Discrimination of mild hypovolemia in spontaneously breathing patients with hemodynamic stability

Abstract Using stroke volume variation (SVV) derived from passive leg raising (PLR) to assess fluid responsiveness has shown high accuracy in both mechanically ventilated and spontaneously breathing patients. However, challenges and limitations exist, particularly in spontaneously breathing patients maintaining hemodynamic stability. First, the hemodynamic effect of isolated leg elevation is temporary and gradually diminishes [1]. Second, the hemodynamic response from isolated leg raising is notably less pronounced than that from upper body elevation [2]. Third, the accuracy of SV measurements can be compromised in spontaneously breathing patients. Regular and consistent breathing patterns may be crucial when assessing fluid responsiveness in these patients [3]. Fourth, the criteria for pulse pressure variation and SVV in assessing fluid responsiveness exist in a grey zone, ranging between 10-15%. Lastly, while the efficacy of PLR-derived SVV as a diagnostic tool is well-supported in hemodynamically unstable patients, its diagnostic utility in stable patients remains unvalidated [4].