated with the more antibiotics administered. They conclude that there is insufficient evidence to support the use of NS. However, their sample included 11 children with cystic fibrosis, which also was the group requiring multiple antibiotic infusions. The inclusion of these subjects could have biased the results. In light of the findings from 7 earlier studies that support NS, this study should be replicated with a general pediatric population.
The evidence for NS flush in 24-gauge catheters is less well defined. Of nine studies, six support the use of NS for this size catheter (see References). The reasons for the different outcomes are unclear. It is possible that small catheters are more affected than larger catheters by factors independent of flush solution, such as flush techniques, frequency of use, and method of securement. For example, most studies that investigated the variable of IV usage found that more frequent use, regardless of types of flush, prolonged dwell times. Beecroft and others (1997) reported no difference in flush solutions for 24-gauge catheters in children in an ICU, but longer dwell times with heparin for children in an acute care unit. They propose that better surveillance of the ICU subjects and/or a greater number of IV entries may account for this finding.
Other authors suggest that their results favoring NS may have been due to every four hour flush schedules compared with studies using every 8 hour schedules (Kotter, 1996). Paisley and others (1997) offer additional support for flush frequency. Although they found no difference in IV patency for the two solutions, they reported that several catheters flushed with NS had "microclots" that prevented the catheter from flushing immediately, but then flushed easily with continued instillation of the NS. However, in a study of flush intervals using only heparin, the authors found that catheters lasted 18 to 20 hours longer with 6- and 8-hour flushes than with 4-hour flushes. These findings apply to both 22- and 24-gauge catheters (Crews and others, 1997).
Several studies used multiple data collectors, which could have introduced different flush techniques as a contributing factor with 24 gauge catheters. For example, only two studies reported that nurses used the positive pressure technique, described as clamping the tubing when the final 0.1ml is instilled (Heilskov and others, 1998). The unproven rationale for this procedure is that the creation of positive pressure as the final flush dose is administered prevents backflow of blood into the catheter, reducing the risk of subsequent thrombi formation. One of the studies found that the flush solutions were equally effective (Heilskov and others, 1998) and the other study found that H was better (Beecroft and others, 1997).
No study considered the effects of securement method, which ranges from extensive immobilization of the extremity with splints (armboards or footboards) to protective IV covers to minimal taping of the PIID to the skin. Infiltration and dislodgment of the catheter may be related to the type of securement, especially in young children who are more likely to have small catheters.
In conclusion, the evidence for the use of NS flush for catheters larger than 24 gauge supports this practice. For 24-gauge or smaller catheters, additional research is needed and should focus on the variables that affect dwell times in addition to flush solution.
*Beecroft PC and others: Intravenous lock patency in children: dilute heparin versus saline, J Pediatr Pharm Practice 2(4):211-223, 1997.
Crews BE and others: Effects of varying intervals between heparin flushes on pediatric catheter longevity, Pediatr Nurs 23(1):87-91, 1997.
*Danek, G.D., and Noris, E.M.: Pediatric IV catheters: efficacy of saline flush, Pediatr Nurs 18(2):111-113, 1992.
Goode, C.J., and others: A meta-analysis of effects of heparin flush and saline flush: quality and cost implications, Nurs Res 40(6):324-330, 1991.
Gyr P and others: Double blind comparison of heparin and saline flush solutions in maintenance of peripheral infusion devices, Pediatr Nurs 21(4):383-389, 366, 1995.
Hanrahan, K.S., Kleiber, C., and Fagan, C.: Evaluation of saline for IV locks in children, Pediatr Nurs 20(6):549-552, 1994.
+Heilskov J and others: A randomized trial of heparin and saline for maintaining intravenous locks in neonates, JSPN 3(3):111-116, 1998.
Kleiber, C., and others: Heparin vs. saline for peripheral IV locks in children, Pediatr Nurs 19:405-409, 1993.
+Kotter RW: Heparin vs saline for intermittent intravenous device maintenance in neonates, Neonat Network 15(6):43-47, 1966.
LeDuc K: Efficacy of normal saline solution versus heparin solution for maintaining patency of peripheral intravenous catheters in children, J Emerg Nurs 23(4):306-309, 1997.
+Lombardi TP and others: Efficacy of 0.9% sodium chloride injection with or without heparin sodium for maintaining patency of intravenous catheters in children, Clinical Pharm 7(11):832-836, 1988.
+McMullen, A., and others: Heparinized saline or normal saline as a flush solution in intermittent intravenous lines in infants and children, MCN 18(2):78-85, 1993.
*Mudge B, Forcier D, and Slattery MJ: Patency of 24-gauge peripheral intermittent infusion devices: a comparison of heparin and saline flush solutions, Pediatr Nurs 24(2):142-149, 1998.
+Nelson TJ & Graves SM: 0.9% sodium chloride injection with and without heparin for maintaining peripheral indwelling intermittent-infusion devices in infants, Am J Health-Syst Pharm 55:570-573, 1998.
+Paisley MK and others: The use of heparin and normal saline flushes in neonatal intravenous catheters, Pediatr Nurs 23(5):521-527, 1997.
Robertson J: Intermittent intravenous therapy: a comparison of two flushing solutions, Contemp Nurs 3(4):174-179, 1994.
* Supports use of Heparin flush in 24-gauge catheters.
+ Supports use of Normal Saline flush in 24-gauge catheters.
See Chapter 22 in Essentials of Pediatric Nursing, 5th edition.
See Chapter 28 in Nursing Care of Infants and Children, 6th edition.
March 15, 2002
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