MAP of 65: target of the past?

Abstract

Septic shock is defined as sepsis with hypotension refractory to fluid challenge and requiring vasopressor support combined with an increase in arterial lactate reflecting impaired cellular energy metabolism and dysoxia. The use of vasoactive drugs to restore mean arterial pressure (MAP) is strongly recommended by the Surviving Sepsis Campaign [1] and the Task Force of the European Society of Intensive Care Medicine (ESICM) on circulatory shock management and monitoring [2].Resuscitation in septic shock aims to restore tissue perfusion pressure without excessive vasoconstriction, which impedes flow and paradoxically worsens organ dysfunction or leads to other adverse events. MAP is a key component of tissue perfusion and is often viewed as a surrogate of organ perfusion pressure. Both the SSC and ESICM guidelines suggest keeping MAP ≥ 65 mmHg and individualizing this target based on comorbidities.The current MAP target of 65 mmHg is mainly based on the results of two retrospective studies investigating sequential MAP readings and the time spent below different threshold values of MAP during the first 24 or 48 h of management of patients with septic shock [3,4]. Both studies showed a correlation between MAP thresholds and survival [3,4] and organ dysfunction [4,5]. Best results were seen with a MAP between 60 and 65 mmHg, and the time spent below these values correlated with risk of mortality [3,4]. There was no survival benefit with higher MAP thresholds. Furthermore, the risk of mortality increased markedly in patients treated with high doses of norepinephrine irrespective of the MAP [5]. Recently, two prospective randomized controlled trials, SEPSIS-PAM and Ovation, compared high versus low target MAP on chances of survival in patients with septic shock [6,7]. In SEPSISPAM, patients were enrolled within 6 h of initiation of vasoactive drug treatment. In OVATION, patients were recruited up to 24 h after the diagnosis of septic shock. Target values were 80-85 vs. 65-70 and 75-80 vs. 60-65 mmHg for the high vs. low MAP in SEP-SISPAM and OVATION, respectively. There was no significant survival difference between the treatment groups at day 28 in either trial. However, both trials were underpowered as the mortality rate in the control groups was lower than expected. In addition, patients assigned to the low MAP target groups achieved higher MAPs than planned according to the study protocol.In a recent article in Intensive Care Medicine, Maheshwari et al. report the results of a retrospective analysis of 8782 patients admitted to 110 US hospitals exploring the association between MAP and acute kidney and myocardial injury as well as in-hospital mortality in patients with septic shock [8]. Using routinely collected data from an electronic health records database, the authors defined total exposure to hypotension as the time-weighted average mean arterial pressure (TWA-MAP) and calculated the cumulative time spent below 55, 65, 75, and 85 mmHg thresholds. The main results were that (1) exposure to hypotension of TWA-M...

Risk factors for and prediction of post-intubation hypotension in critically ill adults: A multicenter prospective cohort study

“…Interestingly, when MAP was used rather than SBP, we found that a threshold below 95 mmHg was associated with PIH. Thus, perhaps aiming for a higher perfusion pressure in the critically ill, either via MAP or SBP would prevent PIH and associated poor outcomes [32]. This would need to be tested via a future interventional trial.…”

Mean arterial pressure and mortality in patients with distributive shock: a retrospective analysis of the MIMIC-III database

“…The Surviving Sepsis Campaign (SSC) guidelines [ 5 ] call for an initial MAP target of 65 mmHg for patients with septic shock, followed by individual titration of vasopressor agents. Although there is a general consensus that MAP should be maintained > 65 mmHg [ 5 – 8 ], there is debate regarding need for higher MAP targets in some patients [ 9 – 14 ].…”

Oxygen therapy for medical patients

“…The strength of the evidence, inclusion of patient preferences, and clear practical guidance should hopefully cut the usual lag time in knowledge translation and encourage early adoption. The move towards “aim for normality, or tolerance of near-normality” also ties into a large body of recent critical care work 161718. The message is becoming more and more familiar, and harder to ignore.…”