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Quantitative assessment of reflux in commercially available needle-free IV connectors

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Quantitative assessment of reflux in commercially available needle-free IV connectors

Abstract and Figures

Methods: In this study, 14 NFC brands representing each of the four market-categories of NFCs were selected for evaluation of fluid movement occurring during connection and disconnection of a syringe. Study objectives were to 1)theoretically estimate amount of blood reflux volume in microliters (μL) permitted by each NFC based on exact component measurements, and 2) experimentally measure NFC volume of fluid movement for disconnection reflux of negative, neutral and anti-reflux NFC and fluid movement for connection reflux of positive displacement NFC. Results: The results demonstrated fluid movement/reflux volumes of 9.73 μL to 50.34 μL for negative displacement, 3.60 μL to 10.80 μL for neutral displacement, and 0.02 μL to 1.73 μL for pressure-activated anti-reflux NFC. Separate experiment was performed measuring connection reflux of 18.23 μL to 38.83 μL for positive displacement NFC connectors. Conclusions: This study revealed significant differences in reflux volumes for fluid displacement based on NFC design. While more research is needed on effects of blood reflux in catheters and NFCs, results highlight the need to consider NFCs based on performance of individual connector designs, rather than manufacturer designation of positive, negative and neutral marketing categories for NFCs without anti-reflux mechanisms.
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J VA
ISSN 1129-7298
J Vasc Access 2017; 00 (00): 000-000
© 2017 The Authors. This arcle is published by Wichg Publishing and licensed under Creave Commons Aribuon-NonCommercial-NoDerivaves 4.0
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ORIGINAL RESEARCH ARTICLE
The use of “engineering controls” included the integraon of
NFCs into the IV access system both for needle safety and for
the prevenon of central-line associated bloodstream infec-
ons (CLABSI) (3-5). NFCs allow for the administraon of IV
uids, medicaons and blood to indwelling venous or arterial
catheters without the use of needles. NFCs are also used for
the withdrawal of blood samples and for aspiraon of blood
to check the catheter for patency. While the introducon
of NFCs greatly reduced the risk of needle-sck injuries for
healthcare workers, their use has been associated with other
complicaons such as an increase in catheter occlusions and
CLABSIs (6-11).
In response to the increase in CLABSI related to the use
of NFCs, medical device companies began designing and de-
veloping lower-risk devices (12). Over the past 20 years, 4
categories of NFC designs have emerged (2, 13). While there
is no regulatory body that recognizes the categories of NFC
as being indicave of funcon or performance (13), NFCs are
typically marketed as being “posive”, “negave”, “neutral”
(6, 12-16) or pressure-acvated an-reux (9, 13, 17). The
characteriscs of each category of NFC indicate the mecha-
nism and acon of the NFC upon connecon/disconnecon.
DOI: 10.5301/jva.5000781
Quantave assessment of reux in commercially
available needle-free IV connectors
Garret J. Hull1, Nancy L. Moureau2, Shramik Sengupta3
1 Cook Medical, Bloomington, Indiana - USA
2 PICC Excellence, Inc, Hartwell, GA; Greenville Memorial Hospital, Greenville, SC; Adjunct Associate Professor, Alliance for Vascular Access
Teaching and Research (AVATAR) Group, Centre for Health Pracce Innovaon, Menzies Health Instute Queensland, Grith University,
Brisbane - Australia
3 Department of Biomedical Engineering, University of Missouri, Columbia, MO - USA
Introducon and background
Prior to the advent of needle-free connectors (NFCs),
stainless-steel needles were used to access intravenous (IV)
y-sites, tubing ports and injecon sites. While this process
was eecve for IV pathway access, needle-sck injuries be-
came a substanal risk to healthcare workers, increasing the
potenal for occupaonally acquired blood-borne diseases
(1). In 1992, the Occupaonal Safety and Health Administra-
on (OSHA) recommended that healthcare facilies incorpo-
rate “engineering controls” to prevent such occurrences (2).
ABSTRACT
Introducon: Blood reux is caused by changes in pressure within intravascular catheters upon connecon or
disconnecon of a syringe or intravenous tubing from a needle-free connector (NFC). Changes in pressure, dif-
fering with each brand of NFC, may result in uid movement and blood reux that can contribute to intraluminal
catheter occlusions and increase the potenal for central-line associated bloodstream infecons (CLABSI).
Methods: In this study, 14 NFC brands represenng each of the four market-categories of NFCs were selected for
evaluaon of uid movement occurring during connecon and disconnecon of a syringe. Study objecves were to 1)
theorecally esmate amount of blood reux volume in microliters (μL) permied by each NFC based on exact
component measurements, and 2) experimentally measure NFC volume of uid movement for disconnecon reux
of negave, neutral and an-reux NFC and uid movement for connecon reux of posive displacement NFC.
Results: The results demonstrated uid movement/reux volumes of 9.73 μL to 50.34 μL for negave displace-
ment, 3.60 μL to 10.80 μL for neutral displacement, and 0.02 μL to 1.73 μL for pressure-acvated an-reux NFC.
Separate experiment was performed measuring connecon reux of 18.23 μL to 38.83 μL for posive displace-
ment NFC connectors.
Conclusions: This study revealed signicant dierences in reux volumes for uid displacement based on NFC
design. While more research is needed on eects of blood reux in catheters and NFCs, results highlight the need
to consider NFCs based on performance of individual connector designs, rather than manufacturer designaon of
posive, negave and neutral markeng categories for NFCs without an-reux mechanisms.
Keywords: Intravenous catheters, Needleless connectors, Occlusion, Reux
Accepted: June 13, 2017
Published online: December 4, 2017
Corresponding author:
Shramik Sengupta, PhD
Department of Bioengineering
University of Missouri
1406 E Rollins St.
MO 65211 Columbia, USA
senguptas@missouri.edu
Assessment of reux in needle-free connectors
2
© 2017 The Authors. Published by Wichg Publishing
NFCs are designed as end caps to lock/luer onto the hub of
catheters. Eciency may be measured on the ability of the
NFC design to prevent movement of uids and inadvertent
reux of blood into the catheter (18, 19). The key features
and dening characteriscs of each NFC design along with
manufacturer recommended clamping sequences are sum-
marized in Table I. The specics of each type of NFC are fur-
ther explored in the Discussion secon of this paper.
Unfortunately, the large variety of NFCs, the dierent de-
signs, performance and instrucons for use with each device
is a source of confusion among clinicians. In a 2011 survey of
4000 healthcare workers in which 554 responded (9):
21.9% did not know which brand of needle-free IV con-
nector was used with their CVCs (2)
25.4% did not know if their connector was ‘positive’,
‘negative’ or ‘neutral’ (2)
47.2% did not understand the correct way to flush and
clamp a catheter with the NFC used by their institution (9).
It is not uncommon for several types or brands of NFCs to be
used on peripheral and central venous access devices within
a single hospital, such as one category for peripheral cath-
eters and a dierent category for central catheters (2, 6, 9).
Evidence suggests that lack of training for device usage cor-
relates with an increase in CLABSI (20). This was demon-
strated in a 2009 study that followed ve hospitals adopng
new NFCs (12). When switching NFC brands from ‘negave’
to ‘posive’ connectors, which may have dierent instruc-
ons for use, some hospitals reported an increase in blood-
stream infecons (8). However, hospitals that went back
to their original NFC subsequently reported infecon rates
had returned to previous levels (8, 15, 21). This evidence
suggests that NFC design dierences, variaons in instruc-
ons for use and inconsistencies in asepc technique may
contribute to increased incidence of CLABSI associated with
NFCs (2, 8, 9, 12).
Central venous access devices (CVAD) have undergone
design changes; some of these changes included the elimina-
on of clamps. Despite the instrucons for use of many NFC
manufactures to use clamps on catheters aer disconnecon,
the opon to perform this acon is oen not present (22).
Given the inconsistencies noted with NFC usage, the aim
of the research was to clarify NFC funcon by quanfying
uid movement and volume of reux occurring within each
NFC aer disconnecon or connecon.
Materials and methods
For this study, 14 commercially available NFCs were se-
lected to quantavely study the uid reux volume in mi-
croliters (µL or mm3) of each NFC. Study objecves were to (i)
theorecally esmate amount of blood reux volume in mi-
croliters (μL) permied by each NFC based on exact compo-
nent measurements, and (ii) experimentally measure amount
of uid movement or reux. The 14 NFCs are represented in
each of the four current markeng categories of NFC (13).
The NFCs selected for evaluaon in this study included:
Negave displacement
BD Carefusion Smartsite
BD Q-Syte
Baxter Interlink
ICU Medical Clave*
Neutral displacement
ICU Medical Microclave Clear
Baxter One-Link
RyMed Invision
Nexus NIS-6P
Pressure acvated an-reux
ICU Medical Neutron
Nexus TKO-5
Nexus TKO-6P
*ICU Medical Clave is included in the negave displacement
NFC group based on terminology and grouping established in
prior publicaon (13).
Posive displacement*
B. Braun Ultrasite
BD Carefusion MaxPlus
B. Braun Caresite
TABLE I - Fluid displacement characteriscs of negave, neutral displacement, pressure acvated an-reux, and posive, needle-free
connectors
Types of NFCs Negave displacement
NFC
Neutral displacement
NFC
An-reux
NFC
Posive displacement
NFC
Fluid movement upon
disconnecon
Blood reuxes into
catheter
Blood reuxes into
catheter
Fluid restricted by
diaphragm
Fluid moves
toward paent
Fluid movement
upon connecon
Fluid moves toward
paent
Fluids moves
toward paent
Fluid restricted by dia-
phragm
Blood reuxes in
to catheter
Manufacturer
recommended
clamping sequence
Clamp before
disconnecon
No specied clamping No specied clamping Clamp aer disconnec on
of male luer
Hull et al 3
© 2017 The Authors. Published by Wichg Publishing
*As dened in publicaons as posive pressure mechanical
valve with reux occurring on connecon with a nal uid
push at disconnecon clearing blood from catheter p, de-
scribed as a compression/decompression mechanism creang
posive (disconnecon) and negave pressure (on acvaon)
resulng in uid displacement uctuaons (2, 16).
To meet the goals of this study, two independent
experiments were performed, with experiment 2 separated
into 2A and 2B to clearly separate dierences of posive
displacement devices from negave, neutral and an-reux
NFC.
Experiment 1: theorecal esmates of NFC reux
volume (Fig. 1)
Purpose
To calculate the amount of blood reux created by sucon
pressure which occurs in NFC designs.
Materials
Computer with SolidWorks® Professional 2015 software
OGP SmartScope Flash 200 Optical Comparator Mea-
surement System
SolidWorks CAD models of each NFC
Method
To esmate the amount of blood reux caused by sucon
pressure during periods of compression and subsequent non-
compression from syringe connecon and disconnecon, di-
mensions of each component of all NFCs were precisely mea-
sured using a computerized opcal measuring system (OGP
SmartScope Flash 200) by Simplicated Innovaon LLC. Each
component of the NFC was precisely dimensioned (±0.001”)
and built into 3-dimensional (3-D) model using Computer
Aided Design (CAD) 3-D soware (SolidWorks™ Professional
2015). These dimensions provided the necessary input for
the computaonal study and the elastomeric compression
in Experiment 1. Geometrical and mass property calculaons
were used to generate data measuring the mechanical reux
created during compression of the so septum during the
connecon and disconnecon of a male luer locking syringe
to each NFC septum.
Two pictorial models were created for each NFC using
SolidWorks modeling tools: the rst was a ‘un-accessed’ or un-
compressed “at rest” representaon in which the NFC is not
connected to a male luer from the syringe or IV tubing set. The
second picture demonstrates what happens when the same
NFC is ‘accessed’ by a male luer connector, showing compres-
sion of the so septum, the corresponding movement inside
the NFC, and the resulng sucon pressure and uid reux or
ow. For this experiment, a 10-mL BD syringe or a blunt can-
nula was used (Fig. 1). The volume of the “accessed” and “un-
accessed” 3-D models were calculated. Subtracng the volume
of the “un-accessed” or uncompressed “at rest” area from the
“accessed” or compressed area of the NFCs produces the theo-
recal amount of uid displacement available to reux into an
IV catheter upon connecon or disconnecon of the male luer.
Theorecal calculaons of reux values obtained for each
of the 14 connectors are listed in Table II.
Experiment 2A: Actual venous simulaon of negave,
neutral and an-reux NFC reux volume (Tab. II)
Purpose
Quanfy the amount of uid movement or reux asso-
ciated with the disconnecon (negave, neutral and an-
reux NFC) of a male luer lock to each of the 11 (of 14)
NFCs.
To measure blood reux or uid movement associated
with each NFC upon disconnecon of a male luer, an in
vitro venous model was created in the laboratory using the
following:
Materials (Fig. 2)
An industry standard 10-mL syringe (BD Luer-Lok™ tip
syringe)
Needle-free connectors (NFCs)
Clear PVC tubing and stopcock
Glass capillary rod (6 mm OD × 1.2 mm ID × 12”)
Fig. 1 - Experiment 1 - Pictorial model of a needle-free connector
(Microcla ve®) sh owing its inter na l me ch anism when (A) unaccessed
and (B) accessed using a 10-mL BD Syringe. Internal uid pathway
is displayed in red, moving silicone par ts in yellow, and the outer
housing as translucent. Below the images are the corresponding
volumes of the uid pathway and the dierences between them,
which yield the expected volume of reux (reux volumes for the
other NFCs were calculated in a similar manner).
Assessment of reux in needle-free connectors
4
© 2017 The Authors. Published by Wichg Publishing
TABLE II - Results of the theorecal calculaons and actual in vitro
venous values
NFC
category
Brand Experiment 1:
theorecal
calculaons
(μL)
Experiment
2: actual in
vitro venous
values (μL)
SD
Negave Carefusion
Smartsite®
27. 92 50.37 1.069
BD Q-Syte® 23.20 38.34 0.721
Baxter Interlink® 11.98 13.18 0.1 34
ICU CLAVE® 8.02 9.73 0.265
Neutral ICU MicroClave® 7.7 7 10.80 0.458
Baxter One-Link® 15.87 8.05 0.058
Rymed InVision 2.93 6.54 0.375
Nexus NIS®-6P 5.21 3.60 1.487
An-reux ICU NeutronTM 5.21 1.73 2.656
Nexus TKO®-5 4.03 0.34 0.661
Nexus TKO®-6P 5.26 0.02 0.029
Posive B. Braun
Ultrasite®
59.69 38.83 2.619
Carefusion
MaxPlus®
75.81 23 .73 1.872
B. Braun Caresite® 10.65 18.23 4.60 4
For Experiment 1, “theorecal” values are in microliter (μL) volumes math-
emacally calculated using the method shown in Figure 1. For Experiment 2,
actual in vitro venous values in microliter (μL) volumes are the results from
uid reux obtained upon disconnecon of negave, neutral displacement
and pressure acvated an-reux NFCs and upon connecon for posive dis-
placement NFC.
NFC = needle-free connector; SD = standard deviaon.
Metric ruler
Collection bag with water (green food coloring added).
Method
The in vitro venous model was designed to replicate the
condions which cause blood reux into an IV catheter dur-
ing disconnecon of a syringe from an NFC. This venous sim-
ulaon apparatus was designed to replicate the peripheral
venous pressure found in the human vasculature (2, 23). For
the purposes of this study, an average venous pressure of
8 mmHg was used. A glass capillary rod was used to allow
for visualizaon as well as accurate measurement of uid
movement.
For the categories of negave displacement, neutral dis-
placement and pressure-acvated an-reux NFCs (Fig. 2),
each of the NFCs was connected to the PVC tubing, which
was aached to a stopcock and the vercally posioned glass
capillary rod on the model. The following procedure was per-
formed a total of 30 mes per NFC type and brand:
1. A 10-mL syringe was filled with water and attached di-
rectly to the NFC.
2. The stopcock on the model was turned “OFF” to the glass
capillary tube.
3. The 10-mL syringe plunger was depressed and all air was
purged from the NFC, PVC tubing and stopcock attached
to the model.
4. The stopcock was turned “ON” to the glass capillary
rod.
5. The syringe plunger was slowly depressed allowing fluid
to fill the glass capillary rod until the fluid level reached
108 mm (equal to 8 mmHg of simulated venous pres-
sure) on the metric ruler.
6. The syringe was disconnected from the NFC and the amount
of fluid reflux in the glass capillary tube was recorded.
Three sterile samples of each NFC were tested; steps 1-6 were
repeated 10 mes for each sample for a total of 30 venous
simulaons per NFC. All 30 tests were totaled and averaged
to obtain a stascally signicant total uid reux distance
into the glass capillary rod. In this study, all experiments were
conducted by one person, minimizing user variances, result-
ing in relavely low standard deviaons.
The inside diameter of the glass capillary rod is 0.60 mm.
The average distance of uid reux volume of each of the 14
NFCs was used to calculate the total reux volume in micro-
liters (mm3 or µL)
Fig. 2 - In vitro venous model used to measure actual reux. Con-
sists of the following: (1) Standard 10-mL BD Luer Lock syringe,
(2) Needle-free connector, (3) Clear PVC tubing , (4) Glass capillary
rod, (5) Metric ruler, (6) 3-way stopcock, (7) Collecon bag with
dyed water.
Hull et al 5
© 2017 The Authors. Published by Wichg Publishing
Fig. 3 - Visual representaon of
the consequences of reux into a
20-gauge catheter lumen using the
Experiment 1, theorecal/mathe-
macal calculaons and Experiment
2, actual in vitro venous values. The
individual pictures of each NFC illus-
trate the distance in microliters (μL)
the amount of blood can reux into
the catheter using both the theo-
recal/mathemacal Experiment 1
(black) and actual in vitro venous
value Experiment 2 (red). On each
of the cross- seco nal views, the vol-
ume of blood reux is depicted in
red. Each NFC illustraon shows the
silicone elastomeric septum in yel-
low, outer NC housings in blue and
uid pathway in light blue.
Vrh=π
2
V = volume, r = radius, and Δh = change in height.
Figure 3 provides a visual representaon of the venous
simulaon experimental reux values as they appear inside a
20-gauge catheter connected to the respecve NFC, illustrat-
ing the implicaons of uid movement and reux within a
catheter.
Results of disconnecon displacement
Four-hundred and twenty NFC uid displacement mea-
surements were performed in vitro for negave, neutral and
an-reux NFC (30 actuaons for each of the rst 11 NFCs,
with a total of 14 NFCs for both experiments 2A and 2B). The
complete results of theorecal and actual venous simula-
on of uid reux are displayed in Table II. The results for
the three categories of negave, neutral and an-reux NFC
were reported per NFC, per category and in ranges of theo-
recal and actual. In the negave displacement group uid
displacement volumes were ranging from 9.73 to 50.37 μL for
all NFCs. This negave displacement group represented the
widest range of values in comparison to the four categories.
The theorecal calculaons were lower than the actual re-
sults by 10%-80%, with standard deviaon.
Table III represents the mean results of the top ve per-
forming NFCs as predicted by the quantave analysis versus
actual reux volumes based on the in vitro experiment.
Assessment of reux in needle-free connectors
6
© 2017 The Authors. Published by Wichg Publishing
TABLE III - Mean results of the top ve performing NFCs
Predicted volumes (μL) Actual volumes (μL)
Model Reux
volume
Model Reux
volume
Rymed InVision 2.93 Nexus TKO-6P 0.02
Nexus TKO-5 4.03 Nexus TKO-5 0.34
Nexus NIS 6P 5.21 ICU Neutron 1.73
ICU Neutron 5.21 Nexus NIS 6P 3.60
Nexus TKO-6P 5.26 Rymed InVision 6.54
Predictors of quantave analysis versus actual reux volumes of in vitro
experiments.
TABLE IV - Predicted versus actual reux volumes of the lowest ve
performers
Predicted volumes (μL) Actual volumes (μL)
Model Reux
volume
Model Reux
volume
BD Carefusion
MaxPlus
75.81 BD Carefusion
Smartsite
50.37
B. Braun Ultrasite 59.69 B.Braun Ultrasite 38.83
BD Carefusion
Smartsite
27. 92 BD Q-Syte 38.34
BD Q-Sy te 23.20 BD Carefusion
MaxPlus
23.7 3
Baxter One-Link 11.98 B. Braun Caresite 18.23
Predictors of quantave analysis versus actual reux volumes of in vitro
experiments with NFCs allowing the most reux.
Similarly, Table IV lists the predicted versus actual reux
volumes of the boom ve performers (NFCs allowing the
most amount of reux).
Figure 4 lists the reux volume range per NFC design cat-
egory from Table II.
Experiment 2B: Actual venous simulaon of posive
pressure NFC reux volume (Tab. II)
Purpose
Quanfy the amount of uid movement or reux associ-
ated with the connecon of a male luer lock to each of three
posive pressure NFC connectors.
To measure blood reux or uid movement associated
with each posive displacement NFC upon connecon of a
male luer, an in vitro venous model was created in the labora-
tory using the following:
Materials (Fig. 2)
An industry standard 10-mL syringe (BD Luer-Lok™ tip
syringe)
Needle-free connectors (NFCs)
Clear PVC tubing and stopcock
Glass capillary rod (6 mm OD × 1.2 mm ID × 12”)
Metric ruler
Collection bag with water (green food coloring added).
Method
The in vitro venous pressure model was designed to replicate
the condions that cause blood reux into an IV catheter during
connecon of a syringe from each NFC. This venous simulaon
apparatus/model was designed to replicate the peripheral ve-
nous pressure found in the human vasculature (2, 23). For the
purposes of this study, an average venous pressure of 8 mmHg
was used. A glass capillary rod was used to allow for visualiza-
on as well as accurate measurement of uid movement.
For the category of posive displacement NFCs:
To eecvely test reux, due to the design and funconal-
ity of the posive displacement NFCs, the tesng was reversed
from the test steps above to measure connecon reux (16).
Each of the posive displacement NFCs were connected to
the PVC tubing aached to a stopcock and the vercal glass
capillary rod on the model. The following procedure was per-
formed a total of 30 mes per NFC brand:
1. A 10-mL syringe was filled with water and attached di-
rectly to the NFC.
2. The stopcock on the model was turned “OFF” to the glass
capillary tube.
3. The 10-mL syringe plunger was depressed and all air was
purged from the NFC, tubing and stopcock on the model.
4. The stopcock was turned “ON” to the glass capillary rod.
5. The syringe plunger was slowly depressed allowing fluid
to fill the glass capillary rod until the fluid level reached
Fig. 4 - Reux volume range per needle-free connector (NFC) design
category from Table II.
Needleless connector design Range of reux
Negave displacement 9.73 μL to 50.37 μL
Neutral displacement 3.60 μL to 10.80 μL
Pressure acvated an-reux 0.02 μL to 1.73 μL
Posive displacement 18.23 μL to 38.83 μL
Hull et al 7
© 2017 The Authors. Published by Wichg Publishing
to provide comparison of potenal blood reux. It is not
known how long it takes for undisturbed blood in an NFC or
catheter to coagulate. It is not known the minimum blood
volume that will occlude an intravenous catheter. These is-
sues are the subject of future study. The funcon of nega-
ve, neutral and an-reux NFC is consistent with the uid
shi occurring primarily at disconnuaon. Posive displace-
ment NFCs have a dierent funcon with a mechanical valve
that required measurement of the uid movement at a dif-
ferent stage. In the posive displacement NFC, the uid shi
upon disconnecon is oset by the outward displacement
of uid, dierent from negave and neutral NFCs. This dif-
ference in the posive displacement NFC required the uid
displacement measurements to be performed at the me
of connecon, rather than disconnecon. Since intravenous
devices with posive displacement NFCs connue to have an
incidence of occlusion with the catheters, the hypothesis was
that signicant reux occurred at some point of connecon or
disconnecon, or even aer the posive pressure push of u-
id, jusfying the measurement and comparison with another
NFC. The researchers recognize that this created a variaon,
which should be considered as a signicant variable in com-
parisons between each of the NFC categories represented in
this study. Since all NFCs have some uid shi that may result
in blood reux upon connecon and/or disconnecon these
measurements do provide value in comparison, but require
an understanding of the disncon between the categories
and NFC funcons which may not facilitate an exact correla-
on.
The design of NFC has a signicant impact on the ability
to clear blood and control reux. Blood provides many of the
nutrients to support the growth of bacteria. Residual blood
inside the uid pathway of an NFC has the potenal to in-
crease the risk of occlusion of the device and may promote
bacterial growth (2, 24, 25). Each of the NFCs tested in this
study was designed to funcon in a specic way, leading it to
be classied as negave, posive, neutral or an-reux. For
the purposes of this study, the NFCs were categorized based
on design and funcon. A brief descripon follows:
Negave displacement NFCs allow uid displacement into
the catheter lumen during disconnecon from a male luer
syringe or IV tubing. This displacement occurs when uid
(blood) is mechanically pulled away from the paent and into
the catheter or NFC lumen based on pressure changes (9, 13).
Because blood is pulled toward the NFC through the catheter
upon disconnecon, protocol states the catheter be clamped
prior to luer-lock disconnecon (2, 6, 14). Apart from blunt
cannulas entering a split-septum, the general mechanism
consists of a plunger depressing a pre-slit septum facilitang
uid ow through the center of the device (6, 26).
Posive displacement NFCs allow uid displacement into
the catheter lumen during connecon of a male luer syringe
or IV tubing. Fluid movement or reux occurs upon connec-
on with sucon created as the syringe is pushed into the
NFC. Upon disconnecon of the syringe from the NFC a nal
uid push/displacement or uid movement occurs out as a
funcon of the posive displacement NFC (27). Several func-
onal characteriscs of posive NFCs dier from other NFCs.
For example, while an elasc or deformable plunger is sll
depressed during luer-lock connecon, the uid ow occurs
108 mm (equal to 8 mmHg of simulated venous pres-
sure) on the metric ruler.
6. The syringe was disconnected from the NFC and the
amount of fluid in the glass capillary tube was recorded.
7. The syringe was again connected to the positive displace-
ment NFC and the amount of fluid reflux in the glass cap-
illary tube was recorded.
Three samples of each NFC were tested; steps 1-7 were re-
peated 10 mes for each sample for a total of 30 venous
simulaons per NFC.
All 30 tests were totaled and averaged to obtain a stas-
cally signicant total uid reux distance into the glass capil-
lary rod. In this study, all experiments were conducted by one
person, minimizing user variances, resulng in relavely low
standard deviaons.
The inside diameter of the glass capillary rod is 0.60 mm.
The average distance of uid reux volume of each of the 14
NFCs was used to calculate the total reux volume in micro-
liters (mm3 or µL)
Vrh=π
2
V = volume, r = radius, and Δh = change in height.
Figure 3 provides a visual representaon of the venous
simulaon experimental reux values as they appear inside a
20-gauge catheter connected to the respecve NFC, illustrat-
ing the implicaons of uid movement and reux within a
catheter.
Results of posive displacement
Four-hundred and twenty NFC uid displacement mea-
surements were performed in vitro (30 for each of the 3
posive pressure NFCs). The complete results of theorecal
and actual venous simulaon of uid reux are displayed in
Table II. The results for the last category of posive NFC were
reported in ranges of theorecal and actual. In the posive
displacement group were uid displacement volumes ranging
from 18.23-38.83 μL with displacement reux occurring upon
connecon. This posive displacement group represented
a narrow range of values in comparison to the other three
categories. The theorecal calculaons were generally higher
for this group than the actual results by approximately 35%,
apart from the B. Braun Caresite where the theorecal calcu-
laon was approximately 41% lower than the actual (Tab. II).
Table III represents the mean results of the top ve per-
forming NFCs as predicted by the quantave analysis versus
actual reux volumes based on the in vitro experiment.
Similarly, Table IV lists the predicted versus actual reux
volumes of the boom ve performers (NFC allowing the
most amount of reux).
Figure 4 lists the reux volume range per NFC design cat-
egory from Table II.
Discussion
All NFCs have some uid movement/reux either on con-
necon, disconnecon or both (16). In this study, we chose to
measure the uid movement for each category of connector
Assessment of reux in needle-free connectors
8
© 2017 The Authors. Published by Wichg Publishing
around the plunger (6, 26). This space between the plunger
and outer housing creates a reservoir where uid is gathered;
when the NFC is disconnected from a syringe or IV tubing,
uid movement occurs and is pushed outward, toward the
paent (13). This design is created to overcome potenal
blood reux that occurs upon disconnecon, but does not
prevent uid displacement associated with connecon (13).
Theorecally, reux in posive NFCs may also occur aer the
uid push occurs on disconnecon, rst shiing uid out and
then retracng uid back. The method to prevent the poten-
al uid movement aer the outward push of uid with dis-
connecon is through clamping (6, 14, 15). Measurement of
pressure variaons of posive displacement NFCs was only
performed in this study upon connecon, not aer posive
uid disconnecon.
Neutral displacement NFCs suggest the absence of uid
movement upon connecon or disconnecon. The mar-
keng term neutral indicates prevenon of blood reux
that is not substanated in other research (18). The name
‘neutral NFC’ inherently suggests that these devices elimi-
nate movement of uid typically observed in negave and
posive NFCs (13, 26). However, the internal mechanisms
that govern funcon of when and how uid movement and
ow is established appear to be like those of other negave
NFCs (13, 18).
An-reux NFCs suggest minimal uid movement upon
connecon or disconnecon. The funcon of an an-reux
NFC is through a 3-posion silicone diaphragm, which opens
and closes based upon uid or infusion pressure. The an-
reux diaphragm opens or closes based on uid pressure
changes from sources such as IV pump, IV bag, when ush-
ing with a syringe or from physiologic body pressure chang-
es (13, 17). Fluid movement and blood reux is minimized
with connecon or disconnecon of a male luer syringe or
IV tubing. The diaphragm within the an-reux NFC sup-
ports connuous bi-direconal uid pressure control when
aached to the hub of a catheter. When the uid pressure
drops, the an-reux diaphragm closes prevenng blood
reux into the catheters. NFCs designed with an an-reux
diaphragm provide connuous uid control while aached
to the catheter.
This study sought to quantavely evaluate uid re-
ux within NFCs. The results demonstrate a wide range of
displacement in dierent NFCs ranging from 10-50 µL for
‘negave’ NFCs, 3-10 µL for ‘neutral’ NFCs, and displace-
ment that approaches 0 with a range of 0.02-1.73 with pres-
sure acvated an-reux NFCs. Recent research validates
the results with similar ndings on some of the included
NFCs (20). Of the commercially available NFCs tested in Ex-
periment 2, pressure-acvated an-reux NFCs performed
best in terms of minimizing uid displacement. The results
suggest NFC designs and funconal variaons represent
potenal clong risk associated with blood reux.
Data shown in Table II and Figure 3 demonstrate the
following:
1. All needless connectors have a measurable volume of re-
flux on connection or disconnection, however small.
2. The amount of reflux within a catheter is dependent on
the individual design of the NFC.
3. The type of NFC device (negative, positive and neutral)
does not inherently guarantee against unintended or un-
controlled fluid movement or reflux of blood.
4. Anti-reflux connector had the lowest measurable volume
of fluid movement.
Clinical implicaons
Blood reux volumes as small as 4-30 µL may result in brin
formaon adequate to occlude the funcon of a catheter (28).
Body movements, muscle exing, respiraons, coughing, vom-
ing, crying, clamping, unclamping, syringe plunger rebound,
and connecon/disconnecon of syringes all cause mechanical
and physiological pressure changes within a catheter that typi-
cally pulls blood into the catheter p (11, 29). Short peripheral
catheters, PICCs and midlines are parcularly aected by blood
reux due to their small lumen diameter and high surface area.
Complicaons such as sluggish ow, inability to aspirate blood,
loss of patency, brin sheath formaon, catheter dysfuncon
and even catheter-related infecons are all complicaons
which may be related to blood reux (30, 31).
NFCs that permit a blood reux volume >10 μL allow
blood to move beyond the smooth-bore of the distal end of a
20-gauge catheter and into the wider lumen. Any amount of
blood moving into the lumen of a catheter may create the op-
portunity for paral or complete occlusion (13, 32); however,
as illustrated in Figure 3, reux volumes >10 μL provide great-
er risk due to the shape of the lumen. While the exact volume
of blood reux into each catheter resulng in occlusion is un-
known, greater blood reux volume and longer me in situ
will cause coagulaon within a catheter lumen. Smaller lumen
catheters, such as PICCs and midlines have higher incidence of
occlusion and may have greater impact from any amount of
blood reux. Catheter dysfuncon with loss of patency is the
most common complicaon of intravascular catheters result-
ing in signicant impact on connued catheter use with add-
ed cost associated with treatment or replacement (33-42).
According to Rupp, Jarvis and others, design features and
complexies of NFCs create higher or lower risk for vascular
access device infecon. Vascular access device infecon rates
have increased in some facilies with the advent of luer-
acvated mechanical valve NFCs (12, 23, 43, 44). The ability to
eecvely disinfect the surface area, gaps and hub designs of
each connector are listed by Jarvis as characteriscs aecng
risk of infecon (8). Ease of ushing and complete clearance of
all blood products and medicaons within the NFC is another
design feature contribung to infecon risk. CLABSIs impact
paent safety and nancial risk. To reduce CLABSIs and com-
plicaons of occlusion, it is crucial that all blood be adequately
ushed from NFCs and the reux of blood be minimized.
Methods to maintain patency and funcon of catheters
include consistent ushing, standardizaon of NFCs through-
out the facility and frequent educaon with competency vali-
daon on use of NFCs per manufacturers recommendaons.
The relaonship between blood reux and occlusion is not
claried in the research, although theorecally NFC pressure
control prevenng reux and minimizing blood within the
catheter would reduce occlusions while maintaining catheter
patency (18, 45, 46). In the Canadian Vascular Access Asso-
ciaon (CVAA hp://cvaa.info/PUBLICATIONS/OcclusionMan
Hull et al 9
© 2017 The Authors. Published by Wichg Publishing
agementGuideline(OMG)/tabid/229/Default.aspx ) Occlusion
Management Guidelines, prevenon strategies note the need
for educaon to: prevent reux of blood into the p of the
catheter by avoiding syringe rebound, keeping the infusion
rate at a level to avoid pressure changes or stasis, ushing
with at least twice the volume of the device and more aer
blood administraon or draws, and consideraon for using
technology designed to prevent catheter occlusions (39).
For those NFC manufacturers who indicate clamping upon
disconnecon within the instrucons for use, the NFCs are
not intended to be used without a clamping sequence. The
signicance of microliter reux volumes on each catheter re-
mains speculaon; results are currently unknown and are the
subject of research to follow this invesgaon.
Limitaons
While the theorecal/mathemacal calculaons were
useful in idenfying best and worst uid reux in this in vitro
invesgaon, several limitaons prevented the exact predic-
on of expected reux with a greater degree of accuracy. The
theorecal calculaons were based purely on the 3-D model
changes in volume and uid displacement created when the
so silicone septum was compressed by the male luer-lock
connector. Addional variables inuencing the actual amount
of uid-movement/reux into the catheter included:
Amount of pressure or distortion of the soft silicone ma-
terial within each NFC
Amount of deflection and speed of contraction of the
soft silicone material when engaging luer-lock or cannula
to the needle-free IV connector
The opening and closing of the split septum seals in the
soft silicone septum
The potential for mechanically created fluid movement
in and out of the system at different rates due to internal
mechanisms, pressures and freely moving bi-directional
flow
Manner in which some irregularly shaped compressible
parts fold, and the amounts of residual fluids these parts
trap as they fold.
Research performed with theorec calculaons and in vitro
tesng is a limitaon where clinical implicaons are dicult
to dene. Clinical relevance of reux volume in intravascular
catheters has yet to be determined. The venous simulaon
experiments yield insight into the amount of reux likely to
occur with a standard venous pressure of 8 mmHg; however,
actual reux in the clinical seng is inuenced by a variety
of other factors. Paents are likely to have condions result-
ing in abnormal blood pressures (both high and low) (47), ab-
normal blood viscosity (usually higher) (48) and are likely to
experience temporary, oen acute, changes in bloodstream
pressure due to factors such as bodily movement, coughing,
sneezing, etc.
The experimental values of reux also have their own
limitaons. First, these values are for unclamped operaon.
Surprisingly, the clamping sequence in some manufacturer
informaon for use is not specied or not clearly described,
whereas others are clear in the instrucons for clamping
aer disconnecon (13, 22, 49, 50). In addion, we have
compared the reux upon disconnecon for negave, neu-
tral and an-reux connectors to the reux upon connecon
for posive connectors. In doing so, we chose to compare the
maximum inward movement of uid into the catheter at any
point during the usage of the NFC, which (as highlighted in
Tab. I) funconally occurs during connecon of a syringe for
posive displacement NFCs, and during disconnecon for all
other NFC types. This dierence in funconal uid movement
establishes a variable and limitaon in direct correlaon of
results from negave, neutral, an-reux and posive dis-
placement NFCs. Surfaces that contact blood (especially sur-
faces in irregularly shaped regions from which blood may not
be completely expelled upon ushing) serve as zones where
adverse events such as occlusion formaon and bacterial
colonizaon can occur. Thus, our work idenes the way in
which NFCs may be expected to perform best, in relaon to
uid movement, through both theorecal and actual quan-
tave measurement methods.
Conclusion
In conclusion, this study serves as a necessary stepping
stone to quantavely inspect and evaluate commercially
available NFCs, while also establishing evidence for educa-
on of healthcare providers regarding risk associated with
NFCs. These results indicate incorporaon of NFC designs
with pressure acvated an-reux diaphragm, which may
minimize blood reux and potenally contribute to the re-
ducon of lumen occlusion. Overall, the results demonstrat-
ed signicant dierences in the volume of uid reux based
on NFC design. More comparave research on the impact of
blood reux and associated outcomes in intravascular cath-
eters is needed.
Disclosures
Financial support: This study was funded by a grant to the Univer-
sity of Missouri from Nexus Medical, LLC. Shramik Sengupta PhD,
Department of Bioengineering, served as principal invesgator on
this grant. The funding source played no role in the research results
or reporng of the data. The results and conclusions of the research
are the work product of the authors. Graphic contribuons were
received from Nexus Medical.
Conict of interest: All authors submied ICMJE Form for Disclosure
of Potenal Conicts of Interest. G Hull reported no conicts of inter-
est, reported no employment and was a full me student. Dr. Sengup-
ta reported serving as a consultant to Fresenius. N Moureau reported
employment with PICC Excellence, Inc, Greenville Memorial Uni-
versity and Medical Center, Greenville, South Carolina; educaonal
speaker and consultant to 3M, Angiodynamics, Access Scienc, B
Braun, BD Carefusion, Chiesi, Entrotech, Excelsior, Fresenius, Linear
Health Sciences, Nexus, Parker Labs, Teleex, and research grant re-
cipient from 3M, Cook and Entrotech.
This research represents potenal limitaon and bias due to com-
mercial funding. Experiments and research process was performed
independently and exclusively by the University of Missouri research
department; the manufacturer had no role in the research results
or reporng of the data. The role of the manufacturer was in pro-
viding the funding, the product, reviewing the inial objecves and
protocol developed by the research department prior to iniaon
of the study.
Clave, Microclave and Neutron are registered trademarks of ICU
Medical, Interlink and One Link are registered trademarks of Baxter
Assessment of reux in needle-free connectors
10
© 2017 The Authors. Published by Wichg Publishing
Healthcare, Smartsite and MaxPlus are registered trademarks of BD/
Carefusion, Q-Syte is a trademark of Becton Dickinson, Ultrasite and
Caresite are registered trademarks of B. Braun, Invision Plus is a reg-
istered trademark of Rymed, and Nexus TKO-5 and Nexus TKO-6P
are registered trademarks of Nexus Medical LLC.
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... Once the conditioning layer is in place, subsequent reflux episodes trigger a cascade of events that attract more blood proteins to continue to layer onto the site, leading to a thrombus. 3 Reflux often results from mechanical and physiological pressure changes within the patient's vasculature caused by patient activity/movement (eg, coughing, sneezing, vomiting) and catheter access management activities such as changing intravenous bags, clamping/unclamping, syringe connection/disconnection, or syringe plunger rebound. 4 The recently released Infusion Nurses Society (INS) standards 4 recommend that infusion staff know which needleless connector is in use because directions vary and can influence reflux. ...
... 5 Since unintentional blood reflux within the catheter is the primary cause A c c e p t e d M a n u s c r i p t of these occlusions, and use of anti-reflux needleless connectors with bidirectional flow control has been demonstrated to result in the least amount of blood reflux, 6 in the study described here we sought to determine if implementation of anti-reflux needleless connectors could reduce occlusions and associated cost. 3,7 A literature review failed to identify any research comparing types of needleless connectors in relation to the incidence of occlusion and costs associated with thrombolytic use in the home infusion setting. The need for strict cost control and emphasis on positive patient outcomes associated with home infusion require scrutiny of options that could reduce the incidence of complications. ...
... Both those researchers and Hull et al and Faintuch noted that as little as 4 µL of blood reflux results in occlusion. 3,10 In this study comparing needleless devices, we noted similar differences when comparing neutral to anti-reflux devices, with significant differences in outcomes. Implementation of anti-reflux connectors reduced the occlusion incidence in this study by almost half, or 48%, and resulted in significant cost savings to the home infusion pharmacy. ...
Article
Purpose: The study's purpose was to measure the impact of anti-reflux needleless connector usage in prevention of intraluminal thrombotic occlusions among central venous catheters, as represented by alteplase usage, in a home infusion patient population. Methods: An18-month before-and-after cohort study of a single home infusion intervention was conducted to compare occlusion outcomes with use of two types of needleless connectors-neutral and anti-reflux-in preventing catheter occlusions, which have been reported to occur in 28% of home infusion patients, resulting in treatment delays, increased nursing encounters and emergency room visits, and higher overall pharmacy costs for supplies and alteplase. Results: A total of 552,707 patient therapy days were studied: 42.5% in the neutral needleless connector group (n = 235,004 therapy days) and 57.5% in the anti-reflux needleless connector group (n = 317,703 therapy days). The rate of alteplase usage with neutral versus anti-reflux needleless connectors was 4.4% versus 2.2% per 1,000 therapy days, with median alteplase use of 112 (95% CI, 89-169) units versus 82 (95% CI, 68-109) units (P < 0.001). Implementation of anti-reflux connectors reduced occlusions and alteplase usage by 48%. Conclusion: Statistical evidence demonstrated that use of anti-reflux needleless connectors with central venous access devices reduced the need for alteplase in the study population. Since 10% of patient occlusions were within 7 days after home infusion admission, future research may indicate that placement of anti-reflux needleless connectors at the time of in-hospital insertion can improve patient outcomes. This quality improvement measure reduced central catheter occlusions, alteplase costs, and the number of required nursing and emergency room visits.
... The devices are used as end caps to Luer Lock onto the hub of peripheral and central catheters. 20 Different types of NFC are commercially available in clinical settings, including negative displacement, neutral displacement, pressure-activated anti-reflux, and positive displacement NFCs. 21 In particular, NFCs in vitro studies showed significant differences in reflux volume at the time of Luer Lock disconnection of the syringe from the catheter after intravenous flushing or infusion. ...
... 21 In particular, NFCs in vitro studies showed significant differences in reflux volume at the time of Luer Lock disconnection of the syringe from the catheter after intravenous flushing or infusion. 20,22 In particular, the pressure-activated anti-reflux NFC, which is one of the latest generation NCFs, can improve patient safety and prevent blood reflux and subsequent intraluminal catheter occlusion. [23][24][25][26] The device incorporates a patented bidirectional silicone valve to help prevent backflow of blood by physically absorbing and compensating for pressure changes that usually cause blood to flow back into the catheter lumen. ...
... In light of the literature review and based on a cost-benefit analysis, a pressure-activated anti-reflux NFC was adopted for the management of vascular catheters and to maintain the catheter free from clots, even if the catheter was not under continuous perfusion. 20,22 The device selected was Neutron™ (ICU Medical, Inc., San Clemente, CA, USA). ...
Article
Objectives To evaluate the effectiveness of needle-free connectors to maintain Central Venous Catheter—CVC patency. Background Loss of patency is a common complication associated with CVC. For patients, this can be stressful and painful, and can result in a delay in infusion therapy. Pressure-activated anti-reflux needle-free connectors are one of the most modern devices; however, no studies have compared this connector with the open-system three-way stopcock in terms of the incidence of CVC occlusion. Methods This study is a prospective before and after intervention study. From March to August 2018, an observation phase was conducted with the three-way stopcock as the standard central venous catheter hub and closure system (phase 1). After implementation of needle-free connectors (phase 2), post-intervention observations were made from September 2019 to January 2020 (phase 3). Results Of 199 CVCs analyzed, 41.2% (40/97) occluded in at least one lumen in the first phase, and 13.7% (14/102) occluded after introducing the technological device, absolute risk reduction 27.5% (95% confidence interval 15.6%–39.4%). The lumens supported by needle-free connectors showed a higher probability of maintaining patency compared with three-way stopcocks. No differences were observed in the rate of infection. Conclusions Pressure-activated anti-reflux needle-free connectors are effective and safe devices suitable for the management of vascular access in cardiac patient care. Staff training, even on apparently simple devices, is essential to avoid the risk of infection.
... Categories have been created for marketing purposes such as negative, positive, neutral, and antireflux to categorize each NC. 2,3 The question remains how much reflux is acceptable for NCs labeled for each category. The labels do not always seem to match the NC performance (Table 1) nor the current definitions (Table 2), yet no agency or governing body has created quantitative guidelines to categorize or classify NCs. ...
... [5][6][7][8] The optimal design of a NC remains unclear and unresolved. 9,10 The labeling of NCs confuses many clinicians, 3 leading to difficulty in the use and management of the device. Inconsistent language creates part of the confusion for health care professionals seeking to understand the function and management of these devices. ...
... 11 Pressure changes influence fluid movement and flow from high to low. [3][4][5] An external source such as a syringe, an infusion pump, or a male Luer connection and disconnection creates mechanical pressure. Coughing, vomiting, exertion, mechanical ventilation, and heart contraction create physiological or internal pressure. ...
Article
Background: Manufacturers designed needleless connectors (NCs) to reduce needlestick injuries and exposures to bloodborne pathogens. All NCs displace fluid, and most do not control fluid movement through the device. The observed bidirectional fluid movement and reflux may not be consistent with how the manufacturer of the device describes NC. Reflux may lead to a significant patient safety risk as it relates to intraluminal thrombotic occlusion and infection. Methods: The in vitro observational study 1 (OS1) systematically tested bidirectional flow control; the ability prevented retrograde fluid from flowing into the infusion system. Researchers tested 13 commonly used NCs. The observational study 2 (OS2) measured the amount of displaced fluid in each NC paired grouping during connection and disconnection of a Luer locking device. Results: OS1: Eleven NCs failed bidirectional flow control, and 2 passed bidirectional flow control. OS2: All 13 NCs had varying amounts of fluid displacement or reflux. The measured volume of reflux for NCs during disconnection was 0.17 μL to 114.65 μL. The measured volume of reflux for NCs during connection was 11.73 μL to 34.43 μL. Conclusion: NC labeling does not appear to correspond with manufacturer claims. Neutral displacement does not appear to be present in the NCs used in this observational study. To properly instruct health care professionals about using the various NCs available, it is imperative to know the accurate bidirectional control, reflux cycle, and volume of reflux beyond the manufacturer's performance claims. Precise information may assist the clinician in reducing intraluminal blood exposure of vascular access devices.
... A multitude of NFCs are available commercially but most share common design features relating to the access port. In almost all cases, access to the catheter is activated through the insertion of a male Luer connector (from a fluid giving set or syringe) which causes the deformation of a silicone septum and therein provides access to the catheter line [25][26][27]. Three of the more common approaches are highlighted in Figure 2. ...
... Removing blood from the NFC is a critical concern and there has been an increasing shift from opaque NFC structures to more transparent polymers that can enable visual inspection of the internal working of the hub. The movement of blood within the catheter and its propensity to travel (reflux) to the needle free hub upon the insertion and disconnection of the external Luer is however dependent on the design of the NFC hub [25,26]. A variety of engineering features have been implemented in recent years as a means of improving the performance of such devices in terms of haemocompatibility and in reducing the potential for CRBSI. ...
... The presence of blood within the fluid pathway of an NFC can result in haemolysis of the red blood cells which increases the risk of a fibrin clot leading to occlusion and ultimately prevents fluid transfer. Moreover, it provides a pool of nutrients that can promote the growth of bacteria [25]. Body movements (muscle flexing, respiration, coughing etc.) and clamping of the catheter can all induce changes in the mechanical and physiological pressure within the catheter that can serve to push blood along the line [28,29]. ...
Article
Full-text available
Catheter related blood stream infection is an ever present hazard for those patients requiring venous access and particularly for those requiring long term medication. The implementation of more rigorous care bundles and greater adherence to aseptic techniques have yielded substantial reductions in infection rates but the latter is still far from acceptable and continues to place a heavy burden on patients and healthcare providers. While advances in engineering design and the arrival of functional materials hold considerable promise for the development of a new generation of catheters, many challenges remain. The aim of this review is to identify the issues that presently impact catheter performance and provide a critical evaluation of the design considerations that are emerging in the pursuit of these new catheter systems.
... 1,2,5,6 These devices come in numerous designs, which include positive, negative, and neutral fluid displacement abilities, using mechanical or pressure-sensitive valves. 7 Advances in NC design have reduced a number of undesirable design features, such as dead space, interstitial spaces, opaque housings, significant reflux volumes, priming volumes, and fluid displacement. 1,2,5,6 The potential for bacterial colonization of NCs and subsequent associated catheter-related infection has also been a major concern. ...
Article
Full-text available
Needleless connectors are used widely across all types of vascular access devices and provide safe, needleless administration of intravenous fluids and medications. An analysis of patients from an outpatient parenteral antimicrobial therapy program is presented in which elastomeric pumps had failed to flow due to incomplete tightening of Luer lock needleless connections. An alert was issued to community nursing staff responsible for daily elastomeric pump changes to ensure that needleless connectors were properly checked for full tightening. The frequency of failure of flow events before and after the alert was reviewed. Force and torque profiles required to activate the internal mechanism of connectors were measured in the 4 most frequently used needleless connectors in the outpatient parenteral antimicrobial therapy program. The degree of torque and force required to activate the different needleless connectors varied and was identified as a factor contributing to inadequate connection with the elastomeric pump and consequent failure of flow. Repeated feedback to nursing staff over the study period about the force and torque required for needleless connector flow activation resulted in a highly significant decrease in the rate of failure of flow events per elastomeric pump from a rate of 0.0147 events per elastomeric pump per year in the last 3 months of 2018 to 0.0003 in the first 6 months of 2020 (difference = 0.0144 [CI, 0.0097–0.02]; P < .0001).
Article
Intraluminal thrombotic catheter occlusions are associated with a greater risk of delayed treatment, morbidity, and mortality and higher healthcare costs. The Vascular Access Specialist Team at Hartford Hospital used Lean Six Sigma methodology to identify and address waste, variability, and defects associated with occlusion management. Beginning in 2015, all central venous catheter occlusions in acute inpatient care were assessed by a vascular access nurse specialist. First, the decisions to treat with tissue plasminogen activator were determined using a catheter patency algorithm. Second, negative displacement needleless connectors were replaced by antireflux needleless connectors to reduce unintentional blood reflux and other complications associated with intraluminal thrombotic catheter occlusion. A total of 159 934 central line days were reported between 2014 and 2020. The hospital achieved a 71.3% reduction in annual tissue plasminogen activator used for occlusions over the study period. There was a sustained decrease in annual average needleless connector consumption of 41% after switching to antireflux needleless connectors in 2015. The 5-year cost savings for these 2 interventions were estimated to be $356 005. Lean occlusion management interventions were associated with reduced pharmacy use, medical supply waste, and spending, which have been sustained for over a 5-year period.
Article
Needleless connectors (NCs) for vascular access have limited needlestick injuries, but complications including occlusion, thrombosis, and infections have increased despite reduced needlestick injuries. These complications relate to the ability of an NC design to limit volume fluctuations that can lead to fluid reflux with potential for microbial contamination. Different NC designs requiring specific usage protocols and training, a lack of clarity in NC function relative to manufacturer-designated categories, and confounding results from a limited number of studies comparing different NCs have resulted in confusion, ultimately leading to complications from undesirable fluid movement within the vascular access. The authors therefore quantified the magnitude of reflux with current commercially available NCs using a venous stimulator. Thirteen blinded NC designs spanning the categories of negative and positive displacement, neutral, and antireflux were tested to quantify fluid movement upon disconnection and reconnection from a representative intravenous pressure (3 NCs per design; 10 trials per NC). Trials for each NC tested followed consistent displacement trends leading to tight error bars. Blinded NCs were then characterized according to their function and compared with their category designation after unblinding. All positive and negative NCs functioned in a manner consistent with their respective category designations. Conversely, all NCs categorized as neutral actually functioned with negative displacement (ie, reflux upon disconnection; 4/5 NCs) or positive displacement (1/5 NCs). Only NCs classified as antireflux functioned as neutral, which was confirmed in a blinded bidirectional flow test. These results suggest that the neutral NC-marketed category may be confusing to users unless the particular NC design has an integrated antireflux component.
Article
Injection safety is essential to reduce healthcare-associated infection (HAI) risks when accessing vascular catheters. This general review evaluates vascular catheter access port contamination and associated HAIs in acute care settings focusing on open lumen stopcocks (OLSs) and disinfectable needleless closed connectors (DNCCs). PubMed was searched from January 2000 to February 2021. OLS intraluminal surfaces are frequently contaminated during patient care, increasing HAI risks, and neither an isopropyl alcohol (IPA) pad nor a port-scrub device effectively reduces contamination. In contrast, DNCCs can be disinfected, with most studies indicating less intraluminal contamination than OLSs and some studies showing decreased HAIs. While the optimal DNCC design for reducing HAIs needs to be determined, DNCCs alone or stopcocks with a DNCC bonded to the injection port should replace routine use of OLSs, with OLSs restricted to use on sterile fields. Disinfection compliance is essential immediately before DNCC access since using a non-disinfected DNCC can be an equivalent or greater HAI risk than using an OLS. The recommendations for access port disinfection in selected national and international guidelines vary. When comparing in vitro studies, clinical studies and published guidelines a consensus is lacking, therefore additional studies are needed including large randomized controlled trials. IPA caps disinfect DNCCs passively, eliminate scrubbing and provide a contamination barrier; however, their use in neonates has been questioned. Further study is needed to determine whether IPA caps are more efficacious than scrubbing with disinfectant for decreasing HAIs related to use of central venous, peripheral venous and arterial catheters.
Article
Split septum medical devices are used in tubing for intravenous (IV) fluid administration—an extremely common clinical task. These tubing caps contain a needleless, valveless system that allows fluid to flow directly through the lumen of the catheter but prevents backflow of fluid or blood when the tubing extension is not connected. We experienced complete failure of a needle-free connector extension set with a Luer-access split septum device in multiple patients due to the split septum remaining fused and essentially unsplit despite being connected on both ends. This led to an adverse event in a patient due to repeated unnecessary IV insertion attempts. This case shows how even the simplest of devices can malfunction and highlights the need for vigilance in clinical practice.
Article
Full-text available
Purpose: To evaluate fluid reflux, when disconnecting syringe, for different needleless connectors. Materials: Nine connectors were tested; 540 measurements were carried out. Results: The connectors tested showed very different performances, about reflux, on disconnection of the syringe used for flushing. The calculated reflux volumes are: Max Zero® - BD: 6.90 (±2.47) mm3; MicroClave Clear® - ICU Medical: 6.14 (±1.46) mm3; Bionecteur® - Vygon: 1.24(±0.73) mm3; Neutron® - ICU Medical: 0.12 (±0.15) mm3; SmartSite® Carefusion: 33.51 (±11.50) mm3; Safe Plus® - Cremascoli: 23.54 (±3.56) mm3; NeutraClear® - Cair: 9.36 (±1.87) mm3; NeutroX® - Cair: 0.33 (±0.31) mm3; Dasa® BTC: 2.38 (±1.67) mm3. Differences between investigated devices were statistically significant (p<0.001). Discussion: It is difficult to establish the best quality-price ratio for needleless connectors. It is important to consider several variable factors: continuous or discontinuous infusion, catheter type, usage environment and caliber of catheter used. It would therefore be useful to have an indication of the intraluminal space potentially affected by blood reflux in relation to a specific device. Conclusions: Needleless connector is one of the main factors involved in keeping catheter patency. It is important to perform the best choice among the connectors available. An empirical reflux measurement, relative to the needleless connector and the catheter in use, can be obtained using an 18G cannula.
Article
Full-text available
Background: Central venous catheter (CVC) occlusion is common, affecting 30% of all CVCs. Objective: To compare length of stay (LOS), costs, and readmissions associated with the use of alteplase to clear catheter blockage to outcomes associated with catheter replacement. Design: Retrospective observational study utilizing a large hospital database. Participants: Hospitalized patients treated for catheter occlusion from January 2006 to December 2011. Main measures: Univariate analyses of patient characteristics and treatment patterns and multivariable regression analyses of postocclusion hospital costs, LOS, and 30- and 90-day readmissions were conducted. Key results: We included 34,579 patients treated for a CVC occlusion by replacement (N=1028) or by alteplase (2 mg) administration (N=33,551). Patients receiving alteplase were somewhat younger than those having catheter replacement (60 ± 19 vs 62 ± 20 years old, P=0.0002). After adjusting for patient and hospital factors via regression modeling, average daily postocclusion costs were $317 lower for alteplase recipients than for catheter replacement patients (95% confidence interval [CI]: 238.22-392.24; P<0.0001). Adjusted total postocclusion costs were $1419 lower for alteplase recipients versus patients receiving catheter replacement (95% CI: 307.27-2458.12; P=0.0121). Postocclusion operating room/surgery, radiology, and supply costs were significantly lower for alteplase recipients (P<0.001). Average adjusted postocclusion LOS was similar for both groups (P>0.05). Odds of readmission were not significantly different at 30 or 90 days. Conclusions: Among patients treated for an occluded CVC, alteplase-treated patients had lower daily and total postocclusion costs than patients receiving catheter replacement. Cost differences were mainly driven by lower operating room/surgery, radiology, and supplier costs.
Article
Full-text available
This was a multicenter, quasiexperimental, 140-month, acute care study comparing central line-associated bloodstream infection rates associated with positive or negative intravenous connectors to a zero fluid displacement connector. A decrease in central line-associated bloodstream infections was found after changing from either negative or positive intravenous connectors to the zero fluid displacement connector (P = .005) with total cost savings of over $3 million.
Article
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An investigation into an alleged failure to disclose COI was conducted by an interdisciplinary scientific review committee convened by senior leadership at Georgia Regents University (GRU). The committee reached the findings of a failure to properly disclose the relationship. During the course of that investigation, questions were raised about the methods and data presented in this article. The questions focused in particular on the consistency of the statistics over various study periods as well as the methods by which study sites were chosen. The investigation concluded that the science was flawed.
Article
Impaired blood flow due to abnormal rheologic characteristics results in a multiplicity of clinical manifestations, collectively termed the hyperviscosity syndrome. A basic knowledge of the principles of rheology is important in the understanding of its pathophysiology, especially the relationship between viscosity and flow conditions. The flow characteristics in different types of blood vessels are also determinants in the location of the clinical manifestation. The syndrome can occur in a wide variety of diseases and is best grouped according to the causative element or elements in blood. Abnormalities in the cellular components of blood can occur in the quantity and the quality of erythrocytes, leukocytes, and platelets. Abnormal plasma components can also be in both the quantity and quality of the plasma proteins. Clinical manifestations are the result of vascular occlusion, especially in the microcirculation. The altered rheologic characteristics of either the cellular or the protein component may be temperature dependent, being abnormal only at temperatures below 37 degrees C, so that only the cooler parts of the body are affected. The management of these conditions should be primarily directed at the removal of the abnormal component. At the same time, it should be accompanied by measures that can control the production of the causative element.
Article
Objective: To assess the relative importance of independent risk factors for peripheral intravenous catheter (PIVC) failure. Methods: Secondary data analysis from a randomized controlled trial of PIVC dwell time. The Prentice, Williams, and Peterson statistical model was used to identify and compare risk factors for phlebitis, occlusion, and accidental removal. Setting: Three acute care hospitals in Queensland, Australia. Participants: The trial included 3,283 adult medical and surgical patients (5,907 catheters) with a PIVC with greater than 4 days of expected use. Results: Modifiable risk factors for occlusion included hand, antecubital fossa, or upper arm insertion compared with forearm (hazard ratio [HR], 1.47 [95% confidence interval (CI), 1.28-1.68], 1.27 [95% CI, 1.08-1.49], and 1.25 [95% CI, 1.04-1.50], respectively); and for phlebitis, larger diameter PIVC (HR, 1.48 [95% CI, 1.08-2.03]). PIVCs inserted by the operating and radiology suite staff had lower occlusion risk than ward insertions (HR, 0.80 [95% CI, 0.67-0.94]). Modifiable risks for accidental removal included hand or antecubital fossa insertion compared with forearm (HR, 2.45 [95% CI, 1.93-3.10] and 1.65 [95% CI, 1.23-2.22], respectively), clinical staff insertion compared with intravenous service (HR, 1.69 [95% CI, 1.30-2.20]); and smaller PIVC diameter (HR, 1.29 [95% CI, 1.02-1.61]). Female sex was a nonmodifiable factor associated with an increased risk of both phlebitis (HR, 1.64 [95% CI, 1.28-2.09]) and occlusion (HR, 1.44 [95% CI, 1.30-1.61]). Conclusions: PIVC survival is improved by preferential forearm insertion, selection of appropriate PIVC diameter, and insertion by intravenous teams and other specialists. Trial registration: The original randomized controlled trial on which this secondary analysis is based is registered with the Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au; ACTRN12608000445370).
Article
Background The University Hospital of Northern British Columbia (UHNBC) utilized an opaque positive displacement intravenous (IV) line connector in 2011 and for several years previously. With concerns generated in the United States surrounding positive displacement and the potential increased risk for infection, as well as the training requirements related to ensuring that a proper clamping sequence was followed, a neutral displacement IV connector was implemented in October 2011.Methods Catheter-related blood stream infections and catheter occlusions were monitored at UHNBC for 4 months before (June through September 2011) and 4 months after (November 2011 through February 2012) the implementation of the neutral displacement IV connector by the Parenteral Services nursing team. A staff survey was conducted that reviewed the satisfaction with the newly implemented IV connector.ResultsThe results of tracking catheter occlusions with a neutral displacement IV connector showed an average of 4.04 occlusions that required tissue plasminogen activator per 1,000 catheter days, compared with 5.47 occlusions that required tissue plasminogen activator per 1,000 catheter days with the positive displacement IV connector. During the evaluation period there was a 26% decrease in catheter occlusions with the implementation of the neutral displacement IV connector. Blood stream infection rates remained at zero for the entire evaluation with both displacement types of IV connectors. Nursing staff members were satisfied with the newly implemented IV connector.ConclusionsUHNBC will continue to utilize the neutral displacement IV connector hospital-wide, and continues to monitor both catheter occlusions and catheter-related blood stream infections. Following UHNBC, facilities in the rest of Northern Health have implemented the neutral displacement IV connector.