Renal autoregulation and blood pressure management in circulatory shock

Abstract

The importance of personalized blood pressure management is well recognized. Because renal pressure-flow relationships may vary among patients, understanding how renal autoregulation may influence blood pressure control is essential. However, much remains uncertain regarding the determinants of renal autoregulation in circulatory shock, including the influence of comorbidities and the effects of vasopressor treatment. We review published studies on renal autoregulation relevant to the management of acutely ill patients with shock. We delineate the main signaling pathways of renal autoregulation, discuss how it can be assessed, and describe the renal autoregulatory alterations associated with chronic disease and with shock.

Keywords: Acute kidney injury; Cardiogenic shock; Hemorrhagic shock; Renal blood flow; Septic shock.

Fig. 1

Main elements of the signaling pathway underlying the myogenic response

Fig. 2

Main elements of the signaling pathway underlying tubuloglomerular feedback (TGF)

Fig. 3

Static renal autoregulation. a Linear regression can be used to fit two straight lines to the data. b If there is a more gradual transition to pressure-dependent flow, a logistic curve may be fitted. The shoulder of the curve can be calculated and used to define the lower limit of renal autoregulation (A_LL). AI autoregulatory index

Fig. 4

Dynamic renal autoregulation in the time domain: the myogenic response generates the initial, steep rise in renal vascular resistance. Tubuloglomerular feedback (TGF) starts to contribute after approximately 5–10 s

Fig. 5

Dynamic renal autoregulation in the frequency domain. a Power spectra for pressure and flow are constructed from their respective time series. b Both power spectra are combined to construct a transfer gain function. Negative gain values imply effective renal autoregulation in the given frequency range