Central venous cannulation is commonly performed in ICU’s & in major surgeries that requires hemodynamic monitoring that requires large volume of fluid or blood transfusion & requiring noxious medication administration like vasopressors for rapid therapy. Central venous catheterization is also required for chemotherapy, TPN & insertion of invasive devices like pulmonary artery catheter, transvenous pacemakers etc.

 Central venous catheters are inserted into large veins like subclavian vein, Internal jugular vein, Femoral vein. Subclavian CVC’s are commonly performed since it has less rate of infection & in trauma patients with suspected cervical spine injury. But there are potential complications of abnormal placement of CVC like venous perforation, cardiac tamponade, extravasation, arrhythmias. So correct placement of CVC tip prevents these potential complications. Here in this study, we have tried to determine optimal depth of CVC insertion through right SCV for correct placement of CVC tip. CVC tip determined by landmark & ECG methods. Our primary objective was to determine optimal depths of CVC in both landmark & ECG methods & our secondary objective was to see whether there is any relationship between landmark & ECG methods.

After institutional ethical committee approval, we conducted a prospective randomized study which included 60 patients of ASA status grade I & II between age group of 20–60 yrs of either sex undergoing major surgery or patients admitted in Trauma ICU in our institute which is tertiary health care institute. The study was conducted for a period of 1 year. Patients younger than 20 yrs & older than 60 yrs with puncture site infection, with deranged coagulation profile, with pneumothorax, any cardiac disorder were excluded from the study. Sample size estimation was done based on our pilot study by J.H. Lee et al. according to which, to estimate depth of CVC with 95% confidence limit & assuming of 0.4 cm of two-sided type I error, we required minimum of 55 subjects which was rounded off to 60 patients. Therefore, we included 30 patients in each group keeping in mind the number of dropouts that could exist. Patients were randomly allocated into 2 groups – Group L (landmark technique) & Group E (ECG technique) using random number table. Every patient admitted to TICU or patient admitted for major surgery that requiring central line insertion were allocated to groups alternatively & then after informed, valid, written consent, right SCV was cannulated with 7 Fr triple lumen CVC according to technique allotted to them. On arrival of patient, baseline vitals like pulse rate, ECG, NIBP, SpO₂ noted. After written consent, under aseptic precautions, patient in supine position with head turned to left side, anterior aspect of chest and neck were painted & draped with sterile hole towel. Puncture site was anesthetized using 2% plain lignocaine, then right SCV-CVC was inserted using Seldinger’s technique with 7 Fr triple lumen catheter. In group L patients, where CVC was to be inserted through landmark technique, pre-determined CVC length to be inserted was calculated by measuring “R length” i.e. distance from prick point to sternoclavicular notch & “C length” i.e. distance from sternoclavicular notch to manubriosternal joint. Both were added to get final length of CVC to be inserted. Then post CVC CXR was taken to note for position of CVC tip (Figure 1). Figure 1: Showing measuring Pre-determined length of CVC for Landmark technique In group E patients, length of CVC was determined by length of guidewire determined by ECG adapter. In this technique, we used an instrument called ‘ECG adapter’ which had alligator clip which was attached to guidewire & that in turn was attached to right arm electrode of ECG monitor. Then the guide wire which is connected to ECG adapter was inserted till deflection in ‘P wave of ECG noted’. Once deflection noted, guide wire withdrawn till P wave deflection normalized which is noted as ‘R point’ on guide wire. This length of guide wire till ‘R point’ is the length of CVC to be inserted. Then post CVC CXR taken, position of CVC tip noted. (Figure 2) A B Figure 2: (A)ECG adapter (B)Changes in ECG as the guidewire is inserted inside All the data were collected. The primary outcome was measured as optimal length of CVC through landmark technique and the optimal length of CVC through ECG technique. The secondary outcome was measured as relationship between 2 techniques. STATISTICAL ANALYSIS Data was entered into Microsoft excel data sheet & analysed using SPSS 23 version software. Continuous variables were male, female, landmark technique & ECG technique were summarized as Mean ± SD & Median with interquartile range. Difference between group was summarized using t test. Categorical variables like age, depth, carina level were summarized in frequencies & percentage. Analysed using Chi-square test. Figure 3: Consort Diagram

The demographic data, that are age, sex & body weight were analyzed using Chi-square test. Chi-square test showed that both the groups were comparable with no significant difference (Table 1).

Table 1: Comparison of Landmark Technique and ECG Technique According to Number of Attempts

Graph 1: Comparison of Landmark Technique and ECG Technique According to Number of Attempts

Number of attempts to insert CVC were analyzed in numbers using Chi-square test. Chi-square test showed that both the groups had no significant difference except in one case of Group E took 3 attempts to insert CVC, so p value turned out to be 0.5 comparing the easiness of CVC insertion through landmark technique (Table 1).

 Number of complications through both techniques were comparable with no significant difference (Table 1).

The tips of CVC were analyzed in percentage using Chi-square test. Chi-square test showed that both groups were comparable with no significant difference. 66.67% of CVC tips were at the level of carina in landmark technique where as 63.33% of CVC tips were at the level of carina in ECG technique. Showing relationship of equivalence between both group “our secondary outcome” (Table 2).

Table 2: Comparison of Landmark technique and ECG technique according to position of CVC tip in post-CVC chest x-ray.

Graph 2: Comparison of Landmark technique and ECG technique according to position of CVC tip in post-CVC chest x-ray.

The mean length of CVC was analyzed in Mean ± SD using independent t test. Independent t test showed that mean length of CVC were nearly equal with no significant difference. The mean length of CVC through landmark was 14.29 cm whereas through ECG was 14.31 cm. Hence both the techniques are efficient and appropriate enough for optimal positioning of right SCV CVC, our primary outcome (Table 3).

Table 3: Comparison of Landmark Technique and ECG Technique with Mean Length of Catheter by Independent t-test

Graph 3: Comparison of Landmark Technique and ECG Technique with Mean Length of Catheter by Independent t-test

Central venous catheter is catheter that is inserted into large veins that directly end into central circulation. They can be inserted near shoulder into SCV, in neck into IJV, in groin into femoral vein. CVC insertion is most commonly used in ICU, major surgeries and trauma patients. It helps in volume resuscitation, TPN, administration of inotropes, cardiac pacing and for chemotherapy. Since catheter tip directly ends up in central circulation, the correct positioning of CVC tip plays very important role in minimizing potential risks associated with CVC insertion. In many studies, it has been proved that CVC tip at the carina or 4 cm above carina is junction of SVC/RA which corresponds to upper limit of pericardial reflection. Since pericardial reflection cannot be seen on CXR, carina is used as landmark. Safe position of CVC tip location is above cephalic limit of pericardial reflection not merely above SVC/RA junction. SVC can be divided into 3 zones for easy understanding of anatomy & complications related to position of CVC tip. Zone A – lower SVC & upper RA where upper RA is within pericardial reflection. Hence high chances of cardiac tamponade present in this zone. Zone B – area around junction of left & right innominate veins & upper SVC. This is suitable area for CVC tip since lesser complications except risk of abutting lateral wall of SVC & wall perforation. Zone C – area where left innominate vein proximal to SVC. This is preferred site for left CVC insertion. Carina on CXR corresponds to Zone A & 0.8 cm above the pericardial reflection of upper RA of Zone A & Zone B corresponds to 4 cm above carina, which is safe site for CVC tip position. It was also shown that P wave of ECG returned to normal configuration at carina. Hence carina was chosen as landmark for correct position of CVC tip on post CVC CXR. Figure 4: Schematic diagram showing the extrapericardial length (EP), the intrapericardial length (IP), and the length of the medial duplicated part (MD) of the superior vena cava (SVC). RA = right atrium, BC = brachiocephalic vein. Figure 5: SVC divided into 3 zones. In our study, we have attempted to determine optimum length of CVC insertion by 2 techniques, the ECG & landmark technique. In many studies, it was shown that ECG & landmark techniques are most reliable & accurate in CVC insertion. In our study, it was found that both ECG & landmark technique were equivalent in correct positioning of CVC inserted through right SCV. The demographic data in our study were equivalent in both groups & didn’t show any statistical significance with respect to age, gender, height & weight. In our study of landmark group, 73.34% of CVC tip were successfully placed at correct position with minimal complications. The optimal length got was 14.29 cm. This method is very simple, bedside & considers variable insertion points & anatomical & radiological landmarks. Since carina is located in centre of thorax, measurement errors due to image distortion & parallax effect is negligible. This was comparable to Khatodkar JK et al. study, which showed that 13 cm of average insertion length with 90% CVC tip to be at or above level of carina. In our study of ECG group, it was shown that 70% of CVC tips were successfully placed in correct position with minimal complication. The optimal length got was 14.3 cm. This was comparable with J.H. Lee et al. study, which showed 95.9% of CVC tips were at level of carina. Complications associated with CVC insertion through landmark technique were 13%, which showed hematoma as complication. Complications associated with ECG technique were 6% hematoma & 6% CVC went to opposite SCV in ECG technique. Hence concluding that complications associated with landmark & ECG technique were minimal & none of them were potential life threatening. Hence both techniques lead to safe placement of CVC tips. Complications were comparable with Y.L. Angotti et al. studies. The 1st limitation of our study was that all CVC’s were put into right SCV through infraclavicular approach. Since rate of SCV-CVC insertion is easy & failure rates were less, SCV-CVC were considered. Our 2nd limitation was ASA I & ASA II patients were considered. Patients with cardiac disease with baseline ECG findings, its difficult to note change in ‘P wave’ morphology. Our 3rd limitation was in rib anomalies, clavicle fracture, it is difficult to insert CVC & interpretation of post CVC chest x-ray is difficult. In conclusion, both landmark & ECG techniques are equivalent in determining optimal length of CVC insertion. Both showed high rates of correct placement of CVC tips & both technique had least complications.

We concluded that both Landmark and ECG techniques of Right SCV-CVC insertion are equivalent and can be used to determine optimal length of CVC to be inserted and has less rate of complications with more success rate of correct placement of CVC.

1. J.-H. Lee, J.-H. Bahk, H.-G. Ryn, C.-W. Jung and Y. Jeon. Comparison of the bedside central venous catheter placement techniques: landmark vs electrocardiogram guidance. Br J Anaesth 102 (5): 662-6 (2009).
2. Jatin Kumar Khatodkar, Arvind Kumar Rathiya, Sudhakar Dwivedi. Correlation of Surface Landmarks Based Insertion Length of Right Subclavian Central Venous Catheter with Post Insertion Location of Catheter Tip. International Journal of Scientific Study, Feb 2018, 5:11.
3. Ryu HG, Bahk JH, Kim JT, Lee JH. Bedside prediction of central venous catheter insertion depth. Br J Anaesth 2007;98:225-7.
4. Gebhard RE, Szmuk P, Pivalizza EG, Melnikov V, Vogt C, Warters RD. The accuracy of electrocardiogram-controlled central line placement. Anesth Analg 2007;104:65-70.
5. Deepak Sharma, V. P. Singh, M. K. Malhotra, and Kumkum Gupta. Optimum depth of central venous catheter- Comparision by pere’s, landmark and endocavitory (atrial) ECG technique: A prospective study. Anesthesia: Essays and Researches (Google scholar).
6. Schummer W. Towards Optimal Central Venous Catheter Tip Position. Vasc Med Surg 2016, 4:2.
7. Anandaswamy TC, Marulasiddappa V. A comparative study of landmark-based topographic method versus the formula method for estimating depth of insertion of right subclavian central venous catheters. Indian J Anaesth 2016;60:496-8.
8. Shah N, Appukutty J, Kane D. Depth of central venous catheterization by intracardiac electrocardiogram in adults. Anesth Pain 2013;2:111-4.
9. Chalkiadis GA, Gouke CR. Depth of central venous catheter insertion in adults: an adult and assessment of a technique to improve tip position. Anaesth Intensive Care 1998;26:61-6.
10. Kwon TD, Kim KH, Ryu HG, Jung CW, Goo JM, Bahk JH. Intra and extra-pericardial lengths of the superior vena cava in vivo: implication for the positioning of central venous catheters. Anaesth Intensive Care 2005;33:384-7.
11. Stonelake PA, Bodenham AR. The carina as a radiological landmark for central venous catheter tip position. Br J Anaesth 2006;96:335-40.
12. Schuster M, Nave H, Piepenbrock S, Pabst R, Panning B. The carina as a landmark in central venous catheter placement. Br J Anaesth 2000;85:192-4.
13. Albrecht K, Nave H, Breitmeier D, Panning B, Troger HD. Applied anatomy of superior venacava- the carina as a landmark to guide central venous catheter placement. Br J Anaesth 2004;92:75-7.
14. Argoti-Velasco YL, Carrillo-Torres O, Sandoval-Mendoza RA. Proper electrocardiography-guided placement of central venous catheter. Rev Med Hosp Gen Mex 2018;81(4):262-267.
15. Stelter J, Sarwark J. Complications of central venous catheters. The New England Journal of Medicine 2015;373(13):1220-9.
16. Michael Beheshti. A concise history of central venous access. Techniques in Vascular and Interventional Radiology Dec 2011;14(4):184-5.
17. Marino PL. The ICU book. 4th ed. Wolters Kulwer; 2014. p4-44.
18. O’Grady NP, Alexander M, Burns LA, et al. and the Healthcare Infection Control Practices Advisory Committee (HICPAC). Guidelines for the prevention of intravascular catheter related infections. Clin Infect Dis 2011;52:e1-e32.
19. Dwarkadas KB, Vandana VL. Understanding anaesthetic equipment and procedures: A Practical Approach. 2nd ed. Jaypee Publications; 2014; pp 349-355.
20. Marin HK, Warren I, A. Cole Burks, Vladimir ND. The Washington Manual of Critical Care. 3rd ed. Wolters Kluwer; 2019; p660-668.
21. Institute for Healthcare Improvement. Implement the central line bundle.
22. Sharma D. Adaptor for endocavitory ECG monitoring. J Anaesth Clin Pharmacol 2009;25:327-28.
23. Andrew DB, Jonathan MH. Oh’s intensive care manual. 8th ed. Elsevier; 2019; p138-139.
24. Mike Cadogan and James Miers. Seldinger technique. In: LITFL, March 19, 2023.
25. Sternbach G. Sven Ivar Seldinger: catheter introduction on flexible leader. J Emerg Med 1990 Sep-Oct;8(5):635-7.
26. Higgs ZC et al. The Seldinger technique: 50 years on. Lancet 2005 Oct 15-21;366(9494):1407-9.
27. Seldinger SI. Catheter replacement of the needle in percutaneous arteriography. A new technique. Acta Radiol Suppl (Stockholm) 2008 Aug;434:47-52.
28. McGee DC, Gould MK. Preventing complication of central venous catheterization. New Engl J Med 2003;348:1123-1133.
29. R. Raviraj, G. Korula, K. Subramani. A simple method of electrocardiogram: controlled central venous catheterization. Ann Cardiac Anaesth 2011;14:p.2.
30. L. A. Mermel. Prevention of intravascular catheter-related infections. Ann Intern Med 2000;132:391-402.
31. L. Makau, M. A. Talmini, J. V. Sitzmann. Risks factors for central venous catheter-related vascular erosions. J Parenter Enteral Nutr 1991;15:513-516.
32. American Society of Anesthesiologists Task Force on Central Venous Access. Practice guidelines for central venous access: a report by American Society of Anesthesiologists task force on central venous access. Anesthesiology 2012;116:539-573.
33. C. A. Czepizak, J. M. O’Callaghan, B. Venus. Evaluation of formulas for optimal positioning of central venous catheters. Chest 1995;107:1662-1664.
34. I. Raad. Intravascular-catheter-related infections. Lancet 1998;351:893-898.
35. M. Pittiruti, D. Bertollo, E. Briglia. The intracavitary ECG method for positioning the tip of central venous catheters: results of an Italian multicenter study. J Vasc Access 2011;1:1-7.
36. G. Wang, L. Guo, B. Jiang. Factors influencing intracavitary electrocardiographic P-wave changes during central venous catheter placement. PLOS ONE 2015;10:1-7.
37. Francis KR, Picard DL, Fajardo MA, Pizzi WF. Avoiding complications and decreasing costs of central venous catheter placement electrocardiographic guidance. Surg Gynecol Obstet 1992;175:208-11.
38. Roldan CJ, Paniagua L. Central venous catheter intravascular malpositioning: causes, prevention, diagnosis, and correction. West J Emerg Med 2015;16:658-664.
39. Schummer W, Schummer C, Rose N et al. Mechanical complications and malpositions of central venous cannulations by experienced operators. A prospective study of 1794 catheterizations in critically ill patients. Intensive Care Med 2007;33:1055-1059.
40. Bayer O, Schummer C, Richter K et al. Implications of anatomy of the pericardial reflection on positioning of central venous catheters. J Cardiothorac Vasc Anesth 2006;20:777-780.
41. Fletcher SJ, Bodenham AR. Safe placement of central venous catheters: where should the tip of the catheter lie? Br J Anaesth 2000;85:188-191.
42. Calabria M, Zamboli P, D’Amelio A et al. Use of ECG in the positioning of central venous catheters. G Ital Nefrol 2012;29:49-57.
43. Peres PW. Positioning central venous catheter- a prospective survey. Anaesth Intensive Care 1990;18:536-39.
44. Kujar R, Roa MS, Mrinal M. How correct is the correct length for central venous catheter insertion. Indian J Crit Care Med 2009;13:159-62.
45. McGee WT, Moriarty KP. Accurate placement of central venous catheter using a 16 cm catheter. J Intensive Care Med 1996;11:19-22.
46. Iovino F, Pittiruti M, Buononato M et al. Central venous catheterization complications of different placement. Ann Chir 2001;126:1001-6.
47. Ruesch S, Walder B, Tramer MR. Complications of central venous catheter: internal jugular versus subclavian access- A systemic review. Critical Care Med 2002;30:454-60.