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

Abstract

IntroductionBecause of disturbed renal autoregulation, patients experiencing hypotension-induced renal insult might need higher levels of mean arterial pressure (MAP) than the 65 mmHg recommended level in order to avoid the progression of acute kidney insufficiency (AKI).MethodsIn 217 patients with sustained hypotension, enrolled and followed prospectively, we compared the evolution of the mean arterial pressure (MAP) during the first 24 hours between patients who will show AKI 72 hours after inclusion (AKIh72) and patients who will not. AKIh72 was defined as the need of renal replacement therapy or "Injury" or "Failure" classes of the 5-stage RIFLE classification (Risk, Injury, Failure, Loss of kidney function, End-stage renal disease) for acute kidney insufficiency using the creatinine and urine output criteria. This comparison was performed in four different subgroups of patients according to the presence or not of AKI at the sixth hour after inclusion (AKIh6 as defined as a serum creatinine level above 1.5 times baseline value within the first six hours) and the presence or not of septic shock at inclusion.The ability of MAP averaged over H6 to H24 to predict AKIh72 was assessed by the area under the receiver operating characteristic curve (AUC) and compared between groups.ResultsThe MAP averaged over H6 to H24 or over H12 to H24 was significantly lower in patients who showed AKIh72 than in those who did not, only in septic shock patients with AKIh6, whereas no link was found between MAP and AKIh72 in the three others subgroups of patients. In patients with septic shock plus AKIh6, MAP averaged over H6 to H24 or over H12 to H24 had an AUC of 0.83 (0.72 to 0.92) or 0.84 (0.72 to 0.92), respectively, to predict AKIh72 . In these patients, the best level of MAP to prevent AKIh72 was between 72 and 82 mmHg.ConclusionsMAP about 72 to 82 mmHg could be necessary to avoid acute kidney insufficiency in patients with septic shock and initial renal function impairment.

Low Systemic Oxygen Delivery and BP and Risk of Progression of Early AKI

“…When sequentially increasing the NE infusion rate to target a MAP of 60, 75, and 90 mmHg, restoration of MAP from 60 to 75 mmHg improved renal DO 2 , GFR, and renal oxygenation, but there was no significant difference between MAP 75 and 90 mmHg. An observational study in 217 critically ill patients suggested that a MAP of 72-82 mmHg may be necessary to avoid AKI in patients with septic shock and early renal impairment (30). A Finnish study showed that patients with sepsis who developed AKI within 5 days of ICU admission had a significantly lower MAP (74 mmHg) compared with patients with sepsis without AKI (MAP 79 mmHg) (31).…”

A high mean arterial pressure target is associated with improved microcirculation in septic shock patients with previous hypertension: A prospective open-label study

“…Correa and colleagues [9] have evaluated the effects of different MAP targets in septic pigs, and show that targeting a MAP between 50 and 60 mmHg in septic shock is associated with increased incidence of acute kidney injury when compared with a target MAP of between 75 and 85 mmHg. Moreover, Badin and colleagues [10] have reported that acute kidney injury is decreased with a MAP of at least 72 mmHg. However, which MAP levels should be targeted to improve microcirculation remains controversial [11][12][13].…”

Where is the vascular waterfall in septic shock?

“…Some of these studies revealed that MAP under 65 mmHg was associated with highest mortality in patients with septic shock 2 , but targeting a MAP higher than 65 mmHg conferred no additional benefit 3,4 . Looking specifically at renal function, however, other studies found that targeting a higher MAP was beneficial [5][6][7] . In reality, the majority of critical care practitioners seem to be targeting a MAP higher than 65 mmHg 8 .…”