Thèse de doctorat
Résumé : Skin blood flow in patients with circulatory shockWasineenart MONGKOLPUNErasme Hospital, Faculty of Medicine, Univerité Libre de Bruxelles (ULB)Introduction : In patients with circulatory shock, skin blood flow (SBF) is altered early before the significant change of global haemodynamic parameters. Moreover, skin hypoperfusion including its endothelial dysfunction persist after the treat of shock and are related to worst outcomes. Furthermore, an increase in SBF during resuscitation has been shown to be correlated with an improvement in organ function. Therefore, it should be monitored during resuscitation for diagnosis of tissue hypoperfusion and evaluating the resolution of tissue hypoperfusion. SBF is evaluated by physical examination: capillary refill time or the presence of mottled skin or cold, clammy extremities. However, because of difficulties in reliably assessing skin perfusion via clinical examination, skin laser doppler (SLD) has been developed to more precisely quantify SBF. Interestingly, non-invasive techniques such as SLD can assess SBF and skin microvascular endothelial function when combined with a local heating test (thermal challenge test; TCT). Nevertheless, the most suitable area to monitor SBF by SLD, the expression of the TCT response, the reliability and reproducibility all need to be studied and validated in patients with shockObjective : The aim of this thesis was to determine whether SBF and skin microvascular endothelial function (TCT), as measured using SLD, change during resuscitation and during therapeutic interventions and whether alterations in SBF and skin microvascular endothelial function are related to the severity of disease. Outline and Main results : Background part reviews current methods for assessing and monitoring skin perfusion, and Chapter 1 evaluates use of SBF, using SLD at finger, toe, forearm, and ear sites at different skin temperatures to discover which area is the most suitable for monitoring skin perfusion in circulatory shock, including its reliability and reproducibility. From Chapter 1, we demonstrated that SBF including TCT, measured on the finger and great toe were suitable area to monitor and they had good repeatability and reproducibility in patients with circulatory shock. The prognostic value of SBF including its response to a TCT measured using the SLD technique, on outcomes such as mortality or the development of organ dysfunction in patients with circulatory shock is presented in Chapter 2 and we observed that both SBF and endothelial function (TCT) were predictors of mortality. In Chapter 3, we consider the evolution of SBF and TCT during a fluid challenge to determine that the change is related to the correction of tissue hypoxia. In Chapters 4 and 5, we explain the evolution of SBF and TCT during fluid withdrawal therapy and their correlation with haemodynamic intolerance or development of acute kidney injury after a negative fluid balance was achieved or the alteration of tissue perfusion. Chapter 6, the final chapter, provides an overview of potential future approaches to monitoring skin perfusion using SLD during the treatment of shock.Conclusion : SBF measurement using SLD is a feasible technique to assess skin perfusion and skin microcirculatory endothelial function in patients with circulatory shock. This technique should be considered a useful tool to keep at the bedside to evaluate skin perfusion and skin endothelial vasodilatory function during the treatment of shock.