A panel by correspondence. Fat embolism

The Potential Role of Corticosteroid Prophylaxis for the Prevention of Microscopic Fat Embolism Syndrome in Gluteal Augmentations

BACKGROUND

Microscopic fat embolism syndrome (micro-FES) has been recently identified as a potentially fatal complication following gluteal augmentation utilizing autologous fat grafts; safety recommendations advocating for subcutaneous lipo-injections may be insufficient for its prevention.

OBJECTIVES

The authors of this systematic review evaluated the potential role of corticosteroid prophylaxis for the prevention of micro-FES in gluteal augmentation procedures.

METHODS

The authors performed a systematic search employing the National Library of Medicine (PubMed), Medline, and Embase databases. Search terms were those pertaining to studies reporting the efficacy of prophylactic corticosteroid administration on micro-FES incidence in a high-risk surrogate population.

RESULTS

Thirteen articles met the inclusion criteria for review, comprising 2 studies reporting on the efficacy of a single intravenous (IV) corticosteroid dose for the prophylaxis of micro-FES, 9 studies reporting on multiple prophylactic IV doses, and 2 additional studies reporting on the efficacy of inhaled corticosteroids in this context. All studies were identified from the orthopedic literature given that none were available directly from within plastic surgery. The prophylactic efficacy of multiple IV doses of methylprednisolone, or a single larger dose, was established, whereas the efficacy of inhaled corticosteroids remains elusive.

CONCLUSIONS

A single perioperative IV dose of methylprednisolone may be most appropriate for utilization by plastic surgeons; the safety and implication of this therapy on wound healing and fat graft survival are discussed. Further studies directly evaluating the efficacy of corticosteroid prophylaxis in the gluteal augmentation population are indicated. Finally, recommendations pertaining to the prevention, timely recognition, and effective management of micro-FES are discussed.

Fat embolism syndrome: Experience from an Australian trauma centre

BACKGROUND

Fat Embolism Syndrome (FES) is a rare condition where circulating fat emboli can lead to life threatening multisystem dysfunction. Diagnosis of FES occurs mainly by exclusion. The aim of this study was to describe the injury, event details, and factors associated with the diagnosis of FES following trauma presenting to a Level 1 Trauma Centre in Melbourne, Australia.

METHODS

Medical records of all patients with a complication of FES between 2006 and 2018 were retrospectively reviewed. Demographics, injury factors, hospital event details, radiological procedures and length of stay were collected.

RESULTS

Thirty six patients, with median age of 26 years (IQR 19, 42) and median Injury Severity Score (ISS) of 18.5 (IQR 10, 27) were diagnosed with FES. Other associated factors included male gender (86%) and having one or more long bone fractures (97%). Of the major FES diagnostic criteria, 94% of patients experienced hypoxia, 36% had mental status changes, whereas only 11% had petechiae. Computed Tomography Pulmonary Angiogram (CTPA) was performed on 19 patients (53%) with all being negative for pulmonary embolus. Most demonstrated ground glass opacity (58%), and FES was reported as the likely cause of patient presentation in 53% of cases.

CONCLUSION

FES following trauma was rare, with its diagnosis based on clinical factors including long bone fracture and hypoxia, and the exclusion of other respiratory diagnoses. CTPA was frequently used since 2008 and further research is warranted to determine if this radiological procedure can assist with more definitive diagnosis of FES.

A case report of fat embolism syndrome: Treatment and neurological and cognitive rehabilitation

Se reporta el proceso de recuperación y rehabilitación neurológica y cognitiva de una mujer joven que desarrolló un síndrome de embolia grasa con repercusiones neurológicas, después de sufrir un politraumatismo. La paciente era una mujer de 21 años de edad con fractura cerrada de húmero y fémur izquierdos, que presentó un síndrome de embolia grasa, neumotórax izquierdo e hipertensión pulmonar, en las primeras 24 horas después de un accidente. Estuvo hospitalizada un mes y quedó con varios déficits neurológicos centrales, como infartos 'lacunares' y necrosis cortical laminar occipital, así como limitaciones en la bipedestación, la marcha, la visión y las funciones cognitivas. A partir del primer mes después del alta hospitalaria, se comenzó un proceso integral de rehabilitación neurológica y cognitiva en casa, y posteriormente, en una unidad médica de rehabilitación. Durante los primeros dos años después del accidente, la paciente recibió estimulación sensorial, sensoperceptiva y motora, así como rehabilitación motora y visual intensiva. Una vez se recuperó físicamente, se inició un proceso de rehabilitación neuropsicológica. Seis años después del accidente, la paciente terminó sus estudios universitarios y hoy está laboralmente activa. El proceso de rehabilitación neurológica es complejo, individual y difícil, aunque no imposible, y no se puede estandarizar un patrón de recuperación para todos los pacientes. Si bien existe la recuperación espontánea, la cual se da en los primeros seis meses, el caso aquí reportado demuestra que, en la fase crónica, la recuperación se puede lograr, pero requiere de evaluaciones y técnicas coordinadas de rehabilitación neurológica.

Fat embolism syndrome

OBJECTIVES

To assess the incidence and risk factors for fat embolism syndrome.

MATERIALS AND METHODS

Data from the National Hospital Discharge Survey (NHDS) were analyzed using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes.

RESULTS

From 1979 through 2005 among 928,324,000 patients discharged from short-stay hospitals in the United States, 41,000 (0.004%) had fat embolism syndrome. Among 21,538,000 patients with an isolated fracture of the femur (any site), tibia, fibula, pelvis, ribs, humerus, radius, or ulna, 25,000 (0.12%) developed fat embolism syndrome. Patients with multiple fractures of the femur (excluding neck) more often had fat embolism syndrome than those with isolated fractures (1.29% versus 0.54%). The incidence of fat embolism syndrome was lower with isolated fractures of the tibia or fibula (0.30%) and even lower with isolated fractures of the neck of the femur (0.06%). The incidence of fat embolism was too low to calculate with isolated fractures of the pelvis, ribs, humerus, radius, or ulna. Nonorthopedic conditions rarely, if ever, were accompanied by fat embolism syndrome. The fat embolism syndrome was more frequent in men (relative risk 5.71). Children, aged 0 to 9 years rarely had fat embolism syndrome. The fat embolism syndrome most commonly affected patients aged 10 to 39 years.

CONCLUSIONS

The incidence of the fat embolism syndrome depends on the bone involved, whether fractures are isolated or multiple, the age of the patient and the gender. It rarely occurs as a result of medical conditions.

Forensic Lung Pathology

Sudden and unexpected natural deaths and nonnatural deaths may result from various pulmonary conditions. Additionally, several nonpulmonary conditions of forensic significance may be complicated by the development of respiratory lesions. Certain situations with pulmonary pathology are particularly likely to be critically scrutinized and may form the basis of allegations of medical negligence, other personal injury liability, or wrongful death.1

Fat embolism syndrome: history, definition, epidemiology

The first clinical case of fat embolism was described over 100 years ago and significant progress has been made in the understanding of this condition since then. Gurd's criteria, consisting of major and minor clinical features, is the most commonly used diagnostic tool in the literature. Due to the lack of a gold standard for diagnosis, clinical criteria cannot be validated. It is now recognized that although fat embolization occurs in the majority of patients with long bone fractures, clinical signs and symptoms occur only in 1-10% of patients with fractures.

Prevention of fat embolism syndrome

Fat embolism syndrome is a condition of acute respiratory distress following long-bone trauma. This condition may involve not only the lungs but also a number of other body systems. The pathophysiology is not as yet clearly understood, however, intravasation of fat from long-bone fractures may play a role. Early recognition of the severity of injury both on clinical and biochemical grounds and early surgical stabilization of long bones may help to decrease its incidence. However, the best surgical technique with which to do this stabilization has not yet been clearly determined. Surgical and pharmacological techniques have been developed in an attempt to either decrease the intravasation of fat during long-bone stabilization or block the inflammatory cascade with varying degrees of efficacy. Ongoing research focuses on both the prevention and treatment of this condition.

Prevention of posttraumatic hypoxaemia in isolated lower limb long bone fractures with a minimal prophylactic dose of corticosteroids

The efficacy of a minimum dose of methylprednisolone for the prevention of posttraumatic hypoxaemia and fat embolism syndrome (FES) was prospectively studied in 87 patients with isolated, closed or grade I open, femoral and tibial fractures. On admission, the patients were randomly allocated either to a control group given placebo (40 patients) or to a methylprednisolone-treated group (47 patients). A total dose of 6 mg/kg BW methylprednisolone (SoluMedrol, Upjohn) was administered intravenously, divided in six equal doses at 8 h intervals. Six patients (12.8%) in the control group and one patient (2.5%) in the trial group developed FES (P = 0.079) but the difference is not statistically significant. Twenty-four hours after admission, the steroid-treated patients displayed statistically significant higher p(O2) values compared to the control group (P = 0.035) and this difference persisted on the second and the third post-admission day as well (P = 0.008). No corticosteroid-related side-effects were noticed in any of the patients during hospitalisation. Our results support the prophylactic administration of methylprednisolone in small dosage to prevent posttraumatic hypoxaemia and probably FES in patients with isolated lower limb long bone fractures, especially when early fracture stabilisation is not possible.

Critical care in orthopedic and spine surgery

Complications of orthopedic and spine operations can be life threatening. Proper patient selection, careful planning of patient care, and prophylactic measures are important determinants of a successful outcome. After elective orthopedic surgery such as total joint replacement, the intensivist should be aware of potential systemic complications common to any major surgical intervention (pneumonia, pulmonary embolism, sepsis, myocardial infarction) and also of procedure-specific problems (cement-related cardiac events, fat embolism) and local complications (neurovascular injuries). Patients undergoing spine procedures should have close neurologic monitoring for immediate and delayed deficits.

Nontraumatic pulmonary fat embolism syndrome: radiologic and pathologic correlations

The authors report a case of pulmonary fat embolism syndrome without identifiable cause that was seen on chest radiographs and high-resolution computed tomography as diffuse ground-glass attenuation, particularly in nondependent portions of both lungs. The radiologic findings were shown on open-lung biopsy to represent diffuse pulmonary hemorrhage caused by fat embolism.

Early development of vasogenic edema in experimental cerebral fat embolism in cats: correlation with MRI and electron microscopic findings

RATIONALE AND OBJECTIVES

To evaluate the magnetic resonance imaging and electron microscopic findings of the hyperacute stage of cerebral fat embolism in cats and the time needed for the development of vasogenic edema.

METHODS

Magnetic resonance imaging was performed at 30 minutes (group 1, n = 9) and at 30 minutes and 1, 2, 4, and 6 hours after embolization with triolein (group 2, n = 10). As a control for group 2, the same acquisition was obtained after embolization with polyvinyl alcohol particles (group 3, n = 5). Magnetic resonance images were analyzed qualitatively and quantitatively. Electron microscopic examination was done in all cats.

RESULTS

In group 1, the lesions were iso- or slightly hyperintense on T2-weighted (T2W) and diffusion-weighted (DWIs) images, hypointense on the apparent diffusion coefficient (ADC) map image, and markedly enhanced on the gadolinium-enhanced T1-weighted images (Gd-T1WIs). In group 2 at 30 minutes, the lesions were similar to those in group 1. Thereafter, the lesions became more hyperintense on T2WIs and DWIs and more hypointense on the ADC map image. The lesions were enhanced on Gd-T1WIs at all acquisition times. In group 3, the lesions showed mild hyperintensity on T2WIs at 6 hours but hypointensity on the ADC map image from 30 minutes, with a tendency toward a greater decrease over time. The lesions were not enhanced on Gd-T1WIs at any time point. Electron microscopic findings revealed discontinuity of the capillary endothelial wall, perivascular and interstitial edema, and swelling of glial and neuronal cells in groups 1 and 2. Cellular swelling and interstitial edema were more prominent in group 2. In group 3, interstitial edema was seen; however, discontinuity of the endothelial wall was absent.

CONCLUSIONS

The lesions were hyperintense on T2WIs and DWIs, hypointense on the ADC map image, and enhanced on Gd-T1WIs. On electron microscopy, the lesions showed cytotoxic and vasogenic edema with disruption of the blood-brain barrier. Vasogenic edema seems to develop within 30 minutes in cerebral fat embolism in cats.

Fat distribution and changes in the blood brain barrier in a rat model of cerebral arterial fat embolism

This study was designed to determine the distribution of fat which reaches the brain by the internal carotid artery, and the consequent alterations in the blood brain barrier, in a rat model of cerebral arterial fat embolism. The distribution of the blood flow in this model was determined by the injection of radiolabelled microspheres. Over 44% were trapped in the brain, 43% in the extracerebral tissues of the head and neck, and 7% in the lungs. Over 30% of radiolabelled triolein was present within the brain 30 min after injection, and 4% still remained after 17 days. Approximately 25% of the triolein which went to the brain moved through the cerebral vessels and left within the first 15 min. The majority of the triolein distributed to the ipsilateral cerebral hemisphere, with significantly less to the contralateral cerebral hemisphere, brain stem and cerebellum. The blood brain barrier opened, as measured by uptake of 99mTc, within the first 15 min and remained open for at least 3 days. A significant percentage of fat reaching the brain persists for days, and causes rapid and long-lasting damage to the blood brain barrier.

Effect of proximal and distal venting during intramedullary nailing

During intramedullary manipulation, 2 main phenomena occur. A dramatic rise in intramedullary pressure occurs followed by intravasation of damaged marrow tissue. There are concerns about the development of increased interosseous pressure during reaming and the potential for this to contribute to fat embolism syndrome. The intramedullary pressures generated with various intramedullary devices was determined and the effects of a fracture, with and without proximal and distal venting on these pressures were studied. Pressures generated in 78 embalmed anatomic specimen femurs and tibias were studied, leaving all soft tissues intact. Pressures were recorded for awl, guide rod, reamer, and nail insertion. Venting was done by creating a 4.5-mm hole in the cortex directly opposite the transducer. Proximal venting reduced proximal pressures to 80 mm Hg in the tibia (90% reduction) and 460 mm Hg in the femur (70% reduction). Distal venting reduced distal pressures to 65 mm and 30 mm in the tibias and femurs, respectively (90% reduction in pressures). Intramedullary pressures generated during nail or alignment rod insertion in anatomic specimen bone greatly exceeds the critical thresholds (150 mm Hg) thought to be responsible for fat emboli to the lung in the dogs. The introduction of a vent may reduce the chance of fat embolism. Despite the high association of raised intramedullary pressures and fat emboli in animal studies, there is no known critical threshold for humans. Therefore, although venting seems effective in reducing the intramedullary pressure in anatomic specimen bones, its efficacy in the patient with trauma remains to be determined.

Fat embolism syndrome

Since it was initially described, fat embolism syndrome (FES) has remained one of the least clearly understood complications of trauma. This article is a review of the classic and current literature on FES with regard to its causes, pathophysiology, clinical presentation, diagnosis, and treatment. FES is associated with many traumatic and nontraumatic conditions, but is most commonly associated with fractures of long bones of the lower extremity. The pathophysiology is thought to be a cascade of events which can lead to adult respiratory distress syndrome (ARDS). Signs and symptoms of clinical FES usually begin within 24 to 48 hours after trauma. The classic triad involves pulmonary changes, cerebral dysfunction, and petechial rash. Clinical diagnosis is key because laboratory and roentgenographic diagnosis is not specific. Treatment consists of careful initial handling, early stabilization of fractures, careful volume replacement, analgesia, respiratory support, and perhaps steroids. The vast majority of patients today survive FES without sequelae.

Cerebral arterial fat embolism in the rabbit

This study was designed to measure the effects of cerebral arterial fat embolism on cerebral blood flow and function. Rabbits were injected via the left internal carotid artery with the neutral triglyceride triolein. Left cerebral blood flow was measured by laser Doppler flowmetry, and left sided brain function by electrocorticogram and cortical somatosensory evoked responses following electrical stimulation of the forepaw. Readings were taken for 2 h before injection to establish a baseline, and for 3 h after injection. Cerebral blood flow was significantly decreased at 45 min after the injection of the lipid, then progressively decreased further to approximately 50% of baseline after 2 h, at which level it remained for the last hour of the experiment. The electrocorticogram was rapidly, but transiently, suppressed. The evoked responses did not differ from baseline at each of the time points measured. Using 125I-triolein, 2.49% of the injected dose was measured in the brain 3 min after injection. The results show that in this rabbit model of cerebral arterial fat embolism only a small percentage of injected lipid passes into the brain, but this is sufficient to cause a reduction in cerebral blood flow over the following 2 h. The evoked responses never alter significantly from baseline values.

Fat embolism syndrome in a child with muscular dystrophy

Fat embolism syndrome is a relatively common complication of orthopedic trauma. Once thought to be rare in children, it probably occurs with a similar frequency as in adults, but is often subclinical. Clinically apparent fat embolism syndrome may exhibit neurologic, pulmonary, and cutaneous manifestations. It often resolves without sequelae if it is recognized promptly and supportive treatment is provided. We present a pediatric case of fat embolism syndrome and review the literature on its diagnosis and management in children.

Tissue-fat pulmonary embolism occurring in a patient with a severe pelvic fracture

The fat embolism syndrome following trauma is associated with fat droplets in the pulmonary microvasculature. This is the first case report of a large adipose tissue embolus obstructing a pulmonary artery after blunt injury. This embolism occurred during the resuscitation of a patient with a laceration of an iliac vein and disruption of the adjacent fatty tissue secondary to a severe pelvic fracture. Theories of the pathogenesis of the fat embolism syndrome and implications for early therapeutic modalities are discussed.

Cerebral fat embolism: a neuropathological study of a microembolic state

Multiple cerebral petechiae associated with intravascular globules of neutral fat and localized primarily within the white matter are distinctive lesions which secure the pathologic diagnosis of cerebral fat embolism. The abundance of these lesions in an unknown, but presumably small, percentage of cases of fat embolism, along with the even more widespread distribution of embolic fat droplets throughout both white and gray matter, suggest that these lesions and emboli must have a profound effect on neurologic function. Nevertheless, respiratory insufficiency is by far a more common clinical manifestation of the fat embolism syndrome and the neurologic involvement of such patients is often attributed to the secondary effects of generalized hypoxia. The following patient with overt respiratory and neurologic symptoms re-emphasizes the direct primary effect of fat emboli within the central nervous system as a cause of white matter hemorrhages and neurologic deterioration. Explantations for the selectivity of the lesions for the cerebral white matter are explored.

Fat embolism syndrome: a puzzling phenomenon

Fat emboli are a life-threatening source of respiratory insufficiency. Whether they are of mechanical or chemical origin remains a subject of controversy. Fat embolism syndrome is most often seen after fracture of long bones, and immobilization of the fracture site may decrease risk of its development. Adequate oxygenation is the most important aspect of therapy; most patients given vigorous supportive treatment recover with no residual lung injury.

The role of hypovolemic stress in the production of fat embolism in rabbits. 2. Changes in arterial blood gas levels and static compliance

The purpose of this study was to assess the possible role of hypovolemia as a factor in the production of impaired pulmonary function in pulmonary fat embolizaiton. Iv vivo static lung compliance was measured by inflating the lungs with known volumes of air and recording the transpulmonary pressure, monitoring intraesophageal pressure as an index of intrapleural pressure. Arterial blood was drawn from the central artery of the ear. Embolization was produced by the intravenous injection of homologous fat cells either as the sole experimental procedure or in conjunction with hypovolemic shock. Two types of shock were studied. In one, 20 percent of the blood volume was removed, producing hypovolemia associated with hemodilution, and in the other a tourniquet was applied to induce hypovolemia and hemoconcentration. The results indicate that embolization is associated with significantly greater impairment of pulmonary function if it develops on a background of shock than if it occurs in an otherwise healthy animal. These pathophysiologic findings parallel the results of a morphologic study.

The role of hypovolemic stress in the production of fat embolism in rabbits. 1. Morphologic alterations of the lungs

In rabbits, an experimental model of fat embolism was produced that simulates the course of events in the clinical situation. Small doses of fat-cell suspension (0.075 ml/kg of body weight), prepared by collagenase treatment of homologous adipose tissue, were injected intravenously. Concomitantly, hypovolemia was produced in two animal groups by either withdrawing 20 percent of the estimated blood volume or by application of a hind-limb ischemic tourniquet for 90 minutes. The presence of pathoanatomic characteristics typical of fat embolism was evaluated by recording lung/body weights, macroscopic appearance, and semiquantitative microscopic estimation in the lungs of edema, hemorrhage, atelectasis, intravascular coagulation, and leukocytic thrombi. Mean indices of lung/body weight were higher in all animals receiving injections of fat-cell suspension, as compared to controls. The score for microscopic generalized pulmonary damage was significantly higher in rabbits exposed to both fat-cell injections and hypovolemia than in controls or after fat-cell injections alone. It is concluded that hypovolemia enhances the development of fat embolism in rabbits subjected to small doses of fat-cell suspension.

Pathology of cerebral embolization caused by nonthrombotic agents

Although apparently infrequent, a variety of agents other than thrombotic material are known to cause cerebral embolization, often with serious consequences. The emboli may originate in different parts of the body or may be introduced from outside under diverse circumstances. The pathologic aspects of these individual embolic phenomena are described with particular emphasis on their recognition at autopsy. Adequate autopsy study appears to be the most important source of information for further elucidation of the incidence, mechanism, and sequelae of these heterogeneous embolic lesions of the brain. Such information is essential for clinical evaluation, management, and, more importantly, prevention of some of these potentially serious embolic phenomena.