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CARDIOVASCULAR ANESTHESIA

Central Venous Access: The Effects of Approach, Position, and Head Rotation on Internal Jugular Vein Cross-Sectional Area

Thomas Suarez, MD^*, Jeffrey P. Baerwald, PhD, and Chadd Kraus

*Sinai Hospital of Baltimore, Johns Hopkins University, Baltimore, Maryland; and Loyola College in Maryland, Baltimore, Maryland

Address correspondence and reprint requests to Thomas Suarez, MD, Sinai Hospital/Johns Hopkins Medical System, Department of Anesthesia, Division of Cardiac Anesthesia, 5th Floor, 2401 W. Belvedere Ave., Baltimore, MD 21215. Address e-mail to toms1636{at}eathlink.net

	Abstract

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We investigated the effects of approach (lateral versus anterior), position (supine versus Trendelenburg), and head rotation (0°, 20°, and maximum) during central venous catheterization on the area of the right internal jugular vein. Twenty-four patients were placed in supine position, followed by 25° of Trendelenburg position. In each position, measurement of the anterior and lateral right internal jugular vein cross-sectional areas was obtained by using planimetry with the patient’s head oriented at 0°, 20°, and maximum rotation. The largest cross-sectional areas were achieved in the lateral approach with the Trendelenburg position. In this position, no differences were detected among head rotation conditions. Data suggest that for those patients who tolerate the Trendelenburg position, the lateral access approach yields the statistically largest target area regardless of head rotation. When the Trendelenburg position is contraindicated, the results of this study suggest other approaches, e.g., the anterior approach, for central venous catheter placement that maximize the internal jugular vein area.

IMPLICATIONS: Central venous catheter insertion is commonly performed in the neck by using the right internal jugular vein. This study assesses factors affecting the cross-sectional area of this vein during central venous catheterization.

	Introduction

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Central venous access, for both surgical procedures and nonsurgical reasons, has become a valuable adjunct to patient care. Placement of central venous catheters via the right internal jugular vein has become one of the most popular routes (1,2). Although there are many effective methods to achieve internal jugular cannulation, there are very few quantitative data that identify the optimum conditions for successful placement. The specific anatomical relationships between the internal jugular vein and carotid artery have previously been well elucidated by Troianos et al. (3) and others (4). However, which cannulation approach is best is often a point of controversy, and supporting arguments are often not based on data. The variables in the control of the physician include the amount of head rotation to the contralateral side, the degree of Trendelenburg position, and the point of entry of the needle(s). The combination of these variables that results in the largest cross-sectional area of the internal jugular vein can reasonably be assumed to give optimum conditions (5,6). Using a surface ultrasound technique to locate the position of the internal jugular vein can greatly facilitate the placement of central venous catheters (7–9). However, this method may not be available or practical for some physicians. Although many studies have evaluated the common techniques for central catheter placement, both with and without ultrasound assistance, the authors did not find any that reported which method/approach yields the greatest cross-sectional area without the concurrent use of ultrasound guidance.

	Methods

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After IRB approval and subsequent informed consent, 24 subjects (13 men and 11 women; age range, 30–86 yr; weight range, 63–100.5 kg) participated in the study. Seventeen of the participants were patients who were to have coronary bypass surgery later that same day. Six of the patients were healthy volunteers. The NPO status of the subjects ranged from 4 to 10 h. No patient received premedication, and no other procedure (including IV catheter placement) was performed within 1 h of the start of each study. Exclusionary criteria included previous neck surgery (including carotid endarterectomy), history of head and neck masses or cancer, superior vena cava syndrome, or reported limited neck mobility. Patients who could not tolerate brief periods of Trendelenburg position, because of discomfort or shortness of breath, were also excluded. On the basis of these criteria, six patients were excluded from participation. No patient was hypotensive or hemodynamically unstable at the time of data collection.

Two areas for ultrasound analysis were chosen because they correspond to commonly used approaches for internal jugular access. The anterior position was defined at a point medial to the right sternocleidomastoid muscle and lateral to the cricoid cartilage. The lateral (often called the central) approach was established by locating the apex of the triangle formed by the two heads of the sternocleidomastoid muscle (10,11).

To obtain ultrasound measurements of the right internal jugular vein, a Sonus 4500 ultrasound machine with a 3.5-MHz surface probe was used. Each patient was placed in the supine position with no pillow under the occiput. An overarching protractor was then placed over each patient, and the head was adjusted such that 0° corresponded to a point on the upper portions of the nasal bones (between the eyes). With the stretcher in a neutral position (supine), mea-surements of the anterior and lateral cross-sectional areas were obtained by using planimetry after freezing the real-time image. After measurements were obtained in the 0° position, the patient’s head was rotated such that the upper nasal bones aligned with the 20° position, and again measurements were obtained. For the third set of measurements, the maximum lateral head rotation was used. Each of the 24 subjects was able to obtain at least 58° of lateral rotation (range, 58°–71°; mean, 68.3°).

For the second procedure, the stretcher was adjusted to 25° of Trendelenburg position. The patients were kept in this position for at least 1 min before any measurements were obtained. The same measurements described previously were obtained in the 0°, 20°, and maximum head rotations across anterior and lateral positions.

To achieve consistency in measurements, the same investigator obtained each of the 288 images (i.e., 6 images per patient) from the 24 patients. For each mea-surement, the investigator obtained the largest cross-sectional area for a given approach and position. It was deemed logistically impractical to blind the researcher to the results of the measurements because visual contact with the screen is important in obtaining sharp images and accurate measurements. A second investigator reviewed each of the 288 measurements.

	Results

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The descriptive statistics (mean ± SD) for each of the 24 patients across each of the conditions are presented in Figure 1. As Figure 1 suggests, there was a trend for the mean area of the internal jugular vein to increase with greater head rotation across both the supine and Trendelenburg positions. The smallest mean area was found in the supine position, 0° head rotation, anterior approach (mean, 0.78; SD, 0.46), whereas the largest mean area was detected in the Trendelenburg position, maximum head rotation, lateral approach (mean, 1.32; SD, 0.54).

View larger version (27K): [in this window] [in a new window]   Figure 1. Descriptive statistics for internal jugular vein area across supine and Trendelenburg positions, anterior and lateral approaches, and head rotation conditions. Boxes represent means and wings indicate ± 1 SD.

View larger version (17K): [in this window] [in a new window]   Figure 2. Difference scores between anterior and lateral approaches across supine and Trendelenburg positions across three head rotations. Values > 0 indicate greater internal jugular vein area in the lateral approach. Boxes represent means and wings indicate ± 1 SD.

Analysis of differences between the internal jugular vein area in the supine and Trendelenburg positions showed that in the anterior approach, the size of the internal jugular vein was significantly larger in the 0° (t₂₃ = 3.58, P < 0.002) and 20° (t₂₃ = 5.42, P < 0.001) head rotation conditions (see Fig. 3). No difference between positions was found in the maximum head rotation condition in the supine position.

View larger version (17K): [in this window] [in a new window]   Figure 3. Difference scores between supine and Trendelenburg approaches across anterior and lateral approaches across head rotation. Values > 0 indicate greater internal jugular vein area in the Trendelenburg approach. Boxes represent means and wings indicate ± 1 SD.

As Table 1 indicates, analysis of the head rotation data found weak significances in the Trendelenburg position across both the anterior and lateral approaches. Applying Bonferroni’s correction to control for Type I (false positives) error, no post hoc differences were detected across rotations in the anterior and lateral approaches or the supine and Trendelenburg positions.

	Discussion

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Safe and efficient placement of central venous catheters is an essential skill in many fields of clinical medicine. Previous work by Lobato et al. (12) measured the cross-sectional area of the right and left internal jugular veins. However, no other study has explored the effects of body position, head rotation, and approach on the area of the internal jugular vein.

In this study, power analysis was computed for a moderate effect size ( = 0.75) for 2 factors (anterior and lateral) across a combination of 12 conditions (head rotation and position) (12). The significance level (P value) was set to = 0.05. Results of power analysis yielded a projected n of 24 to achieve a moderate effect size.

For analysis of approach (anterior versus lateral), head rotation (0°, 20°, and maximum rotation) and position (Trendelenburg versus supine) difference scores were calculated by using one-sample Student’s t-tests with the comparison value set to 0 (i.e., the null hypothesis was that there is no difference between approaches). The results are presented in box and wing plots, with the heavy line representing the mean, the box representing 50% of the scores, and the whiskers representing 1 SD. The analyses of head rotation were conducted with a series of analyses of variance for repeated measures with post hoc matched paired Student’s t-tests to assess within-subject differences. This common statistical procedure is used when analyzing multiple points of data drawn from single subjects and controlling for the loss of the independence assumption associated with most parametric statistical tests. A P value of 0.05 was considered to be statistically significant. When multiple procedures were conducted, a Bonferroni correction was applied to control for the possibility of increased Type I error (detecting a false positive) when multiple statistical analyses were run on a single family of data (13). This correction applies a stringent reduction in the level, reducing the probability that significant findings are due to chance.

Table 2 shows that there was no statistical difference between the lateral and anterior approaches in either the supine or Trendelenburg position when the head was at 0° rotation. However, at 20° rotation, the venous area was larger in the lateral approach in the supine and Trendelenburg positions (8% and 15% larger, respectively). At maximum head rotation, there were mixed findings. In the supine position, there was no statistical difference between the lateral and anterior approaches; however, in the Trendelenburg position, the lateral approach yielded a 10% larger cross-sectional area compared with the anterior approach.

This study does not demonstrate that either the anterior or lateral approach is superior in all cases. When the patient can tolerate at least 25° of Trendelenburg position, the lateral approach with 20° of head rotation did result in the largest cross-sectional areas. Also, in the supine position with 20° of head rotation, the lateral approach yielded the larger internal jugular area. It is noteworthy that with 0° and maximum head rotation, there were no differences found when the approach was varied. Assuming that the patient can tolerate the Trendelenburg position and rotate his or her head, the lateral approach most often results in the largest cross-sectional area.

Although this study indicates which conditions and approach yield the largest target, our data do not take into account important qualitative factors that facilitate catheter placement into the right internal jugular vein. It is important to note that other factors not analyzed here, especially a clinician’s experience with a particular approach, will also affect the ease of catheter placement.

Analyzing the effect of the Trendelenburg position resulted in a larger right internal jugular vein cross-sectional area in all approaches (anterior and lateral) and in all degrees of head rotation, except in the anterior approach with maximum rotation, where no difference was found between the supine and Trendelenburg positions. This observation may have clinical relevance in those patients who have particularly severe coronary artery disease or poor pulmonary reserve. The Trendelenburg position shifts the visceral mass upward, thus reducing the functional residual capacity of the lungs. In addition, this position can shift Zone 3 (alveolar perfusion dependent on the arterial/venous pressure difference) upward and result in an abnormal ventilation/perfusion ratio (14). Work by Kubal et al.¹ has shown that this position is not without some risk in patients who are awake and preparing to undergo coronary artery bypass surgery. In some of these patients, myocardial oxygen consumption may increase, and even mild degrees of Trendelenburg position can result in ischemia²(15).

Studying the effect of head rotation on right internal jugular vein area across the conditions of anterior versus lateral approach and supine versus Trendelenburg position yielded valuable information. Using the anterior approach in the supine position, the maximum head rotation yielded the most favorable results. Further analysis of head rotation in the supine position shows that there was no difference between the 0° head rotation with either the anterior or lateral approach. When the 20° rotations in the supine position are compared, the lateral approach yields a larger cross-sectional area. The two maximum head rotation conditions in the supine position were also statistically equivalent. For those patients who cannot rotate their head secondary to an anatomical limitation or because of a painful pathology and those who cannot tolerate the Trendelenburg position, there is no advantage of the lateral over the anterior approach. Similarly, for those patients who cannot tolerate the Trendelenburg position but are not limited in neck mobility, the lateral approach with maximum rotation resulted in the largest cross-sectional area.

There are limitations to this study, including small sample size, the assumption that the largest cross-sectional area yields the best conditions, and the lack of standardization of patients on the basis of medication regimen. Because a similar study has not been reported in the literature, the investigators believed that a moderate effect size while controlling for Type I error was reasonable. Although many of the statistical analyses reported significant P values, further research with a larger sample size is warranted. In addition to the limitation of sample size, the participants in this study were not standardized with regard to medications. Even though no participant was hypotensive or hemodynamically unstable at the time of data collection, the effects of medication on vascular tone and intravascular volume should be controlled for in future studies. Given the wide variance of medication choice and administration often seen in this population, it was opined that for an initial study, the inclusion of this variable would have resulted in too much heterogeneity that would have required an unrealistic number of patients.

In conclusion, this study suggests that the cross-sectional area of the right internal jugular vein varies with the body position of the patient (supine versus Trendelenburg), head angle, and approach (anterior versus lateral). The largest cross-sectional area was found when the lateral approach was used with maximum head rotation in the Trendelenburg position. However, all clinical situations do not allow optimal positioning of a patient. In those cases, outlined previously, this study indicates which other conditions may produce the largest cross-sectional area for that given limitation.

	Footnotes

 
¹ Kubal K, Komatsu T, Sanchala V, et al. Trendelenburg position used during venous cannulation increases myocardial oxygen demands [abstract]. Anesth Analg 1984;63:239.

² Reich DL, Konstadt SN, Hubbard M, Thys DM. Do Trendelenburg and passive leg raising improve cardiac performance [abstract]? Anesth Analg 1988;67 (suppl):S184.

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Suarez, T. Articles by Kraus, C. Search for Related Content PubMed PubMed Citation Articles by Suarez, T. Articles by Kraus, C. Related Collections Cardiovascular Monitoring (Cardiac)