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Original Article
European Journal of Anaesthesiology 2004; 21: 594–599
© 2004 European Academy of Anaesthesiology
ISSN 0265-0215
Central venous catheter placement: comparison of the
intravascular guidewire and the fluid column
electrocardiograms
M. T. Pawlik, N. Kutz, C. Keyl, P. Lemberger, E. Hansen
University of Regensburg, Department of Anaesthesiology, Regensburg, Germany
Summary
Background and objective: Placement of central venous catheters in patients is associated with several risks
including endocardial lesions and dysrhythmias. Correct positioning of central venous catheters in the supe-
rior vena cava is essential for immediate use. The objective of a first study was to evaluate the signal quality of
an intravascular electrocardiogram (ECG) during position control using a guidewire compared with the cus-
tomary fluid column-based ECG system, and to assess its efficacy of correct placement of the central venous
catheter. A second study tested if dysrhythmias can be avoided by intravascular ECG monitoring during
catheter and guidewire advancement.
Methods: The jugular or subclavian vein of 40 patients undergoing heart surgery or who were being treated
in the intensive care unit was cannulated. Intravascular ECGs were recorded during position control, and
guidewire and water column lead were compared in the same patient with regard to the quality of the ECG
reading and P-wave enhancement. In another 40 patients, the guidewire was inserted only 10 cm and the cen-
tral venous catheter advanced under guidewire ECG control. Correct position of all the central venous catheters
was confirmed by chest radiography.
Results: All central venous catheters were correctly positioned in the superior vena cava. For the same catheter
position, the P-wave was significantly larger in the guidewire ECG than in the fluid column system. No changes
in the quality of the ECG were detected when the guidewire was advanced or withdrawn by 1 cm relative to the
catheter tip. Cardiac dysrhythmias were not seen during ECG-monitored advancement of the guidewire.
Conclusions: ECG quality using a guidewire lead is superior to the water column-based system. Furthermore,
it is independent from the exact position of the guidewire as related to the tip of the catheter. Using intra-
vascular guidewire ECG during advancement can prevent induction of dysrhythmias.
Keywords: CENTRAL VENOUS CATHETERIZATION, adverse effects, methods; DYSRHYTHMIA, prevention;
ELECTROCARDIOGRAM (ECG), intravascular.
Correct positioning of a central venous catheter (CVC)
is essential to avoid serious complications such as per-
foration, thrombosis or dysrhythmias caused by inter-
actions with the vessel wall or the endocardium [1].
The correct position of the tip of the CVC for therapy
and measurement of the central venous pressure is
considered to be in the superior vena cava close to its
entrance to the right atrium [2]. Blood flow condi-
tions are then optimal to keep the catheter away from
the intima and to dilute infused drugs immediately.
Owing to the risk of malpositioning, the most com-
mon way to control the catheter position is still by
radiography or fluoroscopy during or after placement,
Correspondence to: Michael Pawlik, Department of Anaesthesiology, University of
Regensburg, D-93042 Regensburg, Germany. E-mail: michael.pawlik@klinik.
uni-regensburg.de; Tel: 49 941 944 7801; Fax: 49 941 944 7802
Accepted for publication November 2003 EJA 1579
2108-02.qxd 8/12/04 12:10 PM Page 594
Central venous catheter placement 595
© 2004 European Academy of Anaesthesiology, European Journal of Anaesthesiology 21: 594–599
which is occasionally enhanced by injection of con-
trast medium [3]. The reliability of this method is
limited and additional costs and radiation exposure
are involved. Moreover, repeated catheterization and
chest radiographical films are required if the CVC is
located incorrectly. An alternative method for correct
placement of the CVC is to record an intravascular
electrocardiogram (ECG), which was first described
by Hellerstein and colleagues in 1949 [4]. Using this
technique, an increased P-wave can be detected only if
the catheter tip is intravascular and has passed through
the entrance to the right atrium. Further advancement
of the catheter tip turns the P-wave biphasically after
passing the sinoatrial node and changes its deflection
as the tip reaches the right ventricle, when a broad-
ened R-peak appears. Originally, the method was
used for positioning pacer probes and for intra-
cardial diagnosis of complex cardiac dysrhythmias [5],
and later for accurate positioning of ventriculoatrial
shunts [6]. With increasing use of CVC, the method
was also adopted as an accurate means of confirm-
ing the correct CVC position [7–10]. The technique
was further simplified and made commercially avail-
able with the Arrow-Johans®electrographical adapter
(ARROW, Erding, Germany) [11].
Recently, a modification of this technique has been
described using the Seldinger guidewire as a unipo-
lar lead of intravascular ECG [12,13]. The CVC set
includes a connecting cable with an alligator clip
to connect the guidewire, which is marked to indi-
cate when the tips of the wire and the catheter are
co-located. It also includes a universal adapter, which
allows connection to the usual ECG lead systems.
Several lumen CVC sets are available and in clini-
cal use (Certofix®Mono, Duo, Trio, Trio HF, Quinto,
and Cavafix®Certodyn®; all catheters by: B. Braun,
Melsungen, Germany).
The hypothesis of the present authors was that the
intravascular ECG obtained by guidewire would
show better quality in terms of an enhanced P-wave
than a system based on a fluid column. Furthermore,
it was desirable to discover whether advancing the
guidewire under immediate ECG monitoring after
introduction could prevent any cardiac dysrhyth-
mias from occurring.
Methods
The authors’ institutional review board approved the
protocol, and informed consent was obtained from
80 patients, who were enrolled into two studies.
Patients were excluded if less that 18 yr of age, if they
were carrying a pacemaker or if they had manifest
cardiac dysrhythmia. A triple-lumen CVC (Certofix®
Trio, B. Braun, Melsungen, Germany) – indicated for
clinical reasons – was placed using intravascular ECG
monitoring via a guidewire. A modified bipolar lead II
configuration was recorded. ECG placement was stan-
dardized in all patients by connecting the reference
red electrode to a universal adapter equipped with
a switching function (Certodyn®– Universal adapter,
B. Braun, Melsungen, Germany) on the right thoracal
side (mid-clavicular, second intercostal space). The
yellow electrode was placed on the left thoracic side
(mid-clavicular, second intercostal space) and the
neutral green electrode on the lower left chest (mid-
axillary, eighth intercostal space) (Fig. 1).
In the first study on 40 patients undergoing car-
diac surgery (n20) or requiring intensive care
therapy (n20), the correct position of the CVC
introduced via the subclavian (n20) or internal
jugular vein (n20) was confirmed by chest radiog-
raphy. After venepuncture, the guidewire was intro-
duced and advanced without strict regulation in the
Monitor
Universal
adapter
Clamp
Guidewire
CVC
Yellow
Green
Red
A
B
Switch Figure 1.
Position control of the central venous catheter using
intra-atrial electrocardiogram monitoring via a
guidewire. A: external electrode; B: intra-atrial
electrode.
2108-02.qxd 8/12/04 12:10 PM Page 595
596 M. T. Pawlik et al
© 2004 European Academy of Anaesthesiology, European Journal of Anaesthesiology 21: 594–599
study. Adjusting the black marking on the guide-
wire to the end of the CVC connector matched the
tips of the catheter and the wire. To test the influence
of the exact position of the guidewire relative to the
tip of the catheter, ECG readings were recorded at
different positions, namely with the wire 1 cm inside
or outside the catheter. After the CVC had reached an
intra-atrial position as seen from an enhanced P-wave,
the guidewire was changed to the fluid column
method (i.e. the lumen flushed with physiological
saline solution 0.9%) to compare the ECG signal
quality. Therefore, at this position of the CVC, the
guidewire was withdrawn and the electrolyte-filled
system (Alphacard®, B. Braun, Melsungen, Germany)
connected to record again the intra-atrial ECG. Sub-
sequently, the guidewire was reinserted and the
catheter and wire retracted until there was a decrease
of the P-wave, with an additional 2 cm. ECG readings
were again recorded at various wire positions. After
taking a chest radiograph in the supine position, the
distance of the catheter tip to the entrance of the
atrium was measured and documented.
In a second part of the study on another 40 patients,
the authors tried to avoid guidewire-induced dys-
rhythmias by continuous intravascular ECG reading
during CVC advancement. After venepuncture, the
Seldinger guidewire was introduced through the intra-
venous needle not more than 10 cm for a position just
safely within the vessel. The needle was withdrawn,
the catheter inserted and the tips matched by adjust-
ing the connector and mark on the wire. The catheter
and wire were then slowly advanced under continu-
ous ECG monitoring. After recording of an increased
P-wave, they were drawn back immediately until
P-wave amplitude returned to normal, and an addi-
tional 2 cm.
Data and statistical analysis
P-wave increases were quantified as the peak height
(mV) of the printed ECG signal. All patient data
from trials of cannulation were averaged. Data
(mean standard deviation, SD) were analysed for
statistical significance of differences between the
groups using the U-test with P0.05 being taken
as the level of significance.
Results
All 80 catheters were placed in the correct position
without any complications. Regardless of the venous
access sites, up to three trials of punctures were nec-
essary. In all cases, the catheter was placed in the
superior vena cava. During the first study, brief dys-
rhythmias without clinical impact were observed in
16 of 40 patients (40%). By contrast, no case of dys-
rhythmia occurred in the 40 patients during the
second study where unmonitored advancement of
the guidewire was avoided.
In all 80 patients, a variable but distinct increase
of the P-wave was seen (Fig. 2; 2a), allowing a cor-
rect position to be reached. After withdrawal until
complete restoration of the original P-wave configu-
ration (Fig. 2; 4a) and an additional 2 cm, the radio-
logically controlled tip of the catheter showed a
position 2.3 0.5 cm above the entrance level to
the right atrium in the 40 patients. The correct posi-
tion was evaluated by a radiologist.
The positioning of the guidewire tip 1 cm inside
or outside of the catheter did not change the config-
uration of the P-wave, except for some noise, when
fluid conductivity was added by drawing back
1
2a
3
ECG during withdrawal of catheter
4a
4b
4c
2b
2c
Figure 2.
Electrocardiogram via a guidewire or a fluid-filled column during
position control of the central venous catheter (CVC). 1: CVC tip
extra-atrial, 7 cm below the skin level, tip of CVC and wire match;
2a: CVC tip intra-atrial, tip of CVC and wire match; 2b: CVC tip
intra-atrial, guidewire 1 cm advanced over CVC; 2c: CVC tip
intra-atrial, guidewire 1 cm drawn back into the CVC; 3: CVC
tip intra-atrial, guidewire removed, CVC filled with sodium chlo-
ride solution, Arrow-Johans®system established; 4a: CVC tip extra-
atrial, guidewire reinserted, drawn back until original P-wave
restored, tip of CVC and wire match; 4b: CVC tip extra-atrial,
drawn back, guidewire 1 cm advanced over CVC; 4c: CVC tip
extra-atrial, drawn back, guidewire 1 cm drawn back into CVC.
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Central venous catheter placement 597
© 2004 European Academy of Anaesthesiology, European Journal of Anaesthesiology 21: 594–599
the wire into the catheter (Fig. 2; 2b, c). The change-
over to a pure lead via the fluid column was always
accompanied by a disturbance of the electric signal,
sometimes accompanied by a decrease in P-wave
amplitude, sometimes by a drifting baseline from the
monitor (3 in Fig. 2). In 19 of 40 (47.5%) of patients,
the P-wave increase was more pronounced when the
intra-atrial ECG was measured via guidewire instead
of the fluid-filled catheter. The Pmax/Pmin ratio was
significantly increased when the intra-atrial ECG was
measured via the guidewire instead of the fluid-
filled catheter (6.5 1.8 versus 4.8 1.1; P0.05
(Fig. 3a). Similarly, no significant change was seen with
different positions of the guidewire in the catheter
after the CVC was withdrawn to the original P-wave
amplitude (Fig. 2; 4b, c). The Pmax/R ratio was sig-
nificantly increased using the ECG wire lead com-
pared with the fluid lead (0.60 0.11 versus
0.44 0.15; P0.05) (Fig. 3b).
Discussion
The present study showed that monitoring of intra-
vascular ECG tracing via the guidewire is a reliable
method for the control of correct placement of a CVC
and it offers a number of advantages (Table 1). A
brief increase of the P-wave proves an intra-atrial
position of the catheter tip; the subsequent normal-
ization after withdrawal indicates the correct posi-
tion. A chest radiograph is then only required to
control for complications.
Guidelines for CVC placement recommend that
catheter tips never enter the atrium, and previous
studies have shown that the tips of catheters can
migrate 1–3 cm caudally with movement of the
patient’s arms. A further 1–3cm withdrawal is
therefore essential, since otherwise an intra-atrial
position or an impingement angle between catheter
and vessel wall 40° with an increased risk of vena
cava traumatization may occur [14]. The intravascu-
lar lead has also been successfully used for position
control in the sitting position in specific neurosurgi-
cal procedures, where a CVC is used for diagnosis and
therapy of intraoperative air embolism and the cor-
rect position of the catheter tip is intra-atrial [15,16].
After the insertion of CVCs, chest radiographs are
usually obtained to ensure correct positioning of the
catheter tip in the superior vena cava and to exclude
mechanical complications such as pneumothorax.
Thus, using the intravascular lead is accompanied by
a significant saving of time, labour and costs, with a
reduction in risks associated with exposure to radia-
tion and contrast medium. In a recent analysis of the
time and cost expenditure, 13-fold higher costs were
calculated for the radiographic control compared
with the ECG control [12,17]. The efficacy rate with
regard to the correct position of the method is 92%
[10,17], but correction of a malposition can be achieved
in the remaining 8% without delay and in most cases
without a new puncture.
0
2
4
6
8
10
*
Pmax /Pmin ratio
Figure 3a.
Pmax/Pmin ratio. Data are mean SD. *P0.05 compared with
a fluid column-based electrocardiogram. : fluid column-based
ECG; : guidewire ECG.
0.0
0.5
1.0
1.5
2.0
*
Pmax /R ratio
Figure 3b.
Pmax/R ratio. Data are mean SD. *P0.05 compared with a
fluid column-based electrocardiogram. : fluid column-based ECG;
: guidewire ECG.
Table 1. Advantages of position control via an intra-atrial
electrocardiogram.
Simple technique
Short time requirement
No chest radiograph for position control necessary
No exposure to radiation of contrast medium (less risks)
Less cost of material and staff
Immediate correction of malposition possible
Immediate assurance of correct central venous catheter position
(immediate infusion possible)
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598 M. T. Pawlik et al
© 2004 European Academy of Anaesthesiology, European Journal of Anaesthesiology 21: 594–599
After blind placement of a CVC, an intracardial
position is found in up to 50% of cases [11], but with
the risk of endocardial injury that can cause cardiac
tamponade, a rare but serious complication with a
mortality rate between 65 and 78% [18,19]. Intra-
operative dysrhythmias are further complications of
an intra-atrial CVC position [20]. Brief dysrhythmias
induced during insertion of a catheter or a guidewire
usually lack a clinical impact in otherwise healthy car-
diac patients, but they still must be regarded as indica-
tors of endocardial irritation. In patients with impaired
cardiac output or aortic valvular stenosis, iatrogenic
dysrhythmias can be deleterious if the introduced
guidewire induces atrial flutter. As demonstrated in
the present paper, such dysrhythmias can be easily
avoided by using intravascular ECG monitoring soon
after introduction during catheter advancement.
The use of the guidewire as a lead provides several
advantages compared with the fluid column. With
fluid-filled catheters, the ECG tracing can be impaired
by air bubbles, even when solutions of high ionic
strength are used. However, the metal of the wire pro-
vides constant excellent conductivity and a clear-cut
recording of an increase in the P-wave. The universal
adapter permits switching of ECG monitoring from
the patient to the catheter and back while maintain-
ing sterility, thus avoiding the need for technical
assistance.
The exact position of the wire tip related to the
catheter tip turned out not to be crucial. Therefore,
intra-atrial ECG can be used for position control even
with catheters that are too short to reach the atrium,
e.g. cannulas for dialysis (Table 2). Failure of ECG-
guided CVC positioning has been reported for cases
where sodium chloride solution-filled short catheters
were used [17]. Instead, when the ECG has shown
the intra-atrial position of the guidewire, a correct
position of the catheter advanced over the wire can
be assumed. Pre-existing atrial fibrillation has been
considered a limitation, but in a prospective study
on 40 patients, sinus rhythm was no absolute pre-
requisite for registration of increased P-waves and its
use for position control [21]. Neither atrial fibrilla-
tion, nor atrial flutter nor paroxysmal atrial tachy-
cardia with block interfere with ECG tracing for
CVC placement. Cardiac pacemakers pose a problem
if no P-wave is available. Knot formation cannot be
detected, but it can be excluded with some certainty
if the distance from the tip to the skin does not exceed
20 cm and a P-wave increase was previously seen in
the ECG. While the guidewire is in place, defibrilla-
tion, cardioversion or electrocauterization is allowed
after disconnection of the lead.
The authors are unaware of any previous study that
prospectively and directly compared signal qualities
of intravascular ECG in the same patient using dif-
ferent lead systems. It is concluded that placement of
CVCs using the guidewire assists placement of the
CVC in the correct position because ECG quality is
improved. Furthermore, iatrogenic dysrhythmias can
be avoided by CVC placement in the described manner.
Acknowledgement
The authors thank David Tracey, PhD, Department of
Anatomy, University of New South Wales, Sydney,
Australia, for helpful comments on the manuscript.
There was no financial support or author involvement
with organizations with financial interest in the
subject-matter.
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