Effect of Remote Ischemic Conditioning on Bleeding Complications in Surgery: A Systematic Review and Meta-Analysis.

Remote ischemic conditioning (RIC) is administered with an inflatable tourniquet by inducing brief, alternating cycles of limb ischemia and reperfusion. RIC possibly impacts the hemostatic system, and the intervention has been tested as protective therapy against ischemia-reperfusion injury and thrombotic complications in cardiac surgery and other surgical procedures. In the present systematic review, we aimed to investigate the effect of RIC on intraoperative and postoperative bleeding complications in meta-analyses of randomized controlled trials including adult patients undergoing surgery. A systematic search was performed on November 7, 2020 in PubMed, Embase, and the Cochrane Central Register of Controlled Trials. Randomized controlled trials comparing RIC versus no RIC in adult patients undergoing surgery that reported bleeding outcomes in English publications were included. Effect estimates with 95% confidence intervals were calculated using the random-effects model for intraoperative and postoperative bleeding outcomes. Thirty-two randomized controlled trials with 3,804 patients were eligible for inclusion. RIC did not affect intraoperative bleeding volume (nine trials; 392 RIC patients, 399 controls) with the effect estimate -0.95 [-9.90; 7.99] mL (p = 0.83). RIC significantly reduced postoperative drainage volume (seven trials; 367 RIC patients, 365 controls) with mean difference -83.6 [-134.9; -32.4] mL (p = 0.001). The risk of re-operation for bleeding was reduced in the RIC group (16 trials; 838 RIC patients, 839 controls), albeit not significantly, with the relative risk 0.65 [0.39; 1.09] (p = 0.10). In conclusion, RIC reduced postoperative bleeding measured by postoperative drainage volume in this meta-analysis of adult patients undergoing surgery.

Remote ischemic perconditioning attenuates acute inflammation of experimental musculocutaneous flaps following ischemia-reperfusion injury.

BACKGROUND: In free flap reconstruction and replantation surgery, prolonged ischemia time may lead to flap or replantation failure. The aim of the study was to investigate the effects of hypothermic flap ischemia or remote ischemic perconditioning (RIPER) during normothermic ischemia on acute inflammation of musculocutaneous flaps subjected to ischemia-reperfusion injury. MATERIALS AND METHODS: In 24 pigs, a musculocutaneous latissimus dorsi flap was dissected and subjected to 4 hours of arterial ischemia and 7 hours of reperfusion. The animals were allocated into two experimental groups: hypothermic flap ischemia at 4°C (n = 8) or normothermic flap ischemia with RIPER (n = 8), and one control group with normothermic flap ischemia (n = 8). The hypothermic ischemic flaps were cooled in a basin with fresh water and ice. RIPER was initiated 1 hour before reperfusion, by inducing three 10 min cycles of hind limb ischemia with a tourniquet, each separated by 10 min of reperfusion. Acute inflammation was described by inflammatory cytokine secretion (IL-1ß, IL-6, IL-10, IL-12p40, and TNF-α) from the flap during reperfusion, and by quantitative determination of macrophages in flap biopsies of dermis, subcutaneous tissue, and skeletal muscle following reperfusion. RESULTS: No significant differences were found between normothermic and hypothermic flap ischemia in inflammatory cytokine secretion. However, the IL-6 secretion was significantly reduced in the RIPER group compared with the control group at 5 hours of reperfusion (P = 0.036), and in the RIPER group compared with the hypothermic ischemia group at 3 (P = 0 0.0063), 5 (P = 0.0026), and 7 hours of reperfusion (P = 0.028). The IL-12p40 secretion was significantly reduced in the RIPER group compared with the control group (P = 0.0054) as well as the hypothermic ischemia group (P = 0.028) at 5 hours of reperfusion. No significant difference was found among groups in macrophage infiltration. CONCLUSION: RIPER reduced IL-6 and IL-12p40 secretion during reperfusion of porcine musculocutaneous flaps, when compared with hypothermic ischemic flaps and normothermic ischemic flaps without RIPER. © 2016 Wiley Periodicals, Inc. Microsurgery 37:148-155, 2017.

Postoperative monitoring of free flaps in autologous breast reconstruction: a multicenter comparison of 398 flaps using clinical monitoring, microdialysis, and the implantable Doppler probe.

Many techniques for flap monitoring following free tissue transfer have been described; however, there is little evidence that any of these techniques allow for greater rates of flap salvage over clinical monitoring alone. We sought to compare three established monitoring techniques across three experienced microsurgical centers in a comparable cohort of patients. A retrospective, matched cohort study of 398 consecutive free flaps in 347 patients undergoing autologous breast reconstruction was undertaken across three institutions during the same 3-year period, with a single form of postoperative monitoring used at each institution: clinical monitoring alone, the Cook-Swartz implantable Doppler probe, or microdialysis. Both objective and subjective measures of efficacy were assessed. Clinical monitoring alone, the implantable Doppler probe, and microdialysis showed statistically similar rates of flap salvage. False-negative rates were also statistically similar (only seen in the clinically monitored group). However, there was a statistically significant increase in false-positive alarms causing needless take-backs to theater in the microdialysis and implantable Doppler arms, P < 0.001. This study did not find any technique superior to clinical monitoring alone. New monitoring technologies should be compared objectively with clinical monitoring as the current standard in postoperative flap monitoring.

Novel Technique with Double Free Flap Design for Advanced Mandibular Osteoradionecrosis: A Case Series.

Advanced mandibular osteoradionecrosis is arguably among the most challenging cases for reconstructive head and neck surgeons. Several reconstructive methods for complex mandibular defects have been reported; however, for advanced mandibular osteoradionecrosis, a safe option that minimizes the risk of renewed fistulation and infections is needed. For this purpose, we present a new technique using a fascia-sparing vertical rectus abdominis musculocutaneous flap as protection for a vascularized free fibula graft (FFG). This technique also optimizes recipient site healing and functionality while minimizing donor site morbidity. Our initial experiences from a 4 patient case series are included. Mean operative time was 551 minutes (SD: 81 minutes). All donor sites were closed primarily. Mean time to discharge was 13 days (SD: 7 days), and mean time to full mobilization was 2 days (SD: 1 days). This double free flap technique completely envelops the FFG and plate with nonirradiated muscle. It allows for the transfer of an FFG without a skin island, thus avoiding the need for split skin graft closure. This results in faster healing and minimizes the risk of fibula donor site morbidity. The skin island of the vertical rectus abdominis musculocutaneous flap has the added benefit of providing intraoral lining, which minimizes contractures and trismus. Although prospective long-term studies comparing this approach to other double flap procedures are needed, we argue that this technique is an optimal approach to safeguard the mandibular FFG reconstruction against the inherent risks of renewed complications in irradiated unhealthy tissue.

Remote Ischemic Preconditioning in Microsurgical Head and Neck Reconstruction: A Randomized Controlled Trial.

The free flap failure rate is 5% in head and neck microsurgical reconstruction, and ischemia-reperfusion injury is an important mechanism behind this failure rate. Remote ischemic preconditioning (RIPC) is a recent intervention targeting ischemia-reperfusion injury. The aim of the present study was to investigate if RIPC improved clinical outcomes in microsurgical reconstruction. METHODS: Head and neck cancer patients undergoing tumor resection and microsurgical reconstruction were included in a randomized controlled trial. Patients were randomized (1:1) to RIPC or sham intervention administered intraoperatively just before transfer of the free flap. RIPC was administered by four 5-minute periods of upper extremity occlusion and reperfusion. Clinical data were prospectively collected in the perioperative period and at follow-up on postoperative days 30 and 90. Intention-to-treat analysis was performed. RESULTS: Sixty patients were randomized to RIPC (n = 30) or sham intervention (n = 30). All patients received allocated intervention. No patients were lost to follow up. At 30-day follow-up, flap failure occurred in 7% of RIPC patients (n = 2) and 3% of sham patients (n = 1) with the relative risk and 95% confidence interval 2.0 [0.2;20.9], P = 1.0. The rate of pedicle thrombosis was 10% (n = 3) in both groups with relative risk 1.0 [0.2;4.6], P = 1.0. The flap failure rate did not change at 90-day follow-up. CONCLUSIONS: RIPC is safe and feasible but does not affect clinical outcomes in head and neck cancer patients undergoing microsurgical reconstruction.

Anatomical variations in the harvest of anterolateral thigh flap perforators: a cadaveric and clinical study.

BACKGROUND: The anterolateral thigh (ALT) flap has become increasingly popular due to its versatility and minimal donor site morbidity. Its major limitation has been uncertainty in predicting perforator anatomy, with the occasional absence of suitable perforators and high variability in their size and course. The variability of this anatomy has not been adequately explored previously. METHODS: A cadaveric study was undertaken, in which 19 thighs (from 10 fresh cadavers) underwent contrast injection and angiographic imaging. Anatomical variations of the vasculature were recorded. A clinical study of 44 patients undergoing ALT flap reconstruction was also undertaken. Perforator anatomy was described in the first 32 patients, and the subsequent 12 patients underwent computed tomography angiography with a view to predicting individual anatomy and improving operative outcome. RESULTS: Cadaver angiography was able to highlight and classify the variations in arterial anatomy, with four patterns observed and marked variability between cases. In 32 patients undergoing ALT flaps without preoperative CT angiography (CTA), five patients (16%) did not have any suitable perforators from the descending branch of the lateral circumflex femoral artery. By selecting the limb of choice with preoperative CTA, the incidence of flap unsuitability was reduced to 0%. Comparing CTA with Doppler, CTA was more accurate (sensitivity 100%) and provided more information. CONCLUSION: The perforators supplying the ALT flap show significant variability in location and course, with the potential for unsuitable perforators limiting flap success. Preoperative CTA can demonstrate the vascular anatomy and can aid perforator selection and operative success.

Preserving the neurovascular supply in the Hall-Findlay superomedial pedicle breast reduction: an anatomical study.

BACKGROUND: The Hall-Findlay superomedial pedicle technique is widely used for breast reduction, and, despite low complication rates, nipple-areola complex (NAC) necrosis and denervation are still the two most common complications, particularly when resection volumes exceed 600g. An understanding of the anatomy of the neurovascular pedicle of the NAC is paramount in avoiding these complications. METHODS: An anatomical study was undertaken on 11 female cadaveric breast specimens (nine fresh and two embalmed). The neurovascular anatomy of the breast was explored through dissection, microdissection, radiographic, computed tomographic, photographic and cross-sectional studies. The superomedial pedicle was mapped out on each specimen, and the course of the relevant nerves and vasculature was identified. RESULTS: The arterial supply to the superomedial pedicle was found to originate from a single dominant vessel in each specimen, while the venous drainage was via an extensive branching network. Both vascular patterns traversed the pedicle in a superficial plane. The innervation of the pedicle was via intercostal branches, which coursed extremely superficially in the pedicle. CONCLUSION: De-epithelialisation or superficial thinning of the superomedial pedicle for breast reduction is at high risk for complications related to vascular compromise or denervation. Where greater resection is needed, this should be done from the deep surface or the base of the pedicle, contrary to previous descriptions.

The lumbar artery perforators: a cadaveric and clinical anatomical study.

BACKGROUND: The lumbar region has been scarcely explored as a donor site for free tissue transfer or as a free flap recipient site. The lumbar integument provides a versatile prospective flap site, with a potentially well-concealed scar. Similarly, defects of this region can require recipient vessels that may be difficult to identify. Although lumbar artery perforators have been described, the reliability of perforators in this region remains questionable. METHODS: An anatomical study was undertaken combining both cadaveric and in vivo analysis of the lumbar vessels. The cadaveric component comprised both dissection and angiographic studies in fresh and embalmed cadavers (36 lumbar regions in 18 cadavers), and the clinical study comprised a computed tomographic angiographic study (44 sides in 22 patients) and an operative case report. RESULTS: Perforators were shown to arise from all eight lumbar arteries to enter the lumbar integument, with their size, location, and course described. Lower lumbar perforators were more often septocutaneous and of larger caliber. A case in which the fourth lumbar artery and concomitant vein were used as free flap recipient vessels is described, the first such reported case in the literature. CONCLUSIONS: Improving the incidence of identifying lumbar perforators of large caliber and with a septocutaneous course can be achieved by selecting lower lumbar vessels, or with the use of preoperative computed tomographic angiography. Computed tomographic angiography can successfully identify the location, size, and course of lumbar artery perforators and can aid flap design. Lumbar artery perforators are highly useful for both donor and recipient vessels in free flap surgery.

Avoiding denervation of rectus abdominis in DIEP flap harvest II: an intraoperative assessment of the nerves to rectus.

BACKGROUND: The deep inferior epigastric artery perforator (DIEP) flap aims to reduce donor-site morbidity by minimizing rectus muscle damage; however, damage to motor nerves during perforator dissection may denervate rectus muscle. Although cadaveric research has demonstrated that individual nerves do not arise from single spinal cord segments and are not distributed segmentally, the functional distribution of individual nerves remains unknown. Using intraoperative nerve stimulation, the current study describes the motor distribution of individual nerves supplying the rectus abdominis, providing a guide to nerve dissection during DIEP flap harvest. METHODS: Twenty rectus abdominis muscles in 17 patients undergoing reconstructive surgery involving rectus abdominis (DIEP, transverse rectus abdominis musculocutaneous, or vertical rectus abdominis musculocutaneous flaps) underwent intraoperative stimulation of nerves innervating the infraumbilical segment of the rectus. Nerve course and extent of rectus muscle contraction were recorded. RESULTS: In each case, three to seven nerves entered the infraumbilical segment of the rectus abdominis. Small nerves (type 1) innervated small longitudinal strips of rectus muscle, rather than transverse strips as previously described. There was significant overlap between adjacent type 1 nerves. In 18 of 20 cases, a single large nerve (type 2) at the level of the arcuate line supplied the entire width and length of rectus muscle. CONCLUSIONS: Nerves innervating the rectus abdominis are at risk during DIEP flap harvest. Small, type 1 nerves have overlapping innervation from adjacent nerves and may be sacrificed without functional detriment. However, large type 2 nerves at the level of the arcuate line innervate the entire width of rectus muscle without adjacent overlap and may contribute to donor-site morbidity if sacrificed.