“The armor phenomenon” in obese patients with penetrating thoracoabdominal injuries: A systematic review and meta-analysis

Abstract

BACKGROUND:Obesity represents a growing global health threat, which generally portends increased morbidity and mortality in the context of traumatic injuries. We hypothesized that there may exist a protective effect related to increased weight and truncal girth provided for obese patients in penetrating torso injuries, although this may not exert a significant positive impact overall upon clinical outcomes. METHODS:A comprehensive review of the literature was conducted across five databases up to March 2021 (Medline, Pubmed, Embase, Web of Science and the Cochrane library) to examine the effect of obesity on penetrating thoracoabdominal injuries. The primary outcome was to determine the rate of nonsignificant injury and injury patterns. Secondary outcomes examined were lengths of stay, complications, and mortality. Comparisons were drawn by meta-analysis. The study protocol was registered with PROSPERO under CRD42020216277. RESULTS:There were 2,952 publications assessed with 12 meeting the inclusion criteria for review. Nine studies were included for quantitative analysis, including 5,013 patients sustaining penetrating thoracoabdominal injuries, of which 29.6% were obese. Obese patients that sustained stab injuries underwent more nontherapeutic operations. Obese patients that sustained gunshot injuries had longer intensive care and total hospital length of stay. Obese patients suffered more respiratory complications and were at an increased risk of death during their admission. CONCLUSION:The "armor phenomenon" does not truly protect obese patients, a population that experiences increased morbidity and mortality following penetrating thoracoabdominal injuries.

Relationship of Obesity and Severe Penetrating Thoracic and Abdominal Injuries in Adolescent Patients

“…Some authors have proposed possible protective mechanisms of excess body mass, such as the "cushion effect," where abdominal fat functions as insulating tissue from blunt abdominal trauma 3 and the "armor phenomenon," where subcutaneous fat distribution limits the wound depth from a penetrating injury (ie, stab wound or gunshot wound). 4 Previous authors have investigated if obesity is truly associated with decreased injury severity and morbidity after trauma in the adult population with varied results. A higher body mass index (BMI) has been associated with a lower mortality 5,6 and injury severity score (ISS) 3 for adult blunt trauma patients, and a recent meta-analysis by Chen et al, concluded that an armor phenomenon may exist for adolescents with obesity that sustain thoracoabdominal stab injuries, but this may not lead to improved outcomes.…”

“…A higher body mass index (BMI) has been associated with a lower mortality 5,6 and injury severity score (ISS) 3 for adult blunt trauma patients, and a recent meta-analysis by Chen et al, concluded that an armor phenomenon may exist for adolescents with obesity that sustain thoracoabdominal stab injuries, but this may not lead to improved outcomes. 4 In fact, some studies have found that patients with obesity have a longer length of stay (LOS) in the intensive care unit (ICU) after trauma 7 and obesity is an independent risk factor for complications such as nosocomial infections, 8 prolonged mechanical ventilation, and postoperative pulmonary complications. 9 However, studies in the adolescent population evaluating the effect of obesity on injury after penetrating trauma are limited.…”

“…Some authors have proposed possible protective mechanisms of excess body mass, such as the “cushion effect,” where abdominal fat functions as insulating tissue from blunt abdominal trauma 3 and the “armor phenomenon,” where subcutaneous fat distribution limits the wound depth from a penetrating injury (ie, stab wound or gunshot wound). 4…”