Fat Embolism Does Not Alter Cardiac Structure or Induce Pathological Changes in a Rat Model.

INTRODUCTION: Fat embolism (FE) encompasses conditions in which fatty substance becomes embedded in a tissue/organ. Fat emboli most commonly affect the lungs in a trauma setting. This can lead to both significant pathology locally and systemically including changes in structure, inflammatory response, activation of the renin-angiotensin system, and subsequent hypoxia. In fact, changes in skin, brain, lungs, and kidneys have been noted in FE syndrome. Because there is an extensive record of pathology reports on this condition without evidence of direct cardiac involvement, as well as our studies showing apparent complete recovery after the acute embolism, we hypothesized that structural changes similar to the lung and at the same time course would not be observed in the heart. METHODS: We used a rat model of FE previously described by our group where we have documented significant lung pathology. In this study, we analyzed both pulmonary and cardiac structure, histology, and gene expression at 48 h and 10 wks post fat injection to mimic FE. RESULTS: Despite severe inflammatory evidence and structural changes to the lung and vasculature up to 10 wks after FE, we found no significant alterations to cardiovascular morphometry including lumen patency ratio, adventitia/media ratio, fibrosis content, and heart chamber/wall dimensions in stained histological sections. Additionally, genetic markers of cardiac pathological hypertrophy were not significantly elevated 48 h or 10 wks after fat treatment. Oil Red O staining showed increased fat droplet content within lung and aorta tissue, but not in the myocardium. CONCLUSIONS: Our study suggests that, in contrast to the lungs, the heart is more resistant to the inflammatory and remodeling responses that result from FE, possibly due to the organ-specific differences in fat retention.

A diagnostic strategy for pulmonary fat embolism based on routine H&E staining using computational pathology.

Pulmonary fat embolism (PFE) as a cause of death often occurs in trauma cases such as fractures and soft tissue contusions. Traditional PFE diagnosis relies on subjective methods and special stains like oil red O. This study utilizes computational pathology, combining digital pathology and deep learning algorithms, to precisely quantify fat emboli in whole slide images using conventional hematoxylin-eosin (H&E) staining. The results demonstrate deep learning's ability to identify fat droplet morphology in lung microvessels, achieving an area under the receiver operating characteristic (ROC) curve (AUC) of 0.98. The AI-quantified fat globules generally matched the Falzi scoring system with oil red O staining. The relative quantity of fat emboli against lung area was calculated by the algorithm, determining a diagnostic threshold of 8.275% for fatal PFE. A diagnostic strategy based on this threshold achieved a high AUC of 0.984, similar to manual identification with special stains but surpassing H&E staining. This demonstrates computational pathology's potential as an affordable, rapid, and precise method for fatal PFE diagnosis in forensic practice.

Venoarterial Extracorporeal Membrane Oxygenation Therapy in Patients with Sickle Cell Disease: Case Series and Review for Intensive Care Physicians.

Sickle cell disease (SCD) is associated with substantial morbidity and early mortality in afflicted adults. Cardiopulmonary complications that occur at increased frequency in SCD such as pulmonary embolism, pulmonary arterial hypertension, and acute chest syndrome can acutely worsen right ventricular function and lead to cardiogenic shock. Mechanical circulatory support including venoarterial extracorporeal membrane oxygenation (VA ECMO) is being increasingly utilized to treat hemodynamic collapse in various patient populations. However, a paucity of literature exists to guide the use of mechanical circulatory support in adults with SCD where disease-related sequela and unique hematologic aspects of this disorder may complicate extracorporeal therapy and must be understood. Here, we review the literature and describe three cases of adult patients with SCD who developed cardiogenic shock from acute decompensated right heart failure and were treated clinically with VA ECMO. Using an in vitro ECMO system, we investigate a potential increased risk of systemic fat emboli in patients with SCD who may be experiencing vaso-occlusive events with bone marrow involvement given the high-volume shunting of blood from venous to arterial systems with VA ECMO. The purpose of this study is to describe available extracorporeal life support experiences, review potential complications, and discuss the special considerations needed to further our understanding of the utility of VA ECMO in those with SCD.

Cerebral fat embolism with turbid urine as the initial sign.

BACKGROUND: Cerebral fat embolism (CFE) is a rare but potentially fatal complication that can occur after long bone fractures. It represents one subcategory of fat embolisms (FE). Diagnosing CFE can be challenging due to its variable and nonspecific clinical manifestations. We report a case of CFE initially presenting with turbid urine, highlighting an often neglected sign. CASE PRESENTATION: A 69-year-old male was admitted after a traffic accident resulting in bilateral femoral fractures. Sixteen hours post-admission, grossly turbid urine was noted but received no special attention. Four hours later, he developed rapid deterioration of consciousness and respiratory distress. Neurological examination revealed increased upper limb muscle tone and absent voluntary movements of lower limbs. Brain MRI demonstrated a 'starfield pattern' of diffuse punctate lesions, pathognomonic for CFE. Urine microscopy confirmed abundant fat droplets. Supportive treatment and fracture fixation were performed. The patient regained consciousness after 3 months but had residual dysphasia and limb dyskinesia. CONCLUSION: CFE can present with isolated lipiduria preceding overt neurological or respiratory manifestations. Heightened awareness of this subtle sign in high-risk patients is crucial for early diagnosis and intervention. Prompt urine screening and neuroimaging should be considered when gross lipiduria occurs after long bone fractures.

Brain microbleeds resulting from presumed extensive fat emboli in a patient with bone marrow necrosis following a sickle cell disease vaso-occlusive crisis.

Acute manifestations of sickle cell disease (SCD) are numerous and multisystemic. Cerebral fat embolism (CFE) is a rare but serious complication of SCD caused by bone marrow necrosis (BMN) during vaso-occlusive crises (VOC). We present the case of a 41-year-old man with SCD who developed severe VOC and multi-organ dysfunction. He subsequently experienced neurological deterioration with decreased consciousness and diffuse encephalopathy on serial electroencephalograms. Bone marrow aspiration confirmed BMN. Brain MRI revealed extensive diffuse leukoencephalopathy, vasogenic and cytotoxic edema in the white matter, patchy edema in the cranial vault bone marrow on fat-suppressed FLAIR sequence (a finding consistent with the confirmed BMN), and multiple cerebral microbleeds on susceptibility-weighted imaging consistent with CFE. The management of acute neurological complications of SCD varies depending on the specific complication. Brain MRI plays a crucial role in the accurate diagnosis of these complications to guide appropriate treatment.

Danger Zones of the Gluteal Anatomy: Improving the Safety Profile of the Gluteal Fat Grafting.

INTRODUCTION: Knowledge of the vascular anatomy is critical to performing safe gluteal surgery. To date, only the course of the main blood vessels within the muscles has been outlined. These findings are based on MRI and CTA images that do not conform to a topographically standardized and normalized probability distribution. OBJECTIVES: The aim of this study was to develop a three-dimensional mapping of the gluteal zones of high vascular density in relation to anatomical landmarks. MATERIALS AND METHODS: This single-center retrospective cohort analysis comprised all consecutive patients who underwent cone-beam computed tomography (CBCT) scans between January 2016 and October 2021. The location of blood vessels in the gluteal region was allometrically normalized in relation to anatomical landmarks. Moreover, the caliber and area of the blood vessels were assessed. RESULTS: CBCT scans of 32 patients with an average age of 64 ± 12 years (range 34-87 years) were included. Fifty-three percent were female. The median [IQR] caliber of the intramuscular gluteal vessels was 1.47 [1.15-1.88] mm, significantly greater than that of the subcutaneous vessels 1.09 [0.72-1.44] mm (p < 0.001). Vascular density was higher intramuscularly, as 4.5% of the area of the muscle was occupied by blood vessels, as opposed to 0.3% in the adipose tissue. CONCLUSION: The analysis of the CBCT scans showed a higher vascular density and larger vessels intramuscularly. We, therefore, recommend the injection of autologous fat merely to the subcutaneous plane. LEVEL OF EVIDENCE II: 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 .

In vivo study to assess fat embolism resulting from the Reamer-Irrigator-Aspirator 2 system compared to a novel aspirator-based concept for intramedullary bone graft harvesting.

INTRODUCTION: Fat embolism (FE) following intramedullary (IM) reaming can cause severe pulmonary complications and sudden death. Recently, a new harvesting concept was introduced in which a novel aspirator is used first for bone marrow (BM) aspiration and then for subsequent aspiration of morselized endosteal bone during sequential reaming (A + R + A). In contrast to the established Reamer-Irrigator-Aspirator (RIA) 2 system, the new A + R + A concept allows for the evacuation of fatty BM prior to reaming. In this study, we hypothesized that the risk of FE, associated coagulopathic reactions and pulmonary FE would be comparable between the RIA 2 system and the A + R + A concept. MATERIALS AND METHODS: Intramedullary bone graft was harvested from intact femora of 16 Merino sheep (age: 1-2 years) with either the RIA 2 system (n = 8) or the A + R + A concept (n = 8). Fat intravasation was monitored with the Gurd test, coagulopathic response with D-dimer blood level concentration and pulmonary FE with histological evaluation of the lungs. RESULTS: The total number and average size of intravasated fat particles was similar between groups (p = 0.13 and p = 0.98, respectively). D-dimer concentration did not significantly increase within 4 h after completion of surgery (RIA 2: p = 0.82; A + R + A: p = 0.23), with an interaction effect similar between groups (p = 0.65). The average lung area covered with fat globules was similar between groups (p = 0.17). CONCLUSIONS: The use of the RIA 2 system and the novel A + R + A harvesting concept which consists of BM evacuation followed by sequential IM reaming and aspiration of endosteal bone, resulted in only minor fat intravasation, coagulopathic reactions and pulmonary FE, with no significant differences between the groups. Our results, therefore, suggest that both the RIA 2 system and the new A + R + A concept are comparable technologies in terms of FE-related complications.

[Post-traumatic stroke due to fat embolism]. / Accident vasculaire cérébral post-traumatique sur embolie graisseuse.

Fat embolism syndrome mainly occurs following trauma to the long bones or pelvis. Non-traumatic causes are rarer. Its incidence varies greatly and depends on the number of fractures involved. Two physiopathological theories, one mechanical and the other biochemical, attempt to explain this still poorly understood phenomenon. The complete form of the syndrome results in a combination of pulmonary involvement, neurological disorders and a petechial rash. Given the polymorphism of signs and symptoms, Fat embolism syndrome remains a diagnosis of exclusion. Regarding treatment, the therapeutic strategy combines treatment of the causative process with conservative measures.

Le syndrome d'embolie graisseuse se manifeste majoritairement dans les suites d'un traumatisme des os longs ou du bassin. Les causes non traumatiques sont plus rares. Son incidence varie fortement et dépend du nombre de fractures impliquées. Deux théories physiopathologiques, l'une mécanique et l'autre biochimique, tentent d'expliquer ce phénomène encore mal compris. La forme complète du syndrome se traduit par la combinaison d'une atteinte pulmonaire, de troubles neurologiques et d'une éruption pétéchiale. Étant donné le polymorphisme des signes et des symptômes, le syndrome d'embolie graisseuse reste un diagnostic d'exclusion. Concernant le traitement, la stratégie thérapeutique associe la prise en charge du processus causal combinée à des mesures conservatrices.

Fat embolism after intraosseous catheters in pediatric forensic autopsies.

In our center, we performed the autopsy of a child who died from drowning and presented, at autopsy, a major pulmonary fat embolism (PFE). A cardiopulmonary resuscitation (CPR) was performed, including infusion by intraosseous catheter (IIC). No other traumatic lesions and diseases classically related to a risk of PFE were detected. According to some animal studies, we considered the IIC as the only possible cause for PFE. However, we could not find literature to confirm this hypothesis in humans, especially in a pediatric population. To verify the occurrence of PFE after IIC in a pediatric population, we retrospectively selected 20 cases of pediatric deaths autopsied in our center, in which a CPR was performed, without bone fractures or other possible causes of PFE: 13 cases with IIC (group A) and 7 cases without IIC (group B). Several exclusion criteria were considered. The histology slides of the pulmonary tissue were stained by Oil Red O. PFE was classified according to the Falzi scoring system. In group A, 8 cases showed PFE: 4 cases with a score 1 of Falzi and 4 cases with a score 2 of Falzi. In group B, no case showed PFE. The difference between the two groups was statistically significant. The results of our study seem to confirm that IIC can lead to PFE in a pediatric population and show that the PFE after IIC can be important (up to score 2 of Falzi). To the best of our knowledge, our study is the first specifically focused on the occurrence of PFE after IIC in a pediatric population by using autoptic data.

Pulmonary fat embolism: a potentially new fatal complication of SARS-CoV-2 infection. A case report.

BACKGROUND: So far, there have been more than 761 million confirmed cases of SARS-CoV-2 worldwide, with more than 6.8 million deaths. The most common direct causes of death for COVID-19 are diffuse alveolar injury and acute respiratory distress syndrome. Autopsy results have shown that 80-100% of COVID-19 patients have microthrombi which is 9 times higher than in patients with influenza. There are reported cases of fat embolism associated with Covid-19, but relevant epidemiological investigations and fatal cases of pulmonary fat embolism are lacking. In this report, we describe the first COVID-19 patient to die from pulmonary fat embolism. CASE PRESENTATION: A 54-year-old woman suddenly felt unwell while at work. She had difficulty breathing for 40 min and lost consciousness for 20 min before being taken to the hospital. On admission, her temperature was 36 ℃, but her respiration, heart rate, and blood pressure were undetectable. Laboratory examination revealed C-reactive protein, 26.55 mg/L; D-dimer, 11,400 µg/L; and procalcitonin, 0.21 ng/mL. She was declared clinically dead 2 h after admission due to ineffective rescue efforts. At autopsy, both lungs were highly oedematous with partial alveolar haemorrhage. The presence of microthrombi and pulmonary fat embolism in small interstitial pulmonary vessels was confirmed by phosphotungstic acid haematoxylin staining and oil red O staining. The immunohistochemical results of spike protein and nucleocapsid protein in laryngeal epithelial cells confirmed SARS-CoV-2 infection. CONCLUSIONS: Pulmonary fat embolism may be another fatal complication of COVID-19 infection, and clinicians should pay more attention to it.