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

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.

Intestinal Mucosal and Serosal Microcirculation at the Planned Anastomosis during Abdominal Surgery

INTRODUCTION

Intestinal blood flow is often named as a key factor in the pathophysiology of anastomotic leakage. The distribution between mucosal and serosal microperfusion during surgery remains to be elucidated.

OBJECTIVE

The aim of this study was to assess if the mucosal microcirculation of the intestine is more vulnerable to a surgical hit than the serosal microcirculation during surgery.

METHODS

In an observational cohort study (n = 9 patients), the microcirculation of the bowel serosa and mucosa was visualized with incident dark-field imaging during surgery. At the planned anastomosis, the following microcirculatory parameters were determined: microvascular flow index (MFI), percentage of perfused vessels (PPV), perfused vessel density (PVD), and total vessel density (TVD). Data are presented as median (interquartile range [IQR]).

RESULTS

Perfusion parameters and vessel density were significantly higher for the mucosa than the serosal microcirculation at the planned site for anastomosis or stoma. Mucosal MFI was 3.00 (IQR 3.00-3.00) compared to a serosal MFI of 2.75 (IQR 2.21-2.94), p = 0.03. The PPV was 99% (IQR 98-100) versus 92% (IQR 66-94), p = 0.01. The TVD was 16.77 mm/mm2 (IQR 13.04-18.01) versus 10.42 mm/mm2 (IQR 9.36-11.81), p = 0.01, and the PVD was 15.44 mm/mm2 (IQR 13.04-17.78) versus 9.02 mm/mm2 (IQR 6.43-9.43), p = 0.01.

CONCLUSIONS

The mucosal microcirculation was preserved, while lower perfusion of the serosa was found at the planned anastomosis or stoma during surgery. Further research is needed to link our observations to the clinically relevant endpoint of anastomotic leakage.

Role of Oxidative Stress and Mitochondrial Dysfunction in Sepsis and Potential Therapies

Sepsis is one of the most important causes of death in intensive care units. Despite the fact that sepsis pathogenesis remains obscure, there is increasing evidence that oxidants and antioxidants play a key role. The imbalance of the abovementioned substances in favor of oxidants is called oxidative stress, and it contributes to sepsis process. The most important consequences are vascular permeability impairment, decreased cardiac performance, and mitochondrial malfunction leading to impaired respiration. Nitric oxide is perhaps the most important and well-studied oxidant. Selenium, vitamin C, and 3N-acetylcysteine among others are potential therapies for the restoration of redox balance in sepsis. Results from recent studies are promising, but there is a need for more human studies in a clinical setting for safety and efficiency evaluation.

The microcirculatory failure could not weaken the increase of systematic oxygen extraction rate in septic shock: An observational study in canine models

OBJECT

This study aimed at exploring what level of the microcirculation alteration could weaken the decrease of ScvO2 (or the increase of O2ER) and further result in an abnormally elevated ScvO2.

METHODS

Beagles were randomly assigned into control (n = 5) and shock group (n = 5). The canines in shock group were intravenously injected with live E. coli (3.5×108 cfu/kg), and the ones in control group were injected with sterile saline. The experiment continued to the animals' death or for a maximum of 24 hours. Hemodynamic parameters, blood gas and inflammatory cytokines level were collected. Microcirculatory parameters were assessed with Sidestream Dark Field (SDF) imaging. The correlation between the microcirculation and oxygen metabolism or inflammatory cytokine, meanwhile the correlation between the oxygen metabolism and inflammatory cytokine was assessed.

RESULTS

E. coli infusion induced hypodynamic shock. The correlation between microcirculation and oxygen metabolism or inflammatory cytokine, and The correlation between the oxygen metabolism and inflammatory cytokine (O2ER vs. MFI: r = -0.700, P < 0.01; O2ER vs. PVD: r = -0.677, P < 0.01; O2ER vs. PPV: r = -0.538, P < 0.01; MFI vs. IL-6: r = -0.780, P < 0.01; PPV vs. IL-6: r = -0.621, P < 0.01; MFI vs. TNF-α: r = -0.636, P < 0.01; PPV vs. TNF-α: r = -0.561, P < 0.01) were observed.

CONCLUSIONS

The increase of O2ER cannot be weakened by the microcirculatory failure.

Haemodynamic coherence - The relevance of fluid therapy

The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing macrocirculation. This haemodynamic coherence is often altered in patients with haemorrhagic shock and sepsis. The loss of haemodynamic coherence is associated with adverse outcomes. It may be influenced by the mechanisms of the underlying disease and properties of different fluids used for resuscitation in these critically ill patients. Monitoring microcirculation and haemodynamic coherence may be an additional tool to predict the response to fluid administration. In addition, microcirculatory analysis may support the clinician in his decision to not administer fluids when microcirculatory blood flow is preserved. In future, the indication, guidance and termination of fluid therapy may be assessed by bedside microvascular analysis in combination with standard haemodynamic monitoring.