Effects of various protocols of ischemic preconditioning on rat tram flaps

Application of supraclavicular island flap in oral and maxillofacial reconstruction

Several surgical modalities are available for maxillofacial reconstruction as locoregional or microvascular free flaps.

PURPOSE

(a) Evaluate the reliability of the supraclavicular flap in cervico-orofacial region; (b) investigate the role of computed tomography angiography (CTA) in predicting the post-operative viability of the flap; (c) assess the speech, feeding, and esthetics after reconstruction using this flap.

METHODS

Eleven patients included in this study underwent either conventional or delayed harvesting of the supraclavicular flap (SCF). All the patients had diagnostic computed tomography angiography (CTA) of the supraclavicular flap before the surgery.

RESULTS

The mean harvesting time of the flap was 45.45 ± 4.16 min. The average length of the flap was 22.64 ± 1.12 cm, whereas the mean width of the flap was 6.14 ± 1.14 cm. The flap survived in 9 patients, while two patients had complete flap loss. After the surgery, three patients complained of speech difficulties. Two patients had swallowing problems. After the surgery, three patients complained of speech difficulties. Two patients had swallowing problems. Only two patients complained of weakness in the donor site. None of the patients reported that the weakness or pain at the donor site affected their daily activities or quality of life.

CONCLUSION

The pedicled SCF represents a safe and feasible option that can be used to reconstruct a wide array of maxillofacial oncologic defects. However, a study with a larger sample size is recommended to achieve more reliable clinical results for the modified delayed technique modification in terms of their effect on the survival of the supraclavicular flap.

[Cytosteatonecrosis after breast reconstruction by fat flap with or without ischemic preconditioning]

INTRODUCTION

Cytosteatonecrosis (CTN) is a frequent postoperative complication after breast autologous reconstruction using DIEP (deep inferior epigastric perforator) flap. CTN radiological diagnostic reveals different types of lesions, as nodes or extended fat necrosis, which become in some cases infected, or pass for tumor recurrence after breast cancer treatment. CTN is caused by intraoperative ischemia of the flap, and no current method can prevent postoperative CTN development after DIEP breast reconstruction. Mechanical ischemic preconditioning, consisting in intraoperative briefs consecutive cycles of ischemia reperfusion using vascular clamp upon the graft pedicle, is used in transplantation surgery. This procedure improves the graft tolerance towards ischemic surgical lesions. The aim of this retrospective observational study was to assess PCIM effects on CTN development after DIEP surgery, comparing CTN occurrence after breast reconstruction using DIEP flap with or without intraoperative PCIM.

MATERIAL AND METHODS

All patients breats reconstructed using DIEP flap between novembre 2020 and may 2022, presenting 6 months postoperative breast echography were retrospectively included. Primary outcome was the ultrasonic existence of CTN, according to the Wagner classification. Clinical data, postoperative outcomes such as infection, hematoma or surgical revision, and length of stay in hospital were also recorded.

RESULTS

Twenty nine patients among which 8 PCIM were included. CTN occurrence rate after PCIM (25%) was quite lower than CTN rate without PCIM (71,4%), although the difference was not significant (P=0,088). Other postoperative complications rates were not significantly different with or without PCIM.

CONCLUSION

PCIM seems to improve CTN occurrence after DIEP breast reconstruction, improving fat flap tolerance to ischemic perioperative lesions. Those preliminary results need to be confirmed with clinical prospective study.

The Language of Implant-based Breast Reconstruction: Can We Do Better?

The management of breast cancer has experienced tremendous changes in the last half-century. In today's multimodal approach to breast cancer, patients have the prospect of achieving a sense of normalcy after mastectomy thanks to advancements in oncology and breast reconstruction. Although the oncologic management of breast cancer has evolved over multiple centuries, implant-based breast reconstruction (IBBR) has only been around since the 1960s. The last half century has seen the conception of multiple techniques, novel devices, and new possibilities in hopes of achieving outcomes that are similar to or even better than the patient's premorbid state. However, with all these changes, a new problem has arisen-inconsistencies in the literature on how IBBR is described. In this article, we will discuss potential sources of confusion in the IBBR literature and lexicon, highlighting specific terms that may have multiple meanings or interpretations depending on perspective, context, and/or intent. As a first step toward clarifying what we perceive as a muddied landscape, we propose a naming convention for IBBR that centers around four important variables especially pertinent to IBBR-the type of mastectomy performed, the timing of reconstruction, the type of device that is placed, and the pocket location for device placement. We believe that adoption of a more standardized, consistent, and descriptive lexicon for IBBR will help provide clearer communication and easier comparisons in the literature so that we may continue to deliver the best outcomes for our patients.

CoenzymeQ10 and Ischemic Preconditioning Potentially Prevent Tourniquet-Induced Ischemia/Reperfusion in Knee Arthroplasty, but Combined Pretreatment Possibly Neutralizes Their Beneficial Effects

Tourniquet (TQ) use during total knee arthroplasty (TKA) induces ischemia/reperfusion (I/R) injury, resulting in mitochondrial dysfunction. This study aims to determine the effects of coenzyme Q10 (CoQ10) and ischemic preconditioning (IPC), either alone or in combination, on I/R-induced mitochondrial respiration alteration in peripheral blood mononuclear cells (PBMCs) and pain following TKA. Forty-four patients were allocated into four groups: control, CoQ10, IPC, and CoQ10 + IPC. CoQ10 dose was 300 mg/day for 28 days. IPC protocol was three cycles of 5/5-min I/R time. Mitochondrial oxygen consumption rates (OCRs) of PBMCs were measured seven times, at baseline and during ischemic/reperfusion phases, with XFe 96 extracellular flux analyzer. Postoperative pain was assessed for 48 h. CoQ10 improved baseline mitochondrial uncoupling state; however, changes in OCRs during the early phase of I/R were not significantly different from the placebo. Compared to ischemic data, IPC transiently increased basal OCR and ATP production at 2 h after reperfusion. Clinically, CoQ10 significantly decreased pain scores and morphine requirements at 24 h. CoQ10 + IPC abolished analgesic effect of CoQ10 and mitochondrial protection of IPC. In TKA with TQ, IPC enhanced mitochondrial function by a transient increase in basal and ATP-linked respiration, and CoQ10 provides postoperative analgesic effect. Surprisingly, CoQ10 + IPC interferes with beneficial effects of each intervention.

Effects of açaí and cilostazol on skin microcirculation and viability of TRAM flaps in hamsters

BACKGROUND

Tissue necrosis caused by insufficient perfusion is a major complication in flap transfer. This study evaluated whether treatment with cilostazol or hydroalcoholic extract of seeds of Euterpe oleracea Mart. (açaí) protects the transverse rectus abdominis myocutaneous (TRAM) flap against ischemic damage in hamsters.

MATERIALS AND METHODS

Fifty-four hamsters were divided into three oral treatment groups: placebo, açaí, or cilostazol. Caudally based, unipedicled TRAM flaps were raised, sutured back, classified into four vascular zones (I-IV), and evaluated for tissue viability, capillary blood flow (CBF), perfused vessel density (PVD), and microvascular flow index (MFI) by orthogonal polarization spectral imaging at three time points: immediately postoperatively (IPO), 24 h postoperatively (24hPO), and 7 d postoperatively (7POD).

RESULTS

Comparing to placebo, açaí increased PVD at IPO and açaí and cilostazol increased CBF and PVD at 24hPO in zone I; cilostazol increased CBF, PVD, and MFI at IPO, and CBF at 24hPO in zone II; açaí and cilostazol increased CBF at all time points and PVD and MFI at IPO and 24hPO in zone III; cilostazol increased CBF at IPO and 7POD, açaí increased CBF at 7POD, and both increased PVD and MFI at all time points in zone IV; and açaí and cilostazol increased the percentage of viable area in zones III and IV.

CONCLUSIONS

Açaí and cilostazol treatments had a protective effect against ischemic damage to TRAM flaps in hamsters, improving microvascular blood flow and increasing the survival of flap zones contralateral to the vascular pedicle (zones III and IV).

Etanercept protects myocutaneous flaps from ischaemia reperfusion injury: An experimental study in a rat tram flap model

Background Being an inevitable component of free tissue transfer, ischemia-reperfusion injury tends to contribute to flap failure. TNF-α is an important proinflammatory cytokine and a prominent mediator of the ischemia-reperfusion injury. Etanercept, a soluble TNF-α binding protein, has shown anti-inflammatory and anti-apoptotic effects in animal models of renal and myocardial ischemia-reperfusion injury. We have designed an experimental study to investigate the effect of etanercept on myocutaneous ischemia-reperfusion injury on transverse rectus abdominis myocutaneous flap model in rats. Methods Twenty-four male Sprague-Dawley rats were divided into 3 groups: In group 1 (sham), the TRAM flap was raised and sutured back without further intervention. In group 2 (control), the flap was raised and the ischemia-reperfusion protocol was followed. In group 3, etanercept (10 mg/kg, i.v.) was administered 10 minutes before reperfusion. At the end of the reperfusion period, biochemical and histolopathological evaluations were performed on serum and tissue samples. Results In the etanercept group the IMA and 8-OHdG levels (p = 0.005 and p = 0.004, respectively) were found significantly lower, and the GSH and SOD levels (p = 0.01 and p < 0.001, respectively) significantly higher in comparison to the control group. The histopathological analysis has revealed a lower degree of hyalinization, degenerated muscle fibers and nuclear change in the etanercept group compared to the control group. Conclusion The results of our experimental study indicate that etanercept offers protection against ischemia-reperfusion injury in skeletal muscle tissue, enhancing the TRAM flap viability. The ability of etanercept to induce ischemic tolerance suggests that it may be applicable in free-flap surgery.

Effect of ischemia preconditioning and leech therapy on cutaneous pedicle flaps subjected to prolonged ischemia in a mouse model

We sought to determine the effect of ischemic preconditioning (IPC) and hirudotherapy (leech therapy) on cutaneous pedicle flaps after they underwent prolonged ischemia (global ischemia) in a mouse model. Twenty cutaneous pedicle flaps were elevated in 20 mice, and the animals were randomized into four groups: sham, control, IPC and leech (5 flaps in each group). Except in the sham group, all flaps were subjected to global ischemia for 5 h via pedicle clamping. The control group did not receive any treatment before or after global ischemia. In the IPC group, global ischemia was preceded by three 10-min episodes of ischemia, each followed by 10 min of reperfusion. In the leech therapy group, after global ischemia, hirudotherapy was performed. Flap survival area and histopathological changes were evaluated on the 10th day after surgery. Flap survival areas were significantly higher in both the IPC and leech groups than in the control group and were significantly higher in the leech group than in the IPC group (p < 0.05). In conclusion IPC and hirudotherapy had definite effects on the survival area of cutaneous pedicle flaps that underwent prolonged ischemia in a mouse model.

The Delay Phenomenon: A Compilation of Knowledge across Specialties

Objective The purpose of this article is to review and integrate the available literature in different fields to gain a better understanding of the basic physiology and optimize vascular delay as a reconstructive surgery technique. Methods A broad search of the literature was performed using the Medline database. Two queries were performed using "vascular delay," a search expected to yield perspectives from the field of plastic and reconstructive surgery, and "ischemic preconditioning," (IPC) which was expected to yield research on the same topic in other fields. Results The combined searches yielded a total of 1824 abstracts. The "vascular delay" query yielded 76 articles from 1984 to 2011. The "ischemic preconditioning" query yielded 6534 articles, ranging from 1980 to 2012. The abstracts were screened for those from other specialties in addition to reconstructive surgery, analyzed potential or current uses of vascular delay in practice, or provided developments in understanding the pathophysiology of vascular delay. 70 articles were identified that met inclusion criteria and were applicable to vascular delay or ischemic preconditioning. Conclusion An understanding of IPC's implementation and mechanisms in other fields has beneficial implications for the field of reconstructive surgery in the context of the delay phenomenon. Despite an incomplete model of IPC's pathways, the anti-oxidative, anti-apoptotic and anti-inflammatory benefits of IPC are well recognized. The activation of angiogenic genes through IPC could allow for complex flap design, even in poorly vascularized regions. IPC's promotion of angiogenesis and reduction of endothelial dysfunction remain most applicable to reconstructive surgery in reducing graft-related complications and flap failure.

Paradoxical effects of heme arginate on survival of myocutaneous flaps

Ischemia reperfusion injury (IRI) contributes to partial flap and solid organ transplant failure. Heme-oxygenase 1 (HO-1) is an inducible, cytoprotective enzyme which protects against IRI in solid organ transplant models. Heme arginate (HA), a HO-1 inducer, is a promising, translatable, preconditioning agent. This study investigated the effects of preconditioning with HA on the clinical outcome of a myocutaneous IRI model. Forty male Lewis rats were randomized to intravenously receive 1) Control-NaCl, 2) HA, 3) HA and tin mesoporphyrin (SnMP), a HO-1 inhibitor; and 4) SnMP alone. Twenty-four hours later, an in situ transverse rectus abdominis myocutaneous flap was performed under isoflurane anesthesia. Viability of flaps was measured clinically and by laser-Doppler perfusion scanning. In vitro work on human epidermal keratinocytes (HEKa) assessed the effects of HA, SnMP, and the iron chelator desferrioxamine on 1) cytotoxicity, 2) intracellular reactive oxygen species (ROS) concentration, and 3) ROS-mediated DNA damage. In contrast to our hypothesis, HA preconditioning produced over 30% more flap necrosis at 48 h compared with controls (P = 0.02). HA-containing treatments produced significantly worse flap perfusion at all postoperative time points. In vitro work showed that HA is cytotoxic to keratinocytes. This cytotoxicity was independent of HO-1 and was mediated by the generation of ROS by free heme. In contrast to solid organ data, pharmacological preconditioning with HA significantly worsened clinical outcome, thus indicating that this is not a viable approach in free flap research.

A comparison of the effects of epidural and spinal anesthesia with ischemia-reperfusion injury on the rat transverse rectus abdominis musculocutaneous flap

The purpose of this study is to compare the effects of spinal and epidural anesthesia on a rat transverse rectus abdominus myocutaneous flap ischemia-reperfusion injury model.Forty Sprague-Dawley rats were divided into 4 experimental groups: group I (n = 10), sham group; group II (n = 10), control group; group III (n = 10), epidural group; and group IV (n = 10), spinal group. After the elevation of the transverse rectus abdominus myocutaneous flaps, all groups except for the sham group were subjected to normothermic no-flow ischemia for 4 hours, followed by a reperfusion period of 2 hours. At the end of the reperfusion period, biochemical and histopathological evaluations were performed on tissue samples.Although there was no significant difference concerning the malonyldialdehyde, nitric oxide, and paraoxonase levels in the spinal and epidural groups, the total antioxidant state levels were significantly increased, and the total oxidative stress levels were significantly decreased in the epidural group in comparison to the spinal group. The pathological evaluation showed that findings related to inflammation, nuclear change rates and hyalinization were significantly higher in the spinal group compared with the epidural group.Epidural anesthesia can be considered as a more suitable method that enables a decrease in ischemia-reperfusion injuries in the muscle flaps.

Remote ischemic perconditioning--a simple, low-risk method to decrease ischemic reperfusion injury: models, protocols and mechanistic background. A review

Interruption of blood flow can cause ischemic reperfusion injury, which sometimes has a fatal outcome. Recognition of the phenomenon known as reperfusion injury has led to initial interventional approaches to lessen the degree of damage. A number of efficient pharmacologic agents and surgical techniques (e.g., local ischemic preconditioning and postconditioning) are available. A novel, alternative approach to target organ protection is remote ischemic conditioning triggered by brief repetitive ischemia and reperfusion periods in distant organs. Among the different surgical techniques is so-called remote ischemic perconditioning, a method that applies short periods of ischemic reperfusion to a distant organ delivered during target organ ischemia. Although ischemic reperfusion injury is reduced by this technique, the explanation for this phenomenon is still unclear, and approximately only a dozen reports on the topic have appeared in the literature. In our study, therefore, we investigated the connective mechanisms, signal transduction, and effector mechanisms behind remote perconditioning, with a review on molecular background and favorable effects. In addition, we summarize the various treatment protocols and models to promote future experimental and clinical research.

Effects of taurine on reperfusion injury

Taurine is an organic acid, which has a very important function in the human body. Recently, the antioxidant property of taurine has been much emphasised. In this study, the gracilis muscle flap model was used to investigate the effect of taurine in ischaemia/reperfusion injury in rats. Totally 32 Sprague-Dawley rats were divided into two groups: control group (n = 16) and the treatment group with taurine (n = 16). After elevation of the gracilis muscle flap, 4 h of ischaemia was performed in both groups. Thirty min before the reperfusion, taurine (200 mg kg(-1)) was injected intravenously. After 24 h of reperfusion, the amount of malondialdehyde (MDA), tissue water content and flap viability were evaluated. After 72 h of reperfusion, histological findings were evaluated. Amount of MDA and tissue water content were significantly lower (p < 0.005), and the flap viability was significantly higher (p < 0.005) in the treatment group 24 h after reperfusion. On comparing the outcomes of histological analysis between control and treatment groups, the amounts of collagen, fibroblast and angiogenesis in treatment group were significantly higher than those in the control group. However, the amount of polymorphonuclear leucocyte and tissue necrosis in the treatment group were significantly lower than in the control group. Our results showed that taurine played an important role in the process of ischaemia/reperfusion injury and presented certain protective effects with the improvement in flap survival after ischaemia/reperfusion injury.

Effect of cyclooxygenase-2 on ischemic preconditioning of skin flaps

Ischemic preconditioning is a useful tool to fight against reperfusion injury. This phenomenon is very complex and the underlying mechanism has various branches. Every study on ischemic preconditioning helps us to better understand this process. We aimed to investigate the effectiveness of cyclooxygenase-2 (COX-2) on ischemic preconditioning of skin flaps in the rat. A 6 x 3 cm-sized left epigastric artery flap was used and the pedicle was isolated to perform the ischemic preconditioning via microvascular clamp application. The preconditioning protocol was 2 cycles of 15 minutes ischemia and 15 minutes reperfusion periods. Sixty female Wistar rats weighing between 210 and 260 g were used for the experiment. Animals were allocated randomly into 6 groups, each group containing 10 animals. Group 1: Only 6 hours of ischemia was done after the flap elevation, neither ischemic preconditioning nor COX-2 inhibitor was used; Group 2: 6 hours of global ischemia was induced just after the ischemic preconditioning; Group 3: In addition to the same procedures in group 2, 2 doses of COX-2 inhibitor were given before and after the final ischemic insult; Group 4: 6 hours of ischemia was applied to the flap 24 hours after its elevation, no preconditioning or any other interventions were done; Group 5: The same ischemic protocol was used after the flap elevation but the 6 hours of ischemia was performed 24 hours after the preconditioning; Group 6: The same procedures of group 5 were done and in addition, 2 doses of COX-2 inhibitor was given, starting 24 hours after the ischemic preconditioning. All flaps were followed for 1 week then necrotic flap portions were measured and represented as a percentage to the whole flap area. Statistical analyses revealed meaningful differences between groups 2 and 3 (P < 0.05), 2 and 1 (P < 0.05), 5 and 6 (P < 0.05), 5 and 4 (P < 0.05). However, there was no statistical difference between groups 3 and 1 (P > 0.05), 6 and 4 (P > 0.05). As a conclusion, ischemic preconditioning has both early and late protective effects on ischemia-reperfusion injury in the skin flap model. By antagonizing COX-2 receptors the beneficial effects of IP were reversed. This result indicated that COX-2 has a specific role in the mechanism of both early and late effects of ischemic preconditioning in skin flaps.

Investigation of reperfusion injury and ischemic preconditioning in microsurgery

Ischemia/reperfusion (I/R) is inevitable in many vascular and musculoskeletal traumas, diseases, free tissue transfers, and during time-consuming reconstructive surgeries in the extremities. Salvage of a prolonged ischemic extremity or flap still remains a challenge for the microvascular surgeon. One of the common complications after microsurgery is I/R-induced tissue death or I/R injury. Twenty years after the discovery, ischemic preconditioning has emerged as a powerful method for attenuating I/R injury in a variety of organs or tissues. However, its therapeutic expectations still need to be fulfilled. In this article, the author reviews some important experimental evidences of I/R injury and preconditioning-induced protection in the fields relevant to microsurgery.