Relation between mean arterial pressure and renal function in the early phase of shock: a prospective, explorative cohort study

In this study, a difference exists between patients with AKI and those without AKI. Patients with AKI at 6 hours have a significantly higher volume expansion in the last 6 hours before inclusion. Volume expansion (a cornerstone of sepsis treatment) can lead to an increase in abdominal pressure [2]. This condition is not infrequent, even among medical patients [3], particularly during early septic shock [4].Thus, the beneficial effect on renal function of a higher MAP may be linked to the preservation of abdominal perfusion pressure and filtration gradient (FG) rather than to the impairment of renal autoregulation. We have shown (though only with preliminary results) that even a very moderate elevation of intra-abdominal pressure (IAP) can lead to a significant decrease of FG when the systemic hemodynamic is profoundly altered [5].Thus, it cannot be excluded that the higher MAP threshold in the septic group is linked to a higher IAP value. The relevant goal may be not to aim for a minimal MAP of more than 65 mm Hg to prevent AKI at the early phase of septic shock but to target a sufficient MAP value to preserve abdominal perfusion pressure and FG by monitoring IAP.Julie Badin and Thierry BoulainWe thank Dr. Jacobs for his relevant remarks concerning our work [1]. Although we did not measure IAP, we examined the influence of the amount of fluid administered on AKI: the amount of fluid, administered either before or during the first 72 hours and examined by quartiles, was not linked to the proportion of AKI at 72 hours in the whole population or in patients with sepsis or AKI at 6 hours (P >0.1 in all cases by chi-square test). Furthermore, in the population that Dr. Jacobs refers to (septic shock and initial AKI), the areas under the receiver operating characteristic curve of time-averaged MAP to predict AKI at 72 hours were very similar in patients who received less than 2,000 mL (the median amount of fluid received) before inclusion and those who received 2,000 mL o