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Positive pressure intravenous access ports on central venous devices in children: an evidence-based review.

INTRODUCTION

Central venous access devices (CVADs) including tunnelled central venous access catheters (CVCs), for example Hickman catheters, peripherally inserted central catheters (PICCs), and Port-a-Caths are commonly used in children with conditions requiring long periods of treatment, such as cancer, cystic fibrosis, and osteomylitis. CVADs are used to administer medications, fluids, blood products, and total parental nutrition. In addition, CVADs enable blood sampling without the need for painful venepuncture.

While CVADs have the advantage of providing prolonged venous access, complications such as infection and occlusion of the catheter can occur. Routine care of CVADs usually involves flushing the catheter with heparin. However, the concentration of heparin and the frequency of flushing vary depending on each centre's protocol. The use of heparin has risks, including drug interaction, allergic reaction and heparin-induced thrombocytopenia (Cesaro et al, 2009). Little is known about the incidence and significance of heparin-induced thrombocytopenia in children (Newall, Barnes, Ignatovic and Monagle, 2003). The incidence of heparin-induced thrombocytopenia has been reported as 1.1 percent in a neonatal setting (Spadone, Clarke, and James, 1992) and 2.3 percent in an intensive care setting (Schmugge, Risch, Huber, Benn, and Fischer, 2002). In the neonatal study, neonates received heparin as a catheter flush, in the intensive care study children received heparin either as a flush or as prophylaxis. The incidence of heparin-induced thrombocytopenia in children in non-intensive care settings is very low (Risch, Fischer, Herklotz, and Huber, 2004).

Positive pressure mechanical valve (PPMV) intravenous access ports that are designed to prevent backflow of blood have been advocated to reduce occlusion of CVADs and avoid the need for heparin flushing and its associated risks. The adult medical and surgical service at Christchurch Hospital decided to switch to using a particular type of PPMV intravenous access port on CVADs in adult patients. To see whether there was evidence to support a change to using PPMV intravenous access ports in the child health service, a review of the secondary literature was conducted. Two secondary sources were identified--ECRI Institute (2008) and Mitchell, Anderson, Williams and Umscheid (2009).

A recent evaluation of needleless connectors (ECRI institute, 2008) questioned whether particular types of needleless connectors (NC) play a role in increasing catheter-related bloodstream infection (CR-BSI) rates. They concluded "there is not enough evidence at this time to draw a conclusive link between CR-BSI rates and any particular design, model or manufacturer of NC" (p261). The ECRI Institute (2008) review cites two studies that introduced PPMVs (Maragakis et al, 2006; Rupp et al, 2007), one study that introduced a negative fluid displacement (NFD) device (Salgado et al, 2007), and one study that introduced a NFD and a PPMV (Field et al, 2007). In all four studies there was a temporal association with the introduction of the new devices and an increase in CR-BSI rates and a reduction in infection rates after the devices were withdrawn. The four studies cited in the ECRI Institute (2008) review were observational, uncontrolled studies using routine surveillance of bloodstream infections before and after the introduction of new devices. Thus, they do not conclusively prove that the PPMV or NFD intravenous access ports are responsible for causing the increased infection rates seen in the four sites. However, three of the studies do show an association between the introduction of PPMV intravenous access ports and increases in CR-BSI. Of relevance to this review's context was that the study by Maragakis et al (2006) included children and found a greater increase in the rate of CR-BSI among children than adults.

Even more recently, Mitchell et al (2009) reviewed literature up to January 2008 on the effectiveness of different means of maintaining the patency of CVADs including the use of PPMV in adult patients. Their review of PPMV included three paediatric studies because they only found one study in adult patients. They concluded that the evidence about PPMV was inconsistent regarding reducing catheter occlusion but provides "moderate evidence that at least some varieties of caps are associated with increased blood stream infections" (Mitchell et al, 2009).The secondary reviews discussed above raise enough concerns about possible adverse effects of PPMV on CVADs in children to warrant a systematic evidence-based review of the primary literature.

THE REVIEW

Aim

The aim of this review was to assess the evidence regarding the clinical benefits and risks of positive pressure mechanical valve (PPMV) intravenous access ports on central venous access devices (CVADs) in children.

Design

The clinical question that guided this review was "what effect do PPMV intravenous access ports on CVADs in children have on rates of catheter occlusion and blood stream infection?" The clinical question was defined using the PICO framework (Richardson, Wilson, Nishikawa, and Hayward, 1995) (see Table 1). The patient group, intervention, comparison and outcomes defined in the PICO framework formed the criteria for including primary research articles in the review.

Search methods

A search for primary literature up to March 2010 was conducted using MEDLINE, EMBASE and CINAHL. There are a number of commercially available PPMV intravenous access ports, for example CLC2000 (ICU Medical Inc), Smartsite (positive Bolus) (Cardinal Health), BD Posi-flow, Baxter Flolink, B. Braun Ultrsite, Medegan MaxPlus Clear (ECRI Institute, 2008). Consequently, searches of each database combined terms for specific models of PPMV. There are also a variety of general terms for PPMVs which were combined with specific product names in each database search. Searches of each database also combined terms for specific types of CVADs, as well as general terms for CVADs. The searches were limited to studies conducted on human children from birth to 18 years old. The search strategy and results are shown in Table 2.

Studies of adult patients were excluded because adult catheters are larger and typical quantities of heparin used for catheter flushing are different from those used in children. Therefore, the results of adult studies may not be applicable to children.

SEARCH OUTCOMES

Of the four articles retrieved from MEDLINE, three were also found in EMBASE and one additional study was retrieved from EMBASE. The two articles found in CINAHL were also found in MEDLINE. Consequently, from the three databases, five separate studies were identified which reported on PPMV on CVADs in children. The studies covered three different makes of PPMV: the Posiflow, Smartsite and CLC2000. No studies were found that used Ultrasite, Flolink, or MaxPlus Clear devices on CVADs. None of the studies included children with Port-a-Caths. The five studies are summarised in Table 3.

Critical appraisal

The Critical Appraisal Skills Programme (CASP) at the Public Health Resource Unit, Oxford, developed critical appraisal tools which were retrieved from http://www.phru.nhs.uk/pages/PHD/resources.htm and used to critically appraise each study.

RESULTS

Critical appraisal of randomised controlled trials

Only two studies (Buehrle, 2004; Cesaro et al, 2009) had a randomised design. Buehrle's study included 70 children and 232 adults ranging in age from one week to 84 years. No other characteristics of the study population are described and the setting for his study is not described. Consequently it is not possible to assess to which group of patients the results apply. Buehrle's research question focussed on whether the type of needleless IV system used on patients with PICCs reduces the incidence of occlusion and did not address CR-BSI. The study had three groups, each with a different needleless cap on the PICCs, one group had a PPMV (CLC2000), another group had a negative fluid displacement device (CLAVE), and the third group had a three-way, pressure-activated valve (PASV protector). To remove an additional confounding variable, the PICCs in all three groups were flushed with 3mls of 0.9 percent saline and 3mls of 100U/ml heparinised saline every 12 hours.

Buehrle (2004) randomly allocated patients to one of the three groups but no details are provided as to how the random allocation was conducted and no details are provided regarding the equivalence of the groups at entry to the trial. In particular, no details are provided about the number of children in each group. The trial did not blind participants, staff or study personnel to the study group. Furthermore, the results of child participants are not reported separately. Consequently it is not possible from this study to determine the effect of the PPMV (CLC2000) intravenous access port on PICC occlusion rates in children.

Cesaro et al's (2009) research, on the other hand, does provide some evidence on which to determine the clinical benefits and/or risks of PPMV intravenous access ports on CVADs in children. Their research was conducted in a tertiary referral centre in Italy. Cesaro et al's research question focussed on CVAD complication rates associated with a positive-pressure valve cap device (the CLC2000) which was changed and flushed weekly with normal saline in children with oncohaematological diseases and CVADs. The comparison group had an unspecified "standard" CVAD cap device which was changed and flushed twice weekly with 3ml of normal saline and 200IU/ml of heparin. Thus there were four differences in the interventions received by the two groups: the cap device, the frequency with which the cap was changed, the frequency with which the catheter was flushed, and the flushing solution. The number of differences in interventions received by the two groups is the main limitation of this study and means it is not possible to conclude that any one aspect of the intervention or control is responsible for the differences reported in the study outcomes.

Other than the limitation noted above, Cesaro et al's (2009) study is well designed. Children were appropriately allocated to treatment and control groups using computer-generated randomisation. Both groups were well balanced on a range of relevant patient characteristics at entry to the trial. Only two eligible patients refused to participate during the study period. Data was collected the same way on all the participants who entered the trial, and all participants were accounted for at its conclusion. Furthermore, the study had enough participants to detect a 20 percent difference in complication rates between the two groups. Another limitation in the study design was that the trial did not blind participants, staff, or study personnel to the study group.

Cesaro et al (2009) found the incidence of CVAD occlusion was significantly higher in the experimental PPMV group (2.16 occlusions per 1000 days) compared with 1.11 occlusions per 1000 days in the standard control group (p = .0002). Another way to determine if the outcome for those in the PPMV differs significantly from those in the control group is to calculate the relative risk, which equals the risk in the treatment group divided by the risk in the control group (Courtney, 2005). The risk of CVAD occlusion in the PPMV group relative to the risk of occlusion in the standard control group was calculated as 2.04 (95 percent CI 1.58 to 2.63) using Hutcheon's (1999) calculator for confidence intervals of relative risk. The conclusion is that children in the PPMV group had slightly more than twice the chance of having an occlusion in their CVAD than children in the control group. As the lower confidence interval is greater than one, the relative risk is considered statistically significant.

Cesaro et al (2009) also found a higher rate of CR-BSI in the experimental PPMV group (0.62 per 1000 days) compared with 0.24 per 1000 days in the standard control group (p = .01). The risk of CR-BSI in the PPMV group relative to the risk of CR-BSI in the standard control group was calculated as 2.69 (95 percent CI 1.32 to 5.50). The conclusion is that children in the PPMV group had slightly more than two and a half times the chance of having CR-BSI than children in the control group. As the lower confidence interval is greater than one, the relative risk is considered statistically significant.

Critical appraisal of observational studies

Two studies had a sequential design (Jacobs et al, 2004; Schilling, Doellman, Hutchinson and Jacobs, 2006). Jacobs et al (2004) hypothesised that PPMV would reduce CVAD occlusion rates compared with standard cap devices. The population from which the sample was drawn were children in the paediatric intensive care unit, cardiac intensive care unit and step-down unit at Cincinnati Children's Hospital. Outside the national tertiary referral centre, this population is not typical of the children with CVADs in New Zealand hospitals.

Jacobs et al's study design had two phases. In phase one, all CVADs not receiving continuous fluid infusion were capped with a standard device (Interlink System, Becton Dickinson) and flushed with heparin at least every 24 hours or after each use. This phase continued until at least 150 lumens were included. Subsequently phase two commenced. In phase two, all CVADs not receiving continuous fluid infusion were capped with a PPMV (CLC2000, ICU Medical Inc) and flushed with saline in accordance with manufacturers' instructions. In both phases the caps were changed weekly.

Children were not randomly allocated in to the two groups. Consequently, there were significant differences between the two groups at baseline with the standard group having a higher percentage of children diagnosed with cardiovascular disease (28 percent compared with 8 percent, p = .003) and the PPMV group having a higher percentage of children diagnoses classified as miscellaneous (12 percent compared with 0 percent, p = .006). This is the main limitation of this study.

Jacobs et al (2004) found no statistically significant differences between the two groups in the prevalence of partial occlusion (not able to aspirate blood but able to flush fluids) and complete occlusion combined with partial occlusions. However, the prevalence of complete occlusion (inability to flush or aspirate) was significantly lower in CVADs capped with the PPMV (3.7 percent compared with 11.9 percent in the standard device group, p = .012). The risk of complete occlusion in the PPMV group relative to the risk of complete occlusion in the standard control group was calculated as 3.19 (95 percent CI 1.30 to 7.84) using Hutcheon's (1999) calculator for confidence intervals of relative risk. The difference between the upper and lower confidence interval is wide, suggesting the measure is not very precise. The conclusion is that children in the PPMV group had a bit more than three times the chance of having an occlusion in their CVAD than children in the control group. As the lower confidence interval is greater than one, the relative risk is considered statistically significant. However, given the baseline difference in the children in the two groups, it is not possible to conclude whether the intervention (PPMV flushed with saline) or the difference in the characteristics of the children are responsible for the differences reported in the study outcomes. Furthermore, prevalence which is a measure of the total number of cases in the sample is not the same as the incidence. Incidence is a measure of the number of cases over time, eg complete occlusion per 1000 CVAD days. When studying the risk of complication, incidence conveys more information about the risk than does prevalence.

Jacobs et al (2004) report a higher incidence of CR-BSI in the PPMV group: 15.5 per 1000 device days compared with 8.8 per 1000 device days in the control group. Although the incidence of CR-BSI in the PPMV group was almost double the incidence in the control group, this difference was not statistically significant. However, the actual p value was not reported and the study was probably under powered to detect such a difference.

Building on Jacob et al's (2004) study, Schilling et al (2006) conducted a further study at the Cincinatti Children's Hospital. Schilling et al hypothesised that either a single-valve or PPMV would reduce occlusion rates compared with a standard device in children with a CVAD. They also hypothesised that flushing CVADs with saline would be as effective as heparinised saline in preventing occlusion and infection. The population from which the sample was drawn were children in the paediatric intensive care unit, cardiac intensive care unit and children referred to the central venous catheter resource team for insertion of a PICC.

Schilling et al's study design had four phases where one type of access port was used until the desired sample size was reached, then the type of access port was changed until the desired sample size was reached in each of the comparison groups. The study design had four comparison groups. Group one's CVADs were capped with a standard needleless connector (Interlink, Becton Dickinson) and flushed with 10units/ml of heparinised saline. Group two CVADs were capped with a single valve needleless device (Alaris Smartsite, Alaris Medical Systems) and flushed with 10units/ml of heparinised saline. Group three's CVAD were capped with a PPMV (BD Posi-Flow, Becton Dickinson) and flushed with 10units/ml of heparinised saline. Group four's CVAD were capped with a PPMV (BD Posi-Flow, Becton Dickinson) and flushed with normal saline. Complete occlusion of the CVAD was the primary outcome measure and CR-BSI was a secondary outcome measure.

The fact that children were not randomly allocated to the four groups is a major limitation of this study. Furthermore, there were significant differences between the groups at baseline. The mean catheter duration in groups two, three, and four were all significantly less than group one.

Schilling et al (2006) reported the prevalence of complete occlusion in group one (12.7 percent) was statistically significant and higher than the prevalence in groups two (1.3 percent), three (3.3 percent) and group four (4 percent) (p < .001, p < .01, and p < .05 respectively). However, the prevalence does not account for the duration of the catheter placement which was lower in the three comparison groups. When the incidence of complete occlusion per 1000 device days is reported, only the difference between group one and group two remains statistically significant. Although the incidence of complete occlusion in the two PPMV groups (8 per 1000 device days in the PPMV with heparin flush group and 9.3 per 1000 device days in the PPMV with saline flush group) were more than half the incidence in the standard device group (20.1 per 1000 days), these differences were not statistically significant. The study was probably under powered to detect such a difference.

Schilling et al (2006) report a higher incidence of CR-BSI in the PPMV with normal saline group (10.9 CR-BSI per 1000 device days) compared with the PPMV with heparin group (4.8 CR-BSI per 1000 device days), the single valve with heparin flush group (4.1 CR-BSI per 1000 device days) and the standard group with heparin flush (5.3 CR-BSI per 1000 device days). Although the incidence of CR-BSI in the PPMV flushed with normal saline group is more than double the incidence in the other three groups, this difference was not statistically significant. However, the actual p value was not reported and the study was probably under powered to detect such a difference.

Maragakis et al's (2007) study was a retrospective observational cohort study of changes in infection rates before introduction of a PPMV (SmartSite plus, Alaris Medical Systems), while the PPMV was in use, and after it was removed from use. The study is set in the Johns Hopkins Hospital, a tertiary-care medical centre in the United States. For the purpose of this review, only the findings relating to the active surveillance of CRBSI in children in the PICU, NICU and paediatric oncology patients are critically reviewed. Maragakis et al clearly identify the patient population observed and the outcomes considered. The exact date of implementing and removing the PPMV device was known in the child health areas so that it is possible to see the temporal relationship between the introduction and removal of the PPMV and changes in the CR-BSI rates. The CR-BSI outcome was measured using the Centre for Disease Control and Prevention Criteria and National Nosocomial Infection Surveillance definitions. Potential confounding factors were identified. For example there were no changes in the vascular access device policy during the period of the study, one type of mechanical valve was in long term use before the change to a PPMV and was reintroduced after the PPMV was withdrawn, and an investigation of CVAD insertion and maintenance practices did not reveal any infection-control violations. The period of follow-up after withdrawal of the PPMV device was only four months which may have been inadequate.

Maragakis et al's (2007) report shows the CR-BSI rate in the children's centre increased significantly from 1.55 per 1000 catheter days in the 14 months prior to the PPMV device being introduced, to 2.79 per 1000 catheter days in the nine months when the PPMV was in use. The incidence rate ratio was 1.79 (95 percent CI, 1.1-2.9; p=.01). As the lower confidence interval is greater than one, the incidence rate ratio is considered statistically significant. In the four months after the PPMV was withdrawn, the CR-BSI rate decreased to 1.43 per 1000 catheter days. The incidence rate ratio was 0.51 (95 percent CI, 0.22-1.08; p=.06). As the upper confidence interval is greater than one, the incidence rate ratio is not considered statistically significant. As these results are from observational, uncontrolled data from a single study site, it is not possible to prove causation. The data from this study alone only shows a temporal relationship between the introduction of a PPMV and an increase in CRBSI that is not generalisable to other locations.

DISCUSSION

Selecting devices to use on CVADs is a matter of balancing a variety of risks and benefits. The relative benefits and harms of PPMV on CVADs in children have not previously been critically reviewed. This review of the primary literature shows that all four papers which examined CR-BSI provide some evidence that the use of PPMVs on CVADs in children could be associated with increased rates of CR-BSI. While all four studies have some limitations, the strongest evidence for a link between PPMVs and increased CR-BSI is in Cesaro et al's (2009) randomised controlled clinical trial where the increased infection rate was associated with a PPMV which was changed weekly and flushed weekly with normal saline. The two sequential studies both found non-significant increased rates of infections with PPMVs. The one cohort study (Maragakis et al, 2007) found a strong temporal relationship with introduction of a PPMV and a rise in CR-BSI rates followed by a fall in CR-BSI rates after the PPMV was withdrawn from use. Rupp et al (2007) report a very similar pattern in an adult hospital.

The increased rate of CR-BSI is not confined to one particular PPMV device--in fact the studies cover three different PPMV devices. There is no published evidence for or against the use of a number of PPMV devices currently on the market. However, in the absence of evidence related to particular devices, it seems reasonable to consider the current evidence related to similar devices. There is evidence that three different PPMV devices on CVADs in children increase the risk of CR-BSI which are harmful to children. The increased risk of infection may be because of some design aspect of the PPMVs (Rupp et al, 2007) or it may be that saline flushes lack the protective effects of heparin in reducing CVC colonisation (Randolf, Cook, Gonzales and Andrew, 1998).

PPMVs have been advocated as reducing occlusion of CVADs. Four studies included complete and partial occlusion in their outcome measures; however one of those studies did not report the results for children separately. The strongest evidence in relation to the role of PPMVs in preventing partial or complete occlusion comes from Cesaro et al's (2009) randomised controlled clinical trial where an increased rate of total and partial occlusion occurred because of the combination of PPMV and saline flush.

The evidence from the two sequential studies is weaker and somewhat contradictory. Schilling et al's (2006) sequential study found there were no significant differences in total and partial occlusion rates per 1000 CVC days between groups three and four using PPMV and saline and PPMV and heparin respectively and the other comparison groups. Furthermore, they did not find any significant differences in relation to the rate of complete occlusion per 1000 CVC days between the two PPMV groups and the other groups, although the rates were more than half of those in the group receiving a standard connector and heparinised saline flush. Jacobs et al's (2004) sequential study also found no statistically significant difference in complete and partial occlusion rates between the PPMV group and the standard group. However, they did find that when complete occlusions per 1000 CVC days were compared without partial occlusions that there was a statistically significant decrease in the percentage of complete occlusions in the PPMV group. These results are somewhat contradictory and may be explained by limitations in the study designs. While there is some evidence that PPMVs on CVADs in children may reduce the incidence of complete occlusions of the CVAD, there is stronger evidence that they may increase the incidence of complete occlusion.

This critical review has two clear limitations. Firstly, the small number of studies and the heterogeneity in the study designs means it was not possible to conduct a meta-analysis. Secondly, publication bias is a potential limitation. It is well recognised that studies that do not find a difference between groups are less likely to be published than those with statistically significant differences between groups. Similarly, there may be clinical areas that have introduced PPMVs on CVADs in children which have not found an increase in CR-BSI and have not published this. Further high quality studies are required.

CONCLUSION

There is limited evidence about the benefits and risks of PPMV intravenous access ports in children with CVADs. However, current evidence does suggest an increased risk of CR-BSI in children with CVADs when PPMV intravenous access ports are flushed with normal saline.

The evidence about the benefits of PPMVs in preventing partial and/ or total occlusion is at best contradictory and the strongest evidence suggests the use of PPMVs may actually increase the risk of occlusion at least in CVADs in children with cancer. There is the potential for significant morbidity and economic costs associated with bloodstream infections and replacing occluded CVADs. Thus, the current evidence suggests the potential harms of PPMVs on CVADs in children outweigh the potential benefits.

RECOMMENDATIONS

* PPMVs should not be used routinely on CVADs in children (recommendation based on one RCT, two sequential studies, and one observational study: preponderance of harm of use over benefit).

* Further prospective randomised controlled trials are required to confirm or refute the current evidence regarding CR-BSI and occlusion of CVADs associated with PPMV on CVADs in children.

* Child health services should carefully consider the evidence to support the use of new technology on children prior to introducing new technology into child health care.

REFERENCES

Buehrle, D. C. (2004). A prospective randomised comparison of three needleless IV systems used in conjunction with peripherally inserted central catheters. Journal of the Association for Vascular Access, 9(1), 35-38.

Cesaro, S., Tridello, G., Cavaliere, M., Magagna, L., Gavin, P., Cusinato, R., Zadra, N., Zanon, G. F., Zanesco, L. and Carli, M. (2009). Prospective, randomised trial of two different modalities of flushing central venous catheters in pediatric patients with cancer. Journal of Clinical Oncology, 27(12), 2059-2065.

Courtney, M. (2005). Evidence for nursing practice. Sydney, Australia: Elsevier.

ECRI Institute. (2008). Evaluation Needleless Connectors. Health Devices, 37(9), 260-283.

Hutchon, D. J. R. (1999). Calculator for confidence intervals of relative risk. Retrieved 18/04/2010 from http://www.hutchon.net/ConfidRR.htm

Jacobs, B. R., Schilling, S., Doellman, D., Hutchinson, N., Rickey, M. and Nelson, S. (2004). Central venous catheter occlusion: A prospective, controlled trial examining the impact of a positive-pressure valve device. Journal of Parenteral and Enteral Nutrition, 28(2), 113-118.

Maragakis, L. L., Bradley, K. L., Song, X., Beers, C., Miller, M. R., Cosgrove, S. E., and Perl, T. M. (2006). Increased catheter-related bloodstream infection rates after introduction of a new mechanical valve intravenous access port. Infection Control and Hospital Epidemiology, 27(1), 67-70.

Mitchell, M. D., Anderson, B. J., Williams, K., Umscheid, C. A. (2009). Heparin flushing and other interventions to maintain patency of central venous catheters: A systematic review. Journal of Advanced Nursing, 65(10), 2007-2021.

Newall, F., Barnes, C., Ignjatovic, V., and Monagle, P. (2003). Heparin-induced thrombocytopenia in children. Journal of Paediatric and Child Health, 39, 289-292.

Randolph, A. G., Cook, D. J., Gonzales, C. A., and Andrew, M. (1998). Benefit of heparin in central venous and pulmonary artery catheters: A meta-analysis of randomised controlled trials. Chest, 113, 165-171.

Richardson, M. A., Wilson, M. C., Nishikawa, J., and Hayward, R. S. A. (1995). The well-built clinical question: A key to evidence-based decisions. ACP Journal Club, 123(3), A12-A13.

Risch, L., Fischer, J. E., Herklotz, J. E., and Huber, A. R. (2004). Heparin-induced thrombocytopenia in paediatrics: Clinical characteristics, therapy and outcomes. Intensive Care Medicine, 30(8), 1615-1624.

Rupp, M. E., Sholtz, L. A., Jourdan, D. R., Marion, N. D., Tyner, L. K., Fey, P. D., Iwen, P. C., and Anderson, J. R. (2007). Outbreak of bloodstream infection temporally associated with the use of an intravascular needleless valve. Clinical Infectious Diseases, 44, 1408-1414.

Schilling, S., Doellman, D., Hutchinson, N., and Jacobs, B. R. (2006). The impact of needleless connector device design on central venous catheter occlusion in children: A prospective controlled trial. Journal of Parenteral and Enteral Nutrition, 30(2), 85-90.

Schmugge, M., Risch, L., Huber, A. R., Benn, A. and Fischer, J. E. (2002). Heparin-induced thrombocytopenia associated thrombosis in pediatric intensive care patients. Pediatrics, 109, e10.

Spadone, D., Clark, F. and James, E. (1992). Heparin-induced thrombocytopenia in the newborn. Journal of Vascular Surgery, 15, 306-311.

Accepted for publication April 2010

About the author: Paul Watson, RN, PhD, is a nurse lecturer, child health, School of Nursing and Human Services, Christchurch Polytechnic Institute of Technology, NZ; and a nurse educator, Child Health Service, Canterbury District Health Board, Christchurch, NZ. Postal Address: PO Box 540, Christchurch 8140, New Zealand. Email: watsonp@cpit.ac.nz
Table 1. PICO framework

Patients       Children (birth to 18 years) with central
               venous access device (central venous
               catheter, or peripherally inserted central
               catheter, or Port-a-Cath)

Intervention   Positive pressure mechanical valve
               intravenous access ports

Comparison     Any other intervention

Outcomes       Total or partial catheter occlusion,
               catheter-related bloodstream infection

Table 2. Search strategy for primary literature

Search   Keywords                                Results

                                       MEDLINE   EMBASE   CINAHL

1        Positive pressure             50,221    8008     1612

2        Mechanical valve              6939      810      47

3        Positive fluid displacement   112       0        1

4        Ultrasite                     0         0        0

5        Flolink                       0         0        0

6        Posiflow                      2         2        1

7        Smartsite                     3         4        3

8        CLC2000                       1         2        2

9        MaxPlus Clear                 0         0        0

10       1 or 2 or 3 or 4 or 5 or      57,063    8821     1663
         6 or 7 or 8 or 9

11       Central venous access         1625      89       40
         device

12       Central venous catheter       14,197    7401     695

13       Peripherally inserted         444       174      120
         central catheter

14       Port-a-cath                   335       291      27

15       Hickman catheter              664       305      53

16       11 or 12 or 13 or 14          14,859    7950     918
         or 15

17       10 and 16                     191       24       6

18       Limit 17 to humans, all       39        6        3
         child 0 to 18yrs

         Papers retrieved following    4         4        2
         review of titles and
         abstracts  against criteria
         for inclusion

Table 3. Primary studies of positive pressure mechanical valves in
paediatric populations

Author            Study design     Setting           Patients

Cesaro et al      Randomised       Tertiary ref-     n=203 CVCs in
(2009)            open label co-   erral centre      children with
                  ntrolled         for pediatric     cancer 0-17
                  clinical trial   oncology and      years
                                   haematology,
                                   Italy             75,249 CVC days

Maragakis et al   Retrospective    The Johns Hop-    Not reported
(2007)            surveillance     kins Hospital
                  of primary bl-   Children's
                  ood stream       Centre, inclu-
                  infection        des PICU and
                                   NICU oncology

Schilling et al   Prospective      Cincinnati        n=360 children
(2006)            sequential 4     Children's        with 599 CVC
                  group design     Hospital medi-    lumens
                                   cal centre PICU
                                   CICU

Buehrle (2004)    Randomised       Not specified     70 pediatric
                  controlled                         232 adults
                  trial

Jacobs et al      Sequential       Cincinnati        312 CVC lumens
(2004)            design           Children's
                                   Hospital medi-    Mean age 4
                                   cal centre        years
                                   PICU CICU
                                   step-down

                                    Positive          Control and
                  Intravenous       pressure mecha-   experimental
Author            access            nical valve       intervention

Cesaro et al      Broviac Hickman                     - Standard CVC
(2009)            central venous                      cap changed
                  catheters                           2/7, flushed
                                                      with 3 ml n/s
                                                      and heparin
                                                      200IU/ml 2/7

                                    CLC2000 (ICU      - Positive
                                    Medical Inc)      pressure CVC
                                                      valve cap,
                                                      changed 1/7,
                                                      flushed with
                                                      n/s at
                                                      least 1/7

Maragakis et al   Not reported      SmartSite Plus    Observational
(2007)                              Needle-Free       study of infe-
                                    Valve, (Alaris    ction rates
                                    Medical System)   before intro-
                                                      ducing PPMV,
                                                      during PPMV use
                                                      and following
                                                      removal of PPMV

Schilling et al   Tunnelled and                       Group 1
(2006)            non tunnelled                       standard cap
                  CVCs PICCs                          flushed with 10
                                                      units/ ml hepa-
                                                      rinised saline

                                                      Group 2 central
                                                      valve needle-
                                                      less connector
                                                      flushed with 10
                                                      units/ ml hepa-
                                                      rinised saline

                                    BD Posi-flow      Group 3 Posi-
                                                      tive pressure
                                                      valve flushed
                                                      with 10 units/
                                                      ml heparinised
                                                      saline.

                                    BD Posi-flow      Group 4 Posi-
                                                      tive pressure
                                                      valve flushed
                                                      with saline

Buehrle (2004)    PICCs             CLC2000 (ICU
                                    Medical Inc)

                                                      CLAVE (ICU
                                                      Medical Inc)
                                                      negative fluid
                                                      displacement
                                                      device
                                                      PASV Protector
                                                      (Boston
                                                      Scientific
                                                      Corporation)

Jacobs et al      PICCs Tunnelled                     Standard device
(2004)            and non-                            with heparin
                  tunnelled                           flush

                                    CLC2000 (ICU      Positive
                                    Medical Inc)      pressure valve
                                                      with saline
                                                      flush

                  Total + partial          Bloodstream
                  occlusion                infection
Author            results                  results

Cesaro et al      1.11 per 1000 CVC days   0.24 per 1000 CVC days
(2009)

                  2.16 per 1000 CVC days   0.62 per 1000 CVC days
                  p=.0002                  p=.01

Maragakis et al   Not measured             Base rate 1.55 per
(2007)                                     1000 CVC days. 2.79
                                           per 1000 CVC days when
                                           PPMV in use p=.01
                                           1.43 per 1000 CVC days
                                           after PPMV removed

Schilling et al   27.6 per 1000 CVC days   5.3 per 1000 CVC days
(2006)
                  17.7 per 1000 CVC days   4.1 per 1000 CVC days

                  17.6 per 1000 days       4.8 per 1000 CVC days

                  18.7 per 1000 CVC days   10.9 per 1000 CVC
                  days

Buehrle (2004)    1.2 per 1000 CVC days    Not measured

                  3.4 per 1000 CVC days

                  0.3 per 1000 CVC days

Jacobs et al      23/151                   8.8 per 1000 CVC
(2004)            15.2%                    days

                  19/161                   15.5 per 1000 CVC
                  11.8%                    days

Author            Comment

Cesaro et al      Well-designed study
(2009)            Limitations:
                  - Not blinded
                  - 4 parts to intervention
                  - confidence intervals not reported

                  Found significal increases in CVAD occlusions and
                  CR-BSI associated with use of positive pressure
                  device changed 1/7 and flushed 1/7 with n/s

Maragakis et al   An investigation failed to reveal any infection
(2007)            control violations of CVCinsertion or maintenance
                  practices. Study limited by being observational,
                  uncontrolled and at a single site. However strong
                  temporal relationship between introduction and
                  removal of PPMV with changes on infection rate.

Schilling et al   Group 1's mean catheter duration was significantly
(2006)            longer than any of the other groups

                  The complete occlusion rate per 1000 CVC days was
                  significantly less in group 2 compared with group
                  1 (p<.01)

                  There were no significant differences between any
                  groups in total + partial occlusion rates per
                  1000 CVC days.

                  Group 4's infection rate per 1000 CVC days was
                  twice the other groups but did not reach
                  statistical significance.

Buehrle (2004)    All devices flushed with 3mls n/s and 3mls
                  100U/ml heparinised saline Pediatric outcomes not
                  reported separately

Jacobs et al      The % of complete occlusions in CVC capped with
(2004)            PPMV was significantly less than the standard
                  device (p=.012)
                  When partial and complete occlusions are combined
                  there was no significant difference between
                  groups.
                  The PPMV group's infection rate per 1000 CVC
                  days was almost twice the standard rate but did
                  not reach statistical significance.
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Author:Watson, Paul B.
Publication:Kai Tiaki Nursing Research
Article Type:Report
Date:Jun 1, 2010
Words:5961
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