Fat Embolism Syndrome - A Qualitative Review of its Incidence, Presentation, Pathogenesis and Management

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.

Trends and associated outcomes of fat embolism after trauma surgery

BACKGROUND

Fat embolism is a life-threatening complication often occurring in patients with traumatic injuries. However, temporal trends and perioperative outcomes of fat embolism remain understudied. Using a nationally representative cohort, we aimed to characterize temporal trends of fat embolism and its associated resource utilization in operatively managed trauma patients.

METHODS

All patients (≥18 years) undergoing any major operations after traumatic injuries were tabulated using the 2005 to 2020 National Inpatient Sample. Patients were stratified into those with fat embolism and those without. Multivariable logistic and linear regressions were developed to assess the association between fat embolism and outcomes of interest.

RESULTS

Of an estimated 10,600,000 hospitalizations, 7,479 (0.07%) patients had fat embolism. Compared to the non-fat embolism cohort, the fat embolism cohort was younger (55 [26-79] vs 69 [49-82] years, standard mean difference = 0.46) and more likely to receive treatment at a high-volume trauma center (42.9 vs 33.7%, standard mean difference = 0.19). Over the study period, there was an increase in annual mortality and hospitalization costs among the fat embolism group (nptrend <0.001). After risk adjustment, fat embolism was associated with greater odds of mortality (adjusted odds ratio: 2.65, 95% confidence interval: 2.24-3.14) compared to others. Additionally, fat embolism was associated with increased odds of cerebrovascular, infectious, and renal complications.

CONCLUSION

Among all operatively managed trauma patients, those who developed fat embolism had increased mortality, rates of complications, length of stay, and costs. Optimization of early and accurate identification of fat embolism is warranted to mitigate complications and improve resource allocation among trauma patients.

A rare fatal cerebral fat emboli syndrome with large vessel occlusion post femur fracture plating in an older female: A case report

INTRODUCTION AND IMPORTANCE

Cerebral fat embolism syndrome is a rare complication of long bone fractures, often overlooked and found in late stages. We present patient with a late recognition of Cerebral Fat Embolism with Large vessel occlusion post femoral internal fixation.

CASE PRESENTATION

An elderly female suffered right intertrochanteric fracture after falling down. Open reduction internal fixation with Interlocking plate was performed at the fifth day. Upon returning to the ward, the patient did not regain full consciousness and apparent right hemiparesis were observed. A head Computed Tomography was performed and found left hemisphere ischemia consistent with middle cerebral artery occlusion. The patient condition worsened and died 3 days postoperatively.

CLINICAL DISCUSSION

Cases of fat embolism that occur purely isolated in the brain are rare cases that occur after internal fixation of the femur, so they are often not noticed by clinicians. Several factors can increase the risk of the event, delay in fixation and diabetes mellitus which was found in our patient could increase the risk of fat emboli syndrome. Apart from that, osteoporosis also increases the risk of fat embolism syndrome that was found in our subject.

CONCLUSIONS

Cerebral Large Vessel Occlusion Fat Embolism Syndrome is rare case occur following internal fixation. There is a need for early recognition to be carried out to treat early or prevent the occurrence of fat embolism.

Fat embolism: the hidden murder for trauma patients!

INTRODUCTION

fat embolism syndrome (FES) is an acute respiratory disorder that occurs when an inflammatory response causes the embolization of fat and marrow particles into the bloodstream. The exact incidence of FES is not well defined due to the difficulty of diagnosis. FES is mostly associated with isolated long bone trauma, and it is usually misdiagnosed in other trauma cases. The scope of this study was to identify and search the current literature for cases of FES in nonorthopedic trauma patients with the aim of defining the etiology, incidence, and main clinical manifestations.

METHODS

we perform a literature search via the PubMed journal to find, summarize, and incorporate reports of fat embolisms in patients presenting with non-orthopedic trauma.

RESULTS

the final literature search yielded 23 papers of patients presenting with fat embolism/FES due to non-orthopedic trauma. The presentation and etiology of these fat embolisms is varied and complex, differing from patient to patient. In this review, we highlight the importance of maintaining a clinical suspicion of FES within the trauma and critical care community.

CONCLUSION

to help trauma surgeons and clinicians identify FES cases in trauma patients who do not present with long bone fracture, we also present the main clinical signs of FES as well as the possible treatment and prevention options.

Pulmonary fat embolism in non-survivors after cardiopulmonary resuscitation

BACKGROUND

Blunt trauma acting against the human body presents the fundamental cause of pulmonary fat embolism (PFE) and fat embolism syndrome. The aim of the present study was to investigate PFE in non-survivors after cardiopulmonary resuscitation (CPR).

METHODS

This was a prospective cohort study conducted in University Hospital Ostrava, Czech Republic. Within a 4-year study period, all non-survivors after CPR because of out-of-hospital cardiac arrest were assessed for the study eligibility. The presence/seriousness of PFE was determined by microscopic examination of cryo-sections of lung tissue (staining with Oil Red O).

RESULTS

In total, 106 persons after unsuccessful CPR were enrolled in the study. The most frequent cause of death in the study population (63.2% of cases) was cardiac disease (ischemic heart disease); PFE was not determined as the cause of death in any of our study cases. Sternal fractures were identified 66.9%, rib fractures (usually multiple) in 80.2% of study cases; the median number of rib fractures was 10.2 fractures per person. Serious intra-thoracic injuries were found in 34.9% of cases. Microscopic examination of lung cryo-sections revealed PFE in 40 (37.7%) study cases; PFE was most frequently evaluated as grade I or II. Occurrence of sternal and rib fractures was significantly higher in persons with PFE than between persons without PFE (p = 0.033 and p = <0.001). Number of rib fractures was also significantly higher in persons with PFE. The occurrence of serious intra-thoracic injuries was comparable in both our study groups (p = 0.089).

CONCLUSIONS

PFE presents a common resuscitation injury which can be found in more than 30% of persons after CPR. Persons with resuscitation skeletal chest fractures have significantly higher risk of PFE development. During autopsy of persons after unsuccessful CPR, it is necessary to distinguish CPR-associated injuries including PFE from injuries that arise from other mechanisms.

Cerebral fat emboli in a patient with paraplegia caused by bilateral femur fractures

Cerebral fat embolism is a rare cause of stroke and therefore an overlooked diagnosis. Often it is seen as a consequence of major bone fractures or after arthroplasty, and can lead to respiratory or circulatory collapse. We present a case of a patient with a history of paraplegia after a thoracic spinal cord injury that developed cerebral fat embolism following a bilateral femur fracture. Since the patient was paraplegic and with an altered mental state upon admission, femoral bone fractures were not initially suspected. The case shows the difficulties in diagnosing this condition.

Femoral Nailing in a Porcine Model Causes Bone Marrow Emboli in the Lungs and Systemic Emboli in the Heart and Brain

Background

Shaft fractures of the femur are commonly treated with intramedullary nailing, which can release bone marrow emboli into the bloodstream. Emboli can travel to the lungs, impairing gas exchange and causing inflammation. Occasionally, emboli traverse from the pulmonary to the systemic circulation, hindering perfusion and resulting in injuries such as heart and brain infarctions, known as fat embolism syndrome. We studied the extent of systemic bone marrow embolization in a pig model.

Methods

Twelve anesthetized pigs underwent bilateral intramedullary nailing of the femur, while 3 animals served as sham controls. Monitoring included transesophageal echocardiography (TEE), pulse oximetry, electrocardiography, arterial blood pressure measurement, and blood gas and troponin-I analysis. After surgery, animals were monitored for 240 minutes before euthanasia. Post mortem, the heart, lungs, and brain were biopsied.

Results

Bone marrow emboli were found in the heart and lungs of all 12 of the pigs that underwent intramedullary nailing and in the brains of 11 of them. No emboli were found in the sham group. The pigs subjected to intramedullary nailing exhibited significant hypoxia (PaO2/FiO2 ratio, 410 mm Hg [95% confidence interval (CI), 310 to 510) compared with the sham group (594 mm Hg [95% CI, 528 to 660]). The nailing group exhibited ST-segment alterations consistent with myocardial ischemia and a significant increase in the troponin-I level compared with the sham group (1,580 ng/L [95% CI, 0 to 3,456] versus 241 ng/L [95% CI, 0 to 625] at the 240-minute time point; p = 0.005). TEE detected emboli in the right ventricular outflow tract, but not systemically, in the nailing group.

Conclusions

Bilateral intramedullary nailing caused bone marrow emboli in the lungs and systemic emboli in the heart and brain in this pig model. The observed clinical manifestations were consistent with coronary and pulmonary emboli. TEE detected pulmonary but not systemic embolization.

Clinical Relevance

Femoral intramedullary nailing in humans is likely to result in embolization as described in our pig model. Focused monitoring is necessary for detection of fat embolism syndrome. Absence of visual emboli in the left ventricle on TEE does not exclude the occurrence of systemic bone marrow emboli.

The Development of Fat Embolism Syndrome (FES) and Multiple Small Pulmonary Emboli Following Open Reduction Internal Fixation (ORIF) of a Left Femur Fracture: A Case Report

Fat embolism syndrome (FES) is a rare but potentially life-threatening complication that can occur following orthopedic procedures, such as long bone fracture repairs. FES is caused by the release of fat globules into the bloodstream, leading to the obstruction of blood vessels and subsequent tissue damage. Pulmonary embolism (PE), a condition in which a blood clot travels to the lungs, is another potential complication of orthopedic procedures due to the mobilization of blood clots during surgery. We report the case of a 56-year-old female who presented to the emergency department with a left femur fracture following a mechanical fall and underwent open reduction internal fixation (ORIF) surgery for the fracture. The procedure was complicated by the development of FES and multiple small pulmonary emboli. The patient was managed postoperatively in the ICU, requiring support with multiple vasopressors and mechanical ventilation. She remained in the ICU for three days postoperatively and was discharged on postoperative day six to an inpatient rehabilitation facility.

Nontrombotic Pulmonary Embolism: Different Etiology, Same Significant Consequences

Nontrombotic pulmonary embolism represents the embolization of different types of materials (cells, organisms, gas, foreign material) into pulmonary circulation. The disease is uncommon, and clinical presentation together with laboratory findings are nonspecific. Its pathology is usually misdiagnosed based on imaging findings as pulmonary thromboembolism, but the correct diagnosis is essential because different therapeutic approaches are required. In this context, knowledge of the risk factors associated with nontrombotic pulmonary embolism and specific clinical symptoms is fundamental. Our objective was to discuss the specific features of the most common etiologies of nontrombotic pulmonary embolism, gas, fat, amniotic fluid, sepsis and tumors, to provide assistance for a rapid and correct diagnosis. Because the most common etiologies are iatrogenic, knowledge of the risk factors could be an important tool for prevention or rapid treatment if the disease develops during different procedures. The diagnosis of nontrombotic pulmonary embolisms represent a laborious challenge, and endeavors should be made to prevent development and increase awareness of this disease.

Fat embolism syndrome in a patient that sustained a femoral neck fracture: A case report

Background

We present a case of a patient with a femoral neck fracture that shows neurological impairment and respiratory distress 1 day after trauma, caused by the Fat Embolism Syndrome with the presence of Cerebral Fat Embolisms.

Case summary

A 75 year old female remained unresponsive after a hemi arthroplasty was performed because of a 1 day old femoral neck fracture. She rapidly developed respiratory insufficiency and an obstructive shock with right ventricle dilatation on transthoracic echocardiography. The diffusion-weighted MRI brain images showed the "Starfield" pattern, a radiologic phenomenon typical for FES. During 3 weeks of ICU admission the neurologic state slowly ameliorated.

Conclusion

The rare FES is a clinical diagnosis with mainly respiratory, neurologic and dermatologic symptoms in the setting of a trauma patient. Fat embolisms are able to reach the brain without the presence of a patent foramen ovale to cause neurological symptoms. Diagnosing FES remains challenging but the distinctive "Starfield" pattern on MRI scans is promising.