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From the Departments of *Anesthesiology and Pain Medicine, and Radiology, Seoul National University Hospital, Seoul, Korea.
Address correspondence and reprint requests to Jae-Hyon Bahk, MD, Department of Anesthesiology, Seoul National University College of Medicine, No. 28, Yongon-Dong, Jongno–Gu, Seoul 110-744, Korea. Address e-mail to bahkjh{at}plaza.snu.ac.kr.
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Abstract |
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 Top Abstract IntroductionMETHODSRESULTSDISCUSSIONREFERENCES |
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METHODS: Forty-five adult patients with normal body build were retrospectively included in the 3-D computed tomography investigation. Assuming that the clavisternomastoid angle was the skin entry point, and that the subclavian vein on the first rib was a target, the optimal angle of approach was measured on the simulated 3-D images. A 3-D video was developed from these images to explain the approach. In a pilot study, we prospectively tested this approach in 60 adult patients with normal body build requiring central venous catheterization. The number of attempts, success rate, and complications were noted.
RESULTS: The optimal angle of approach was 10.6° ± 5.3° medially and 35.4° ± 12.5° posteriorly from the skin entry point. The estimated depth of the subclavian vein was 13.7 ± 3.1 mm. During the pilot study, the first trial with a finder needle was successful in 87% of patients and the overall success rate of catheterizations was 100% without complications.
CONCLUSIONS: The proposed supraclavicular approach to the subclavian vein is a simple method of central venous catheterization. The pilot study suggests the method is reasonably safe. The video explaining the approach graphically is available in the supplementary material.
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Introduction |
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TopAbstractIntroductionMETHODSRESULTSDISCUSSIONREFERENCES |
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As an alternative, the supraclavicular subclavian vein approach was suggested by Yoffa (6). Owing to well defined surface landmarks and the consistency of the practice, subsequent reports noted better success and fewer complications with the supraclavicular approach than with the infraclavicular approach (7–10). However, the supraclavicular approach has been performed in the past without precise anatomical information, and physicians have been hesitant to use this technique.
A revolutionary advancement in imaging technique, three-dimensional computed tomography (3D-CT), has provided detailed information, in a noninvasive and easily understandable manner, concerning the relationship between surface landmarks and deeply located structures (11). We speculated that 3D-CT be adopted to provide anatomical data and to investigate another possible route to the central veins, preserving the advantages of the supraclavicular approach.
In this study, we defined a supraclavicular approach to the right subclavian vein based on a 3D-CT investigation of the subclavian vein and surrounding anatomy. After defining appropriate landmarks, we performed a pilot study in 60 patients to test the feasibility of the proposed approach.
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METHODS |
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TopAbstractIntroductionMETHODSRESULTSDISCUSSIONREFERENCES |
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Central venous catheterization was simulated on the 3-D images. The skin entry point was assumed to be the junction of the lateral border of the clavicular head of the sternocleidomastoid muscle and the posterior surface of the clavicle (the clavisternomastoid angle) on the right side because this point is a constant and easily identifiable surface landmark that is usually used for the traditional supraclavicular approach. The assumed target was the subclavian vein on the first rib because the first rib was expected to function as a barrier against inadvertent puncture of the lung, and because the route from the clavisternomastoid angle to the subclavian vein on the first rib was the shortest and without intervening obstacles.
After choosing these entry and target points, an imaginary needle path was drawn on the reconstructed multiplanar reformation (MPR) planes, where the measured variables were obtained. On the coronal MPR plane, the degree of inward direction from the sagittal plane was regarded as the medial angle of approach (Am). Other 3D-CT data were retrieved on the oblique MPR plane that was formed on the selected Am in the anteroposterior direction. These data included the diameter of the subclavian vein (Dia), the posterior angle of approach from the coronal plane to puncture the center of the subclavian vein (Av), the distance from the skin entry point to the subclavian vein (Dv), and the posterior angle to the center of the subclavian artery (Aa) (Fig. 1).
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Additional measurements in the same subjects compared the depths of the target veins between the proposed and traditional supraclavicular approaches.
Pilot Study
After approval by the IRB of our hospital and obtaining written informed patient consent, a pilot study was performed in 60 patients with normal body build who underwent surgery requiring central venous catheterizations. All catheterizations were performed by an experienced anesthesiologist. After induction of anesthesia, patients were placed in the supine position with the right arm by the side. The operating room table was level and a rolled towel was not placed under the shoulder. To identify the sternocleidomastoid muscle, the patient's head was minimally turned away from the catheterization side.
Puncture of the subclavian vein was performed after the 3D-CT investigations (rounded Am = 10°, rounded Av = 35°) while ventilation of the intubated patient was held at end-expiration to prevent inadvertent puncture of the lung. After skin preparation, a 1 1/4-inch 21G finder needle attached to a syringe was directed at an angle of 10° medially from the sagittal plane and 35° posteriorly from the coronal plane, just at the clavisternomastoid angle, to locate the subclavian vein. In case of failure, the individual anatomy and approach angles were carefully reconfirmed before the second trial. Once the subclavian vein was accessed with the finder needle, a large bore (17G) introducer needle was inserted following the direction and depth of the finder needle. A guidewire was inserted when free flow of venous blood was obtained. Care was taken to keep the bevel of the introducer needle and the J-tip of the guidewire toward the medial side of the body to prevent the guidewire from being threaded into the ipsilateral axillary vein (Fig. 2). If difficulty in threading a guidewire was met, the bevel of an introducer needle was slightly rotated or the direction of the J-tip was readjusted to face the medial side. After catheter path dilation, double-lumen central venous catheters (BD CareflowTM, BD Medical Systems, Singapore) were inserted.
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All catheters were fixed at 12 cm from the skin entry point on the supraclavicular fossa. A simple chest radiograph was taken immediately after the procedure and 12 h after surgery to determine postprocedure complications and position of catheter tip.
Statistical Analysis
From our preliminary measurements in 10 patients, Am and Av were 8.3° ± 7.2° and 30.4° ± 12.2°, respectively. A sample size calculation was performed to detect a mean difference of 5° and 10° for Am and Av respectively with a Type I error of 0.01 and a desired power of 0.9, which required 45 and 33 measurements; a sample size of 45 subjects was selected as a minimum to detect any significant differences. For the pilot study, we expected an initial success rate to be as high as that reported by Sterner et al. (7) (82.2% by both the infraclavicular and supraclavicular approaches). A sample size of 60 patients was calculated with a Type I error of 0.05 and a desired power of 0.8 expecting 85% initial success rate.
Descriptive statistics were performed for measured values. Data were expressed as mean ± sd (range). Unpaired t-test was performed for comparison of patient characteristics between the 3D-CT investigation and pilot study. Paired t-test was performed to compare Av with Aa and between the depths by the proposed and traditional supraclavicular approaches. A value of P < 0.05 was considered significant. All statistical analyses were performed using SigmaStat software (version 3.10, Systat Software, San Jose, CA).
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RESULTS |
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TopAbstractIntroductionMETHODSRESULTSDISCUSSIONREFERENCES |
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3D-CT Investigation
The diameter of the subclavian vein was 12.9 ± 3.4 (6.5–22.5) mm. The angle of approach to puncture the subclavian vein was 10.6 ± 5.3 (1.5°–23.9°) medially from the sagittal plane and 35.4 ± 12.5 (8.2°–64.8°) posteriorly from the coronal plane. The posterior angle of approach of the subclavian vein was significantly smaller than that of the subclavian artery (35.4 ± 12.5 [8.2°–64.8°] vs 70.6 ± 16.0 [67.9°–77.4°], Av versus Aa, P < 0.001).
The depth of the subclavian vein was 13.7 ± 3.1 (3.5–26.3) mm from the skin entry point, significantly shorter than the depth with the traditional supraclavicular approach (20.5 ± 6.3 [8.1–37.7] mm) (P < 0.001).
Pilot study
During the pilot study, there were neither failures nor complications. The success rate with the finder needle was 87% (52 of 60 patients) on first pass and 100% on second pass in the eight patients in whom a second pass was necessary. The success rate with the introducer was 100% on the first pass. In four cases there was difficulty threading the guidewire. Three of these were resolved by rotating the bevel of the introducer, and one was resolved by rotating the J-tip of the guidewire. Immediate or delayed signs of arterial puncture or pneumothorax were not observed. Two cases of catheter malposition were noted. In both cases the catheters were positioned in the left brachiocephalic vein. All catheters were removed in one to three postoperative days without complications.
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DISCUSSION |
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TopAbstractIntroductionMETHODSRESULTSDISCUSSIONREFERENCES |
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Introduction of multislice CT enabled reconstruction of contiguous transaxial images and enhanced perception of the 3-D anatomy. One of the 3-D visualization techniques currently in use is MPR, which is convenient for displaying the measured data in any arbitrary plane (12). Drawing imaginary paths of a puncture needle along a structure of interest on the arbitrary MPR plane can help clinicians visualize percutaneous approaches to internal structures. The prerequisite for this work was determination of a skin entry and venous target that would minimize the risk of potential complications. The technique permitted devising a new approach to the central venous system with potential advantages, including constant and easily identifiable surface landmarks, short distance without obstacles to the target vein, and possibly reduced complications of arterial puncture, pneumothorax, and malpositions.
The subclavian vein has substantial merit for percutaneous access because it is related to constant bony structures, such as the clavicle and the first rib. However, because the vein is relatively far from the skin entry point, 3-D estimation of the needle tip position may be difficult during the traditional blind infraclavicular approach. Additionally, the relationship between the vein and surrounding anatomies may change during patient positioning (13). As a result, aiming at the target vein becomes difficult and the risk of puncture-related adverse effects increases because of repeated tries (14).
Yoffa (6) first described the supraclavicular approach of the subclavian vein as follows: The approach of a needle by 15° anterior and 45° medial direction from just behind the clavisternomastoid junction ensured successful puncture of the subclavian vein (Fig. 2). A variety of arguments for the advantages of the supraclavicular approach include constant surface landmarks, large target size, high overall and initial success rate (7), successful performance despite lack of experience (8), significantly reduced complications (9), and adequate position of catheters (10). Nevertheless, physicians have been hesitant to use this technique because exploring the deeply concealed target beneath the sternum seemed too dangerous.
A review of the literature revealed that the target of the traditional supraclavicular approach was the venous confluence of the subclavian and internal jugular veins rather than the subclavian vein itself (15,16). However, the target of this study was the true subclavian vein that rests on the first rib. With our proposed technique, the route from the overlying skin to the subclavian vein on the first rib is the shortest of any possible approach to the subclavian vein. Compared with the traditional supraclavicular approach, the distance to the target vein was always shorter during the proposed approach. Therefore, a 1 1/4-inch hypodermic needle could be used successfully as a finder needle in all cases. The underlying first rib serves as a barrier between the subclavian vein and parietal pleura reducing the risk of pneumothorax. Since the puncture site of the subclavian vein lies on the first rib inside the costoclavicular angle, the "pinch-off" syndrome from the catheters can be avoided (17).
The subclavian artery should not be punctured unless the posterior angle is exceptionally increased (approximately 70°) or unless the skin entry point is moved posteriorly over 1 cm. Moreover, in thin patients it is possible to feel the pulsation of the subclavian artery over the supraclavicular fossa. Another warning of potential arterial puncture would be a sense of penetrating the anterior scalene muscle that usually lies anterior to the subclavian artery.
This proposed technique can be performed without changing the patient's position. A roll under the shoulder and caudal traction of the shoulder are not necessary. The approach can be performed by the anesthesiologist from the head of the table. Therefore, this method can also be used as a rescue procedure when there is a need for central venous catheterization after the start of surgery.
There are some limitations to this study. Because the study group was confined to patients with normal body build, the results of this study may not be applied to overweight patients. Additionally, our pilot study should not be viewed as a replacement for a properly powered clinical trial to evaluate relative safety. On the basis of the rule of three by Hanley and Lippman-Hand (18), we speculate that there might have been a complication rate as high as 5% because the recorded event rate of zero complications has a confidence interval of between 0% and 5% (3/60 in this study). Full evaluation of the safety of the proposed approach will require a prospective, randomized study design adequately powered, and stratified to include adequate numbers of obese patients. We also make no claim about the suitability of this technique.
In conclusion, we used 3D-CT images to determine a novel approach to central venous access with acceptable feasibility. From skin entry at the clavisternomastoid angle, a puncture needle directed 10° medially and 35° posteriorly ensured successful placement of catheters into the subclavian vein. Our pilot study demonstrated the high likelihood of success with this approach, and was reassuring as to the apparent safety of the approach. A video of the proposed approach is available as a web supplement to the online version of this manuscript at www.anesthesia-analgesia.org.
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Footnotes |
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