Diagnostic accuracy of a simple ultrasound measurement to estimate central venous pressure in spontaneously breathing, critically ill patients.

BACKGROUND

Early goal-directed therapy for severe sepsis or septic shock improves outcomes but requires placement of a central venous catheter to measure central venous pressure (CVP), which may delay timely resuscitation and cause catheter-related complications. In addition, nonintensivists may not start early aggressive fluid resuscitation because of difficulty estimating CVP and concerns for inadvertent volume overload.

OBJECTIVE

To determine if the CVP target of 8 to 12 mm Hg can be accurately assessed using noninvasive ultrasound to measure the internal jugular vein aspect ratio (height/width).

DESIGN

Prospective observational study.

SETTING

Two academic medical centers.

PARTICIPANTS

Nineteen euvolemic volunteers and a convenience sample of 44 spontaneously breathing, critically ill patients.

MEASUREMENTS

Ultrasound imaging of internal jugular vein aspect ratio; invasive CVP measurement in critically ill patients.

RESULTS

For the volunteers, mean (standard deviation [SD]) aspect ratio of both the right and left internal jugular vein was 0.82 (0.07). Bland-Altman analysis indicated moderate intraobserver and interobserver agreement. Aspect ratio was similar for right and left sides and between men and women. In the critically ill patients, ultrasound accurately estimated a CVP of 8 mm Hg; area under the receiver operating characteristics curve was 0.84. For an invasively measured CVP of <8 mm Hg, the likelihood ratio for a positive ultrasound test (aspect ratio <0.83) was 3.5 and for a negative test (aspect ratio > or =0.83) was 0.30.

CONCLUSIONS

In this exploratory study, noninvasive ultrasound imaging of internal jugular vein aspect ratio accurately estimated a CVP of 8 mm Hg in spontaneously breathing, critically ill patients.