Disparities between peripheral perfusion and sublingual and nailfold microcirculation in patients with septic shock and healthy volunteers.

BACKGROUND: In shock states, microcirculation has been proposed as a potential resuscitation endpoint. However, despite the availability of videomicroscopy, its clinical use remains limited. In contrast, skin perfusion monitoring is simple, widely available and has increasingly been proposed as a surrogate of tissue perfusion. Nevertheless, the relationship between sublingual microcirculation and skin perfusion in shock remains complex. This study aimed to characterize the relationship between peripheral perfusion and sublingual and nailfold microcirculation, in septic shock patients and in healthy volunteers. METHODS: In this cross-sectional study, 34 healthy volunteers and 29 patients with septic shock were enrolled. Sublingual and nailfold microcirculation were assessed using videomicroscopy. Peripheral perfusion was evaluated by capillary refill time (CRT) and oximeter-derived perfusion index (PI). RESULTS: Compared with healthy volunteers, septic shock patients exhibited marked alterations in sublingual and nailfold microcirculation, prolonged CRT and reduced PI. In healthy volunteers, neither CRT nor PI was associated with sublingual or nailfold microcirculatory variables. In septic patients, CRT was correlated with flow related parameters but not with perfused vascular density. Perfusion Index and CRT were correlated both in healthy volunteers and septic patients. Nailfold microcirculation showed no association with PI or CRT. Notably, a proportion of patients with normal CRT exhibited altered microcirculation. ROC curve analysis demonstrated limited diagnostic performance of CRT for identifying altered microcirculation. CONCLUSIONS: In septic shock patients, CRT-a widespread vascular reactivity test- is associated with flow-related microcirculatory variables but not with diffusion-related parameters. Moreover, a normal CRT had limited ability to identify sublingual microcirculatory alterations.