1 Clinic for Anaesthesiology and Intensive Care Medicine, Friedrich-Schiller University of Jena, Erlanger Allee 103, D-07747 Jena, Germany. 2 Department of Cardiothoracic and Vascular Surgery, Friedrich-Schiller University of Jena, Bachstrasse 18, Germany. 3 Institute for Experimental Animals, University of Jena, Dornburger Strasse 23, D-07740 Jena, Germany. 4 Biomagnetic Center, and Klinik fur Innere Medizin III, Friedrich-Schiller University of Jena, University of Applied Sciences, Erlanger Allee 101, D-07747 Jena, Germany
* Corresponding author: E-mail: cwsm.schummer{at}gmx.de
Accepted for publication February 18, 2004.
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. In six juvenile pigs the left external jugular vein and right carotid artery were cannulated. A triple-lumen central venous catheter was positioned by ECG guidance using a Seldinger wire as an exploring electrode. The venous and arterial catheters were suture fixed 2 cm beyond the onset of an increase in P wave size. The corresponding anatomical catheter tip position was determined by open exploration of the vessels and the heart. Subsequently the catheter tip position (during advancement) of a pulmonary artery catheter and the corresponding electrical ECG changes were examined in 10 patients during open chest cardiac surgery.
Results. All cathetersarterial and venous, in animals and humansrevealed an increase in size of the P wave as well as the QRS complex. All venous catheters were positioned in the superior vena cava, beyond the pericardial reflection but outside the right atrium. All arterial catheters were positioned in the ascending aorta thus also beyond the pericardial reflection.
Conclusions. The start of an increase in P wave size does not correspond with the entrance of the right atrium. The anatomic equivalent for the electrophysiological changes of the ECG is the pericardial reflection. ECG guidance is unable to distinguish between venous and arterial catheter position.
Keywords: heart, catheterization, central venous ; veins, internal jugular ; monitoring, electrocardiography
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Optimal positioning of the tip of a CVC is a complex and controversial subject. The United States Food and Drug Administration (FDA), for example, strongly disagree with the practice of positioning the tip of a CVC into the right atrium because of the potential for cardiac-related complications like cardiac tamponade.4 Others, like the National Kidney Foundation: Dialysis Outcomes Quality Initiative (NKF/DOQI) published clinical practice guidelines for tunnelled (cuffed) catheters stating that the tip should be positioned at the superior vena cava-right atrial (SVC-RA) junction or into the right atrium to ensure optimal blood flow.5 With regard to temporary or non-tunnelled haemodialysis catheters, the NKF/DOQI recommend positioning the catheter tip at the SVC-RA junction or in the SVC.
In a recent study, we advanced 57 of 110 triple-lumen catheters 15 cm beyond the correct position as determined by ECG guidance.6 Only five of these catheter tips were found to be positioned 1 cm distal to the crista terminalis, in the right atrium as confirmed by transoesophageal echocardiography (TOE) (Fig. 1). We hypothesized that the ECG amplitude signal is actually detecting another anatomical structure other than the right atrium. In order to investigate this phenomenon, we positioned 100 triple-lumen CVCs either via the right or the left internal jugular vein by ECG guidance using a fluid column in the middle lumen as a detecting electrode (port opening 2.5 cm from catheter tip).7 None of these catheters were found to be intra-atrial. Finally, we postulated that the increase in P wave amplitude corresponds to the pericardial reflection. This study was designed to test this hypothesis. Initially, we recorded the course of electrical changes during ECG-guided central venous and arterial catheter insertions in pigs. Then we adapted the study design to a clinical setting where tip position of a pulmonary artery catheter (PAC) and the associated electrical ECG changes were examined in patients during open chest cardiac surgery.
|
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Animal study
Six juvenile female pigs (2126 kg) received care in compliance with the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health.8
Each pig was pre-medicated with an i.m. injection of ketamine 20 mg kg1, 150 U hylase, and atropine 0.04 mg kg1. Anaesthesia was induced with an i.v. injection of propofol 2 mg kg1 and maintained with a continuous infusion of midazolam 1016 µg kg1 min1, fentanyl 0.20.4 µg kg1 min1, and pancuronium 610 µg kg1 min1. After tracheal intubation, all animals were mechanically ventilated by a volume-controlled ventilator (Servo Ventilator 900 C; Siemens AG Medical Solutions, Erlangen, Germany). A triple-lumen polyurethane CVC was introduced (Certofix® Trio SB 730, length 30 cm, 7 French) into the left external jugular vein using the Seldinger technique. The cannulation kit included a connection cable with a crocodile clip for connecting the guide wire to a Certodyn® universal adapter (both B. Braun Melsungen AG, Melsungen, Germany). The guide wire was used as a unipolar electrode. A black marking on the proximal end of the guide wire indicated the point at which the tip of the wire is just level with the port of the distal catheter lumen. A connection cable was clamped to the guide wire at the marked position in order to connect it with an adapter that allows the operator to switch from a surface to an intravascular ECG. The skin reference electrodes were placed on the left extremities. Using continuous ECG guidance, the catheter was advanced together with the guide wire 2 cm beyond a marked increase in P wave size where the catheter was eventually fixed by sutures. The intravascular baseline ECG and an ECG after the first onset of an increase in P wave size were followed on the ECG-monitor (Cardiocap II, Datex, Helsinki, Finland) and recorded on a paper strip (Sony Model UP-860 CE video graphic printer, Sony Deutschland, Köln, Germany). Markings on the catheter allowed measurement of the depth of insertion. A second catheter was placed intra-arterially through the right carotid artery followed by the same ECG guidance procedure (Fig. 2).
|
|
Human observational study
From July to September 2003, 10 male patients, undergoing open chest cardiac surgery with the need for a PAC and TOE monitoring, were enrolled into the study. Exclusion criteria were absence of sinus rhythm, previous open heart surgery, contraindication to TOE or missing TOE study after CVC placement, failure of the Alphacard®-system and refusal to sign written consent. Patient characteristics recorded were age (4969 yr, median 60.5), sex, BMI (2333.7, median 26.9), and type of surgery.
Following induction of general anaesthesia with i.v. midazolam (0.150.2 mg kg1) and sufentanil (1.52 µg kg1) on inspired oxygen 100%, tracheal intubation was facilitated with pancuronium (0.080.1 mg kg1). Anaesthesia was maintained with sufentanil 2550 µg h1, and sevoflurane and oxygen in air (). The right or left innonimate vein, were then cannulated. The vein was punctured using a sterile Seldinger technique. The guide wire was advanced and a PAC (CCO/SVO2, 744H 7.5 F, Edwards Lifescience, Munich, Germany) was inserted through a percutaneous sheath introducer (8.5 F, SI-09875-E, Arrow Deutschland, Erding, Germany).
A TOE probe (multiplane probe, 6.2 MHz/HP Sonos 5500, Philips, Andover, USA) was inserted to a midoesophageal position and rotated to the right (clockwise). Then the plane of the probe was turned to an angle of 90110° to produce a bicaval view according to the American Society of Echocardiography/Society of Cardiovascular Anesthesiologists (ASE/SCA) guidelines.7
The SVC opens into the upper and back part of the atrium. The direction of its orifice being downward and forward within the confines of the sinus venosus, that area of the right atrium, which is bounded by the atrial septum and the crista terminalis. The echocardiographic correlate of the SVC-RA junction was defined as the base of the superior edge of the crista terminalis (Fig. 1). 8 9 Catheter tip position was determined by ECG-guidance using the Alphacard® system (an electrical-conductive syringe with a cable and a cable joint for connection to the Certodyn® universal adapter, B.Braun Melsungen AG, Melsungen, Germany) by filling the distal lumen with 10% saline. The electrically conductive liquid in the venous catheter lumen served as the intravascular electrode in this procedure (Einthoven lead II). The skin reference electrodes were placed on the left shoulder and left midclavicular line at the sixth intercostal space. A baseline intravascular ECG was documented with the inflated balloon protruding immediately at the luminal end of the percutaneous sheath. An Edwards Vigilance monitor (Edwards Lifescience, Munich, Germany) was connected with the respective optics module (Edwards OM-2E, Edwards Lifescience, Munich, Germany) to the PAC. The fibre-optic light channel emits a red light at the catheter tip. Following sternotomy but before the opening of the pericardial sac, the surgeon freed the innominate vein from surrounding connective tissue. Under continuous ECG-guidance the PAC was advanced until the surgeon noted the balloon or the red light at the pericardial reflection. At this site a second intravascular ECG was recorded. The extra-atrial position was confirmed additionally by TOE. The surgeon was blinded with respect to the ECG.
Statistics
Statistical analysis was performed using SPSS 11.0 (SPSS GmbH Software, Munich, Germany). Data were expressed as mean and 25th and 75th percentiles. Comparison of the two P wave amplitudes was performed using Wilcoxon Signed Ranks test. P values less than 0.05 were considered significant.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
In a previous study we inserted 50 central venous triple-lumen catheters either via the right or 50 via the left internal jugular vein. Catheter tip position was ascertained by ECG guidance. Method A: a Seldinger guide wire in the distal lumen served as an exploring electrode, the respective insertion depth was recorded. Method B: the middle lumen (port opening 2.5 cm from catheter tip, thus the catheter was advanced more towards the atrium) filled with a 10% saline fluid column served as the exploring electrode, and the insertion depth was recorded again. On average, the catheters were advanced by the expected 2 (SD 0.3) cm using Method B beyond the initial insertion by Method A. We therefore concluded that both methods detected the same structure. Confirmed by TOE all 100 CVCs were finally correctly positioned in the SVC. On postoperative CXR not a single catheter abutted the lateral wall of the SVC. As catheters placed by Method B did not result in intra-atrial CVC tip position, the first increase in P wave amplitude does correspond to a structure in the SVC. We hypothesized that a second anatomical structure needs to be responsible for the electrocardiographic phenomenon, most likely the pericardial reflection.17
The adjacent atrial wall tissue is thought to be responsible for the increase in voltage of the P-atriale.12 We postulated that the pericardium might serve as an electrical isolator and is responsible for the phenomenon observed.
Three different mechanisms contribute to an increase in P wave amplitude
The far field effect of electromagnetic fields.
Calculations of isopotential lines accounting for volume conductor effects of pericardial resistivity as well as establishing precise distance-to-amplitude relationships are objectives of our ongoing research in this field. This will clarify the different contributions of these mechanisms to the observed P wave phenomenon.
In all animals the P wave amplitude started to increase significantly outside the heart at the pericardial reflection. Interestingly, this phenomenon was observed in venous as well as arterial intravascular ECGs.
This phenomenon was also confirmed for the SVC in all humans studied. Therefore, we conclude that traditionally ECG-guided catheter tips are located outside the pericardial sac. The site of the pericardial reflection is not identical with the entrance of the right atrium, but crosses the SVC more cephalad.17
Hence, cardiac tamponade caused by perforation of the atrial wall or the SVC below the pericardial reflection can be prevented by ECG guidance, provided catheter migration is averted. Except for cubital CVCs,18 it is more common for CVCs to move back into the great veins than forward into the atrium, if displaced.19
The potential risk of vessel perforation might be minimized by positioning the catheter with its tip parallel to the SVC,20 most easily accomplished with right-sided placements. Because the innominate vein meets the SVC at an angle of almost 90° left-sided catheters passing from the innominate vein into the SVC may impinge on the SVC at an acute angle.21 A review of reported cases and in vitro data suggest, that catheter tips with an impingement angle to the SVC of higher than 40° require repositioning.22 We believe that an unsatisfactory tip position above the heart should not be accepted purely to satisfy FDA guidelines.4 Whenever the catheter negotiates a sharp bend, the catheter must be passed a reasonable distance beyond the bend such that the axes of the catheter and vein are aligned. The low SVC-upper RA is a suitable tip site from any access point in the upper body. Unlike some authors, we believe that the left innominate vein is not a suitable site for the tip of left-sided catheters, especially in patients depending on vasoactive substances and patients with high-flow catheters such as those for haemodialysis.20
In left-sided CVCs X-ray control is strongly recommended because ECG guidance is unable to give any information on the impingement angle.6
To avoid withdrawal of an impinging catheter into the left innominate vein, associated with an increased rate of thrombosis, in our opinion left-sided catheters should always be inserted deeper than indicated by P wave size alteration.7 23
A further incorrect assumption is that a P-atriale is only associated with i.v./right atrial positioning. To clear up with this misconception, we recorded the ECG in the ascending aorta of six pigs. Again the P wave amplitude increased significantly below the site of pericardial reflection crossing the ascending aorta. For obvious reasons, this experiment could not be transferred to humans. However, the results are in keeping with our own observations during inadvertent carotid artery cannulations. Indeed, inadvertent arterial catheterization and advancement of the catheter caused a normal increase in P wave size not suggestive of arterial misplacement.
This is demonstrated by a case report on an intra-arterial CVC where malposition was not detected first hand because ECG guidance showed the expected P wave increase.24 This electric phenomenon finally resulted in the misinterpretation of left-sided intra-atrial positioning of this catheter.24 From our observations, it is implausible, that this catheter had passed the aortic and the mitral valve. It must have been situated in the ascending aorta beyond the pericardial reflection.
In summary, our study shows that an increase in P wave amplitude already starts at the pericardial reflection outside the heart and, ECG guidance cannot distinguish whether a catheter is placed intra-arterially or intravenously.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Weissauer W. The cava-catheter from the medico-legal viewpoint. Anasthesiol Intensivmed Notfallmed Schmerzther 1998; 33: 1178[ISI][Medline]
3 Koscielniak-Nielsen ZJ, Otkjaer S, Hansen OB, Hemmingsen C. CVP catheter electrocardiography: an alternative to radiographic control after cannulation of central veins? Acta Anaesthesiol Scand 1991; 35: 7626[ISI][Medline]
4 Food and Drug Administration. Precautions necessary with central venous catheters. FDA Task Force. FDA Drug Bulletin 1989: 1516
5 Schwab SJ, Besarab A, Beathard G, NKF-DOQI clinical practice guidelines for vasular access. National Kidney Foundation-Dialysis Outcomes Quality Initiative. Am J Kidney Dis 1997; 30 (Suppl.): S15091[ISI][Medline]
6 Schummer W, Herrmann S, Schummer C, et al. Intra-atrial ECG is not a reliable method for positioning left internal jugular vein catheters. Br J Anaesth 2003; 91: 4816
7 Schummer W, Schummer C, Müller A, et al. ECG-guided central venous catheter positioning: does it detect the pericardial reflection rather than the right atrium? Eur J Anaesthesiol (in press)
8 National Institutes of Health. Guide for the Care and Use of Laboratory Animals. 1985; 85: 23
9 Shanewise JS, Cheung AT, Aronson S, et al. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography. Anesth Analg 1999; 89: 87084
10 Nanda NC, Domanski HJ. Normal anatomy. Atlas of Transoesophageal Echocardiography. Baltimore: Williams Wilkins, 1998; 15
11 Nanda NC, Domanski HJ. Superior vena cava and right atrium. Atlas of Transoesophageal Echocardiography. Baltimore: Williams Wilkins, 1998: 368
12 McGee WT, Ackerman BL, Rouben LR, et al. Accurate placement of central venous catheters: a prospective, randomized, multicenter trial. Crit Care Med 1993; 21: 111823[ISI][Medline]
13 Michaelis G, Biscoping J, Hempelmann G. Die Plazierung des zentralvenösen Katheters unter EKG-Kontrolle. Anasth Intensivmed 1988; 30: 2728
14 Corsten SA, van Dijk B, Bakker NC, de Lange JJ, Scheffer GJ. Central venous catheter placement using the ECG-guided Cavafix- Certodyn SD catheter. J Clin Anesth 1994; 6: 46972[ISI][Medline]
15 Salmela L, Aromaa U. Verification of the position of a central venous catheter by intra-atrial ECG. When does this method fail? Acta Anaesthesiol Scand 1993; 37: 268[Medline]
16 Urdaneta F, Lobato EB, Gravenstein N. Vascular access. In: Kirby RR, Gravenstein N, Lobato EB, Gravenstein JS, eds. Clinical Anesthesia Practice, 2nd Edn. Philadelphia: W.B. Saunders, 2002; 52743
17 Schuster M, Nave H, Piepenbrock S, Pabst R, Panning B. The carina as a landmark in central venous catheter placement. Br J Anaesth 2000; 85: 1924
18 Kalso E, Rosenberg PH, Vuorialho M, Pietila K. How much do arm movements displace cubital central venous catheters? Acta Anaesthesiol Scand 1982; 26: 3546[ISI][Medline]
19 Kowalski CM, Kaufman JA, Rivitz SM, Geller SC, Waltman AC. Migration of central venous catheters: implications for initial catheter tip positioning. J Vasc Interv Radiol 1997; 8: 4437[Abstract]
20 Fletcher SJ, Bodenham AR. Safe placement of central venous catheters: where should the tip of the catheter lie? Br J Anaesth 2000; 85: 18891
21 Tocino IM, Watanabe A. Impending catheter perforation of superior vena cava: radiographic recognition. Am J Roentgenol 1986; 146: 48790[ISI][Medline]
22 Gravenstein N, Blackshear RH. In vitro evaluation of relative perforating potential of central venous catheters: comparison of materials, selected models, number of lumens, and angles of incidence to simulated membrane. J Clin Monit 1991; 7: 16[ISI][Medline]
23 Vesely TM. Central venous catheter tip position: a continuing controversy. J Vasc Interv Radiol 2003; 14: 52734
24 Schafer M, Ciesielski K, Kuss B, Link J. Incorrect placement of a vena cava catheter and its prevention by intra-atrial ECG. Anaesthesist 1988; 37: 495[ISI][Medline]