Remote ischemic conditioning in septic shock (RECO-Sepsis): study protocol for a randomized controlled trial

Immune and inflammatory mechanism of remote ischemic conditioning: A narrative review

The benefits of remote ischemic conditioning (RIC) on multiple organs have been extensively investigated. According to existing research, suppressing the immune inflammatory response is an essential mechanism of RIC. Based on the extensive effects of RIC on cardiovascular and cerebrovascular diseases, this article reviews the immune and inflammatory mechanisms of RIC and summarizes the effects of RIC on immunity and inflammation from three perspectives: (1) the mechanisms of the impact of RIC on inflammation and immunity; (2) evidence of the effects of RIC on immune and inflammatory processes in ischaemic stroke; and (3) possible future applications of this effect, especially in systemic infectious diseases such as sepsis and sepsis-associated encephalopathy. This review explores the possibility of using RIC as a treatment in more inflammation-related diseases, which will provide new ideas for the treatment of this kind of disease.

Remote ischemic conditioning in septic shock: the RECO-Sepsis randomized clinical trial

PURPOSE

To determine whether remote ischemic conditioning (RECO), compared to standard care, limits the severity and the consequences of multiple organ failure in patients with septic shock.

METHODS

The RECO-Sepsis trial, a prospective, multicenter, randomized, open-label, parallel group trial with blinded assessment of the outcome, was conducted at six intensive care units in France in adult patients with septic shock. Within 12 h after the onset of septic shock, patients were randomized (1:1 ratio) to receive either RECO applied by inflating/deflating (200/0 mmHg for 5/5 min) 4 times a cuff around an arm or a sham procedure every 12 h for 24 h. The primary endpoint was the severity of multiple organ failure assessed by the mean daily Sequential Organ Failure Assessment (SOFA) score from inclusion to the fourth day after inclusion (day 4). Patients were followed for 90 days.

RESULTS

Among 180 randomized patients, 178 completed the trial (RECO group: 87; control group: 91) and were included in the intention-to-treat analysis (108 men [60.7%], median age 68 [59-75] years). There was no significant difference in the mean daily SOFA score between the intervention group and the control group (7.2 points [5.2-10.7] versus 7.6 points [4.9-10.7], respectively; p = 0.919). Cumulative mortality within 90 days was 27.6% in the RECO group and 39.6% control group (Log-rank test, p = 0.10; adjusted hazard ratio 0.59, 95% CI, 0.35 to 0.99; p = 0.049).

CONCLUSIONS

In patients with septic shock, RECO failed to reduce the severity of organ failures assessed by mean daily SOFA score from inclusion to day 4. Adequately powered trials are needed to assess potential delayed benefits of RECO.

Remote ischemic conditioning for acute respiratory distress syndrome in COVID-19

Acute respiratory distress syndrome and subsequent respiratory failure remains the leading cause of death (>80%) in patients severely impacted by COVID-19. The lack of clinically effective therapies for COVID-19 calls for the consideration of novel adjunct therapeutic approaches. Though novel antiviral treatments and vaccination hold promise in control and prevention of early disease, it is noteworthy that in severe cases of COVID-19, addressing "run-away" inflammatory cascades are likely more relevant for improvement of clinical outcomes. Viral loads may decrease in severe, end-stage coronavirus cases, but a systemically damaging cytokine storm persists and mediates multiple organ injury. Remote ischemic conditioning (RIC) of the limbs has shown potential in recent years to protect the lungs and other organs against pathological conditions similar to that observed in COVID-19. We review the efficacy of RIC in protecting the lungs against acute injury and current points of consideration. The beneficial effects of RIC on lung injury along with other related cardiovascular complications are discussed, as are the limitations presented by sex and aging. This adjunct therapy is highly feasible, noninvasive, and proven to be safe in clinical conditions. If proven effective in clinical trials for acute respiratory distress syndrome and COVID-19, application in the clinical setting could be immediately implemented to improve outcomes.

Remote Ischemic Conditioning in Acute Myocardial Infarction and Shock States

Remote ischemic conditioning is the phenomenon whereby brief, nonlethal episodes of ischemia in one organ (such as a limb) protect a remote organ from ischemic necrosis induced by a longer duration of severe ischemia followed by reperfusion. This phenomenon has been reproduced by dozens of experimental laboratories and was shown to reduce the size of myocardial infarction in many but not all clinical studies. In one recent large clinical trial, remote ischemic conditioning induced by repetitive blood pressure cuff inflations on the arm did not reduce infarct size or improve clinical outcomes. This negative result may have been related in part to the overall success of early reperfusion and current adjunctive therapies, such as antiplatelet therapy, antiremodeling therapies, and low-risk patients, that may make it difficult to show any advantage of newer adjunctive therapies on top of existing therapies. One relevant area in which current outcomes are not as positive as in the treatment of heart attack is the treatment of shock, where mortality rates remain high. Recent experimental studies show that remote ischemic conditioning may improve survival and organ function in shock states, especially hemorrhagic shock and septic shock. In this study, we review the preclinical studies that have explored the potential benefit of this therapy for shock states and describe an ongoing clinical study.

The Role of Heme Oxygenase-1 in Remote Ischemic and Anesthetic Organ Conditioning

The cytoprotective effects of the heme oxygenase (HO) pathway are widely acknowledged. These effects are mainly mediated by degradation of free, pro-oxidant heme and the generation of carbon monoxide (CO) and biliverdin. The underlying mechanisms of protection include anti-oxidant, anti-apoptotic, anti-inflammatory and vasodilatory properties. Upregulation of the inducible isoform HO-1 under stress conditions plays a crucial role in preventing or reducing cell damage. Therefore, modulation of the HO-1 system might provide an efficient strategy for organ protection. Pharmacological agents investigated in the context of organ conditioning include clinically used anesthetics and sedatives. A review from Hoetzel and Schmidt from 2010 nicely summarized the effects of anesthetics on HO-1 expression and their role in disease models. They concluded that HO-1 upregulation by anesthetics might prevent or at least reduce organ injury due to harmful stimuli. Due to its clinical safety, anesthetic conditioning might represent an attractive pharmacological tool for HO-1 modulation in patients. Remote ischemic conditioning (RIC), first described in 1993, represents a similar secure option to induce organ protection, especially in its non-invasive form. The efficacy of RIC has been intensively studied herein, including on patients. Studies on the role of RIC in influencing HO-1 expression to induce organ protection are emerging. In the first part of this review, recently published pre-clinical and clinical studies investigating the effects of anesthetics on HO-1 expression patterns, the underlying signaling pathways mediating modulation and its causative role in organ protection are summarized. The second part of this review sums up the effects of RIC.