The high risk of mortality and morbidity from septic shock is lowered by the prompt, rapid, and precise delivery of fluids (Rhodes, Cecconi). The challenge we face as clinicians is knowing how much fluid is optimal in each patient situation. In order to avoid a subtherapeutic fluid amount or potentially harmful over-resuscitation, an adequate perfusion assessment is necessary to guide proper fluid infusion (Kattan). In a recent review in Annals of Translational Medicine, Kattan et al. provided an updated recommendation on optimal perfusion monitoring in septic shock after the ANDROMEDA-SHOCK trial showed peripheral perfusion-targeted resuscitation was associated with less organ dysfunction when compared to using serum lactate markers.
In the early stages of septic shock, the macro and microcirculation are still coupled, therefore, SvO2, pCO2 gap, and Capillary Refill Time (CRT) can be used to assess the responsiveness to a fluid challenge. Because CRT is quickly performed, simple, universally available, cost-free and without added risk of invasive measures, it is likely the most appropriate perfusion measure. In the advanced, later stages of septic shock, the capillary permeability increases and the micro and macro circulation become dissociated. As a result, SvO2, pCO2 gap, and CRT can all become unreliable perfusion measures, making multimodal monitoring (using these parameters as well as cardiac echocardiogram and macro hemodynamics) the optimal approach for the advanced septic shock patient (Kattan). However, within the multimodal approach, CRT fluid responsiveness could be used as a novel test for hemodynamic coherence (patency between macro and microcirculation) as well as an excellent resuscitation target as reemergence of a normal CRT likely signifies a return from deep hypoperfusion.
(Kattan; Figure 4) Proposed multimodal assessment of patients’ perfusion status, resuscitation strategy and resuscitation target during septic shock. CRT, capillary refill time; ScvO2, central venous oxygen saturation; pCO2 gap, central venous-arterial pCO2 gradients; DO2/VO2, oxygen delivery/consumption balance.
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