Definitions of hospital-acquired pneumonia in trauma research: a systematic review.

PURPOSE: What are reported definitions of HAP in trauma patient research? METHODS: A systematic review was performed using the PubMed/MEDLINE database. We included all English, Dutch, and German original research papers in adult trauma patients reporting diagnostic criteria for hospital-acquired pneumonia diagnosis. The risk of bias was assessed using the MINORS criteria. RESULTS: Forty-six out of 5749 non-duplicate studies were included. Forty-seven unique criteria were reported and divided into five categories: clinical, laboratory, microbiological, radiologic, and miscellaneous. Eighteen studies used 33 unique guideline criteria; 28 studies used 36 unique non-guideline criteria. CONCLUSION: Clinical criteria for diagnosing HAP-both guideline and non-guideline-are widespread with no clear consensus, leading to restrictions in adequately comparing the available literature on HAP in trauma patients. Studies should at least report how a diagnosis was made, but preferably, they would use pre-defined guideline criteria for pneumonia diagnosis in a research setting. Ideally, one internationally accepted set of criteria is used to diagnose hospital-acquired pneumonia. LEVEL OF EVIDENCE: Level III.

Outcome of severely injured patients in a unique trauma system with 24/7 double trauma surgeon on-call service.

BACKGROUND: The presence of in-house attending trauma surgeons has improved efficiency of processes in the treatment of polytrauma patients. However, literature remains equivocal regarding the influence of the presence of in-house attendings on mortality. In our hospital there is a double trauma surgeon on-call system. In this system an in-house trauma surgeon is 24/7 backed up by a second trauma surgeon to assist with urgent surgery or multiple casualties. The aim of this study was to evaluate outcome in severely injured patients in this unique trauma system. METHODS: From 2014 to 2021, a prospective population-based cohort consisting of consecutive polytrauma patients aged ≥ 15 years requiring both urgent surgery (≤ 24h) and admission to Intensive Care Unit (ICU) was investigated. Demographics, treatment, outcome parameters and pre- and in-hospital transfer times were analyzed. RESULTS: Three hundred thirteen patients with a median age of 44 years (71% male), and median Injury Severity Score (ISS) of 33 were included. Mortality rate was 19% (68% due to traumatic brain injury). All patients stayed ≤ 32 min in ED before transport to either CT or OR. Fifty-one percent of patients who needed damage control surgery (DCS) had a more deranged physiology, needed more blood products, were more quickly in OR with shorter time in OR, than patients with early definitive care (EDC). There was no difference in mortality rate between DCS and EDC patients. Fifty-six percent of patients had surgery during off-hours. There was no difference in outcome between patients who had surgery during daytime and during off-hours. Death could possibly have been prevented in 1 exsanguinating patient (1.7%). CONCLUSION: In this cohort of severely injured patients in need of urgent surgery and ICU support it was demonstrated that surgical decision making was swift and accurate with low preventable death rates. 24/7 Physical presence of a dedicated trauma team has likely contributed to these good outcomes.

Management of Hemodynamically Unstable Pelvic Ring Fractures.

Hemodynamically unstable pelvic fractures are challenging high-energy traumas. In many cases, these severely injured patients have additional traumatic injuries that also require a trauma surgeon's attention. However, these patients are often in extremis and require a multidisciplinary approach that needs to be set up in minutes. This calls for an evidence-based treatment algorithm. We think that the treatment of hemodynamically unstable pelvic fractures should primarily involve thorough resuscitation, mechanical stabilization, and preperitoneal pelvic packing. Angioembolization should be considered in patients that remain hemodynamically unstable. However, it should be used as an adjunct, rather than a primary means to achieve hemodynamic stability as most of the exsanguinating bleeding sources in pelvic trauma are of venous origin. Time is of the essence in these patients and should therefore be used appropriately. Hence, the hemodynamic status and physiology should be the driving force behind each decision-making step within the algorithm.

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds.

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived matrix as substrate for endochondral bone regeneration.

Following an endochondral approach to bone regeneration, multipotent stromal cells (MSCs) can be cultured on a scaffold to create a cartilaginous callus that is subsequently remodeled into bone. An attractive scaffold material for cartilage regeneration that has recently regained attention is decellularized cartilage-derived matrix (CDM). Since this material has shown potential for cartilage regeneration, we hypothesized that CDM could be a potent material for endochondral bone regeneration. In addition, since decellularized matrices are known to harbor bioactive cues for tissue formation, we evaluated the need for seeded MSCs in CDM scaffolds. In this study, ectopic bone formation in rats was evaluated for CDM scaffolds seeded with human MSCs and compared with unseeded controls. The MSC-seeded samples were preconditioned in chondrogenic medium for 37 days. After 8 weeks of subcutaneous implantation, the extent of mineralization was significantly higher in the MSC-seeded constructs versus unseeded controls. The mineralized areas corresponded to bone formation with bone marrow cavities. In addition, rat-specific bone formation was confirmed by collagen type I immunohistochemistry. Finally, fluorochrome incorporation at 3 and 6 weeks revealed that the bone formation had an inwardly directed progression. Taken together, our results show that decellularized CDM is a promising biomaterial for endochondral bone regeneration when combined with MSCs at ectopic locations. Modification of current decellularization protocols may lead to enhanced functionality of CDM scaffolds, potentially offering the prospect of generation of cell-free off-the-shelf bone regenerative substitutes.

Endochondral bone formation in gelatin methacrylamide hydrogel with embedded cartilage-derived matrix particles.

The natural process of endochondral bone formation in the growing skeletal system is increasingly inspiring the field of bone tissue engineering. However, in order to create relevant-size bone grafts, a cell carrier is required that ensures a high diffusion rate and facilitates matrix formation, balanced by its degradation. Therefore, we set out to engineer endochondral bone in gelatin methacrylamide (GelMA) hydrogels with embedded multipotent stromal cells (MSCs) and cartilage-derived matrix (CDM) particles. CDM particles were found to stimulate the formation of a cartilage template by MSCs in the GelMA hydrogel in vitro. In a subcutaneous rat model, this template was subsequently remodeled into mineralized bone tissue, including bone-marrow cavities. The GelMA was almost fully degraded during this process. There was no significant difference in the degree of calcification in GelMA with or without CDM particles: 42.5 ± 2.5% vs. 39.5 ± 8.3% (mean ± standard deviation), respectively. Interestingly, in an osteochondral setting, the presence of chondrocytes in one half of the constructs fully impeded bone formation in the other half by MSCs. This work offers a new avenue for the engineering of relevant-size bone grafts, by the formation of endochondral bone within a degradable hydrogel.

Of mice, men and elephants: the relation between articular cartilage thickness and body mass.

Mammalian articular cartilage serves diverse functions, including shock absorption, force transmission and enabling low-friction joint motion. These challenging requirements are met by the tissue's thickness combined with its highly specific extracellular matrix, consisting of a glycosaminoglycan-interspersed collagen fiber network that provides a unique combination of resilience and high compressive and shear resistance. It is unknown how this critical tissue deals with the challenges posed by increases in body mass. For this study, osteochondral cores were harvested post-mortem from the central sites of both medial and lateral femoral condyles of 58 different mammalian species ranging from 25 g (mouse) to 4000 kg (African elephant). Joint size and cartilage thickness were measured and biochemical composition (glycosaminoclycan, collagen and DNA content) and collagen cross-links densities were analyzed. Here, we show that cartilage thickness at the femoral condyle in the mammalian species investigated varies between 90 µm and 3000 µm and bears a negative allometric relationship to body mass, unlike the isometric scaling of the skeleton. Cellular density (as determined by DNA content) decreases with increasing body mass, but gross biochemical composition is remarkably constant. This however need not affect life-long performance of the tissue in heavier mammals, due to relatively constant static compressive stresses, the zonal organization of the tissue and additional compensation by joint congruence, posture and activity pattern of larger mammals. These findings provide insight in the scaling of articular cartilage thickness with body weight, as well as in cartilage biochemical composition and cellularity across mammalian species. They underscore the need for the use of appropriate in vivo models in translational research aiming at human applications.

Extracellular matrix scaffolds for cartilage and bone regeneration.

Regenerative medicine approaches based on decellularized extracellular matrix (ECM) scaffolds and tissues are rapidly expanding. The rationale for using ECM as a natural biomaterial is the presence of bioactive molecules that drive tissue homeostasis and regeneration. Moreover, appropriately prepared ECM is biodegradable and does not elicit adverse immune responses. Successful clinical application of decellularized tissues has been reported in cardiovascular, gastrointestinal, and breast reconstructive surgery. At present, the use of ECM for osteochondral tissue engineering is attracting interest. Recent data underscore the great promise for future application of decellularized ECM for osteochondral repair. This review describes the rationale for using ECM-based approaches for different regenerative purposes and details the application of ECM for cartilage or osteochondral repair.