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Patency of 24-gauge peripheral intermittent infusion devices: a comparison of heparin and saline flush solutions.

Peripheral intermittent infusion devices (PIIDs) are capped intravenous catheters that are used to maintain fluid balance, deliver intermittent medication, and provide access for emergency treatment. Nurses caring for neonates and infants spend a significant amount of time starting and managing intravenous (IV) catheters. A variety of management strategies are employed to prolong catheter duration thereby decreasing the frequency with which IV catheters need to be restarted. Inserting an IV catheter can be stressful to the child, the nurse, and the parents. Infants and children may experience the physical burden of pain and cold stress, and emotionally, they experience fear. Parents may become upset when they see their child in pain and may be concerned about their child's health status and potential tissue scarring at the insertion site. The time and energy expended in starting IV catheters can be a source of stress to nurses as well.

Historically, methods used to maintain patency of PIIDs have varied. Multiple studies comparing the effects of heparin flush solution and saline flush solution on the patency of IV catheters have been conducted with adults (Ashton, Gibson, & Summers, 1990; Epperson, 1989; Garrelts, LaRocca, Ast, Smith, & Sweet, 1989; Hamilton, Plis, Clay, & Sylvan, 1988; Shoaf & Oliver, 1992; Taylor, Hutchinson, Milliken, & Larson, 1989; Tuten & Gueldner, 1991). Based on the results of those studies and a meta-analysis conducted by Goode and colleagues (1991), the IV flush policy changed in our institution from using heparin to normal saline flush for routine PIID maintenance. However, after changing from heparin to saline flushes, nurses caring for the pediatric patients perceived an increase in the frequency of PIID replacement.

Review of the Literature

Research evaluating heparin 10 units/ml in 0.9% sodium chloride versus 0.9% sodium chloride flush solutions for maintaining patency of PIIDs in pediatric patients is limited. Lombardi, Gundersen, Zammett, Walters, and Morris (1988) compared IV catheters flushed with heparin and catheters flushed with saline in a sample of 74 pediatric patients, age 4 weeks to 18 years. They found no significant difference in the patency or incidence of phlebitis in 18- to 22-gauge catheters at 48 and 72 hours.

McMullen, Fioravanti, Pollack, Rideout, and Sciera (1993) compared the efficacy of heparin and saline used to maintain PIID patency in a sample of patients ranging in age from birth to 18 years. Variables affecting IV catheter patency such as age of the child, type of medication infused, frequency of IV catheter usage, IV catheter type and gauge, insertion site, and patient comfort were measured in 142 subjects. The investigators demonstrated that for 18- to 24-gauge catheters, normal saline was as effective as heparin in maintaining patency, but they did have more problems (e.g., infiltration, phlebitis, and clotting) than those flushed with heparin. There was a trend toward longer patency with older subjects regardless of flush solution but with younger subjects the trend was for saline to be more effective in maintaining patency. The authors suggested that since the subsample of 24-gauge catheters was small, further study of 24-gauge catheters was recommended.

Kleiber, Hanrahan, Fagan, and Zittergruen (1993) studied the efficacy of maintaining catheter patency using saline and heparin flushes in the IV catheters of 124 infants older than 28 days of age. Excluded from the study were patients receiving anticoagulants and chemotherapy. The main outcome variables were mean catheter duration and the incidence of IV catheter complications. Results of the study indicated that there was no difference in mean catheter duration or the incidence of MID complications based on the type of flush solution. As in other studies, the subsample of 24-gauge catheters was small (n = 23, 5%).

Three studies investigated the patency of small gauge catheters. Treas and Latinis-Bridges (1992) studied continuous and intermittent infusion of 24-gauge IV catheters and found longer patency and no complications with the heparin solution. In another study, Danek and Noris (1992) compared the use of heparin and saline flushes for PIIDs in pediatric patients with 22- and 24-gauge catheters. No significant differences in IV catheter longevity were found for the 40 patients with 22-gauge catheters. However, for 120 pediatric patients with 24-gauge catheters, the median length of duration of patency in IV catheters flushed with heparin was significantly greater (p = .03) than in catheters flushed with saline (34 hours and 22 hours respectively).

A recent study by Gyr and colleagues (1995) evaluated the effect of flush solution type and frequency of flushing on maintaining patency of PIIDs as well as the incidence of phlebitis. Two hundred and nine assessments were made of 68 PIIDs on 53 children. Subjects ranged in age from I month to 19 years. Catheter size ranged from 16- to 24-gauge. Eighty-nine percent were 22-gauge and 8% were 24-gauge. Results indicated that there was a longer duration of IV catheter patency and less tenderness at the catheter site in those PIIDs flushed with heparin. There was a longer duration of patency in 22-gauge catheters than in 16- to 20-gauge catheters regardless of the flush solution. In addition, a significantly greater incidence of clotting and infiltration was found in PIIDs flushed with saline as well as those flushed less frequently (5-8 hr vs. 1-2 hr). Based on the results of the study, Gyr and colleagues recommended that MID protocols continue to use heparin flush solution and to flush at short intervals (4 hr).

In summary, the research related to the efficacy of heparin and saline for flushing PIIDs in pediatric patients is inconclusive and recommendations made by investigators are inconsistent. In addition, the smallest catheter, 24 gauge, used with neonatal and small pediatric patients has not been studied sufficiently.

The purpose of this study was to determine if there was a significant difference in the duration of patency in 24-gauge PIIDs when flushed with normal saline compared to heparinized saline 10 u/ml.


A prospective, non-randomized, sequential, blinded study design was conducted in a tertiary medical center on two units: a general pediatrics and a neonatal intensive care unit. Eligibility criteria included: age less than 18 years, presence of a 24-gauge IV catheter, and the absence of any medications known to affect coagulation (anti-inflammatory agents, heparin, streptokinase, urokinase, etc.). Human subjects approval was granted and informed consent was obtained from a parent by a nurse on the research team.

The two IV catheter flush solutions used in this study, heparin sodium 10 units in 0.9% sodium chloride per 1 ml (Solution A) and 0.9% sodium chloride per 1 ml (Solution B), were prepared by the hospital pharmacy and rotated on a monthly basis. All other personnel were blinded to the type of flush solution in use. Catheters were flushed with only one solution type for the life of the catheter. To avoid crossover, catheters that were still functioning at the end of the month continued to be flushed with their initial solution. No attempt was made to control for flushing frequency. PIIDs were flushed per unit protocol, either every 8 or 12 hours, and used a modified SASH procedure (saline-medication-saline-flush solution) with the administration of medications. All catheters were made of Teflon and had a T-connector with a "safe-site" valve.

The investigators developed the data collection tool. It contained information about demographics, catheter size, brand, placement site, time of insertion, time of conversion to an intermittent device, time of catheter removal or conversion to continuous infusion, reasons for use, and reasons for removal. The instrument was reviewed by a group of clinicians currently working with the pediatric population for clarity and content validity. The tool was pilot tested with 10 patients and minor revisions were made. The investigators oriented the staff nurses to the study protocol and to data collection procedures. The staff nurses collected data for each catheter used in an enrolled patient.

Reasons for use of the PIID included the administration of medications, blood products, hyperalimentation, lipids and fluids, and for emergency treatment. Reasons for removal included both elective and non-elective reasons. Reasons for elective discontinuation of PIIDs included completion of therapy, conversion to a continuous IV, or patient discharge or transfer. Reasons for non-elective discontinuation of PIIDs included problems such as erythema, edema, loss of patency, resistance to flushing, leaking from the site, and patient discomfort.

Based on input from a pediatric pharmacist and from a review of the literature, medications and other substances administered via PIIDs were categorized according to severity of irritation to the vein. The following substances were used in the study and considered severely irritating to the vein: penicillin, nafcillin, pippercillin, vancomycin, gentamycin, tobramycin, amphotericin B, cephtazadine, acyclovir, hyperalimentation, and lipids.

Catheter duration was calculated from the time the catheter was inserted or converted to a PIID to the time the catheter was removed or converted to a continuous infusion. Catheters were categorized by their initial function. Thirty-seven catheters were started as continuous IVs and later converted to a PIID. Ninety-five catheters were started as PIIDs. Kaplan-Meier Survival Analysis (Parmar & Machin, 1995) was used to compare the differences in catheter duration between the heparin and saline flush groups. This analysis takes into consideration the fact that some of the catheters were electively discontinued and some were nonelectively discontinued due to problems. To control for whether a catheter was started as a continuous or intermittent device, a stratified log-rank test was used. For all analyses, a p value of [is less than] .05 was considered significant.


The sample consisted of 134 catheters in 61 patients. All catheters were 24-gauge. The most common diagnosis for these patients was that of prematurity (57%). Most of the catheters (n = 124) were placed in neonates from the Intensive Care Nursery (ICN). The mean admission weight was 2236 grams (SD = 1646) and ranged from 503 grams to 10.90 kilograms. Ages ranged from newborn to 2 years with the majority of the sample (84%) less than 2 months old and 69% less than 1 month of age. Of the 61 patients, 29 (47.5%) had only one catheter placed during the study. The remaining 32 patients had from 2 to 11 catheters placed during the study.

There were 56 catheters (42%) in the heparin flush group and 78 catheters (58%) in the saline flush group. Based on Chi-square analysis, there was no significant difference between the groups for factors such as: age of patient ([is greater than] 30 days vs [is less than] 30 days), catheter placement site, irritating substances infused, and whether the catheter was started as a continuous infusion prior to conversion to a PIID (see Table 1). The mean admission weight of the heparin group (2600 grams) was significantly greater than that of the saline group (1972 grams) (Student's t = 2.21, p = .029). Based on Pearsons' correlation coefficient, weight was not found to be correlated with catheter duration (r = .027, p = .758).
Table 1. Comparison of Characteristics of Heparin and Saline
Groups (n = 134)

                     Heparin       Saline       Chi-Square      P
                     n = 56        n = 78
 < 30 days         31 (55.4%)    48 (61.5%)   [sup.2] =.514   .473
 > 30 days         25 (44.6%)    30 (38.5%)

PIID Placement
 Scalp             11 (19.6%)     6 (7.7%)    [sup.2] = 5.93  .20
 Hand              18 (32.1%)    26 (33.3%)
 Arm                8 (14.3%)    18 (23.1%)
 Antecubital        2  (3.6%)     1 (1.3%)
 Foot/Leg          17 (30.4%)    27 (34.6%)

 Nonsevere          7 (14.3%)    12 (16.0%)   [sup.2] = .067  .796
 Severe            42 (85.7%)    63 (84.0%)
Initial function
of IV
  Continuous       20 (37%)      17 (22%)     [sup.2] = 3.67  .06
  Intermittent     34 (63%)      61 (78%)

Nurses identified one or more problems as reasons for non-elective discontinuation of the PIIDs in this study. The most frequent problem for both the heparin and saline flush groups was that of erythema (25% and 32% respectively). A list of problems associated with discontinuation of PIIDs is found in Table 2. Catheters were then coded as having been removed either nonelectively because of problems or electively without problems. Fifty-two percent (n = 29) of the catheters flushed with heparinized saline were removed due to problems compared to 71% (n = 55) of catheters flushed with saline. This was a statistically significant difference ([chi square] = 4.89, p .027).
Table 2. Comparison of Problems Identified as Reasons
for PIID Removal (n 134)

                                        Heparin          Saline
                                         n = 56          n = 78

Total Catheters with Problems           29 (52%)        55 (71%)
Problems Identified:
  Erythema                              14 (25%)        25 (32%)
  Edema                                 12 (21%)        17 (22%)
  Will not flush/not patent             11 (20%)        22 (28%)
  Crying/discomfort                      7 (13%)        11 (14%)
  Leaking from site                      5 (9%)         10 (13%)

Total # Problems Listed                 49              85

Catheters flushed with heparin had a median duration of 42 hours (range 5.9 - 116.5 hours). Catheters flushed with normal saline had a median duration of 35 hours (range 4-125 hours). Of the catheters removed because of problems, there was an 8.7 hour difference in median duration between those flushed with heparin and those flushed with saline (see Table 3).
Table 3. Catheter Duration By Reason for Removal for Heparin and
Saline Flush Solutions (n = 130)

Reason for PIID Removal           Flushing Solution

                                Heparin         Saline
Removed for Problems              29             55
  Median Duration (hours)         39.6           30.9
Removed Electively                25             21
  Median Duration (hours)         46.0           39.5
Total Group                       54             76
  Median Duration (hours)         42.0           35.3

The Kaplan-Meier Survival curves indicate that the median survival half-lives for the heparin and saline groups were 61 and 38 hours respectively (see Figure 1). Catheters flushed with heparin lasted significantly longer than catheters flushed with saline ([chi square] stratified = 5.43, p = .02).



The results of this study demonstrated that median duration of patency of 24-gauge catheters was significantly greater when flushed with heparin than for catheters flushed with normal saline. In addition, it was also shown that there were more complications requiring removal in catheters flushed with saline than in catheters flushed with heparin. Nurses have been frustrated by patency loss in their patients' PIIDs for many years. During these times when cost containment, quality of care, and patient satisfaction are of utmost importance, nurses need to know the most effective and efficient way to care for these babies. The impact this information has on the daily assignment is important since nurses who care for sick infants also care for their families. Every time nurses need to restart a PIID, precious time is wasted which could be spent teaching, collaborating with, or comforting their patients and/or families.

The results of this study are similar to those of Danek and Noris (1992) and Gyr and colleagues (1995) who demonstrated that 24-gauge PIIDs flushed with heparin lasted longer than those flushed with normal saline. The effects of heparin versus saline for both continuous infusions and PIIDs were studied by Treas and Latinis-Bridges (1992). They also showed that the duration of IV catheter patency in neonates with 24-gauge catheters was significantly longer for those receiving heparinized intravenous fluid or intermittent heparin flush. In this study, when controlling for whether a catheter was begun as a continuous infusion prior to conversion to a PIID, catheters flushed with heparin lasted longer than those flushed with saline.

This study's finding that there were more complications using saline flush was different from that of Kleiber and colleagues (1993), who found a greater incidence of erythema and induration with heparin. Their study was different in that only 5% of the sample was 24-gauge catheters, and their infants were all older than 28 days. Although conclusions provide insight into the patency of 24-gauge PIIDs, limitations of this study include: non-randomized study design, multiple catheter use per patient, and absence of validation of RN's assessment of the IV sites.


At this institution the cost of heparin flush exceeds that of saline flush by 13 cents. When analyzing cost, nursing time used to replace IV catheters must be considered. As we move toward outcomes-based practice, cost is only one factor when deciding to make practice changes. We cannot, in good conscience, use saline knowing the catheter may have a shorter patency and that the patient may experience more problems. In an effort to contain cost and maintain quality of care and patient satisfaction, nurses must be knowledgeable about the most effective and efficient way to care for patients with PIIDs.

The pediatric population of neonates is not a population where there is proliferation of literature on 24-gauge catheter patency. Further studies need to be conducted that examine very small gauge catheters in patients less than 28 days of age.

This study adds to the body of knowledge regarding 24-gauge catheters in the neonatal and pediatric population. It demonstrated that heparin flush is more effective and associated with fewer problems than normal saline for maintaining patency of 24-gauge PIIDs. Based on the results of this study, we conclude that heparin flush solution should be used for hospitalized children requiring the use of 24-gauge PIIDs. These findings are in contrast to the adult literature and those pediatric studies using larger gauge catheters. It may no longer be appropriate to assume that the characteristics of small catheters in small veins are the same as those of adults.


Ashton, J., Gibson, V., & Summers, S. (1990). Effects of heparin versus saline solution on intermittent infusion device irrigation. Heart & Lung: Journal of Critical Care, 19(6), 608-612.

Danek, G.D., & Noris, E.M. (1992). Pediatric IV catheters: Efficacy of saline flush. Pediatric Nursing, 18(2), 111-113.

Epperson, E.L. (1989). Efficacy of 0.9% sodium chloride injection with and without heparin for maintaining indwelling intermittent injection sites. Clinical Pharmacy, 3(6), 626-629.

Garrelts, J., LaRocca, J., Ast, D., Smith, D.F., & Sweet, D.E. (1989). Comparison of heparin and 0.9% sodium chloride injection in the maintenance of indwelling intermittent IV devices. Clinical Pharmacy, 8(1), 34-39.

Goode, C.J., Titler, M., Rakel, B., Ones, D.S., Kleiber, C., Small, S., & Triolo, P.K. (1991). A meta-analysis of effects of heparin flush and saline flush: Quality and cost implications. Nursing Research, 40(6), 324-330.

Gyr, P., Smith, K., Pontious, S., Burroughs, T, Mahl, C., & Swerczek, L. (1995). Double blind comparison of heparin and saline flush solutions in maintenance of peripheral infusion devices. Pediatric Nursing, 21(4), 383-389, 366.

Hamilton, R.A., Plis, J.M., Clay, C., & Sylvan, L. (1988). Heparin sodium versus 0.9% sodium chloride injection for maintaining patency of indwelling intermittent infusion devices. Clinical Pharmacy, 7(6), 439-443.

Kleiber, C., Hanrahan, K., Fagan, C.L., & Zittergruen, M.A. (1993). Heparin vs. saline for peripheral IV locks in children. Pediatric Nursing, 19(4), 405-409, 376.

Lombardi, T.P., Gundersen, B., Zammett, L.O., Walters, J.K., & Morris, B.A. (1988). Efficacy of 0.9% sodium chloride injection with or without heparin for maintaining patency of intravenous catheters in children. Clinical Pharmacy, 7(11), 832-836.

McMullen, A., Fioravanti, I.D., Pollack, V., Rideout, K., & Sciera, M. (1993). Heparinized saline or normal saline as a flush solution in intermittent intravenous lines in infants and children. The American Journal of Maternal Child Nursing, 18(2), 78-85.

Parmar, M., & Machin, D. (1995). Survival analysis: A practical approach. New York: John Wiley & Sons.

Shoaf, J., & Oliver, S. (1992). Efficacy of normal saline injection with and without heparin for maintaining intermittent intravenous site. Applied Nursing Research, 50), 9-12.

Taylor, N., Hutchinson, E., Milliken, W., & Larson, E. (1989). Comparison of normal versus heparinized saline for flushing infusion devices. Journal of Nursing Quality Assurance, 3(4), 49-55.

Treas, L.S., & Latinis-Bridges, B. (1992).

Efficacy of heparin in peripheral venous infusion in neonates. Journal of Obstetrics, Gynecology, and Neonatal Nursing, 21(3), 214-219.

Tuten, S.H., & Gueldner, S.H. (1991). Efficacy of sodium chloride versus dilute heparin for maintenance of peripheral intermittent intravenous devices. Applied Nursing Research, 4(2), 63-71.

Acknowledgment: The authors would like to thank the staff of the Intensive Care Nursery and Pediatrics at DHMC. We would also like to thank Gladys Tice, Lyrel Gillette, Amy Wasicko, Marc Semprebon, Viki Shutak, Mia Graham, Barbara Bradford, and Linda Cronenwett for their support and assistance with this project. This study was supported by a grant from the Hearst Foundation of the Department of Pediatrics, Dartmouth Medical School.

Bridget Mudge, MS, RN, is a Pediatric Clinical Nurse Specialist, Dartmouth-Hitchcock Medical Center, Children's Hospital at Dartmouth, Lebanon, NH.

Dion Forcier, RN, is a Clinical Resource Coordinator, Intensive Care Nursery, Dartmouth-Hitchcock Medical Center, Children's Hospital at Dartmouth, Lebanon, NH.

Mary Jo Slattery, MS, RN, is Nursing Research Coordinator, Dartmouth-Hitchcock Medical Center, Children's Hospital at Dartmouth, Lebanon, NH.
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Author:Mudge, Bridget; Forcier, Dion; Slattery, Mary Jo
Publication:Pediatric Nursing
Date:Mar 1, 1998
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