Blood Supply to the Integument of the Abdomen of the Rat: A Surgical Perspective

Gross anatomy of vascular supply and drainage of mammary fat pads in mice models

This work extensively studied the vasculature of mice mammary fat pads (BALB/c and C57BL/6) with special reference to haematogenous drainage routes. Mammary fat pads were five pairs (first cervical, second and third thoracic, fourth abdominal and fifth inguinal), bilaterally symmetrical, extending laterally and continuously with the subcutaneous fascia. The superficial cervical artery and vein primarily accomplished the blood vasculature of the first mammary fat pad, while the lateral thoracic and external thoracic arteries and veins supplied the second and third mammary fat pads. The superficial cervical vein (found parallel to the superficial cervical artery) drained into the external jugular vein. The lateral thoracic artery and external thoracic artery branched almost at the same level as the axillary artery (branch of subclavian artery), the latter being more medial in position. However, in some specimens, the branching of both arteries appeared to be at the same level, and their origins were indistinguishable. The lateral thoracic vein that was parallel to the lateral thoracic artery drained to the axillary vein close to the drainage of the external thoracic vein. The lateral thoracic, superficial caudal epigastric, iliolumbar and external thoracic arteries and veins vascularized the fourth mammary fat pad and displayed anastomosis among themselves. The iliolumbar vein (found parallel to the iliolumbar artery) drained into the inferior vena cava. The superficial caudal epigastric vein (found parallel to the superficial caudal epigastric artery (SCaEA)) drained into the femoral vein. Unlike humans, the internal thoracic artery and vein did not participate in the vasculature of mammary fat pads. The SCaEA and vein supplied blood and drained the fifth mammary fat pad. The anatomical continuity of the fourth and fifth mammary fat pads provided common drainage for both mammary fat pads. The BALB/c and C57BL/6 mice strains studied did not differ in topography and size of mammary fat pads. The vascular supply and drainage of the mammary fat pads also did not differ in the strains studied. Only minor variations could be noted in the small veins draining into the lateral thoracic vein. Lateral tributaries seen in the terminal end of the lateral thoracic vein were absent in the C57BL/6 mice.

Wearable flexible body matched electromagnetic sensors for personalized non-invasive glucose monitoring

This work introduces novel body-matched, vasculature-inspired, quasi-antenna-arrays that act as electromagnetic sensors to instantaneously, continuously, and wirelessly sense glucose variations in the bloodstream. The proposed sensors are personalized, leverage electromagnetic waves, and are coupled with a custom machine-learning-based signal-processing module. These sensors are flexible, and embedded in wearable garments such as socks, which provide conformity to curved skin surfaces and movement resilience. The entire wearable system is calibrated against temperature, humidity, and movement resulting in high accuracy in glucose variations tracking. In-Vivo experiments on diabetic rats and pigs exhibit a 100% diagnostic accuracy over a wide range of glucose variations. Human trials on patients with diabetes and healthy individuals reveal a clinical accuracy of continuous glucose monitoring of 99.01% in twenty-eight subjects who underwent Oral Glucose Tolerance Tests. Hence, our approach ensures the continuous tracking of glucose variations from hypo-to-hyper glycemic levels with great fidelity.

Anatomical differences in the abdominal wall between animal species with implications for the transversus abdominis plane block: a systematic review

PURPOSE

With the increased use of simulation-based training using animal models for the education of surgical and anaesthetic techniques, an increased understanding of the anatomy of such models and how they compare to humans is required. The transversus abdominis plane block is a regional anaesthetic technique that requires an understanding of the abdominal wall anatomy along with proficient ultrasound use. The current review aims to compare the anatomy of the abdominal wall across species, particularly focussing on the pertinent differences within the class of mammals, and secondarily, it aims to address the implications of these differences for the use of simulation-based training of the transversus abdominis plane block.

METHODS

To achieve this, the PubMed, Web of Science and Google Scholar databases were searched for relevant literature. Studies pertaining to the musculature, vasculature or innervation of the anterolateral abdominal wall across species were included.

RESULTS

The mammalian abdominal wall differs in its musculature, vasculature or innervation from that of amphibians, birds or reptiles; however, among species of mammals, the structure of the abdominal wall follows a similar framework. Particular differences among mammals include the additional muscular layer of the panniculus carnosus found in most mammals other than humans, the variable arterial origins and dominant vascular supply of the abdominal wall and the number of thoracolumbar nerves innervating the abdominal wall.

CONCLUSION

When using animal models for simulation-based training, the pig is recommended for the transversus abdominis plane block given its closely homologous abdominal wall structure, availability and larger comparative size.

TULUA: Effects of Flap Undermining and Type of Wall Plicature in a Rat Model Abdominoplasty

BACKGROUND

TULUA, a transverse plication lipoabdominoplasty, which excludes elevation of the supraumbilical flap and includes a skin graft neoumbilicoplasty, claims greater safety and better results. An animal study was designed to compare it, with two current techniques.

MATERIALS AND METHODS

Three matched groups of 12 rats had combined liposuction and abdominoplasty. Liposuction was extensive and unrestricted. Groups 1 and 2 had vertical plication and transposition umbilicoplasty, and group 3 had transverse plication and neoumbilicoplasty. Flap elevation in the epigastrium was wide to costal margins in group 1, limited to a tunnel in group 2, and no dissection in group 3. The animals were observed for 21 days and then euthanized. Intraoperative, postoperative, and postmortem variables and findings were measured and analyzed to find differences between groups.

RESULTS

Transverse lipoabdominoplasty demonstrated a wider wall plication area, as well as a decrease in tension to close the wound, causing the horizontal scar to remain in a low position. In vertical plication lipoabdominoplasty groups, flap necrosis and seromas were more frequent, and the umbilical position descended due to secondary healing and scar contraction. The scar's scores were better in the transverse group and were confirmed when evaluated by external observers.In postmortem examination, horizontal plication presented less widening; perforator vessels were preserved when surgical undermining of the upper abdomen was not performed, and there were fewer seromas.

CONCLUSION

In a rat model, TULUA demonstrates superior results and a decrease in complications when compared to lipoabdominoplasties with vertical plication and wide or tunneled dissection in the upper abdomen.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of short-term ischemia on microcirculation and wound healing of adipocutaneous flaps in the rat

PURPOSE

Composite flaps used in reconstructive surgery may intra- and postoperatively suffer from hypoperfusion and/or ischemia-reperfusion influencing wound healing. We aimed to follow-up the effect of ischemia on adipocutaneous flaps' wound healing and microcirculation.

METHODS

In anesthetized rats groin flaps were formed bilaterally. In Control group the flaps were repositioned and sutured back. In Ischemia-Reperfusion (I/R) group before repositioning and suturing the flap pedicles were clamped for 60 minutes. Laser Doppler (LD) fluxmetry and temperature probes were applied on the cranial, central and caudal flap regions before/after preparation and ischemia, re-suturing, and on the 1st-3rd-5th-7th-14th postoperative days, before the final examinations and biopsies for histology.

RESULTS

Flaps' skin temperature quickly recovered after repositioning. LD values were lower in the I/R group, reaching a significant level by the 3rd postoperative day, and remained lowered till the 14th day. The magnitude of alterations differed in the flap regions. Histologically normal wound healing process was seen, except for some I/R flaps, where hypertrophized mammary glands were found.

CONCLUSIONS

Short-term ischemia could influence flap microcirculation and wound healing, and may result in hypertrophized mammary glands. Laser Doppler could be used to evaluate intra- and postoperative microcirculatory changes and may have significance in predicting complications.

BD-2 and BD-3 increase skin flap survival in a model of ischemia and Pseudomonas aeruginosa infection

The main aim of this work was to study the usefulness of human β-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap survival in the context of a P. aeruginosa infection associated with a foreign body. The secondary endpoints assessed were: bacterial counts, and biofilm formation on the surface of the foreign body. A local ischemic environment was created by producing arterialized venous flaps in the left epigastric region of rats. Flaps were intentionally infected by placing underneath them two catheters with 105 CFU of P. aeruginosa before the surgical wounds were hermetically closed. Flap biopsies were performed 3 and 7 days post-operatively, and the specimens submitted to immunohistochemical analysis for BD-2 and BD-3, as well as to bacterial quantification. Subsequently, the catheter segments were analyzed with scanning electron microscopy (SEM). Flaps transduced with BD-2 and BD-3 showed expression of these defensins and presented increased flap survival. Rats transduced with BD-3 presented a net reduction in the number of P. aeruginosa on the surface of the foreign body and lesser biofilm formation.

In vitro Flow Perfusion Maintaining Long-term Viability of the Rat Groin Fat Flap: A Novel Model for Research on Large-scale Engineered Tissues

BACKGROUND

Large-scale muscle tissue engineering remains a major challenge. An axial vascular pedicle and perfusion bioreactor are necessary for the development and maintenance of large-scale engineered muscle to ensure circulation within the construct. We aimed to develop a novel experimental model of a large-scale engineered muscle flap from an existing rat groin fat flap.

METHODS

A fat flap based on the superficial inferior epigastric vascular pedicle was excised from rats and placed into a perfusion bioreactor. The flaps were kept in the bioreactor for up to 7 weeks, and transdifferentiation of adipose to muscle tissue could have taken place. This system enabled myogenic-differentiation medium flow through the bioreactor at constant pH and oxygen concentration. Assessment of viability was performed by an immunofluorescence assay, histological staining, a calcein-based live/dead test, and through determination of RNA quantity and quality after 1, 3, 5, and 7 weeks.

RESULTS

Immunofluorescence staining showed that smooth muscle around vessels was still intact without signs of necrosis or atrophy. The visual assessment of viability by the calcein-based live/dead test revealed viability of the rat adipose tissue preserved in the bioreactor system with permanent perfusion. RNA samples from different experimental conditions were quantified by spectrophotometry, and intact bands of 18S and 28S rRNA were detected by gel electrophoresis, indicating that degradation of RNA was minimal.

CONCLUSIONS

Flow perfusion maintains the long-term viability of a rat groin engineered muscle flap in vitro, and a large-scale vascularized muscle could be engineered in a perfusion bioreactor.