Central Venous Pressure Change With Volume Challenge in Patients With Hemodynamic Instability

In patients with shock a primary goal of treatment is to restore and maintain organ perfusion, for which an adequate cardiac preload is required. Apart from the situations in which hypovolemia is evident and a favourable response to fluid administration will be seen, clinical and biological parameters often fail to predict hypovolemia. Inappropriate use of volume expansion carries out the risk of generating volume overload and pulmonary oedema. Consequently, reliable predictors of fluid responsiveness are needed especially in the early phase of cardiocirculatory deterioration. In the clinical setting, different static and dynamic indices have been shown to be useful indicators of cardiac preload. Central venous pressure (CVP) is widely used to measure right ventricular preload in patients requiring invasive hemodynamic monitoring. However, the use of the CVP is much criticized because CVP poorly predicts cardiac preload and volume status. However several decades ago, Weil and Henning proposed the fluid challenge technique, based on the 2-5 rule using CVP. There is a method for guiding volume repletion based on measurements of the patient's response to fluid load. This method has not been validated in the prediction of fluid responsiveness. We therefore conducted a prospective study that in all patients we measured CVP change and stroke volume variation (SVV) after administration of fluids. Patients were classified as fluid responders when their SVV is >10% after volume expansion and non-responders if SVV is ≤10%.

Inclusion criteria

• mechanically ventilated patients
• acute circulatory failure defined by the need of vasopressive drugs (dopamine >5µg/kg/per minute or norepinephrine) with signs of tissue hypoperfusion (e.g., altered mental state, mottled skin, urine output below 0.5 ml per kilogram of body weight per hour during at least 2 h).
• admission serum lactate level more than 2.5mmol/L

Exclusion criteria

• severe hypoxemia defined as a ratio of arterial oxygen pressure to fraction of inspired oxygen [PaO2/FiO2] < 100 mmHg