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.