Non-invasive central venous pressure measurement by compression ultrasound--a step into real life.

AIM OF THE STUDY: Information on central venous pressure (CVP) is helpful in clinical situations like cardiac failure and sepsis. Compression ultrasound (CU) of a forearm vein has been shown to be a reliable method for CVP measurement when assessed by experienced personal under study conditions. To test the hypothesis, that CU can be reliably used for CVP measurement after a training program and using a portable ultrasound system, we investigated feasibility and accuracy of CU, comparing the results of vascular experts vs. trainees as well as high-end vs. a portable ultrasound system. METHODS: CU with non-invasive CVP measurement (CVP(ni)) was performed by four investigators in 50 patients of an intensive care unit and compared with invasive CVP measurement (CVP(i)). RESULTS: Feasibility was between 88 and 92% in the different investigator groups. CVP(ni) measurement showed a significant linear correlation (r=0.58-0.68; p<0.001) with CVP(i) in all groups. Mean difference between CVP(i) and CVP(ni) was 2.4+/-3.1mmHg and similar between the investigators. No differences were observed between measurements done by vascular experts and trainees, as well as between high-end and portable ultrasound systems. Further we demonstrated, that CU is able to detect changes in CVP during the respiratory cycle. CONCLUSIONS: After a training program CU can be used by non-vascular clinician for reliable CVP measurement with good quality portable systems. Furthermore, respiratory changes in CVP are detectable by CU. These data suggest CU to be an efficient method for measuring CVP under real life conditions.

Noninvasive central venous pressure measurement by controlled compression sonography at the forearm.

OBJECTIVES: We sought to validate a new noninvasive technique to determine central venous pressure (CVP) using high-resolution compression sonography. BACKGROUND: Information concerning CVP is crucial in clinical situations, including cardiac failure, volume overload, and sepsis. The measurement of CVP, however, requires puncture of a vein with attendant risk of complication. METHODS: After a proof-of-concept study in healthy subjects, a prospective blinded evaluation was performed comparing CVP measurement using a central venous catheter with measurement using compression sonography in critically ill (intensive care unit) patients. RESULTS: In healthy subjects with experimentally induced venous hypertension with a wide range of pressure values, a strong correlation (r = 0.95; p < 0.001) between noninvasive and invasive peripheral venous pressure at the forearm was shown. High interobserver agreement with an intraclass correlation coefficient of 0.988 shows excellent reliability of the system. Noninvasive peripheral venous pressure measurement at the forearm showed a good correlation with CVP in 50 intensive care unit patients with the forearm positioned both below heart level (r = 0.84; p < 0.001) and at heart level (r = 0.85; p < 0.001). The mean difference between invasive and noninvasive measurement was negligible (-0.1 +/- 3.5 cm H2O and -0.7 +/- 3.4 cm H2O, respectively). CONCLUSIONS: Controlled-compression sonography is a valuable tool for measuring venous pressure in peripheral veins and allows reliable indirect assessment of CVP without intravenous catheterization.

Estimation of central venous pressure by ultrasound.

INTRODUCTION: Increasing blood volume and cardiac output is one of the most commonly needed intervention in the primary care of traumatized and severely ill patients. Although cardiac filling pressures have severe limitations in assessing the preload, central venous pressure (CVP) is the invasive measure most frequently used in clinical practice for the assessment of volume status and cardiac preload. We combined ultrasound and tissue pressure measurement for non-invasive jugular and brachial venous pressure estimation. MATERIALS AND METHODS: CVP was measured invasively and non-invasively using the new technique in 32 critically ill patients. In six volunteers, increasing PEEP was used for the assessment of changes in non-invasive CVP. RESULTS: Non-invasive CVP increased linearly with increasing PEEP, independent of the investigator. Median (range) coefficient of variation (CV) for five consecutive measurements performed by three investigators in volunteers was 15% (6-31%), 14% (4-31%), and 21% (8-42%). Absolute differences between the average non-invasive CVP between investigators was 1.7 cm H2O (0.4-6.6 cm H2O), and the inter-examiner CVP was high (182%, 40-415%). In patients, invasive CVP was 10 mmHg (5-18 mmHg), and the corresponding non-invasive venous pressures were 8 mmHg (3-14 mmHg, basilic vein, p<0.01) and 6 mmHg (3-13 mmHg, jugular vein, p<0.01). The coefficients of variation were 4% (<1%-64%, invasive CVP), 22% (5%-51%, non-invasive basilic vein pressure), and 17% (7%-34%, non-invasive jugular vein pressure). CONCLUSION: Ultrasound-based, non-invasive measurement of venous pressure provides a relatively easy method rapid estimation of changes in CVP, although absolute values may differ substantially from invasive CVP and between different investigators.