Assessment of Intravascular Fluid Status and Fluid Responsiveness during Mechanical Ventilation in Surgical and Intensive Care Patients

Fluid management of critically ill patients and those undergoing major surgery can be extremely difficult. It is important to predict which patients will respond to volume expansion in order to avoid undesired hypovolaemia and fluid overload. Traditionally, central venous pressure and pulmonary artery occlusion pressure have been used to guide fluid management. However, assimilation of available evidence from the past twenty years demonstrates that neither central venous pressure nor pulmonary artery occlusion pressure appears to be a useful predictor of haemodynamic response to fluid challenge. Recent evidence suggests that stroke volume variation, pulse pressure variation and the variation of the amplitude of the pulse oximeter plethysmographic waveform are far more accurate in predicting volume responsiveness in the intensive care unit. It is important for intensivists and perioperative physicians to understand the strengths and limitations of each method in order to scrutinise and interpret such data appropriately.