Abstract
BackgroundMaintenance of mean arterial pressure (MAP) at levels sufficient to avoid tissue hypoperfusion is a key tenet in the management of distributive shock. We hypothesized that patients with distributive shock sometimes have a MAP below that typically recommended and that such hypotension is associated with increased mortality.MethodsIn this retrospective analysis of the Medical Information Mart for Intensive Care (MIMIC-III) database from Beth Israel Deaconess Medical Center, Boston, USA, we included all intensive care unit (ICU) admissions between 2001 and 2012 with distributive shock, defined as continuous vasopressor support for ≥ 6 h and no evidence of low cardiac output shock. Hypotension was evaluated using five MAP thresholds: 80, 75, 65, 60 and 55 mmHg. We evaluated the longest continuous episode below each threshold during vasopressor therapy. The primary outcome was ICU mortality.ResultsOf 5347 patients with distributive shock, 95.7%, 91.0%, 62.0%, 36.0% and 17.2%, respectively, had MAP < 80, < 75, < 65, < 60 and < 55 mmHg for more than two consecutive hours. On average, ICU mortality increased by 1.3, 1.8, 5.1, 7.9 and 14.4 percentage points for each additional 2 h with MAP < 80, < 75, < 65, < 60 and < 55 mmHg, respectively. Multivariable logistic modeling showed that, compared to patients in whom MAP was never < 65 mmHg, ICU mortality increased as duration of hypotension < 65 mmHg increased [for > 0 to < 2 h, odds ratio (OR) 1.76, p = 0.005; ≥ 6 to < 8 h, OR 2.90, p < 0.0001; ≥ 20 h, OR 7.10, p < 0.0001]. When hypotension was defined as MAP < 60 or < 55 mmHg, the associations between duration and mortality were generally stronger than when hypotension was defined as MAP < 65 mmHg. There was no association between hypotension and mortality when hypotension was defined as MAP < 80 mmHg.ConclusionsWithin the limitations due to the nature of the study, most patients with distributive shock experienced at least one episode with MAP < 65 mmHg lasting > 2 h. Episodes of prolonged hypotension were associated with higher mortality.
Highlights
Shock is a state of acute circulatory failure characterized by inadequate tissue oxygen delivery, resulting in end-organ dysfunction and high risk of death [1,2,3]
Data source Data were obtained from the Medical Information Mart for Intensive Care (MIMIC-III, Version 1.4), which contains comprehensive, time-stamped information for > 60,000 intensive care unit (ICU) admissions at Beth Israel Deaconess Medical Center (BIDMC) in Boston, Massachusetts between 2001 and 2012, representing > 46,000 unique patients [15]
Baseline characteristics Of the 61,532 ICU admissions included in the MIMICIII database, 5347 met all the criteria for inclusion (Additional file 1: Figure S1); 2066 of these admissions were designated “high-dose.”
Summary
Shock is a state of acute circulatory failure characterized by inadequate tissue oxygen delivery, resulting in end-organ dysfunction and high risk of death [1,2,3]. For patients in septic shock, even relatively brief periods of hypoperfusion are associated with poor outcomes [6]. When mean arterial pressure (MAP) is below a certain threshold, organ blood flow falls linearly. 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. Maintenance of mean arterial pressure (MAP) at levels sufficient to avoid tissue hypoperfusion is a key tenet in the management of distributive shock. We hypothesized that patients with distributive shock sometimes have a MAP below that typically recommended and that such hypotension is associated with increased mortality
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