An Ultrasound- Guided Algorithm for the Management of Oliguria in Septic Shock

BACKGROUND & INTRODUCTION:

Acute Kidney Injury (AKI) develops in 88% to 30% of critically ill patients admitted to an intensive care unit. While AKI of any severity is a strong predictor of mortality (1-4), both morbidity and mortality increase with increasing severity of renal injury(2). Therefore any management strategy that prevents progression of renal risk to injury or failure has the potential to improve outcomes in these patients.

Conventional management of acute oliguria in shock has been to blindly 'push' fluids to improve renal perfusion or to give loop diuretics once fluid loading has been considered as accomplished. However both volume overload and 'blind' attempts at fluid removal can worsen renal injury and have been associated with higher mortality by venous overcongestion (5) and inappropriate hypovolemia (6-8). It seems reasonable to assume that a bedside test to visualize volume status and renal perfusion may assist in improving outcomes in this cohort. Intensive care unit (ICU) bedside ultrasound has become the standard of care for critically ill patients(9-18). In patients with shock, inferior vena cava ultrasonographic evaluation for 'fluid responsiveness' is routinely used to direct resuscitation (19-21) by direct measurement of IVC diameter and respiratory variation or by the response to a noninvasive fluid bolus from a passive leg raise (22). Doppler ultrasound of intrarenal vessels has also been described as a tool to assess renal perfusion (23-27).

The investigators developed a goal-directed ultrasonographic protocol to provide immediate hemodynamic information in acutely oliguric patients with shock as well as a management algorithm for guiding therapy. The investigators incorporated IVC diameter measurement, respiratory variation and response to a passive leg raise to assess whether further fluid boluses were required and a measurement of renal perfusion to determine whether diuretics or renal replacement therapy were indicated.

The objectives are to measure the effects of this management protocol on the rates of AKI in the study participants as compared to prior to the implementation of the protocol.