Central Venous Pressure Monitoring; Introduction of a New Device

Hemodynamic monitoring is needed in up to 58% of patients presented to the emergency department (1). Although central venous pressure (CVP) monitoring is generally useful to assess general volume status, its reliability as a guide to resuscitation in critically ill patients is a subject of debate (2, 3). Generally, there are several methods of CVP measurement, which can be categorized as invasive and non-invasive. Currently two methods are available for direct and invasive measurement of CVP. In the first method, after fixing a CV line catheter, CVP is measured using a CVP manometer connected to patient’s CV line. In the other method, an electronic transducer, connected to the CV catheter from one side and to the digital monitor from the other, is used to demonstrate measured CVP. There are also non-invasive methods such as direct observation and ultrasonography, which are used for indirect measurement of CVP. Observation of internal jugular venous pulsation remains an acceptable method to estimate right atrial pressure (4). In addition, ultrasonography can be used to determine elevated jugular venous pressure (5). If the jugular vein appears larger than the adjacent common carotid artery when the patient is in a semi upright position, CVP is probably >10 cmH2O. Another method of measurement is plethysmography. Change in forearm volume in response to externally applied pressure to upper arm veins is an indicator of CVP measure (6). Forearm volume may be measured by mercury-in-silastic strain gauge plethysmography. The correlation between CVP measured by this technique and invasive CVP is about 0.97 (7).