Microcirculatory changes during open label magnesium sulphate infusion in patients with severe sepsis and septic shock

MAGNESIUM SULFATE AMELIORATES HISTONE-INDUCED COAGULATION DYSFUNCTION AND LUNG DAMAGE IN MICE

ABSTRACT

Introduction: Extracellular histones have been determined as significant mediators of sepsis, which can induce endothelial cell injury and promote coagulation activation, and ultimately contribute to multiorgan failure. Evidence suggests that magnesium sulfate (MgSO 4 ) exerts a potential coagulation-modulating activity; however, whether MgSO 4 ameliorates histone-induced coagulation dysfunction and organ damage remains unclear. Methods: To measure circulating histone levels, blood specimens were collected from septic patients and mice, and the relationship between circulating histone levels, coagulation parameters, and Mg 2+ levels in sepsis was investigated. Furthermore, to explore the possible protective effects of MgSO 4 , we established a histone-induced coagulation model in mice by intravenous histone injection. The survival rate of mice was assessed, and the histopathological damage of the lungs (including endothelial cell injury and coagulation status) was evaluated using various methods, including hematoxylin and eosin staining, immunohistochemistry, immunofluorescence, electron microscopy, and quantitative polymerase chain reaction. Results: The circulating histone levels in septic patients and mice were significantly associated with several coagulation parameters. In septic patients, histone levels correlated negatively with platelet counts and positively with prothrombin time and D-dimer levels. Similarly, in cecal ligation and puncture mice, histones correlated negatively with platelet counts and positively with D-dimer levels. Interestingly, we also observed a positive link between histones and Mg 2+ levels, suggesting that Mg 2+ with anticoagulant activity is involved in histone-mediated coagulation alterations in sepsis. Further animal experiments confirmed that MgSO 4 administration significantly improved survival and attenuated histone-mediated endothelial cell injury, coagulation dysfunction, and lung damage in mice. Conclusion: These results suggest that therapeutic targeting of histone-mediated endothelial cell injury, coagulation dysfunction, and lung damage, for example, with MgSO 4 , may be protective in septic individuals with elevated circulating histone levels.

Microcirculation-guided resuscitation in sepsis: the next frontier?

Microcirculatory dysfunction plays a key role in the pathogenesis of tissue dysoxia and organ failure in sepsis. Sublingual videomicroscopy techniques enable the real-time non-invasive assessment of microvascular blood flow. Alterations in sublingual microvascular perfusion were detected during sepsis and are associated with poor outcome. More importantly, sublingual videomicroscopy allowed to explore the effects of commonly applied resuscitative treatments in septic shock, such as fluids, vasopressors and inotropes, and showed that the optimization of macro-hemodynamic parameters may not be accompanied by an improvement in microvascular perfusion. This loss of "hemodynamic coherence," i.e., the concordance between the response of the macrocirculation and the microcirculation, advocates for the integration of microvascular monitoring in the management of septic patients. Nonetheless, important barriers remain for a widespread use of sublingual videomicroscopy in the clinical practice. In this review, we discuss the actual limitations of this technique and future developments that may allow an easier and faster evaluation of the microcirculation at the bedside, and propose a role for sublingual microvascular monitoring in guiding and titrating resuscitative therapies in sepsis.

Manipulating the Microcirculation in Sepsis - the Impact of Vasoactive Medications on Microcirculatory Blood Flow: A Systematic Review

BACKGROUND

Sepsis is life-threatening organ dysfunction because of a dysregulated host response to infection. Disturbed microvascular blood flow is associated with excess mortality and is a potential future target for interventions. This review addresses the evidence for pharmacological manipulation of the microcirculation in sepsis assessed by techniques that evaluate the sublingual microvasculature.

METHODS

Systematic review using a published protocol. Eligibility criteria were studies of septic patients published from January 2000 to February 2018. Interventions were drugs aimed at improving perfusion. Outcome was improvement in microvascular flow using orthogonal polarization spectral, sidestream dark field, or incident dark field imaging (Grades of Recommendation, Assessment, Development, and Evaluation criteria used).

RESULTS

Two thousand six hundred and six articles were screened and 22 included. (6 randomized controlled trials, 12 interventional, 3 observational, and 1 pilot, n = 572 participants). Multiple measurement techniques were described, including: automated analyses, subjective, and composite scoring systems. Norepinephrine was not found to improve microvascular flow (low-grade evidence, n = 6 studies); except in chronic hypertension (low, n = 1 study). Addition of arginine vasopressin or terlipressin to norepinephrine maintained flow while decreasing norepinephrine requirements (high, n = 2 studies). Neither dobutamine nor glyceryl trinitrate consistently improved flow (low, n = 6 studies). A single study (n = 40 participants) demonstrated improved flow with levosimendan (high). In a risk of bias assessment 16/16 interventional, pilot and observational studies were found to be high risk.

CONCLUSIONS

There is no robust evidence to date that any one agent can reproducibly lead to improved microvascular flow. Furthermore, no study demonstrated outcome benefit of one therapeutic agent over another. Updated consensus guidelines could improve comparable reporting of measurements and reduce bias, to enable meaningful comparisons around the effects of individual pharmacological agents.

Hemodynamic coherence in sepsis

Microvascular alterations are a hallmark of sepsis and play a crucial role in its pathophysiology. Such alterations are the result of overwhelming inflammation, which negatively affects all the components of the microcirculation. As the severity of microvascular alterations is associated with organ dysfunction and mortality, several strategies have been tested for improving microcirculation. Nevertheless, they are mainly based on the conventional manipulation of systemic hemodynamics to increase the total flow to the organs and tissues. Other therapeutic interventions are still being investigated. In this review, we discuss the pathophysiology of septic microcirculatory dysfunction and its implications for possible treatments.

Hypomagnesemia in Critically Ill Sepsis Patients

Magnesium (Mg), also known as “the forgotten electrolyte”, is the fourth most abundant cation overall and the second most abundant intracellular cation in the body. Mg deficiency has been implicated in the pathophysiology of many diseases. This article is a review of the literature regarding Mg abnormalities with emphasis on the implications of hypomagnesemia in critical illness and on treatment options for hypomagnesemia in critically ill patients with sepsis. Hypomagnesemia is common in critically ill patients, and there is strong, consistent clinical evidence, largely from observational studies, showing that hypomagnesemia is significantly associated with increased need for mechanical ventilation, prolonged ICU stay and increased mortality. Although the mechanism linking hypomagnesemia with poor clinical outcomes is not known, experimental data suggest mechanisms contributing to such outcomes. However, at the present time, there is no clear evidence that magnesium supplementation improves outcomes in critically ill patients with hypomagnesemia. Large, well-designed clinical trials are needed to evaluate the role of magnesium therapy for improving outcomes in critically ill patients with sepsis.

Magnesium status and magnesium therapy in critically ill patients: A systematic review

PURPOSE

Magnesium is frequently measured and administered in general intensive care unit patients. However, magnesium status, its association with outcomes, and therapeutic utility in such patients are unclear. We performed a systematic review of the relevant literature to define current knowledge in this field.

MATERIALS AND METHODS

We searched MEDLINE, CENTRAL, and EMBASE from 1975 to July 2014 for adult English language articles excluding obstetric, non-intensive care unit based, and specific population (poisoning, cardiothoracic, and neurosurgery) studies. We identified articles on magnesium measurement, associations, and therapy. We calculated pooled effect estimates from reported adjusted risk estimates.

RESULTS

We identified 34 relevant studies. Total serum total magnesium was the most commonly measure of magnesium status. Risk of mortality was significantly increased with hypomagnesemia (odds ratio, 1.85; 95% confidence interval, 1.31-2.60). No consistent associations existed between magnesemia or magnesium administration and any other outcomes.

CONCLUSIONS

Total serum magnesium levels are generally used to estimate magnesium status in critical illness. Hypomagnesemia appears associated with greater risk of mortality, but the efficacy of magnesium administration is open to challenge.

Effects of ketanserin on microcirculatory alterations in septic shock: An open-label pilot study

INTRODUCTION

Microcirculatory alterations in sepsis are associated with increased morbidity and mortality. These alterations occur despite macrohemodynamic resuscitation. Alternative pro-microcirculatory strategies, including vasodilatory drugs, have been suggested to improve capillary blood flow. Ketanserin, a serotonin receptor antagonist, is an attractive candidate because of its vasodilatory, antithrombotic, and anti-inflammatory effects.

METHODS

This is an open-label pilot study on the effect of ketanserin administration on microcirculatory alterations in septic shock, defined as microvascular flow index (MFI)≤2.5 after a strict macrohemodynamic resuscitation protocol. Sidestream dark-field imaging was applied to assess the microcirculation. A stepwise incremental dose regiment was applied until an MFI>2.9, the primary end point, was reached.

RESULTS

Ten patients (Acute Physiology and Chronic Health Evaluation IV scores of 115 [100-136]) were included. Baseline MFI was 1.71 (1.31-2.32) and was significantly increasing to 2.96 (2.54-3.00; P=.021) during the ketanserin infusion. The total ketanserin dose was 0.09 (0.08-0.13) mg/kg per patient in 60 (30-60) minutes. In 3 patients (30%), the ketanserin infusion was discontinued due to refractory hypotension.

CONCLUSION

An improvement in microcirculatory perfusion was observed during ketanserin administration in patients with septic shock after macrohemodynamic resuscitation. This finding needs further exploration in a placebo-controlled setting.

Effects of antenatal magnesium sulfate treatment on cerebral blood flow velocities in preterm neonates

OBJECTIVE

The objective of this study is to investigate the effects of antenatal magnesium sulfate (MgSO4) on cerebral blood flow (CBF) velocities in preterm neonates.

STUDY DESIGN

In this prospective case-control study, we included 53 neonates born between 26 and 34 weeks of gestation. Twenty neonates were exposed to MgSO4 antenatally and 33 were not. Serial daily Doppler flow measurements of middle cerebral artery (MCA) were performed.

RESULT

Significantly increased MCA mean velocities were found in the MgSO4 group. A progressive increase in serial Doppler measurements of MCA mean velocity from day 1 to day 5 of life was detected in both groups.

CONCLUSION

There is significant increase in MCA mean velocities in preterm neonates receiving antenatal MgSO4. This increment in CBF velocities might explain the protective role of MgSO4 in ischemic events and hypoxic brain damage.

Pathophysiology of microcirculatory dysfunction and the pathogenesis of septic shock

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the various mechanisms that are potentially involved in their development and the implications of these alterations. Endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability are the main mechanisms involved in the development of these alterations. Microcirculatory alterations increase the diffusion distance for oxygen and, due to the heterogeneity of microcirculatory perfusion in sepsis, may promote development of areas of tissue hypoxia in close vicinity to well-oxygenated zones. The severity of microvascular alterations is associated with organ dysfunction and mortality. At this stage, therapies to specifically target the microcirculation are still being investigated.

Study Design of the Microcirculatory Shock Occurrence in Acutely Ill Patients (microSOAP): an International Multicenter Observational Study of Sublingual Microcirculatory Alterations in Intensive Care Patients

Objective. Sublingual microcirculatory alterations are associated with an adverse prognosis in several critical illness subgroups. Up to now, single-center studies have reported on sublingual microcirculatory alterations in ICU patient subgroups, but an extensive evaluation of the prevalence of these alterations is lacking. We present the study design of an international multicenter observational study to investigate the prevalence of microcirculatory alterations in critically ill: the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP). Methods. 36 ICU's worldwide have participated in this study aiming for inclusion of over 500 evaluable patients. To enable communication and data collection, a website, an Open Clinica 3.0 database, and image uploading software have been designed. A one-session assessment of the sublingual microcirculation using Sidestream Dark Field imaging and data collection on patient characteristics has been performed in every ICU patient >18 years, regardless of underlying disease. Statistical analysis will provide insight in the prevalence and severity of sublingual alterations, its relation to systemic hemodynamic variables, disease, therapy, and outcome. Conclusion. This study will be the largest microcirculation study ever performed. It is expected that this study will also establish a basis for future studies related to the microcirculation in critically ill.