Measuring skin necrosis in a randomised controlled feasibility trial of heat preconditioning on wound healing after reconstructive breast surgery: study protocol and statistical analysis plan for the PREHEAT trial

Hyperbaric Oxygen Therapy for Complications in Nipple-Sparing Mastectomy with Breast Reconstruction: A Systematic Review

Background: Research advancing effective treatments for breast cancer is crucial for eradicating the disease, reducing recurrence, and improving survival rates. Nipple-sparing mastectomy (NSM), a common method for treating breast cancer, often leads to complications requiring re-operation. Despite advancements, the use of hyperbaric oxygen therapy (HBOT) for treating these complications remains underexplored. Therefore, we analyze the efficacy of HBOT in the post-operative care of patients undergoing NSM. Methods: A systematic search was conducted using PubMed, Scopus, and the Cochrane Library. Studies were assessed for eligibility using the PICO (Population, Intervention, Comparison, Outcome) framework and classified based on American Society of Plastic Surgeons (ASPS) levels of evidence. Seven studies, totaling a pool of 63 female patients, met the inclusion criteria. Among these studies, four were categorized as Level III (57.1%), one as Level IV (14.3%), and two as Level V (28.6%). These studies focused on HBOT's role in wound healing, the successful salvage of breast reconstruction, and the optimal timing for HBOT. Results: This review revealed that HBOT indeed has potential for improving tissue oxygenation, vascularization, and, consequently, wound healing. It is noted that HBOT is efficacious for mitigating post-NMS complications, including infections, re-operation, flap loss, seroma, and hematoma. Conclusions: Overall, HBOT could be beneficial in standard post-surgical care protocols for patients undergoing NSM due to its role in mitigating common adverse effects that occur after mastectomy. Despite promising outcomes, the recent literature lacks rigorous clinical trials and well-defined control groups, underscoring the need for further research to establish standardized HBOT protocols.

Thermal preconditioning can reduce the incidence of intraoperatively acquired pressure injuries

Intraoperatively acquired pressure injuries (IAPIs) occur frequently among patients who undergo surgical procedures that last longer than 3 h. Several studies indicated that heat shock proteins (HSPs) play an important role in the protection of stress-induced damages in skin tissues. Hence, the aim of this study was to investigate the potential preventive effect of thermal preconditioning (TPC) on IAPIs in surgical patients and rats and to identify the differentially expressed HSP genes in response to the above treatment. TPC was performed on one group of hairless rats before the model of pressure injuries was established. Subsequently, the size of skin lesions was measured and the expression levels of mRNA and protein of HSPs of the pressured skin were detected by real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemical staining. For human studies, 118 surgical patients were randomly divided into the TPC group (n = 59) and the control group (n = 59), respectively. The temperature and pressure of sacral skin, as well as the incidence of pressure injury (PI) were detected and compared. In animal studies, TPC significantly reduced both the size and incidence of PI in rats on the second, third and fourth days post treatment. In addition, the expression levels of both mRNA and protein of HSP27 were increased in the TPC group, compared with the control group. Immunohistochemical staining showed that HSP27 was distributed in various types of dermal cells and increased in basal cells. In human studies, a significant reduction (75%) of IAPIs was observed among the patients in the TPC group. TPC can reduce the incidence of PI in rats and humans, and the upregulation of HSP27 may play an important role in this biological progress. Further studies are warranted to explore the molecular mechanism of the preventive effect in PI mediated by HSP27.

Human stem cells prevent flap necrosis in preclinical animal models: A systematic review

Background and Aim

Adipose-derived mesenchymal stem cells (ADSCs) have been proven effective to prevent distal skin flap necrosis in preclinical models. However, to appropriately translate these findings to clinical trials, the effect of ADSC of human origin (hADSC) needs to be evaluated. We hypothesize that hADSC treatment is as effective as animal ADSC treatment at preventing distal skin flap necrosis in animal flap models.

Methods

Three databases were inquired on August 17, 2020, to evaluate the necrotic flap area after using hADSCs in animal models of ischemic flaps. No publication status or dates were considered. Studies were included if they used hADSCs, measured the surviving or necrotic skin area of flaps, used animal models, and were in English. Studies were excluded if they did not use cells of human origin. The flap survival or necrotic area, perfusion, capillary density, vascular endothelial growth factor secretion and HIF-1α expression were extracted.

Results

Ten studies met inclusion criteria. The mean absolute risk reduction (ARR) in necrotic skin area was 22.37% (95% confidence interval [CI] 16.98-27.76%, P<0.05) for flaps treated with animal ADSCs and 18.04% (95% CI 2.74-33.33%, P<0.05) for flaps treated with hADSCs. The difference between mean ARRs was not statistically significant (4.33%, 95% CI - 34.47-43.13%, P>0.05).

Conclusion

Human ADSCs prevent skin flap necrosis to the same degree as animal ADSCs in rodent and rabbit flap models.

Relevance for Patients

This review found that adipose-derived stem cells of human origin are equally effective at reducing the risk of surgical flap necrosis in preclinical models of small animals as autologous animal cells. The findings in this review should encourage researchers to use human adipose-derived stem cells in animal models of ischemic flaps to accelerate their translation into clinical trials and, eventually, surgical practice. The low immunogenicity of these cells should be leveraged to gain insight into the effects of the products that will be ultimately administered to patients. Furthermore, human adipose-derived stem cells' pro-angiogenic mechanism of action sets this therapy as a promising preventive measure for flap necrosis.

Thermal Preconditioning for Surgery: A Systematic Review

BACKGROUND

Optimising patients pre-operatively reduces the chance of complications. This may be achieved by preconditioning. Thermal preconditioning refers to the supraphysiological heating of organisms or specific organs prior to an environmental insult. This review explores the current application and efficacy of thermal preconditioning for surgery.

METHODS

A comprehensive search of Medline (via PubMed), Embase and the Cochrane library was performed. Only articles evaluating the use of supraphysiological heating prior to a surgical intervention were included. Qualitative syntheses of data were undertaken due to the heterogeneity of the studies. The quality of each article was appraised using risk of bias tools (Cochrane and SYRCLE).

RESULTS

The primary literature search returned 3175 articles. After screening and reviewing reference lists, 28 papers met the inclusion criteria. The majority of studies were performed in animals, with only three clinical trials. Although there was broad coverage of different surgical techniques, flap transfer was the most commonly performed procedure. Most studies demonstrated a beneficial effect of thermal preconditioning, ranging from increased joint mobility to improved flap or organ transplant survival rates. The quality of evidence was variable, with experimental animal studies limited by a lack of methodological detail.

CONCLUSIONS

Thermal preconditioning for surgery has been primarily investigated using animal models. A beneficial effect has been demonstrated in most cases, across specialties ranging from plastic to general surgery. Future studies should aim to assess the clinical significance through large multicentre randomised controlled trials.

A randomised controlled feasibility trial to evaluate local heat preconditioning on wound healing after reconstructive breast surgery: the preHEAT trial

Objective

preHEAT was a randomised controlled feasibility trial to determine how best to measure skin necrosis in breast reconstruction to inform the design of a larger multicentre trial.

Background

Mastectomy skin flap necrosis (MSFN) is a serious complication resulting in prolonged wound healing. Local heat preconditioning of the MSF before surgery has been shown to reduce skin necrosis in immediate breast reconstruction patients (IBR).

Method

preHEAT was a single-centre, randomised control two-arm single-blind parallel arm feasibility trial of local heat preconditioning in breast cancer patients undergoing SSM and NSM at Guy’s and St Thomas’ Hospital, London, UK. All patients undergoing IBR above the age of 18 were included. Intervention patients heated breast skin to 43 °C in three, 30-min cycles interrupted by spontaneous cooling using hot water bottles. The primary aim was to compare measurement of skin necrosis using binary ‘yes/no’ assessment, the SKIN score, and wound area.

Results

One hundred forty-one patients were randomised over a 2-year period (71 heated group, 70 controls). There was near perfect agreement between assessors using the “yes/no” measurement of necrosis. The proportion of patients experiencing necrosis in controls was 35% (n = 23/66) in the heated 26% (n = 18/68]). In the control group, 17% (n = 4/23) patients experiencing necrosis required surgical intervention for necrosis compared to 11% (n = 2/18) in the heated group.

Conclusion

The binary outcome of MSFN “yes/no” is a suitable and reliable primary outcome measure of necrosis and was superior to the SKIN Score or necrosis area. The trial study design is feasible for a larger definitive trial.

Trial registration

ISRCTN15744669. Date of registration: 25/02/2018

Electronic supplementary material

The online version of this article (10.1186/s40814-019-0392-y) contains supplementary material, which is available to authorized users.