Comments on “Commentary on: The Potential Role of Corticosteroid Prophylaxis for the Prevention of Microscopic Fat Embolism Syndrome in Gluteal Augmentations”

We read with great interest the commentary on our recent article “The Potential Role of Corticosteroid Prophylaxis for the Prevention of Microscopic Fat Embolism Syndrome in Gluteal Augmentations” published in the Aesthetic Surgery Journal.1,2 We thank the author for his insightful comments and for stimulating further discussion on this topic, as the aesthetic surgery community continues to evaluate all aspects of the gluteal augmentation procedure with the goal of improving safety and outcomes for our patients. As detailed in our paper, the author notes in his commentary that it is critical for plastic surgeons today to understand the distinction between macroscopic fat embolism, microscopic fat embolism, and microscopic fat embolism syndrome (micro-FES).2 During the lipoinjection process in gluteal augmentations, damage to the deep gluteal vasculature may allow macroscopic fat lobules to enter the pelvic venous circulation.3 This is known as macroscopic fat embolism and may lead to electromechanical disassociation and cardiac arrest.3 As the author notes from his own personal experience, the large amounts of fat seen in the vena cava, heart, and lungs during autopsies of these patients illustrate why macroscopic fat embolism is incompatible with life.2,3 Microscopic fat embolism, by contrast, is a result of the embolization of smaller globules or liquefied fat, through smaller caliber veins, which may culminate in micro-FES.4 Microscopic fat emboli first obstruct small-caliber pulmonary vessels leading to vessel engorgement and an increase in lung stiffness.5 Hydrolyzed fat and circulating free fatty acids then act to increase the permeability of capillary networks, destroy alveolar architecture, and promote the release of inflammatory cytokines.5 This then culminates in systemic inflammation, central nervous system depression, and respiratory insufficiency.3,5,6 Mortality from micro-FES may be as high as 20% as previously described in the literature.1,6-8 To reduce the risk of macroscopic fat embolism, safety recommendations from the Aesthetic Surgery Education and Research Foundation (ASERF) task force, published in this journal, advocate for the use of large-bore blunt cannulas for fat grafting, injecting only when the canula is in motion, and primarily within the subcutaneous plane.9 As the author mentions in his commentary, this appears to be protective against macroscopic fat embolism by preventing injury to the deep gluteal veins.2 However, the author seems to also suggest that the subcutaneous lipoinjection technique may protect from micro-FES as well; this point can be discussed. The author cites a review by Cardenas-Camarena et al4 to explain the pathogenesis of micro-FES. Although Garcia2 discusses thoroughly one of the mechanisms proposed by Cardenas-Camarena et al,4 he seems to omit pertinent details from his argument emphasized in that review.2,4 The commentary suggests that fat injected into highly vascularized areas, such as muscle, may allow for the absorption of smaller fat globules into small-caliber veins within the muscle itself; and thus argues that avoidance of highly vascularized areas such as muscle may prevent micro-FES. However, the significance of liquified fat entering the bloodstream is not highlighted, regardless of whether it is injected into the muscular or subcutaneous planes. Indeed, Camarena et al4 stress that in fact the biggest danger lies in the liquid phase of the aspirated fat, which is “the most irritating part of the material collected by means of liposuction, and is the most harmful if it enters the bloodstream.” 4 Cardenas-Camarena et al4 further add that “the answer to preventing microscopic fat embolism could lie in the liposuction bottles,” referring to the avoidance of injection of the upper liquified fat fractions, whether this is into the muscular or subcutaneous planes. As seen in one of the Garcia’s own publications discussing subcutaneous vascular integrity in areas of extensive liposuction,10 “contrast studies reveal that the vascular disruption caused by blunt tip cannulas takes place in the microvasculature connecting the perforating system to the subdermal plexus.” 10 Extensive lipoinjections into the subcutaneous plane may thus cause similar damage. Therefore, and according to the author’s own findings, it is clear that there exists a risk that liquified or microscopic fat injected within the subcutaneous plane may enter venous circulation and culminate in micro-FES. To ensure the highest safety standards, it is therefore critical to evaluate any available prophylactic measures at our disposal in addition to abiding by the ASERF recommendations.9 Cardenas-Camarena et al corroborate this point in the very review the author cites.2,4 By evaluating the available literature pertaining to the prophylactic efficacy of corticosteroids for the prevention of micro-FES, our paper was but an essential first step in this direction.1 In line with a previous meta-analysis in the orthopedic literature,11 the prophylactic efficacy of intravenous corticosteroids in the prevention of micro-FES incidence was established. The absence of clinical studies directly within the gluteal augmentation population is a call for more focused efforts in the plastic surgery research community, as emphasized in our paper. The author comments that patients deemed to be at high-risk for micro-FES warranting corticosteroid prophylaxis should avoid this surgery altogether, seemingly interpreting that a high-risk patient population must harbor marked comorbidities and surgical contraindications. Although we agree with the author on the point that any patient at high risk for complications due to surgical contraindications should avoid an elective surgery, we emphasize that healthy patients without medical comorbidities may remain at high risk for micro-FES. With societal beauty standards today favoring augmented breast and gluteal regions on an otherwise lean body type, high-risk patients in this context may be healthy women with limited fat reserves seeking gluteal augmentation through autologous fat grafts, or a “skinny Brazilian buttock lift.” Aggressive liposuction and fat processing may increase the risk of liquified fat delivery into the bloodstream, either from the aggressive liposuction process and fat processing, or from the delivery of lysed and compromised fat harvests. Avoiding this surgery in this large patient population would be unrealistic. Finally, the author reports being unaware of any deaths resulting directly from micro-FES alone.2 To continue raising awareness on this topic, we draw to the author’s attention the Bayter-Marin et al paper referenced in the commentary.12 This recent review of medical records and autopsy reports of 16 patients who had undergone gluteal augmentation with autologous fat grafts demonstrated that macroscopic fat emboli were identified in 10/16 patients examined, whereas all 16 patients exhibited microscopic fat emboli in their lungs. Six out of 16 patients had only microscopic fat emboli and appear to have died from micro-FES alone.12 The comprehensive literature review conducted by Cardenas-Camarena et al also identified five further reports of micro-FES following gluteal augmentation.4 We thank the author once again for his insightful comments and take this opportunity to encourage further endeavors on this subject, as we continue to work towards improving safety outcomes in our field. As plastic surgeons, it is a great pleasure to be able to have access to forums and conferences where such subjects can be debated. We are thrilled that this paper has stimulated discussion, and hope to see more clinical studies focusing on the gluteal augmentation population to further our progress on this subject. The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. The authors received no financial support for the research, authorship, and publication of this article.