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Objectives
We developed a novel human cadaveric perfusion model with continuous extracorporeal femoral perfusion suitable for performing intra-individual comparison studies, training of interventional procedures and preclinical testing of endovascular devices. Objective of this study was to introduce the techniques and evaluate the feasibility for realistic computed tomography angiography (CTA), digital subtraction angiography (DSA) including vascular interventions, and intravascular ultrasound (IVUS).
Methods
The establishment of the extracorporeal perfusion was attempted using one formalin-fixed and five fresh-frozen human cadavers. In all specimens, the common femoral and popliteal arteries were prepared, introducer sheaths inserted, and perfusion established by a peristaltic pump. Subsequently, we performed CTA and bilateral DSA in five cadavers and IVUS on both legs of four donors. Examination time without unintentional interruption was measured both with and without non-contrast planning CT. Percutaneous transluminal angioplasty and stenting was performed by two interventional radiologists on nine extremities (five donors) using a broad spectrum of different intravascular devices.
Results
The perfusion of the upper leg arteries was successfully established in all fresh-frozen but not in the formalin-fixed cadaver. The experimental setup generated a stable circulation in each procedure (ten upper legs) for a period of more than six hours. Images acquired with CT, DSA and IVUS offered a realistic impression and enabled the sufficient visualization of all examined vessel segments. Arterial cannulating, percutaneous transluminal angioplasty as well as stent deployment were feasible in a way that is comparable to a vascular intervention in vivo. The perfusion model allowed for introduction and testing of previously not used devices.
Conclusions
The continuous femoral perfusion model can be established with moderate effort, works stable, and is utilizable for medical imaging of the peripheral arterial system using CTA, DSA and IVUS. Therefore, it appears suitable for research studies, developing skills in interventional procedures and testing of new or unfamiliar vascular devices.
Multiorgan recovery in a cadaver body using mild hypothermic ECMO treatment in a murine model
(2023)
Background
Transplant candidates on the waiting list are increasingly challenged by the lack of organs. Most of the organs can only be kept viable within very limited timeframes (e.g., mere 4–6 h for heart and lungs exposed to refrigeration temperatures ex vivo). Donation after circulatory death (DCD) using extracorporeal membrane oxygenation (ECMO) can significantly enlarge the donor pool, organ yield per donor, and shelf life. Nevertheless, clinical attempts to recover organs for transplantation after uncontrolled DCD are extremely complex and hardly reproducible. Therefore, as a preliminary strategy to fulfill this task, experimental protocols using feasible animal models are highly warranted. The primary aim of the study was to develop a model of ECMO-based cadaver organ recovery in mice. Our model mimics uncontrolled organ donation after an “out-of-hospital” sudden unexpected death with subsequent “in-hospital” cadaver management post-mortem. The secondary aim was to assess blood gas parameters, cardiac activity as well as overall organ state. The study protocol included post-mortem heparin–streptokinase administration 10 min after confirmed death induced by cervical dislocation under full anesthesia. After cannulation, veno-arterial ECMO (V–A ECMO) was started 1 h after death and continued for 2 h under mild hypothermic conditions followed by organ harvest. Pressure- and flow-controlled oxygenated blood-based reperfusion of a cadaver body was accompanied by blood gas analysis (BGA), electrocardiography, and histological evaluation of ischemia–reperfusion injury. For the first time, we designed and implemented, a not yet reported, miniaturized murine hemodialysis circuit for the treatment of severe hyperkalemia and metabolic acidosis post-mortem.
Results
BGA parameters confirmed profound ischemia typical for cadavers and incompatible with normal physiology, including extremely low blood pH, profound negative base excess, and enormously high levels of lactate. Two hours after ECMO implantation, blood pH values of a cadaver body restored from < 6.5 to 7.3 ± 0.05, pCO2 was lowered from > 130 to 41.7 ± 10.5 mmHg, sO2, base excess, and HCO3 were all elevated from below detection thresholds to 99.5 ± 0.6%, − 4 ± 6.2 and 22.0 ± 6.0 mmol/L, respectively (Student T test, p < 0.05). A substantial decrease in hyperlactatemia (from > 20 to 10.5 ± 1.7 mmol/L) and hyperkalemia (from > 9 to 6.9 ± 1.0 mmol/L) was observed when hemodialysis was implemented. On balance, the first signs of regained heart activity appeared on average 10 min after ECMO initiation without cardioplegia or any inotropic and vasopressor support. This was followed by restoration of myocardial contractility with a heart rate of up to 200 beats per minute (bpm) as detected by an electrocardiogram (ECG). Histological examinations revealed no evidence of heart injury 3 h post-mortem, whereas shock-specific morphological changes relevant to acute death and consequent cardiac/circulatory arrest were observed in the lungs, liver, and kidney of both control and ECMO-treated cadaver mice.
Conclusions
Thus, our model represents a promising approach to facilitate studying perspectives of cadaveric multiorgan recovery for transplantation. Moreover, it opens new possibilities for cadaver organ treatment to extend and potentiate donation and, hence, contribute to solving the organ shortage dilemma.
Loss of intestinal epithelial barrier function is a hallmark in digestive tract inflammation. The detailed mechanisms remain unclear due to the lack of suitable cell-based models in barrier research. Here we performed a detailed functional characterization of human intestinal organoid cultures under different conditions with the aim to suggest an optimized ex-vivo model to further analyse inflammation-induced intestinal epithelial barrier dysfunction. Differentiated Caco2 cells as a traditional model for intestinal epithelial barrier research displayed mature barrier functions which were reduced after challenge with cytomix (TNFα, IFN-γ, IL-1ß) to mimic inflammatory conditions. Human intestinal organoids grown in culture medium were highly proliferative, displayed high levels of LGR5 with overall low rates of intercellular adhesion and immature barrier function resembling conditions usually found in intestinal crypts. WNT-depletion resulted in the differentiation of intestinal organoids with reduced LGR5 levels and upregulation of markers representing the presence of all cell types present along the crypt-villus axis. This was paralleled by barrier maturation with junctional proteins regularly distributed at the cell borders. Application of cytomix in immature human intestinal organoid cultures resulted in reduced barrier function that was accompanied with cell fragmentation, cell death and overall loss of junctional proteins, demonstrating a high susceptibility of the organoid culture to inflammatory stimuli. In differentiated organoid cultures, cytomix induced a hierarchical sequence of changes beginning with loss of cell adhesion, redistribution of junctional proteins from the cell border, protein degradation which was accompanied by loss of epithelial barrier function. Cell viability was observed to decrease with time but was preserved when initial barrier changes were evident. In summary, differentiated intestinal organoid cultures represent an optimized human ex-vivo model which allows a comprehensive reflection to the situation observed in patients with intestinal inflammation. Our data suggest a hierarchical sequence of inflammation-induced intestinal barrier dysfunction starting with loss of intercellular adhesion, followed by redistribution and loss of junctional proteins resulting in reduced barrier function with consecutive epithelial death.
Background
Perioperative bridging of oral anticoagulation increases the risk of bleeding complications after elective general and visceral surgery. The aim of this study was to explore, whether an individual risk-adjusted bridging regimen can reduce bleeding events, while still protecting against thromboembolic events.
Methods
We performed a quality improvement study comparing bridging parameters and postoperative outcomes before (period 1) and after implementation (period 2) of a new risk-adjusted bridging regimen. The primary endpoint of the study was overall incidence of postoperative bleeding complications during 30 days postoperatively. Secondary endpoints were major postoperative bleeding, minor bleeding, thromboembolic events, postoperative red blood cell transfusion, perioperative length-of-stay (LOS) and in-hospital mortality.
Results
A total of 263 patients during period 1 and 271 patients during period 2 were compared. The included elective operations covered the entire field of general and visceral surgery. The overall incidence of bleeding complications declined from 22.1% during period 1 to 10.3% in period 2 (p < 0.001). This reduction affected both major as well as minor bleeding events (8.4% vs. 4.1%; p = 0.039; 13.7% vs. 6.3%; p = 0.004). The incidence of thromboembolic events remained low (0.8% vs. 1.1%). No changes in mortality or length-of-stay were observed.
Conclusion
It is important to balance the individual thromboembolic and bleeding risks in perioperative bridging management. The risk adjusted bridging regimen reduces bleeding events in general and visceral surgery while the risk of thromboembolism remains comparably low.
This study evaluated the influence of different vascular reconstruction kernels on the image quality of CT angiographies of the lower extremity runoff using a 1st-generation photon-counting-detector CT (PCD-CT) compared with dose-matched examinations on a 3rd-generation energy-integrating-detector CT (EID-CT). Inducing continuous extracorporeal perfusion in a human cadaveric model, we performed CT angiographies of eight upper leg arterial runoffs with radiation dose-equivalent 120 kVp acquisition protocols (CTDIvol 5 mGy). Reconstructions were executed with different vascular kernels, matching the individual modulation transfer functions between scanners. Signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were computed to assess objective image quality. Six radiologists evaluated image quality subjectively using a forced-choice pairwise comparison tool. Interrater agreement was determined by calculating Kendall’s concordance coefficient (W). The intraluminal attenuation of PCD-CT images was significantly higher than of EID-CT (414.7 ± 27.3 HU vs. 329.3 ± 24.5 HU; p < 0.001). Using comparable kernels, image noise with PCD-CT was significantly lower than with EID-CT (p ≤ 0.044). Correspondingly, SNR and CNR were approximately twofold higher for PCD-CT (p < 0.001). Increasing the spatial frequency for PCD-CT reconstructions by one level resulted in similar metrics compared to EID-CT (CNRfat; EID-CT Bv49: 21.7 ± 3.7 versus PCD-CT Bv60: 21.4 ± 3.5). Overall image quality of PCD-CTA achieved ratings superior to EID-CTA irrespective of the used reconstruction kernels (best: PCD-CT Bv60; worst: EID-CT Bv40; p < 0.001). Interrater agreement was good (W = 0.78). Concluding, PCD-CT offers superior intraluminal attenuation, SNR, and CNR compared to EID-CT in angiographies of the upper leg arterial runoff. Combined with improved subjective image quality, PCD-CT facilitates the use of sharper convolution kernels and ultimately bears the potential of improved vascular structure assessability.
Brain μ-opioid receptors (MORs) stimulate high-fat (HF) feeding and have been implicated in the distinct long term outcomes on body weight of bariatric surgery and dieting. Whether alterations in fat appetite specifically following these disparate weight loss interventions relate to changes in brain MOR signaling is unknown. To address this issue, diet-induced obese male rats underwent either Roux-en-Y gastric bypass (RYGB) or sham surgeries. Postoperatively, animals were placed on a two-choice diet consisting of low-fat (LF) and HF food and sham-operated rats were further split into ad libitum fed (Sham-LF/HF) and body weight-matched (Sham-BWM) to RYGB groups. An additional set of sham-operated rats always only on a LF diet (Sham-LF) served as lean controls, making four experimental groups in total. Corresponding to a stage of weight loss maintenance for RYGB rats, two-bottle fat preference tests in conjunction with small-animal positron emission tomography (PET) imaging studies with the selective MOR radioligand [\(^{11}\)C]carfentanil were performed. Brains were subsequently collected and MOR protein levels in the hypothalamus, striatum, prefrontal cortex and orbitofrontal cortex were analyzed by Western Blot. We found that only the RYGB group presented with intervention-specific changes: having markedly suppressed intake and preference for high concentration fat emulsions, a widespread reduction in [\(^{11}\)C]carfentanil binding potential (reflecting MOR availability) in various brain regions, and a downregulation of striatal and prefrontal MOR protein levels compared to the remaining groups. These findings suggest that the suppressed fat appetite caused by RYGB surgery is due to reduced brain MOR signaling, which may contribute to sustained weight loss unlike the case for dieting.
Ureaplasma species (spp.) are considered commensals of the adult genitourinary tract, but have been associated with chorioamnionitis, preterm birth, and invasive infections in neonates, including meningitis. Data on mechanisms involved in Ureaplasma-driven neuroinflammation are scarce. The present study addressed brain inflammatory responses in preterm lambs exposed to Ureaplasma parvum (UP) in utero. 7 days after intra-amniotic injection of UP (n = 10) or saline (n = 11), lambs were surgically delivered at gestational day 128–129. Expression of inflammatory markers was assessed in different brain regions using qRT-PCR and in cerebrospinal fluid (CSF) by multiplex immunoassay. CSF was analyzed for UP presence using ureB-based real-time PCR, and MRI scans documented cerebral white matter area and cortical folding. Cerebral tissue levels of atypical chemokine receptor (ACKR) 3, caspases 1-like, 2, 7, and C–X–C chemokine receptor (CXCR) 4 mRNA, as well as CSF interleukin-8 protein concentrations were significantly increased in UP-exposed lambs. UP presence in CSF was confirmed in one animal. Cortical folding and white matter area did not differ among groups. The present study confirms a role of caspases and the transmembrane receptors ACKR3 and CXCR4 in Ureaplasma-driven neuroinflammation. Enhanced caspase 1-like, 2, and 7 expression may reflect cell death. Increased ACKR3 and CXCR4 expression has been associated with inflammatory central nervous system (CNS) diseases and impaired blood–brain barrier function. According to these data and previous in vitro findings from our group, we speculate that Ureaplasma-induced caspase and receptor responses affect CNS barrier properties and thus facilitate neuroinflammation.
Endoscopic management of umbilical and incisional hernias has adapted to the limitations of conventional laparoscopic instruments over the past 30 years. This includes the development of meshes for intraperitoneal placement (intraperitoneal onlay mesh, IPOM), with antiadhesive coatings; however, adhesions do occur in a significant proportion of these patients. Minimally invasive procedures result in fewer perioperative complications, but with a slightly higher recurrence rate. With the ergonomic resources of robotics, which offers angled instruments, it is now possible to implant meshes in a minimally invasively manner in different abdominal wall layers while achieving morphologic and functional reconstruction of the abdominal wall. This video article presents the treatment of ventral and incisional hernias with mesh implantation into the preperitoneal space (robot-assisted transabdominal preperitoneal ventral hernia repair, r‑ventral TAPP) as well as into the retrorectus space (r-Rives and robotic transabdominal retromuscular umbilical prosthetic repair, r‑TARUP, respectively). The results of a cohort study of 118 consecutive patients are presented and discussed with regard to the added value of the robotic technique in extraperitoneal mesh implantation and in the training of residents.
The surgical treatment of parastomal hernias is considered complex and is known to be prone to complications. Traditionally, this condition was treated using relocation techniques or local suture repairs. Since then, several mesh-based techniques have been proposed and are nowadays used in minimally invasive surgery. Since the introduction of robot-assisted surgery to the field of abdominal wall surgery, several adaptations to these techniques have been made, which may significantly improve patient outcomes. In this contribution, we provide an overview of available techniques in robot-assisted parastomal hernia repair. Technical considerations and preliminary results of robot-assisted modified Sugarbaker repair, robot-assisted Pauli technique, and minimally invasive use of a funnel-shaped mesh in the treatment of parastomal hernias are presented. Furthermore, challenges in robot-assisted ileal conduit parastomal hernia repair are discussed. These techniques are illustrated by photographic and video material. Besides providing a comprehensive overview of robot-assisted parastomal hernia repair, this article focuses on the specific advantages of robot-assisted techniques in the treatment of this condition.
Background
Simulator training is an effective way of acquiring laparoscopic skills but there remains a need to optimize teaching methods to accelerate learning. We evaluated the effect of the mental exercise ‘deconstruction into key steps’ (DIKS) on the time required to acquire laparoscopic skills.
Methods
A randomized controlled trial with undergraduate medical students was implemented into a structured curricular laparoscopic training course. The intervention group (IG) was trained using the DIKS approach, while the control group (CG) underwent the standard course. Laparoscopic performance of all participants was video-recorded at baseline (t0), after the first session (t1) and after the second session (t2) nine days later. Two double-blinded raters assessed the videos. The Impact of potential covariates on performance (gender, age, prior laparoscopic experience, self-assessed motivation and self-assessed dexterity) was evaluated with a self-report questionnaire.
Results
Both the IG (n = 58) and the CG (n = 68) improved their performance after each training session (p < 0.001) but with notable differences between sessions. Whereas the CG significantly improved their performance from t0 –t1 (p < 0.05), DIKS shortened practical exercise time by 58% so that the IG outperformed the CG from t1 -t2, (p < 0.05). High self-assessed motivation and dexterity associated with significantly better performance (p < 0.05). Male participants demonstrated significantly higher overall performance (p < 0.05).
Conclusion
Mental exercises like DIKS can improve laparoscopic performance and shorten practice times. Given the limited exposure of surgical residents to simulator training, implementation of mental exercises like DIKS is highly recommended. Gender, self-assessed dexterity, and motivation all appreciably influence performance in laparoscopic training.