4 DISCUSSION
Ultrasound-guided BCV approach has gained increasing popularity for CVCs
insertion in children11-13 and TIVAPs implantation in
adults.20-22 Anatomically, the BCV approach has
potential advantages during central venous cannulation compared with its
counterparts of IJV and SCV approach. On one hand, the BCV is formed by
the confluence of IJV and SCV posterior to the sternoclavicular joint
with fewer anatomical variants, whose caliber is also not affected by
patient’s hemodynamic and volume status, respiratory motion, and
ultrasound probe compression;17 while puncturing the
BCV under ultrasound guidance, the entire needle trajectory, which is
parallel to the pleura, can be visualized in real-time by the operator,
decreasing the risk of pneumothorax. On the other hand, the lumen size
and blood flow of BCV are the largest among those available central
veins including IJV and SCV,18 and the
catheter-to-vein diameter ratio of the catheter (Babyport, 4.5F =
1.49mm) and BCV (about 3.2mm-diameter in infants)9 is
less than 45%, which has been considered as a protective factor for
CRT;11 meanwhile, the flow of BCV is close to that of
the superior vena cava with low risk of flow disturbance, which further
decreases the risk of CRT.12Moreover, the cannulation site of
the catheter is located in the supraclavicular
fossa,17 which may alleviate patient discomfort at the
neck,7 reduce the risk for
infection,12,18 and maintain a smoother catheter
curvature.21
To our knowledge, no previous
literature has evaluated using BCV approach for TIVAPs placement in
pediatric oncology population. Right-sided approach was adopted
universally in the present study group due to the operator preference
and the theoretical risk of thoracic duct injury during left-sided BCV
access. However, previous
literature suggested that the left BCV approach could be safe and
reliable in infants,14-16,23children19,24 and adults10 for CVCs
catheterization. Some authors even considered the left BCV approach to
be superior to the right15,16,19,24 because the left
BCV courses horizontally, the ultrasound-guided manipulation is
easier,16 with a higher successful cannulation rate by
first attempt.15 On the contrary, Avanzini et
al.11 believed that the left BCV approach may increase
the risk of CRT due to the greater surface contact between the catheter
and the vessel wall, so the right BCV should be recommended as the
preferred mode for access.
The technical success rate was 100% in the present study group,
consistent with previous literature on BCV approach for CVCs
catheterization in children (94%-100%)11-13,16 and
TIVAPs placement in adults (96.5%-100%).10,21 In the
present study, the success rate for cannulation by first attempt was
91.42% (32/35), similar to previous reports in adult studies
(90%-99.30%).10,21 But it was higher than those
reported for children (65.4%-73.8%),9,12,16,17,25which can be attributed to differences in age and weight among different
patient populations. The majority of the children in the present study
were older than 12 months, while most of the patients included in most
other studies were infants and even premature
infants9,16,17,25 with weigh as low as
2.5kg.9,16,17 According to the finding reported by
Breschan et al.,9the younger age and lower weight are associated with higher risk for
repeated attempts in gaining BCV access.9
The correlation between proceduralist experience and patient outcome for
pediatric TIVAPs insertion continues to be a subject of investigation.
Recently, a study from Shilati et
al.8 demonstrated that, individual surgery volume and
specialty training might influence the incidence of early revision or
replacement with an inverse correlation. Limited by the small number of
cases in the single institutional children’s hospital, it is difficult
to accumulate a large amount of experience in a short time. However, our
surgeons were from the integrated medical union of people’s hospital,
and we had extensive experience with hundreds of ultrasound-guided BCV
punctures for adult TIVAPs procedures. In our children’s population, no
intraoperative complications occurred despite the small sample cohort,
the average procedural time of 44.6 mins was comparable with the 41.7-47
mins reported by Bawazir et al.,26 and the median
fluoroscopy time of 10 seconds was obviously shorter than that in other
study.8 Likewise, Oulego-Erroz et
al.17 emphasized the necessity for specialists to
receive training and gain experience in adults in advance, in order to
shorten the learning curve in children as soon as possible.
Within a cumulative 19,723
catheter-days in the present study, the total and postoperative
complication rates were both 11.43% (4/35) due to no occurrence of
intraoperative complications, which translated into 0.20 complications
per 1000 catheter-days. Such finding was in accordance with prior
published literature on children reporting complication rates ranging
from 7.46% to 30%7,27-29 and from 0.15 to 0.90
complications per 1000 catheter-days.30 However, the
incidence of total complications in adult literatures on BCV approach
ranged from 3.18% to 6.00%,21,22 which was lower
than that of our pediatric population. Thus, such difference in spectrum
of complications between adults and children is likely attributable to
differences in body size, vessel caliber and vertical growth, which
warrants further investigation.
Currently, there is no consensus regarding the safety of TIVAPs
placement in children with small body sizes, especially infants less
than 1 year of age. Two recent retrospective cohort studies showed that
patients with low weight (less than 7 kg) might be associated with an
increased risk of intra- or post-operative
complications.29,31 An infant with 6.3-kg-weight from
the present study developed local hematoma and catheter dysfunction
postoperatively. The hematoma was treated by repeated wet compress and
local pressure during the initial
three days after surgery, then slowly resolved after nearly two months.
Chemotherapy had to be carried out simultaneously due to disease
progression. Generally, suturing is not required for the skin incision
at the exit of the catheter, but suture was implemented in the present
infant due to blood oozing to achieve hemostasis at the end of the
procedure. It is hypothesized that, the blood from the venipuncture site
seeped into the tunnel and accumulated around the catheter and port
pocket, leading to subsequent local subcutaneous hematoma. In a
challenging pediatric group with hemophilia, early pocket site bleeding
was not associated with increased episodes of infectious
complications.32 Therefore, noninvasive methods are
preferred for managing the local hematoma, and surgical debridement
should be a matter of prudence.
Catheter dysfunction, defined as inability of blood withdrawal with or
without difficulty of fluid injection, can be a sequela of fibrin sheath
formation, catheter thrombosis, or catheter tip adherence to the
vascular wall.2 This complication occurred in two
patients in the present study group, which were likely related to
intraluminal thrombotic obstruction without ability of blood aspiration
and fluid injection, one of whom was the infant presented with local
hematoma as described above. Patency was restored in both catheters by
thrombolytic treatment using urokinase (5,000 IU/ml). Previous studies
on TIVAPs and central venous catheters in children suggested catheter
dysfunction being the most common complications,6,29and the occurrence or recurrence of such complication might be a warning
of the increased risk of CRT.33 Thus, once the event
of catheter dysfunction occur, it warrants sufficient attention by
clinicians.
While some authors reported that infection is most common and serve as
the leading cause of unplanned device removal,34,35 no
infectious complications such as CRBSI and local infection were found in
the present pediatric series. For instance, in a large prospective
investigation including more than 4,000 adult
patients,36 port related infection was the most
frequent complication, which was associated with neutropenia after
high-intensity chemotherapy; the authors hypothesized that intravenous
chemotherapy should be carried out at least 6 days after TIVAPs
implantation to reduce infection risk. By contrast, in a
multi-institutional study of 500 children under 5-year-old, the most
common complications identified were mechanical in nature instead of
infectious events.30 Notably, the proportion of
infectious events was certainly not low, almost being the one of the top
two. Similar findings were also reported by two retrospective cohort
studies comprising infants less than 1-year-old.29,31By comparison, all our patients received chemotherapy within 3 days
after surgery, though infection did not occur. Larger prospective study
is warranted to exclude the possibility of the present study’s
underpowering as the cause of low infection rate.
The present study should be interpreted with several caveats. Due to its
retrospective, single-center, and small-sample design, further
prospective, multi-institutional, large-sample sized study is required
to elucidate whether the new vascular access can be widely applied to
this specific patient population. And then, the outcome of the left BCV
access option was lacking in our pediatric series, deserving further
investigation. Furthermore, this study is noncomparative in nature,
comparative studies with IJV and/or SCV access are warranted to
determine the safety and efficacy of BCV access.