Effects of changes in arterial pressure on organ perfusion during septic shock

Abstract

IntroductionSeptic shock is characterized by altered tissue perfusion associated with persistent arterial hypotension. Vasopressor therapy is generally required to restore organ perfusion but the optimal mean arterial pressure (MAP) that should be targeted is uncertain. The aim of this study was to assess the effects of increasing MAP using norepinephrine (NE) on hemodynamic and metabolic variables and on microvascular reactivity in patients with septic shock.MethodsThis was a single center, prospective, interventional study conducted in the medico-surgical intensive care unit of a university hospital. Thirteen patients in septic shock for less than 48 hours who required NE administration were included. NE doses were adjusted to obtain MAPs of 65, 75, 85 and (back to) 65 mmHg. In addition to hemodynamic and metabolic variables, we measured thenar muscle oxygen saturation (StO2), using near infrared spectroscopy (NIRS), with serial vaso-occlusive tests (VOTs) on the upper arm. We also evaluated the sublingual microcirculation using sidestream dark field (SDF) imaging in 6 of the patients.ResultsIncreasing NE dose was associated with an increase in cardiac output (from 6.1 to 6.7 l/min, P<0.05) and mixed venous oxygen saturation (SvO2, from 70.6 to 75.9%, P<0.05). Oxygen consumption (VO2) remained stable, but blood lactate levels decreased. There was a significant increase in the ascending slope of StO2 (from 111 to 177%/min, P<0.05) after VOTs. SDF imaging showed an increase in perfused vessel density (PVD, from 11.0 to 13.2 n/mm, P<0.05) and in microvascular flow index (MFI, from 2.4 to 2.9, P<0.05).ConclusionsIn this series of patients with septic shock, increasing MAP above 65 mmHg with NE was associated with increased cardiac output, improved microvascular function, and decreased blood lactate concentrations. The microvascular response varied among patients suggesting that individualization of blood pressure targets may be warranted.

Mean arterial pressure drop is an independent risk factor of death in patients with HBV-related cirrhosis ascites

“…A recent research also demonstrated that a history of hypertension serves as a protective factor for liver-associated clinical decompensation and mortality (7). Another study also showed that a lower MAP of 50-60 mmHg has a positive correlation with a higher morbidity in case of kidney dysfunction (8).…”

“…MAP is regarded as perfusion pressure of the organs required to maintain blood flow and is considered as the most important hemodynamic parameter for the function of the circulation system. MAP is the determinant factor for maintaining cerebral and renal blood flow (6,8).…”

“…Low MAP has been shown to be closely associated with hyperdynamic circulation (5-7), seroperitoneum (5,7), and advancement of hepatorenal syndrome (8), thereby indicating that optimal MAP may be an important factor to ameliorate the prognosis of patients with liver cirrhosis ascites. However, which MAP level should be maintained to ameliorate the prognosis of patients with liver cirrhosis ascites remains controversial, and no prospective studies have determined the long-lasting impact of MAP on the prognosis of these patients.…”

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

“…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].…”

Pourquoi ne fais-je pas de monitoring hémodynamique ?

“…Avant l'intervention, la sévérité des anomalies était très variable d'un individu à l'autre. De plus, chez certains patients, ils ont observé une amélioration du pourcentage de petits vaisseaux perfusés et chez d'autres une franche aggravation [45]. Le groupe de Ince a confirmé ces résultats sur un groupe plus important de patients [46].…”