Identification of cervicothoracic intervertebral spaces by surface landmarks and ultrasound

Precise localization of the cervicothoracic vertebral levels is essential for accurate placement of epidural catheters. Previous studies have demonstrated that anesthesiologists are inaccurate when using surface anatomy to locate lumbar vertebral levels. Our study was designed to determine the agreement between anatomical landmarks and the ultrasound technique in identifying the T7-8 and C7-T1 intervertebral spaces.

Adult healthy volunteers were assessed for the identification of cervicothoracic intervertebral spaces, initially in the anatomic position (AP)-upright, back straight, arms at the sides, and palms forward and then in the epidural position (EP) routinely used for epidural placement-seated, back arched, neck flexed, and arms across the chest. The T7 and C7 spinous processes were identified by one investigator using the inferior tip of the scapula and the vertebra prominens, respectively, as landmarks. Ultrasound was then used by a second investigator to identify the intervertebral spaces corresponding to the previously marked levels.

Fifty-five volunteers (23 males, 32 females) were recruited. The T7-8 intervertebral space determined by ultrasound coincided with the landmark findings in the AP and in the EP in 18% and 36% of the cases, respectively. The C7-T1 interspace identified by ultrasound corresponded with the surface landmarks in the AP and in the EP in 53% and 58% of the cases, respectively. In most cases, when the surface landmark and ultrasound findings of T7-8 did not agree, the surface landmark identified a lower interspace than ultrasound.

Identification of cervicothoracic intervertebral spaces by surface landmarks corresponded poorly with their identification using ultrasound. However, compared with the upright position, agreement in identifying the T7-8 interspace improved in the epidural position.