About this Research Topic
Circulatory shock is defined as the imbalance between oxygen delivery and demand and may be associated with systemic arterial hypotension, clinical signs of hypoperfusion, and increase in arterial lactate. Maintaining adequate tissue perfusion is amongst the main goals for hemodynamic resuscitation. When mean arterial pressure (MAP) decreases critically, such as in circulatory shock, organ blood flow becomes dependent from perfusion pressure. Retrospective studies by Varpula (2005) and Dünser et al (2009) reported an increased mortality in patients with septic shock and MAP lower than 65 mmHg or 60 mmHg respectively.
However, interventions targeting a MAP value of 70 mmHg or higher failed to demonstrate an improved survival in studies by Dünser et al (2009) and Asfar et al (2014). These findings indicate that therapeutic interventions targeted to the sole improvement of global hemodynamic parameters, such as cardiac output or MAP, may fall short in restoring organ perfusion. In this context, the regional microcirculation may be impaired despite unaltered global circulatory variables.
Strategies outlined by Buwalda et al (2002) aiming to maintain an adequate microcirculation improve regional organ function and issue distress. In 2002 De Backer et al demonstrated that the sublingual microcirculation of patients with sepsis and septic shock was markedly altered compared to that of healthy volunteers and non-septic ICU patients. Studies by Trzeciak et al (2017) showed that early and profound derangements of sublingual microcirculatory perfusion indices were able to discriminate between non-survivors and survivors in severe sepsis and septic shock. To date, growing evidence indicates that microcirculatory alterations are universal in the context of circulatory shock, even with unchanged global hemodynamic variables, and may persist despite effective resuscitation.
A recent prospective observational study by Hutchings et al (2018) reveals that microcirculatory perfusion indices appear to be better predictive indicators for the development of multi organ dysfunction syndrome than other more commonly used markers of posttraumatic shock such as lowest systolic blood pressure (SBP) or highest plasma lactate concentration. In the last 17 years a variety of different methods were established, and consensus was reached on how to analyse the microcirculation at the bed side. However, studies incorporating a microcirculation-targeted resuscitation protocol are still missing. Furthermore, to make the situation more complicated, it seems that there are conceptual differences between microcirculatory monitoring in clinical and experimental investigations. In a recent editorial attempt to reach consensus on the question 'could resuscitation be based on microcirculation data?' (Intensive Care Medicine, 2018, 44, 950 -953) the viewpoints ranged from firmly negative (see the paper by David Naumann and Alexandre Lima on pp 947 -949, same issue) to definite “yes” (by Matthieu Legrand, Hafid Ait-Oufella and Can Ince, on pp 944 -946).
We invite investigators to contribute original research and reviews dealing with studies including but not limited to the following topics:
1. Potential mechanisms underlying microcirculatory disturbances
2. Monitoring of microcirculatory indices
3. Role of the microcirculation in the development and progression of (multi) organ dysfunction
4. Microcirculation-targeted preventive or therapeutic strategies under compromised conditions like sepsis or haemorrhagic shock.
Keywords: microcirculation, monitoring, sepsis, hemorrhagic shock, targeted therapeutic strategies
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