This prospective, double-blind, randomized controlled trial aimed to observe the effects of hydrocortisone combined with vitamin C and vitamin B1 versus hydrocortisone alone on microcirculation in patients with septic shock. The sublingual microcirculation in the treatment group was significantly better than that in the control group at 24 hours after treatment. It suggests that combination therapy can protect microcirculation. The results were further supported by the protective effect of the combination therapy on renal perfusion monitored by renal CEUS.
Septic shock is associated with microthrombosis, impaired endothelial barrier function, microvascular abnormalities, and mitochondrial dysfunction [19–21]. Hydrocortisone combined with vitamin C and vitamin B1 protects endothelial function and improves microcirculation through multiple pathways [15]. First, the antioxidant effect of vitamin C can reduce the permeability of endothelial cells, protect the function of microcirculation and reduce apoptosis by maintaining endothelial integrity [22–24]. Second, vitamin C has an immunomodulatory function, which reduces the production of inflammatory mediators and regulates the function of macrophages [25, 26]. Third, vitamin C plays an important role in the generation of vasopressors and maintaining vasopressor responsiveness [27]. Fourth, vitamin B1 is a key component of cell metabolism and can improve mitochondrial function, increase lactate clearance and protect organ function [28, 29]. However, vitamin C and vitamin B1 deficiency is common in septic shock patients and is associated with a poor prognosis [28, 30, 31]. Therefore, supplementation with vitamin C and vitamin B1 in septic shock patients protects endothelial barrier function and improves microcirculation.
Hydrocortisone and vitamin C have synergistic effects on protecting endothelial barrier function and microcirculation. First, oxygen-free radicals reduce the activity of glucocorticoid receptors, and vitamin C may protect and restore glucocorticoid receptor function. Second, vitamin C uptake by cells is mediated by the sodium-vitamin C transporter 2 (SVCT2). However, SVCT2 is downregulated in septic shock, and glucocorticoids increase the expression of SVCT2 [16, 32]. Thus, the combination of hydrocortisone and vitamin C can improve their physiological effects on protecting endothelial cells and microcirculation.
Current studies have drawn inconsistent conclusions [5–10, 13, 14, 33]. In the VITAMINS study, the combination therapy did not reduce the 90-day mortality but reduced the SOFA score at day 3 in septic shock patients [11]. In the ACTS trial, the combination therapy did not result in a statistically significant reduction in the SOFA score during the first 72 hours after enrollment and the 30-day mortality [12]. However, the subsequent meta-analysis showed that vitamin C alone or in combination with hydrocortisone/thiamine (treatment 3 to 4 days) reduces the 30-day mortality in patients with septic shock [5]. The heterogeneity of these results may be related to the differences in the efficacy of the combination therapy for different septic shock subtypes. A retrospective cohort study explored the effects of combination therapy on different septic shock subtypes and found that clinical outcomes may be better for patients with hyperinflammatory subtypes [34]. Additionally, procalcitonin may be an effective biomarker for monitoring the efficacy of the combination therapy [35]. Our study supports using combination therapy in septic patients because of its protective effect on microcirculation.
This study has some strengths. First, it used a prospective randomized controlled study design to ensure patient comparability between the treatment and control groups. We concealed the randomized results to avoid patient selection bias. Second, two researchers independently analyzed the microcirculation images, and we blinded microcirculation evaluators to the grouping scheme. We scored all microcirculation images to evaluate image quality and eliminated substandard images. Third, we performed bedside monitoring of renal perfusion using renal CEUS and compared the effects of different treatments on renal perfusion to support the primary outcome.
The limitations of this study were as follows. First, this was a single-center study with small sample size, characteristics that could affect the generality of the findings. Second, our grouping scheme did not blind clinicians. Each patient was comanaged by at least three clinicians, and no conflict of interest was found between the clinicians and the study. Third, we did not consider other vasoactive agent doses (epinephrine, dopamine, and vasopressin) when comparing the effects of different treatments on norepinephrine doses. Of the 22 patients included in the analysis, only one in the control group received epinephrine 24 hours after treatment. Fourth, according to the study design, the duration of the three drugs was 24 hours. It makes this study insufficient to evaluate the effects of the combination therapy on clinical outcomes, such as ICU mortality. Fifth, we did not monitor the plasma vitamin C and vitamin B1 levels.