Intra- and Extra-Pericardial Lengths of the Superior Vena Cava in Vivo: Implication for the Positioning of Central Venous Catheters

Anaesth Intensive Care 2005; 33: 384-387

Intra- and Extra-pericardial Lengths of the Superior Vena Cava in Vivo: Implication for the Positioning of Central Venous Catheters

T. D. KWON*, K. H. KIM†, H. G. RYU*, C. W. JUNG§, J. M. GOO**, J. H. BAHK†† Departments of Anesthesiology, Cardiothoracic Surgery and Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea

SUMMARY To reduce the possibility of cardiac tamponade, a rare but lethal complication of central venous catheters, the tip of the central venous catheter should be located above the cephalic limit of the pericardial reflection, not only above the superior vena cava-right atrium junction. This study was performed to measure the superior vena cava lengths above and below the pericardial reflection in cardiac surgical patients. Cardiac surgical patients (n=61; 27 male), whose age [mean±SD (range)] was 47±15 (15-75) years, were studied. The intrapericardial and extrapericardial lengths, and the length of the medial duplicated part were measured separately. The whole vertical lengths of the superior vena cava on either side were calculated respectively by adding the intra-and extrapericardial and medial duplication lengths. The lateral extrapericardial was 29.1±6.5 (Mean±SD) (9-49) mm (range), and lateral extrapericardial length was 32.6±6.9 (20-53) mm. The medial extrapericardial length was 23.3±5.0 (11-39) mm, medical duplicated length was 7.2±3.3 (4-20) mm, and medial intrapericardial was 28.3±7.0 (20-52) mm. The averaged superior vena cava length of both sides was 60.3±9.0 (44.5-90) mm. Almost half of the superior vena cava was found to be within the pericardium and half out. This information may be helpful in deciding how far a central venous catheter should be withdrawn beyond the superior vena cava-right atrial junction during right atrial electrocardiographic guided insertion, and in the prediction of optimal central venous catheter insertion depth. Key Words: VEINS: superior vena cava, length. COMPLICATIONS: central venous catheterization, cardiac tamponade

The United States Food and Drug Administration should be located above the cephalic limit of the peri- guidelines state that central venous catheter (CVC) cardial reflection2-4, not merely above the superior tips should not be placed in, or allowed to migrate vena cava (SVC)-right atrial (RA) junction. Without into the heart1. However, to avoid the rare but lethal information about the SVC length, it may not be pos- complication of cardiac tamponade, the CVC tip sible to determine how far the CVC should be withdrawn after it is located at the level of the SVC-RA junction (e.g. during a right atrial electrocardiographic guided insertion technique), or to identify a potentially dangerous positioning of a CVC tip on the *M.D., Fellow, Department of Anesthesiology, Seoul National University chest X-ray. Hospital, Seoul National University College of Medicine, Seoul, Korea. The SVC length below the cephalic limit of the †M.D., Assistant Professor, Department of Cardiothoracic Surgery, Seoul National University Hospital, Seoul National University College of pericardial reflection has previously been assumed Medicine, Seoul, Korea. to be 20 mm5, or reported to be about 3.0 cm in a §M.D., Clinical Assistant Professor, Department of Anesthesiology, Seoul 6 National University Hospital, Seoul National University College of study of 34 cadavers of very old people . However, Medicine, Seoul, Korea. cadaveric studies measuring anatomic structures may **M.D., Assistant Professor, Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, be limited by the post mortem factors causing distor- Seoul, Korea. tion of anatomical structures and the emptied vessels. ††M.D., Associate Professor, Department of Anesthesiology, Seoul National University Hospital, Seoul National University College of Thus, measurements of the SVC lengths below and Medicine, Seoul, Korea. above the cephalic limit of pericardial reflection in Address for reprints: Dr Jae-Hyon Bahk, Department of Anesthesiology, live, blood-filled vessels were warranted. Seoul National University Hospital, Seoul National University College of Medicine, 28 Yongon-Dong, Chongno-Gu, Seoul, Korea 110-744. The purpose of this study was to measure the intra- Accepted for publication on February 28, 2005. pericardial (IP) and extrapericardial (EP) lengths on

Anaesthesia and Intensive Care, Vol. 33, No. 3, June 2005 LENGTH OF THE SUPERIOR VENA CAVA 385 the blood-filled SVC during cardiac surgery, and to seek for any anatomical landmarks for the prediction of the cephalic limit of pericardial reflection or SVC lengths on the chest X-ray. METHODS After receiving Hospital Review Board approval and obtaining informed consent, 61 elective cardiac surgical patients (27 males and 34 females) were enrolled in the study. Twenty-six of the patients underwent aortic valve replacement; six mitral valve replacement; 22, coronary artery bypass surgery, and four, off-pump coronary artery bypass surgery. Patients who required a re-operation were not in- cluded. After routine sternotomy, a self-retaining retractor was placed. The pericardial sac was opened. The IP part of SVC was exposed as usual. The EP part of SVC was exposed after removing the loose connective tissue medially and laterally. The cephalic limit of pericardial reflection on the medial side was taken as the angular transitional junction between the left brachiocephalic vein and the SVC. The cephalic limit of pericardial reflection on the lateral side was regarded to be at the same level as the medial. The vertical lengths on each side of SVC were measured as follows: black suture silk of about 10 cm long was pinched with two forceps. The between-forceps length was adjusted to be exactly the same as the part of SVC length that we were trying to FIGURE 1: Schematic diagram showing the extrapericardial length measure, while keeping the silk tight. Afterwards, we (EP), the intrapericardial length (IP), and the length of the medial measured the distance between the two forceps with duplicated part (MD) of the superior vena cava (SVC). RA=right a pre-sterilized ruler. The IP and EP lengths on both atrium, BC=brachiocephalic vein. sides, and the length of the medial duplicated part (MD) were measured separately (Figure 1). The whole vertical lengths of the SVC on either side were late the notch-carina and notch-angle lengths for 7 calculated by simply adding the IP and EP lengths, each patient : actual distance=projected distance on and the MD length in the case of the medial SVC the plain film x [distance between X-ray tube and length. The distances were measured by two cardiac object is equal to distance between X-ray tube and surgeons, and with less than 3% inter-observer differ- film]. Distance between X-ray tube and object=the ence. The arithmetic mean of the individual measure- distance between X-ray tube and film (72 inch x ments was used for data analyses. 25.40 mm=1828.8 mm) minus the distance between To find potential anatomical landmarks for the the carina and the anterior chest wall, which was cephalic limit of pericardial reflection or SVC lengths measured on the lateral chest X-ray. To improve that are easily identifiable at bedside or on chest accuracy and reliability, three measurements of the X-ray, the jugular notch of the clavicle to tracheal distances were performed with electronic calipers to carina (notch-carina length) and the jugular notch the nearest 0.1 mm. The arithmetic mean was calcu- to tracheobronchial angle distances (notch-angle lated by using the measurements within 5% variances length) were measured vertically on the preoperative and used for the study. routine posterior-anterior (PA) chest X-ray. The The relationships of the height, weight, body mass distances were measured with electronic calipers on index or age with the SVC length or IP, MD and EP the 12-times enlarged images of the digital PACS lengths were analyzed by the Pearson’s partial corre- (Picture Archiving Communication System) as fol- lation analysis. On the assumption that any disease lows. Because intrathoracic structures appear mag- with the proximal aortic enlargement might lengthen nified on PA views, a correction was made to calcu- the SVC length, SVC lengths depending on the pre-

Anaesthesia and Intensive Care, Vol. 33, No. 3, June 2005 386 T. D. KWON, K. W. KIM ET AL sence or absence of aortic valvular disease were com- pulmonary diseases increases with age, the SVC pared with unpaired t-test. Pearson’s correlation length may be lengthened in the extremely aged analysis was used to assess the relationship between population of the cadaver study6. the notch-carina and notch-angle lengths and the IP, The cephalic limit of pericardial reflection was MD, EP and whole SVC lengths. Values are pre- known to surround the SVC as far as insertion of the sented as mean±SD (range). P values <0.01 were azygos vein5,9, or lie at the same level as the angle considered significant. made by the right main bronchus and the trachea5,10. The tracheal carina was found to be always located RESULTS above the cephalic limit of pericardial reflection on Patients’ age was 47±15 (15-75) years, height cadaver dissection6. The internal jugular vein or the 161.8±8.6 (140.0-186.0) cm, and weight 60.8±9.5 innominate vein is located just behind the jugular (46.0-83.0) kg. Neither the SVC length nor any por- notch of the clavicle11,12, which is easily palpable 0.25 tion of the SVC correlated with the weight, body mass to 1 cm lateral to the sternal end11. Therefore, this index or age of the patients. The only exception was jugular notch may be used as a surface landmark for the height, which had some correlation with medial central venous access. In this study, it was attempted EP length (r=0.343, P=0.007). to correlate the notch-carina and notch-angle lengths The EP, MD and IP lengths of both sides of the with the IP, MD, EP and whole SVC lengths. Because SVC are shown in Table 1. The averaged SVC length the distance between X-ray tube and film is variable of the both sides was 60.3±9.0 (44.5-90) mm. The and relatively short, the parallax effect varies and is SVC length of 13 patients with aortic valvular disease more augmented in the periphery during portable (62.7±8.9 mm) did not appear to be longer than that chest X-ray examination. Thus preoperative routine of 48 patients without aortic valvular disease (59.6± chest X-ray was used for measurements of the notch- 9.0 mm). carina and notch-angle lengths. Although correlation The notch-carina length was correlated with the was not high, the notch-carina and notch-angle TABLE 1 lengths that were correlated with the whole SVC Lengths of the superior vena cava on the lateral and medial sides length may have a role as potential factors for the Lateral side Medial side prediction of optimal CVC insertion depth. However, Extrapericardial length (mm) 29.1±6.5 (9-49) 23.3±5.0 (11-39) it should be noted that correlation alone is not an Medial duplicated part appropriate method to assess predictive value. (mm) – 7.2±3.3 (4-20) The MD part of the SVC, where a duplication of Intrapericardial length (mm) 32.6±6.9 (20-53) 28.3±7.0 (20-52) the pericardial sac fortifies the vessel wall on the medial side, was previously reported to be 24 mm Total length (mm) 61.7±9.6 (45-80) 60.3±9.0 (44-94) (range 16-40 mm)6, but was only 7.2 mm long (range Data are mean±SD (range). n=61. 4-20 mm) in this study. Contrary to the suggestion of a previous report6, it does not seem to be probable that the thickened MD part may have a protective mean and lateral SVC lengths [r=0.361, P=0.006; role against the tip-induced perforation for the right- r=0.437, P=0.001]. The notch-angle length was cor- sided subclavian or antecubital CVC, which may be related with the lateral SVC length [r=0.389, P= prone to abutting on the medial wall. In many 0.003]. anatomy textbooks, the SVC is stated to be about 7 cm in length9, but the actual SVC length in the cur- DISCUSSION rent study was around 6 cm. We speculate that age, The IP part of the SVC [mean (SE)] has been ethnic difference or cardiac disease-associated ana- reported to be 3.0 (0.2) cm (range 1.0-5.0 cm) from tomical changes might explain the differences in the the measurements of 34 cadavers aged 78 (1.7) years6. whole SVC or MD lengths. Since Schuster and colleagues measured the IP length Almost nowhere in the central veins, even above after they had excised the heart by cutting the IP part the heart, would be completely safe from the CVC- of the SVC6, the complicated measuring process may induced complications. Thus individual clinical fac- have introduced some inaccuracy. The flattening of tors must dictate the choice of access point and the the diaphragm in the patients with pulmonary emphy- site of CVC tip placement13. SVC wall puncture below sema pulls the heart downwards and thereby possibly the cephalic limit of pericardial reflection by CVC tip increases the distance between the puncture site and is rare, but is a recognised cause of cardiac tam- the RA8. Since the incidence of chronic obstructive ponade2,14,15. Therefore, positioning of CVC tip above

Anaesthesia and Intensive Care, Vol. 33, No. 3, June 2005 LENGTH OF THE SUPERIOR VENA CAVA 387 the cephalic limit of pericardial reflection should 6. Schuster M, Nave H, Piepenbrock S, Pabst R, Panning B. The reduce the incidence of this lethal complication10. carina as a landmark in central venous catheter placement. Br Although the EP and IP lengths and the whole J Anaesth 2000; 85:192-194. 7. Jeon Y, Ryu HG, Bahk JH, Jung CW, Goo JM. A new SVC length were highly variable, half of the SVC was technique to determine the size of double-lumen endo- found to be within the pericardium and the other half bronchial tubes by the two perpendicularly measured bronchial out of the pericardium. The information from this diameters. Anaesth Intensive Care 2005; 33: 59-63. study, in which the IP and EP lengths of the SVC 8. Salmela L, Aromaa U. Verification of the position of a central were accurately measured on the blood-filled vessels venous catheter by intra-atrial ECG. When does this method fail? Acta Anaesthesiol Scand 1993; 37:26-28. in vivo, may be helpful in deciding how far the CVC 9. Angiology In: Williams PL, Warwick R, eds. Gray’s Anatomy should be withdrawn beyond the SVC-RA junction, 36th ed. Philadelphia; WB Saunders 1980; 622-800. and in the prediction of optimal CVC insertion depth. 10. Rutherford JS, Merry AF, Occleshaw CJ. Depth of central venous catheterization: an audit of practice in a cardiac surgical unit. Anaesth Intensive Care 1994; 22:267-271. REFERENCES 11. Rao TLK, Wong AY, Salem MR. A new approach to per- 1. Food and Drug Administration. Precautions necessary with cutaneous catheterization of the internal jugular vein. central venous catheters. FDA Task Force. In: FDA Drug Anesthesiology 1977; 46:362-364. Bulletin, July 1989; 15-16. 12. Kitagawa N, Oda M, Totoki T et al. Proper shoulder position 2. Greenall MJ, Blewitt RW, McMahon MJ. Cardiac tamponade for subclavian venipuncture: A prospective randomized clinical and central venous catheters. Br Med J 1975; 2:595-597. trial and anatomical perspectives using multislice computed 3. Maschke SP, Rogove HJ. Cardiac tamponade associated with a tomography. Anesthesiology 2004; 101:1306-1312. multilumen central venous catheter. Crit Care Med 1984; 12: 13. Fletcher SJ, Bodenham AR. Safe placement of central venous 611-613. catheters: where should the tip of the catheter lie? Editorial. Br 4. Collier PE, Goodman GB. Cardiac tamponade caused by J Anaesth 2000; 85:188-191. central venous catheter perforation of the heart: a preventable 14. Defalque RJ, Campbell C. Cardiac tamponade from central complication. J Am Coll Surg 1995: 181:459-463. venous catheters. Anesthesiology 1979; 50:249-252. 5. Chalkiadis GA, Goucke CR. Depth of central venous catheter 15. Sheep RE, Guiney WB Jr. Fatal cardiac tamponade: occur- insertion in adults: An audit and assessment of a technique to rence with other complications after left internal jugular improve tip position. Anaesth Intensive Care 1998; 26:61-66. catheterization. JAMA 1982; 248:1632-1635.

Anaesthesia and Intensive Care, Vol. 33, No. 3, June 2005