Sternocleoidomastoid muscle length predicts depth of central venous catheter insertion.

Background: Correct central venous catheter (CVC) insertion avoids serious complications, especially fatal intracardiac impalement. There are only few methods which discussed the depth of CVC insertion previously. Predicting the depth of CVC by body surface landmark is an easy and quick way, which is applied most wildly. Chest X-ray is a standard procedure to examine the depth of CVC. However, chest X-ray is not routinely availale, especially in emergency situations. Recent publications demonstrated that the determination of accurate placement by chest X-ray can be substituted by ECG guidance. We would like to find the correlation between surface anatomic landmarks and the depth of CVC insertion, and a method that could be applied easily and quickly to predict the depth of CVC insertion through ECG guidance.

Methods: Thirty patients receiving orthopedic, neurologic and gastrointestinal operations under general anesthesia were chosen for the study of CVC insertion via the right internal jugular vein puncture. The puncture site is at the mid-point of sternocleidomastoid (SCM) muscle, and direction of puncture is 30-45 degrees, pointing to nipple. ECG guidance is applied for the depth of CVC measurement. Body height, sitting height, length of sternum and SCM muscle were measured for reference.

Results: Both the length of SCM muscle and body height have statistically meaning for predicting the depth of CVC insertion (P < 0.001 vs. P = 0.012). In point of accuracy, SCM muscle length might be more significant in view of yielding a smaller P-value. And, the depth of CVC is equal to half of the length of SCM muscle plus 6.5 cm in adults aged 18 to 78 yrs.