01-12-2016 | Understanding the Disease
Understanding clinical signs of poor tissue perfusion during septic shock
Published in: Intensive Care Medicine | Issue 12/2016
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Acute circulatory failure associated with infection, referred to as septic shock, is characterized by an inadequate tissue perfusion and oxygenation relative to metabolic requirements. This imbalance between delivery and tissue uptake is mainly due to altered microvascular blood flow regulation as a result of dysregulated and/or injured endothelial cells. Endothelial dysfunction is presumably induced by pathogenic bacterial products, inflammatory mediators, and reactive oxygen species produced by activated leukocytes [1]. Cellular and in fine tissue damages are related to ischemia and also to additional mechanisms that are out of the scope of this review such as mitochondria dysfunction. Direct microcirculation visualization using capillaroscopy has highlighted the heterogeneity of organ perfusion and the discrepancy between the overall hemodynamic status and local blood flow during sepsis [2]. In other words, in the presence of normal macro-hemodynamic, there may be regions of inadequate perfusion, underscoring the assessment of regional perfusion and oxygen delivery at the organ level [3]. Regional tissue perfusion has been investigated in different compartments such as the sublingual area or gastric mucosa using different devices, but in this mini-review, we will focus on skin peripheral perfusion, immediately available at the bedside (Table 1).
Table 1
Clinical methods used to measure peripheral perfusion
Method
|
Variable
|
Advantages
|
Limitations
|
Suggested cut-offs for higher mortality
|
---|---|---|---|---|
Mottling of the skin
|
Absence/presence
|
Could be done by nurses
|
Lack of specificity
|
–
|
Mottling score
|
Easy to use and learn reproducible
|
Not useful in patients with dark skin
|
Score 4–5 (scoring from 0 to 5)
|
|
Capillary refill time (CRT)
|
Index CRT
|
Easy to use and learn ± reproducible
|
Inter rater variability
|
Critically ill > 5 s
Septic shock > 2.4 s
|
Knee CRT
|
Reproducible
|
Not useful in patients with dark skin
|
Septic shock > 4.9 s
|
|
Temperature gradient
|
Forearm-to-finger
|
Validated method
|
Requires more complex technology
|
>4 °C
|
Central-to-toe
|
Validated method
|
>7 °C
|