Surgery · Medical Literature
The Effects of Remote Ischemic Preconditioning on the Inflammatory Cytokine Response to Free Flap Head and Neck Reconstruction: A Randomized Controlled Trial.
Abstract
Ischemia-reperfusion injury due to vascular pedicle occlusion is one of the most common causes of free flap failure in head and neck cancer reconstruction. Remote ischemic preconditioning (RIPC) has been proposed as an experimental, non-invasive intervention to attenuate flap ischemia-reperfusion injury; however, the tissue-protective mechanisms remain unclear. RIPC may have multiple effects on the inflammatory system, which plays a central part in the pathophysiology of ischemia-reperfusion injury. The aim of the present study was to evaluate the effect of RIPC on inflammatory cytokine plasma levels during free flap reconstruction. Head and neck cancer patients (n = 60) undergoing tumor resection and subsequent free flap reconstruction between August 2015 and November 2017 at Aarhus University Hospital, Denmark were randomized 1:1 to RIPC or sham intervention in a single-center, single-blinded, randomized controlled trial (RCT) (ClinicalTrials.gov: NCT02548377). The study was approved by The Central Denmark Region Committees on Health Research Ethics (journal no. 1-10-72-140-15) and reported following the CONSORT guidelines. RIPC was administered intraoperatively as four 5-min cycles of upper extremity occlusion and reperfusion with an inflatable tourniquet. Blood samples were collected before surgery, 6 h after RIPC/sham intervention, and on the 1st postoperative day. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, and interferon (IFN)-gamma were analyzed using a multiplex immunoassay. The average age of the RIPC group was 67 years (±10) and 64 years (±12) in the sham group. Plasma levels of the pro-inflammatory cytokines changed significantly between preoperative measures to 1st postoperative day between RIPC and sham; TNF-α (p < 0.001), IL-6 (p < 0.001), IL-8 (p < 0.001), IL-12p70 (p < 0.001), and IFN-γ (p < 0.001). No significant differences in cytokine levels were shown between groups at any specific time points. RIPC does not attenuate pro-inflammatory cytokine release in head and neck cancer patients undergoing free flap reconstruction. ClinicalTrials.gov identifier: NCT02548377.
Clinical relevance
Ischemia-reperfusion injury (IRI) remains a critical mechanism of free flap failure in head and neck cancer reconstruction, a high-stakes surgical population with limited salvage options. Remote ischemic preconditioning (RIPC) has garnered interest as a non-invasive, low-cost adjunct to attenuate IRI, but its immunomodulatory mechanisms in this specific context were previously uncharacterized. This RCT directly addresses that evidence gap by rigorously quantifying the cytokine-level inflammatory response to RIPC in a clinically relevant microsurgical cohort.
Key findings
1. Study design: Single-center, single-blinded RCT (NCT02548377) of 60 head and neck cancer patients randomized 1:1 to intraoperative RIPC (four 5-minute cycles of upper extremity tourniquet occlusion/reperfusion) versus sham intervention at Aarhus University Hospital (August 2015–November 2017). 2. Pro-inflammatory cytokines (TNF-α, IL-6, IL-8, IL-12p70, and IFN-γ) all changed significantly from preoperative baseline to postoperative day 1 within the overall cohort (all p < 0.001), confirming robust systemic inflammatory activation associated with the surgical procedure itself. 3. No statistically significant between-group differences in plasma levels of any of the 10 cytokines measured (TNF-α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, IFN-γ) were detected at any individual time point (preoperative, 6 hours post-intervention, or postoperative day 1). 4. The null finding was consistent across both pro-inflammatory and anti-inflammatory cytokine panels, suggesting RIPC exerts no measurable immunomodulatory effect — neither attenuation of pro-inflammatory nor enhancement of anti-inflammatory cytokine profiles — in this population. 5. Patient demographics were well matched: mean age 67 ± 10 years (RIPC) versus 64 ± 12 years (sham), supporting internal validity of the comparison. 6. No specific effect sizes, confidence intervals, or NNT/NNH values were reported in the abstract; quantitative between-group difference data are not available from this source.
Practice implications
Based on this RCT, intraoperative RIPC using upper extremity tourniquet cycling does not modulate the systemic inflammatory cytokine milieu in head and neck free flap patients and therefore cannot be recommended as an immunoprotective strategy to reduce IRI through this mechanism. Clinicians should not incorporate RIPC into perioperative free flap protocols with the expectation of cytokine-mediated tissue protection, pending further mechanistic studies that evaluate non-cytokine pathways (e.g., neuronal, humoral, or mitochondrial) or alternative RIPC protocols. Future trials should be adequately powered to detect clinically meaningful differences in flap failure rates as a primary endpoint, rather than surrogate cytokine biomarkers, to fully characterize any residual clinical benefit of RIPC in microsurgical reconstruction.