Proper shoulder position for subclavian venipuncture. A prospective randomized clinical trial and anatomical perspectives using multislice computed tomography

Anesthesiology 2004;101:1306-1312

Introduction

Percutaneous catheterization of the subclavian vein using an infraclavicular approach is a relatively safe method of accessing a central vein. Numerous studies have attempted to identify optimal and safe positioning-procedures, but so far no consensus has been reached. The current study examined anatomical relations between right shoulder position and the subclavian vein using Multislice Computed Tomography (MSCT). In a second study the investigators verified these imaging results in a small clinical trial.

Study

In the first part, the authors studied the anatomical relationship between the subclavian vein and the surrounding tissues in 3 different shoulder-positions. The study was conducted in 7 healthy Japanese male adult volunteers without a history of thoracic/neck injury. They were placed in the supine position with both arms by the sides and retracted backwards by placing a small roll under the spine. The head was rotated 30 ° to the left and the shoulder position was determined by an arm-brace in a neutral, 5 cm cranial and 5 cm caudal position. MSCT without contrast medium was performed with inspiratory breath holding for 25 s. The position of the venous structures was projected on a three-dimensional bony reconstruction. Several distances between the subclavian vein and the surrounding structures were determined and the best shoulder-position for safe venipuncture was assessed. The 5 cm caudal position increased the overlap and the proximity between the clavicle and subclavian vein, increased the distance between the vein and the artery and narrowed the space between the vein and the 1st rib (p < 0.05) all suggesting this to be the safest position for puncturing the subclavian vein. Importantly, no significant differences were found for the mean diameter of the vein or distance to the pleura.

The clinical trial had a prospective randomized design in which patients underwent placement of a subclavian catheter after tracheal intubation and general anesthesia. The randomisation procedure is not described. Positioning was supine, head-down 20 °, head rotated 30 ° to the left with a small roll under the spine. The right shoulder was positioned either upward or downward. If the procedure was unsuccessful after 3 attempts the shoulder was switched to the other position. A proper sample size calculation was performed and a total of 30 patients were included. Demographic data between both groups were not significantly different. The procedure was successful within 3 attempts in 7/15 (47%) in the upward position and 15/15 (100%) in the downward position. In the patients with an unsuccessful procedure in the upward position, 7/8 had a successful puncture within 2 attempts in the downward position. In the remaining patient the subclavian vein could not be located in either position. No complications occurred.

Discussion

Both studies were rather small, but well designed and adequately powered. The described insertion procedure is well known and generally accepted although recent publications suggest that a towel roll under the spine may be detrimental. Unfortunately, it is unclear if these data from Japan can be extrapolated to our patients because of the apparent anatomical differences. Furthermore, a neutral shoulder position is the most commonly used position in clinical practice and the clinical study failed to address this. However, it is reasonable to conclude that at least an upward shoulder position should be abandoned during subclavian vein catheterization.

M. Fuchs, Fellow Intensive Care
J.G. van der Hoeven, Intensivist