PURPOSE:Volume expansion is frequently employed in the critically ill with the goal of improving hemodynamics. Determining which patients benefit from volume expansion is not straightforward, and excess fluids can be deleterious. Static measures of hemodynamics currently employed to predict volume responsiveness are inadequate, with historically up to 70 percent of patients treated with volume expansion not demonstrating hemodynamic benefit. Passive leg raising (PLR) in conjunction with Doppler measurements of descending aortic blood flow has been shown to predict a significant hemodynamic response to volume challenge. However, this modality requires placement of an invasive probe which has contraindications and is poorly tolerated in non-sedated patients. The aim of our study is to determine if these limitations to this method can be eliminated with the use of a non-invasive Doppler device.
METHODS:Patients were studied from the medical intensive care unit of a university teaching hospital. All patients examined were determined by the intensive care unit team to require volume expansion. Measurements of stroke volume (SV) were taken using a non-invasive, external Doppler device in four stages. Stage one measurements were taken in the semi-recumbent position, stage two following two minutes of PLR, stage three after two minutes of being returned to the semi-recumbent position, and stage four following volume expansion.
RESULTS:A total of 29 patients were examined. A significant response to volume expansion was considered to be an increase in SV of at least 12%. Eleven patients hade a significant response (responders), while 18 did not (non-responders). An increase in SV of at least 10% with PLR predicted volume responsiveness with a sensitivity of 82% and a specificity of 83%. The positive and negative predictive values were 75% and 88%, respectively.
CONCLUSION:Non-invasive measurements of SV changes in conjunction with passive leg raising reliably predicts a significant hemodynamic response to volume expansion.
CLINICAL IMPLICATIONS:We have demonstrated a simple, non-invasive method that can be employed to optimize hemodynamic status and reduce unnecessary fluid administration in the medical ICU patient.
DISCLOSURE:Steven Thiel, No Financial Disclosure Information; No Product/Research Disclosure Information