Abstract
Objective
This study aimed to compare the impact of saline lock to running a slow continuous infusion to-keep-vein-open (TKVO) on the total time a peripheral intravenous (PIV) catheter remained patent.
Method
A retrospective chart review of all children admitted to the paediatric ward of a regional hospital in Saskatchewan December 1, 2013 through February 28, 2014. Characteristics of patients with PIV catheters were abstracted from the health records, including patient size, catheter size and site, and total time each PIV catheter spent (i) infusing therapeutic fluids or medications, (ii) running a TKVO infusion, or (iii) saline locked. The duration of catheter patency was compared with the proportion of time that TKVO infusions were run, as well as patient gender and age.
Results
During 375 admissions, there were 189 PIVs which met inclusion criteria. The proportion of nontherapeutic time a PIV catheter spent TKVO compared to saline locked did not affect the total time the PIV catheter was patent (P=0.33). Gender had no influence, but older age, a nonmodifiable factor, was associated with increased time a PIV catheter remained patent (P=0.028).
Discussion
Peripheral intravenous (PIV) catheter insertion can be a painful and traumatic procedure. On the paediatric ward of a regional hospital, TKVO infusions were not superior to saline lock for prolonging PIV catheter patency.
Keywords: Child, Intravenous catheter, Intravenous infusion, Paediatric, Peripheral
Peripheral intravenous (PIV) catheter insertion is a painful procedure. Reducing the number of PIV catheter placements a child requires could reduce the stress for the child, parents, and health care team. Previous studies comparing use of a locking device (saline lock) with slow infusion of fluids “to-keep-vein-open” (TKVO) in newborns have not identified a benefit to TKVO infusions for maintaining PIV catheter patency (1). Furthermore, notable case reports of significant morbidity by strangulation in PIV catheter tubing (2) resulted in a Health Canada notice in 2003 urging health care workers to use locking devices in place of slow fluid infusions (3).
Despite this, in our regional paediatric hospital, there is a strong belief among nurses that TKVO infusions improve the duration of PIV catheter patency. A 2013 survey of Canadian vascular access nurses similarly found that over 50% of respondents regularly used TKVO infusions, and that there was considerable variability in the infusion rates used (4). The purpose of this study was to explore the relationship between duration of PIV catheter patency and use of TKVO infusions versus saline locks to maintain IV catheters when not being used for therapeutic infusions in our inpatient paediatric unit.
METHODS
Study design
This was a retrospective chart review approved by the Regina Qu’Appelle Health Region ethics board (REB-14–38).
Patient selection
Children and youth, aged newborn to 17 years, who were admitted to the inpatient paediatric unit of the Regina General Hospital December 1, 2013 through February 14, 2014, and had a PIV catheter inserted. Participants were identified retrospectively through review of medical charts of all children admitted during the study period.
Data collection
We abstracted patient age, gender, height, weight, the total indwelling duration of each PIV catheter, the reason for its discontinuation, and the time each PIV catheter was saline locked, running TKVO, and/or running therapeutic infusions from the paper charts. A PIV catheter was considered to be running TKVO any time fluids were infusing through it at a rate of 10 mL/hour or less. For patients who had multiple PIV catheters placed during their admission, data were collected for each PIV separately. Data were recorded using Microsoft Excel.
Outcomes
The outcome for this study was total time a PIV catheter remained patent. A PIV catheter was considered to be patent until it was documented as having been removed for any reason or having fallen out. Each PIV catheter’s total time was divided into two periods: therapeutic time, during which therapeutic fluids or medications were infused, and nontherapeutic time. The exposure studied was the proportion of nontherapeutic time during which the PIV catheter was saline locked versus running a TKVO infusion.
Data analysis
An adjusted Cox-Proportional Hazard regression model was used to assess the impact of the proportion of nontherapeutic time spent TKVO, age, and gender on total time a PIV catheter remained patent. The Huber–White estimator was used to account for clustering of PIV catheters to single patients. A Kaplan–Meier estimator was used to assess the attrition of PIV catheters over time. Catheters that were intentionally terminated because they were no longer needed were censored for this analysis. Data analysis was completed using R software version 3.5.0 (R core team 2018).
RESULTS
Three hundred and seventy-five patients were admitted during the study period; 150 never had a PIV catheter. The remaining 225 children had a total of 284 PIV catheters inserted. Eighty-two catheters were only used for therapeutic infusions and were never saline locked or maintained with TKVO infusions, and were therefore excluded. A further 13 catheters were excluded due to data entry error, leaving 189 catheters. Patients had a median age of 43 months (25–75th percentile; IQR 15.2 to 105.2), and 56.2% were male.
Combining therapeutic and non-therapeutic time, PIV catheters remained in situ for a median duration of 101 hours; 80.6% (95% confidence interval [CI] 74.1 to 87.8) remained patent at 48 hours, and 64.8% (95% CI 55.4 to 75.8) at 72 hours after insertion. Factors influencing the duration of PIV catheter patency are shown in Table 1. The proportion of nontherapeutic time spent TKVO compared to saline locked did not affect the total time that a PIV catheter was patent (P=0.33). Gender showed no significant association with total time a PIV catheter was patent (P=0.27), but younger age was associated with increased hazard of PIV catheter loss (P=0.028). Figure 1 shows the Kaplan–Meier curve for loss of PIV catheter patency over time.
Table 1.
Factors influencing duration of PIV catheter patency
| Variable | Hazard ratio* | (95% CI) | P-value |
|---|---|---|---|
| Sex | 0.27 | ||
| Female | Reference | ||
| Male | 1.45 | 0.75–2.84 | |
| Age (months) | 0.028 | ||
| 12 | Reference | ||
| 24 | 0.91 | 0.84–0.99 | |
| 36 | 0.84 | 0.71–0.98 | |
| 60 | 0.70 | 0.51–0.96 | |
| 120 | 0.45 | 0.22–0.92 | |
| TKVO** | 0.33 | ||
| 0.10 | 1.51 | 0.75–3.04 | |
| 0.25 | 1.24 | 0.88–1.77 | |
| 0.50 | Reference | ||
| 0.75 | 1.00 | 0.74–1.35 | |
| 0.90 | 1.10 | 0.54–2.23 |
CI Confidence interval; PIV Peripheral intravenous.
*Hazard ratio for loss of PIV catheter patency at any time
**Proportion of nontherapeutic time a PIV catheter was running a slow continuous infusion to-keep-vein-open (TKVO) versus saline locked
Figure 1.
Kaplan–Meier curve demonstrating loss of peripheral intravenous catheter patency over time.
DISCUSSION
In children and youth admitted to an inpatient paediatric unit at our regional hospital, TKVO infusion when a PIV catheter is not being used for therapeutic purposes did not appear to increase the length of time the PIV catheter remained patent. This finding is consistent with previous studies on PIV catheter longevity in the neonatal population, summarized in a Cochrane review which concluded there was no clear benefit to TKVO infusions in preserving PIV catheter patency (1). Catheters remained patent for a shorter time in younger children in the current study, which is consistent with a previous study in children ages zero to 12 years which found that having a smaller-gauge PIV catheter and siting the PIV catheter in the wrist or scalp were associated with shorter total catheter duration, while older patients had longer total catheter duration (5).
While existing variations in practice in our centre with respect to TKVO infusions versus saline lock provided an opportunity to review the impact of these PIV catheter maintenance techniques on duration of PIV catheter patency, the retrospective nature of this study precluded controlling for a number of confounding variables. There is variability in means of securing the PIV catheter, infection control practices, mobility, handedness, overall health status of the child, and the indication for PIV insertion. We were not able to compare patient and family satisfaction, level of mobility possible for the child, or the frequency of entanglement events. Another limitation is the definition of TKVO used: ‘any infusion of 10 mL/hour of less’. Although this is consistent with practice at our regional hospital, a rate of 10 mL/hour is more than half of ‘full maintenance rate’ for children under 5 kg (25 children in our study). Although data were collected more than 5 years ago, this should not alter the conclusions.
Although this study did not assess adverse effects of TKVO, one needs to consider the risk of death from strangulation by PIV tubing, a rare adverse event which has been described in case reports (2). A 2003 Health Canada recommendation includes assessing each child’s risk of entanglement when securing PIV catheters. Factors to consider include the child’s age and cognitive level, mobility, and the number of tubes and leads attached. For any child who has been entangled once already or who is deemed high-risk for entanglement, Health Canada recommendations for use of saline lock should be followed. This study suggests that the total time a PIV catheter will remain patent will not be adversely impacted by saline lock.
Future directions for further study on modifiable factors affecting PIV catheter duration may include larger prospective studies, which would be better able to assess different methods of preserving catheter longevity. However, given the Health Canada recommendations against TKVO, randomization to these two techniques for preserving PIV catheter patency may not be possible. A prospective study could better follow patients for adverse effects related to their PIV catheters such as entanglement events, intravascular catheter-related line infections, patient satisfaction, and impact on mobilization during admission. Perhaps more importantly, need for PIV catheter could be assessed with reference to antimicrobial stewardship efforts and encouraging oral rehydration whenever possible.
ACKNOWLEDGEMENTS
The authors would like to thank Dr. Mamata Pandey, PhD, who kept the team focused and provided a review of the manuscript, and Julie De Groot, Research Analyst, who assisted with initial data analysis.
Approved by the Regina Qu’Appelle Health Region Research Ethics Board.
Funding: There are no funders to report for this submission.
Potential Conflicts of Interest: All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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