Did the beneficial renal outcomes with vasopressin VANISH?

Decreased renal cortical perfusion, independent of changes in renal blood flow and sublingual microcirculatory impairment, is associated with the severity of acute kidney injury in patients with septic shock

Background

Reduced renal perfusion has been implicated in the development of septic AKI. However, the relative contributions of macro- and microcirculatory blood flow and the extent to which impaired perfusion is an intrinsic renal phenomenon or part of a wider systemic shock state remains unclear.

Methods

Single-centre prospective longitudinal observational study was carried out. Assessments were made at Day 0, 1, 2 and 4 after ICU admission of renal cortical perfusion in 50 patients with septic shock and ten healthy volunteers using contrast-enhanced ultrasound (CEUS). Contemporaneous measurements were made using transthoracic echocardiography of cardiac output. Renal artery blood flow was calculated using velocity time integral and vessel diameter. Assessment of the sublingual microcirculation was made using handheld video microscopy. Patients were classified based on the degree of AKI: severe = KDIGO 3 v non-severe = KDIGO 0–2.

Results

At study enrolment, patients with severe AKI (37/50) had prolonged CEUS mean transit time (mTT) (10.2 vs. 5.5 s, p < 0.05), and reduced wash-in rate (WiR) (409 vs. 1203 au, p < 0.05) and perfusion index (PI) (485 vs. 1758 au, p < 0.05); differences persisted throughout the entire study. Conversely, there were no differences in either cardiac index, renal blood flow or renal resistive index. Sublingual microcirculatory variables were not significantly different between groups at study enrolment or at any subsequent time point. Although lactate was higher in the severe AKI group at study enrolment, these differences did not persist, and there were no differences in either ScvO2 or ScvCO2-SaCO2 between groups. Patients with severe AKI received higher doses of noradrenaline (0.34 vs. 0.21mcg/kg/min, p < 0.05). Linear regression analysis showed no correlation between mTT and cardiac index (R-0.18) or microcirculatory flow index (R-0.16).

Conclusion

Renal cortical hypoperfusion is a persistent feature in critically ill septic patients who develop AKI and does not appear to be caused by reductions in macrovascular renal blood flow or cardiac output. Cortical hypoperfusion appears not be associated with changes in the sublingual microcirculation, raising the possibility of a specific renal pathogenesis that may be amenable to therapeutic intervention.

Trial Registration Clinical Trials.gov NCT03713307, 19 Oct 2018.

Septic acute kidney injury: a review of basic research

Sepsis is a major cause of acute kidney injury (AKI) among patients in the intensive care unit. However, the numbers of basic science papers for septic AKI account for only 1% of all publications on AKI. This may be partially attributable to the specific pathophysiology of septic AKI as compared to that of the other types of AKI because it shows only modest histological changes despite functional decline and often requires real-time functional analysis. To increase the scope of research in this field, this article reviews the basic research information that has been reported thus far on the subject of septic AKI, mainly from the viewpoint of functional dysregulation, including some knowledge acquired with multiphoton intravital imaging. Moreover, the efficacy and limitation of the potential novel therapies are discussed. Finally, the author proposes several points that should be considered when designing the study, such as monitoring the long-term effects of the intervention and reflecting the clinical settings for identifying the molecular mechanisms and for challenging the intervention effects.

Regional differences in the treatment of refractory vasodilatory shock using Angiotensin II in High Output Shock (ATHOS-3) data

INTRODUCTION

Despite international guidelines, regional differences in treatment of vasodilatory shock remain. We characterized these differences using data from Angiotensin II in High Output Shock (ATHOS-3) trial.

METHODS

The 321 patients treated in the ATHOS-3 trial were included. Baseline and hour-48 data were analyzed for differences in demographics, clinical characteristics, and treatment patterns, and grouped into four geographical areas: United States, Canada, Europe, and Australasia. Differences were analyzed by Kruskal-Wallis tests for continuous, and chi-square tests for categorical data. Temporal analysis compared changes in the treatment of shock during the treatment period.

RESULTS

Differences in baseline characteristics across geographic areas were noted in BMI, albumin, CVP, MELD score, APACHE II score, and total SOFA score. Baseline norepinephrine and norepinephrine equivalent doses (NED) were higher (p < .0001 and p = .0494, respectively), and vasopressin use was lower (p < .0001) in Europe. Baseline steroids were utilized more in the US and Canada (p = .0011).

CONCLUSIONS

Management of vasodilatory shock differs globally with respect to utilization of steroids and vasopressors. This practice heterogeneity may influence shock trials interpretation and patient outcomes, though more definitive evidence would require larger prospective intervention data.