The effect of obesity on outcomes in trauma patients: a meta-analysis

An evaluation of the "Obesity Paradox" in isolated blunt abdominal trauma in the United States

BACKGROUND

The obesity paradox theorizes a survival benefit in trauma patients secondary to the cushioning effect of adiposity. We aim to evaluate the impact of body mass index (BMI) on abdominal injury severity, morbidity, and mortality in adults with isolated, blunt abdominal trauma in the United States.

METHODS

We reviewed the National Trauma Data Bank (2013-2021) for adults sustaining isolated, blunt abdominal trauma stratified by BMI. We performed a doubly robust, augmented inverse-propensity weighted multivariable logistic regression to estimate the average treatment effect (ATE) of BMI on mortality and the presence of abdominal organ injury.

RESULTS

36,350 patients met the inclusion criteria. In our study, 41.4 % of patients were normal-weight (BMI 18.5-24.9), 20.6 % were obese (BMI 30-39.9), and 4.7 % were severely obese (BMI≥40). In these cohorts, the abdominal abbreviated injury scale (AIS) was 2 (2 -3). Obese and severely obese patients had significantly reduced presence of pancreas, spleen, liver, kidney, and small bowel injuries. The predicted probability of abdominal AIS severity decreased significantly with increasing BMI. Crude mortality was significantly higher in obese (1.3 %) and severely obese patients (1.3 %) compared to normal-weight patients (0.7 %). Obese and severely obese patients demonstrated non-statistically significant changes in the mortality of +26.4 % (ATE 0.264, 95 %CI -0.108-0.637, p = 0.164) and +55.5 % (ATE 0.555, 95 %CI -0.284-1.394, p = 0.195) respectively, compared to normal weight patients.

CONCLUSION

BMI may protect against abdominal injury in adults with isolated, blunt abdominal trauma. Mortality did not decrease in association with increasing BMI, as this may be offset by the increase in co-morbidities in this population.

Association of High BMI With Morbidity and Mortality in Common Emergency General Surgery Procedures

INTRODUCTION

Emergency general surgery (EGS) patients are at increased risk for postoperative morbidity and mortality. Obesity is a risk factor for poor outcomes in this population. Our study aimed to explore the association of body mass index (BMI) with postoperative outcomes in patients requiring common EGS procedures.

METHODS

A retrospective review of the 2018-2020 National Surgical Quality Improvement Program database identified patients undergoing four common EGS procedures: large bowel resection, small bowel resection, cholecystectomy, and appendectomy. Patients were classified by BMI: normal weight (18.5-24.9 kg/m2), obesity classes I (30-34.9 kg/m2), II (35-39.9 kg/m2), III (40-49.9 kg/m2), and IV (≥50 kg/m2). Main outcomes of interest were major adverse event (MAE) and mortality.

RESULTS

From 2018 to 2020, a total of 82,540 patients underwent one of four common EGS procedures. On unadjusted analysis, obesity class IV had higher mortality rates compared to classes I-III (6.2% vs 3.1%, P < 0.001). Patients in obesity classes I-III had lower odds of MAE and death relative to those of normal weight. Compared to other patients with obesity, those in obesity class IV were at increased risk of MAE (odds ratio 1.27; 95% confidence interval 1.13-1.44) and death (odds ratio 1.69; 95% confidence interval 1.34-2.13).

CONCLUSIONS

Patients with varying degrees of obesity have different risk profiles following common EGS procedures. While patients in lower obesity classes had reduced odds of adverse outcomes, those with BMI ≥50 kg/m2 were particularly at greater risk for postoperative morbidity and mortality. This vulnerable population warrants further investigation and increased vigilance to ensure high-quality care.

Predictors of Mortality in Extracorporeal Membrane Oxygenation Support Patients Following Major Trauma

INTRODUCTION

The usage of extracorporeal membrane oxygenation (ECMO) in trauma patients has increased significantly within the past decade. Despite increased research on ECMO application in trauma patients, there remains limited data on factors predicting morbidity and mortality outcome. Therefore, the primary objective of this study is to describe patient characteristics that are independently associated with mortality in ECMO therapy in trauma patients, to further guide future research.

METHODS

This retrospective study was conducted using the Trauma Quality Improvement Program database from 2010 to 2019. All adult (age ≥ 16 y) trauma patients that utilized ECMO were included. A Significant differences (P < 0.05) in demographic and clinical characteristics between groups were calculated using an independent t-test for normal distributed continuous values, a Mann-Whitney U test for non-normal distributed values, and a Pearson chi-square test for categorical values. A multivariable regression model was used to identify independent predictors for mortality. A survival flow chart was constructed by using the strongest predictive value for mortality and using the optimal cut-off point calculated by the Youden index.

RESULTS

Five hundred forty-two patients were included of whom 205 died. Multivariable analysis demonstrated that the female gender, ECMO within 4 h after presentation, a decreased Glasgow Coma Scale, increased age, units of blood in the first 4 h, and abbreviated injury score for external injuries were independently associated with mortality in ECMO trauma patients. It was found that an external abbreviated injury score of ≥3 had the strongest predictive value for mortality, as patients with this criterion had an overall 29.5% increased risk of death.

CONCLUSIONS

There is an ongoing increasing trend in the usage of ECMO in trauma patients. This study has identified multiple factors that are individually associated with mortality. However, more research must be done on the association between mortality and noninjury characteristics like Pao2/Fio2 ratio, acute respiratory distress syndrome classification, etc. that reflect the internal state of the patient.

The association of radiologic body composition parameters with clinical outcomes in level-1 trauma patients

PURPOSE

The present study aims to assess whether CT-derived muscle mass, muscle density, and visceral fat mass are associated with in-hospital complications and clinical outcome in level-1 trauma patients.

METHODS

A retrospective cohort study was conducted on adult patients admitted to the University Medical Center Utrecht following a trauma between January 1 and December 31, 2017. Trauma patients aged 16 years or older without severe neurological injuries, who underwent a CT that included the abdomen within 7 days of admission, were included. An artificial intelligence (AI) algorithm was used to retrieve muscle areas to calculate the psoas muscle index and to retrieve psoas muscle radiation attenuation and visceral fat (VF) area from axial CT images. Multivariable logistic and linear regression analyses were performed to assess associations between body composition parameters and outcomes.

RESULTS

A total of 404 patients were included for analysis. The median age was 49 years (interquartile range [IQR] 30-64), and 66.6% were male. Severe comorbidities (ASA 3-4) were seen in 10.9%, and the median ISS was 9 (IQR 5-14). Psoas muscle index was not independently associated with complications, but it was associated with ICU admission (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.65-0.95), and an unfavorable Glasgow Outcome Scale (GOS) score at discharge (OR 0.62, 95% CI 0.45-0.85). Psoas muscle radiation attenuation was independently associated with the development of any complication (OR 0.60, 95% CI 0.42-0.85), pneumonia (OR 0.63, 95% CI 0.41-0.96), and delirium (OR 0.49, 95% CI 0.28-0.87). VF was associated with developing a delirium (OR 1.95, 95% CI 1.12-3.41).

CONCLUSION

In level-1 trauma patients without severe neurological injuries, automatically derived body composition parameters are able to independently predict an increased risk of specific complications and other poor outcomes.

Body mass index is not associated with time on veno-venous extracorporeal membrane oxygenation or in-hospital mortality

Morbid obesity, as characterized by BMI, is often utilized as an exclusion criterion for VV-ECMO because of presumed poor prognosis and technically complex cannulation. However, the "obesity paradox" suggests obesity may be protective during critical illness, and BMI does not capture variations in body type, adiposity, or fluid balance. This study examines relationships between BMI and patient outcomes. Adult VV-ECMO patients with BMI ≥ 35 kg/m2 admitted January 2012 to June 2021 were identified from an institutional registry. BMI and outcomes were analyzed with Mann-Whitney U tests and Pearson correlations with Bayesian post-hoc analyses. 116 of 960 ECMO patients met inclusion criteria. Median (Q1, Q3) BMI was 42.3 (37.3, 50.8) and min, max of 35.0, 87.8 with 9.0 (5.0, 15.5) ECMO days. BMI was not significantly correlated with ECMO days (r = -0.102; p = .279). Bayesian analyses showed moderate evidence against BMI correlating with ECMO days. In-hospital mortality (27%) was significantly associated with ECMO days (p = .014) but not BMI (p = .485). In this cohort of high-BMI patients, BMI was not associated with survival or time on ECMO. BMI itself should not be used as an exclusion criterion for VV-ECMO.

Intraoperative Complications During Orthopaedic Spinal Surgery in a Polypharmacy Patient With Multiple Comorbidities

Orthopedic spinal surgeries, such as laminectomies or decompressions, have the potential to significantly increase quality of life for patients suffering from a spectrum of health issues ranging from neuropathy to chronic pain. Patients suffering from neurological symptoms such as weakness or neuropathy may lose significant function and become unable to perform the activities of daily living, however these delicate surgical interventions also come with significant risks to the health and well-being of those same patients. This is especially true with patients who have predisposing health conditions. Here, we discuss the effects of surgery on a patient with severe obesity, multiple confounding pre-existing conditions, and significant polypharmacy. An initially unremarkable spinal laminectomy and decompression surgery resulted in severe intraoperative complications that necessitated direct admission to the intensive care unit for significant post-operative management before he was able to be discharged safely. Although not a case of incredible rarity, we hope it can contribute to the growing body of data about the role of predisposing health conditions and polypharmacy in calculating and understanding the risks of orthopaedic surgery.

Blood Count-Derived Inflammatory Markers Correlate with Lengthier Hospital Stay and Are Predictors of Pneumothorax Risk in Thoracic Trauma Patients

(1) Background: Trauma is one of the leading causes of death worldwide, with the chest being the third most frequent body part injured after abdominal and head trauma. Identifying and predicting injuries related to the trauma mechanism is the initial step in managing significant thoracic trauma. The purpose of this study is to assess the predictive capabilities of blood count-derived inflammatory markers at admission. (2) Materials and Methods: The current study was designed as an observational, analytical, retrospective cohort study. It included all patients over the age of 18 diagnosed with thoracic trauma, confirmed with a CT scan, and admitted to the Clinical Emergency Hospital of Targu Mureş, Romania. (3) Results: The occurrence of posttraumatic pneumothorax is highly linked to age (p = 0.002), tobacco use (p = 0.01), and obesity (p = 0.01). Furthermore, high values of all hematological ratios, such as the NLR, MLR, PLR, SII, SIRI, and AISI, are directly associated with the occurrence of pneumothorax (p < 0.001). Furthermore, increased values of the NLR, SII, SIRI, and AISI at admission predict a lengthier hospitalization (p = 0.003). (4) Conclusions: Increased neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), aggregate inflammatory systemic index (AISI), and systemic inflammatory response index (SIRI) levels at admission highly predict the occurrence of pneumothorax, according to our data.

Obesity and outcomes in trauma - a systematic review and meta-analysis

BACKGROUND

The physiological abnormalities relating to obesity and metabolic syndrome can contribute to worse outcomes following trauma especially in class 2 and 3 obesity. The aim of this systematic review was to determine whether patients with a higher class of obesity who suffer traumatic injury have a higher risk of worse outcomes including in-hospital mortality than normal-weight patients.

METHODS

A systematic search of MEDLINE, EMBASE, CENTRAL, Web of Science and CINAHL was performed for studies that reported a comparison of in-hospital obesity-related outcomes against normal-weight individuals aged 15 years and older following trauma. Single or multiple injuries from either blunt and/or penetrating trauma were included. Burn-related injuries, isolated head injury and studies focusing on orthopaedic related perioperative complications were excluded.

RESULTS

The search yielded 7405 articles; 26 were included in this systematic review. 945,511 patients had a BMI>30. A random-effects meta-analysis was performed for analysis of all four outcomes. Patients with class 3 obesity (BMI>40) have significantly higher odds of in-hospital mortality than normal-BMI individuals following blunt and penetrating trauma (OR, 1.75; 95% CI, 1.39-2.19, p=<0.00001), significantly longer hospital LOS (SMD, 0.23; 95% CI, 0.21-0.25; p<0.00001) and significantly longer ICU LOS (SMD, 0.19; 95% CI, 0.12-0.26; p<0.0001). In contrast, studies that examined blunt and penetrating trauma and classified obesity with a threshold of BMI>30 found no significant difference in the odds of in-hospital mortality (OR, 0.94; 95% CI, 0.86-1.02, p=0.13).

CONCLUSIONS

There is a higher risk of in-hospital mortality in patients living with class 3 obesity following trauma when compared with individuals with normal BMI. The management of patients with obesity is complex and trauma systems should develop specific weight related pathways to manage and anticipate the complications that arise in these patients. Systematic review registration number PROSPERO registration: CRD42021234482 Level of Evidence: Level 3.

Outcomes of the overweight and obese major trauma patient in the rural setting

PURPOSE

Overweight and obese patients are more prevalent in rural and remote areas and are of major public health concern in Australia. We aimed to evaluate the mortality and morbidity of overweight and obese trauma patients in the rural Australian context.

METHOD

This was a retrospective cohort study on 207 major trauma patients (injury severity score [ISS] > 12) treated at the Mackay Base Hospital between 2018 and 2021. Data was extracted from the Mackay Base Hospital trauma database and hospital records. Outcomes were compared between body mass index (BMI) groups.

RESULTS

There were 164 males (79%) and 43 females (21%). The average BMI was 27.09 (standard deviation 5.46). 7 patients (3%) were in the underweight category (BMI < 18.5 kg/m²), 70 (34%) were of normal weight (BMI 18.5-24.9 kg/m²), 79 (38%) were overweight (BMI 25-29.9 kg/m²), and 51 (25%) were obese (BMI > 30 kg/m²). The majority of trauma was blunt (n = 203, 98%). Compared to patients with normal BMI, obese patients were significantly more likely to require intubation, intensive care unit (ICU) admission, and have a longer ICU stay. There were no significant differences in requirement for surgery, duration of surgery, hospital length of stay, ventilator time, or mortality (P > 0.05). However, subgroup analysis of the obese patient group showed an increased rate of complications (sepsis, acute kidney injury, fluid overload and pneumonia), longer ventilation times, hospital and ICU length of stay with increasing BMI in these patients.

CONCLUSION

The majority of trauma presentations in our regional community are in overweight or obese patients. Overweight and obese patients are more likely to require intubation and have a longer intensive care unit admission than normal weight counterparts. Amongst obese patients, those with BMI > 40 (obesity class 3) are at significantly increased risk of complications.

The Rate of Postoperative Mortality and Renal and Respiratory Complications are Increased in Patients with Extreme Obesity Undergoing Cardiac Surgery - A Retrospective Observational Cohort Study of 8848 Patients

Introduction

The importance of obesity as a potential risk factor in open heart surgery is well known. The epidemic of extreme obesity is an increasing public health concern and raises alerts regarding postoperative complications and mortality in patients undergoing cardiac surgery. The study aimed to analyze the impact of extreme obesity (BMI≥40) on the frequency of postoperative complications, as well as early and delayed mortality compared to patients with a lower body mass.

Materials and Methodology

This retrospective observational cohort study involved patients, over the age of 18, undergoing cardiac surgery with cardiopulmonary bypass at the Cardiac Surgery Department of the Pomeranian Medical University in Szczecin, Poland between January 1st, 2010 and December 31st, 2018. The patients included in the study were allocated into two subgroups depending on the BMI index (Group I BMI≥40 vs Group II BMI<40).

Results

A total of 8848 adult patients of both genders were included. Baseline characteristics for Group I and Group II were mean age 64.07±7.76 vs 65.10±9.68 years (p=0.123), mean BMI 42.13±2.44 vs 28.55±4.23 (p<0.001), with more females in Group I (58.04% vs 29.06%) and more males in Group II (70.94% vs 29.06%), p<0.001. The predicted perioperative risk using the EuroScore Logistics scale was higher in a group with BMI≥40 (p<0.001). Regression analysis with adjustment for confounding factors showed a statistically significant relationship between BMI≥40 and postoperative respiratory failure (OR=1.760, p=0.043), acute kidney injury AKIN2 (OR=2.082, p=0.044) and AKIN3 (OR=2.743, p=0.039). 30-day mortality in the univariate analysis showed a statistically significant relationship, however, after modifying the results with interfering factors, no statistical significance was obtained.

Conclusion

The risk of postoperative acute respiratory failure and acute renal injury was increased in patients with BMI≥40. The probability of 30-day survival of patients after cardiac surgery was much lower in people with extreme obesity, although it was related to the dominant comorbidities. The 10-year survival was comparable in both groups.

Surgical Rib Fixation in Obese Patients with Isolated Flail Chest Improves Outcomes: A Matched Cohort Study

BACKGROUND

Obesity is associated with adverse outcomes after major operations. The role of operative rib fixation (RF) in obese patients with flail chest is not clear. The presence of other associated injuries may complicate the interpretation of outcomes. This study compared outcomes after RF to nonoperative management (NOM) in obese patients with isolated flail chest injury.

METHODS

Adult obese patients (BMI > 29.9) with flail chest were identified from the Trauma Quality Improvement Program (TQIP) database (2016-2018). Hospital transfers, death within 72 h, and extrathoracic injuries were excluded. RF patients were propensity score matched (1:2) to similar NOM patients. Multivariate regression identified independent factors predicting adverse outcomes.

RESULTS

Overall, 367 patients with isolated flail chest who underwent RF were matched with 734 in the NOM group. After matching, the mortality rate was significantly lower in the RF group (1.4% vs. 3.7%; p < 0.05). RF had longer HLOS (15.7 days vs. 12.8 days; p < 0.05) and ICU LOS (10.1 days vs. 8.6 days; p < 0.05), shorter ventilator days (9.2 days vs. 11.5 days; p < 0.05), and a higher rate of venous thromboembolism (7.1% vs. 3.5%, p < 0.05). On multivariate analysis, RF was associated with decreased mortality (OR 0.27; p < 0.05). Early RF (≤ 72 h) was associated with shorter ICU stay and mechanical ventilation.

CONCLUSION

RF for isolated flail chest in obese patients is associated with decreased mortality and fewer ventilator days. When performed early, fixation decreases the need for prolonged ventilator use and ICU stay. A more aggressive VTE prophylaxis should be considered in patients undergoing RF.

Protective Role of Obesity on Trauma Impact: A Retrospective Analysis of Patients with Surgical Blunt Bowel Mesenteric Injury Due to Road Traffic Accidents

Background

The "cushion effect" theory proposes that increased body mass index (BMI) is associated with less severe abdomen injury following blunt abdomen trauma, while the "obesity paradox" describes the protective effect of obesity against mortality. However, most previous studies used the abdominal abbreviated injury scale as the outcomes seemed to be inadequate owing to the injuries to the abdominal organs, such as the spleen and liver, which may be attributable to the force that caused the chest trauma. This study aimed to use adult trauma patients with surgical blunt bowel mesenteric injuries (BBMIs) to investigate the influence of obesity on the clinical outcomes and overall morbidities.

Methods

This retrospective study reviewed the data of all hospitalized trauma patients between 2009 and 2019 and included all patients with surgically proven small bowel, colon, or mesenteric injuries due to a road traffic accident. Comparison of the outcomes was performed among 123 patients with surgically proven BBMI, who were categorized by BMI into the normal-weight (n = 73, BMI<25 kg/m²), overweight (n = 37, 25≤BMI≤30 kg/m²), and obese groups (n = 13, BMI>30 kg/m²).

Results

The obese group had a significantly lower incidence of isolated bowel injury (0%) compared with the normal-weight (35.6%) and overweight (16.2%) groups (p=0.005), but with higher incidence of isolated mesenteric injury or combined injury, although this was not significant. The obese group (92.3%) had a significantly higher percentage of overall morbidity than the normal-weight (61.6%) and overweight (70.3%) groups (p = 0.047). No significant difference was observed in the in-hospital mortality and 24-hour mortality among the three study groups.

Conclusion

The study findings do not support the existence of a cushion effect and obesity paradox of obesity in blunt abdominal trauma.

The impact of obesity on polytraumatized patients with operatively treated fractures

INTRODUCTION

The objective of this study was to evaluate the effect of obesity on outcomes following operative treatment of fractures in obese polytrauma patients.

METHODS

This was a prospective cohort study at a level I trauma centre from January 2014 until December 2017. The eligibility criteria were adult (age >= 18 years) polytrauma patients who presented with at least one orthopaedic fracture that required operative fixation. Polytrauma was defined as having an Injury Severity Score (ISS) >= 16. Out of 891 patients, a total of 337 were included with 85 being obese. The primary outcome variable was the total hospital length of stay in days. The secondary outcome variables were the number of patients who had an intensive care unit (ICU) admission, the ICU length of stay in days, the number of patients who had mechanical ventilation, the duration of mechanical ventilation in days, perioperative complications, and mortality.

RESULTS

Obesity was associated with increased total hospital stay (36 vs. 27 days; P<0.001), increased ICU stay (13 vs. 8 days; P = 0.04), increased ICU admissions (83.5% vs. 68.6%; P = 0.008) and increased incidence of mechanical ventilation (64.7% vs. 43.7%; P = 0.001). These findings remained statistically significant following adjusted regression models for age, gender, ISS, and injuries sustained. However, the mechanical ventilation duration was not significantly different between both groups on adjusted and unadjusted analyses. However, an increase per unit BMI significantly increases the duration of mechanical ventilation (P = 0.02). In terms of complications, obesity was only associated with an increase in acute renal failure (ARF) on unadjusted analyses (P = 0.004). Whereas, adjusted logistic regression demonstrated that an increase per BMI unit led to a significant increase in the odds ratio for wound infection (P = 0.03) and ARF (P = 0.024).

CONCLUSIONS

This study displayed that obesity was detrimental to polytrauma patients with operatively treated fractures leading to prolonged hospital and ICU length of stay. This highlights the importance of optimizing trauma care for obese polytraumatized patients to reduce morbidity. With 41.1% of our population being obese, obesity presents a unique challenge in the care of polytrauma patients which mandates further research in improving health care for this population group.

Outcomes in Obese vs Non-Obese Injured Patients at a Level 1 Trauma Center and Bariatric Surgery Center of Excellence

BACKGROUND

We hypothesized that the outcomes of trauma patients with a body mass index (BMI) equal to or greater than 30 compared to patients with BMI less than 30 would not differ at a level 1 trauma center that is also a Metabolic and Bariatric Surgery Center of Excellence in the Metabolic and Bariatric Surgery Accreditation Quality Improvement Program (MBSAQIP).

STUDY DESIGN

Patients equal to and greater than 18 years old treated between 1/1/2018 and 12/31/2020 were included. Demographics, BMI, comorbidities, and outcomes (hospital-LOS, ICU-LOS, blood products used, and mortality) were compared between 2 groups: obese (BMI ≥30) vs non-obese (BMI <30).

RESULTS

Of the 4192 patients identified, 3821 met the inclusion criteria; 3019 patients had a BMI <30, and 802 had a BMI ≥30. There was a statistically significant difference between the 2 groups with respect to gender (females: 57% vs 47%, P < .0001) and age (median: 80 [IQR: 63-88] vs 69 [IQR: 55-81], P < .0001). When adjusted for age, sex, DM, dementia, ISS, and ICU admission, there was no statistically significant difference in hospital-LOS (4.30 [95% CI: 4.10, 4.52] vs 4.48 [95% CI: 4.18, 4.79]) or mortality. No statistical differences were seen between the 2 groups in blood product use.

CONCLUSIONS

Obesity did not correlate with poorer outcomes at an ACS-verified level 1 Trauma Center and Bariatric Surgery Center of Excellence. Further studies are needed to determine whether outcomes vary at hospitals without both designations.

Association Between Body Mass Index and Morbidity and Mortality During Hospitalization After Trauma

BACKGROUND

Literature suggests that unhealthy body mass index is a risk factor for adverse clinical outcomes.

OBJECTIVES

To study the association between unhealthy body mass index and morbidity and mortality after trauma using the 2016 American College of Surgeons Trauma Quality Improvement Program database.

METHODS

A retrospective review was conducted comparing the normal weight control group to the underweight, overweight, obese, severely obese, and morbidly obese groups for differences in demographic factors, injury severity score, comorbidities, length of stay, and complications.

RESULTS

Underweight, overweight, obese, severely obese, and morbidly obese body mass indexes, in comparison to normal weight body mass index, were associated with a higher probability of developing at least one complication after trauma. Additionally, we observed a J-shaped curve when analyzing body mass index and mortality, suggesting that both high and low body mass indexes are positively associated with mortality. In fact, morbidly obese patients had the highest mortality rate, followed by underweight patients (p < .001). Interestingly, however, multivariate logistic regression demonstrated that, compared with normal weight body mass index, overweight and obese body mass indexes were independently associated with 9.6% and 10.5% lower odds of mortality, respectively (p < .001 and p = .001).

CONCLUSION

Irrespective of preexisting comorbidities, injury severity score, and mechanism of injury, underweight, overweight, obese, severely obese, and morbidly obese body mass indexes were independently associated with higher risks of morbidity, whereas overweight and obese body mass indexes were associated with lower mortality risks. These findings emphasize the complex relationship between body mass index and clinical outcomes for trauma patients.

'The Armor Phenomenon' in Obese Patients with Penetrating Thoracoabdominal Injuries: A Systematic Review and Meta-Analysis

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 non-significant 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

2,952 publications were assessed with twelve 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 non-therapeutic 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.

LEVEL OF EVIDENCE

Systematic Review and Meta-Analysis, prognostic Level III.

Burn Outcomes at Extremes of Body Mass Index- Underweight is as problematic as Morbid Obesity

Limited evidence suggests that obesity adversely affects burn outcomes. However, the impacts of body mass index (BMI) across the continuum has not been fully characterized. Therefore, we aimed to characterize outcomes after burn injury across the BMI continuum. We hypothesized that 'normal' BMI (18.5-24.9) would have the lowest mortality and complication rates. The US National Trauma Data Bank (NTDB) was queried for adult burn-injured patients from 2007-2015. Admission BMI was calculated and grouped according to World Health Organization (WHO) classification. The primary outcome was in-hospital mortality. Secondary outcomes of time to wound closure, length of stay (LOS), and inpatient complications were similarly assessed. Of the 116,008 burn patient encounters that were identified, 7,243 underwent at least one operation for wound closure. Mortality was lowest in the overweight (p=0.039) and obese I cohorts (BMI 25-29.9, 30.0-34.9) at 2.9% and increased in both directions of the BMI continuum to 4.1% in the underweight (p=0.032) and 5.1% in the morbidly obese (class III) group (p=0.042). Time to final wound closure was longest in the two BMI extremes. BMI >40 was associated with increased ICU days, ventilator days, renal and cardiac complications. BMI <18.5 had increased hospital days and rates of sepsis. Aberrations in metabolism associated with both increases and decreases of body weight may cause pathophysiologic changes that lead to worsened outcomes in burn-injured patients. In addition to morbidly obese patients, underweight patients also experience increased burn-related death and complications. In contrast, overweight BMI patients may have greater physiologic reserves without the burden of obesity or sarcopenia.

The impact of obesity on surgical outcomes in patients undergoing emergency laparotomy for high-risk abdominal emergencies

BACKGROUND

Obesity has been shown to increase the rates of morbidity and occasionally mortality in patients undergoing nonbariatric elective surgery. However, little is known about the impact of obesity on outcomes after surgery for high-risk abdominal emergencies.

METHODS

A single-center retrospective evaluation of outcomes in high-risk abdominal emergency patients categorized by body mass index (BMI) was conducted. Patient demographics, comorbidities, and operative details were analyzed. Patients with normal weight (BMI 18.5-24.9) served as comparators. Multivariable linear and logistic regression analyses were performed to assess the impact of obesity on surgical outcomes.

RESULTS

In total, 886 patients with BMI < 18.5 (underweight; n = 50), 18.5-24.9 (normal weight; n = 306), 25-29.9 (overweight; n = 336) and ≥ 30 (obese; n = 194) based on the World Health Organization (WHO) weight classification criteria met the inclusion criteria. Compared to normal-weight patients, patients with overweight and obesity were older and more likely to be male. The rates of comorbidity (100% vs 91.2%, p =  < 0.0001), morbidity (77.8% vs 65.6%, p = 0.003), and in-hospital mortality (44.8% vs 30.4%, p = 0.001) were all higher in patients with obesity than in normal-weight patients. Patients with obesity had an increased intensive care unit length of stay (ICU LOS) (13 days vs 9 days, p = 0.019) and hospital LOS (21.4 days vs 18.1 days, p = 0.081) and prolonged ventilation (39.1% vs 19.6%, p = 0.003). As BMI deviated from the normal range, the morbidity and mortality rates increased incrementally, with the highest morbidity (87.9%) and mortality (54.5%) rates observed in morbidly obese patients (BMI ≥ 40).

CONCLUSIONS

Patients with obesity were the most likely to have coexisting conditions, experience postoperative complications, and die during the first admission following EL for high-risk abdominal emergencies.

A trauma-related survival predictive model of acute respiratory distress syndrome

Purpose

The purpose of this study was to construct and validate a simple model for the prediction of survival in patients with trauma‐related ARDS.

Methods

This is a single‐center, retrospective cohort study using MIMIC‐III Clinical Database.

Results

842 patients were included in this study. 175 (20.8%) died in‐hospital, whereas 215 (25.5%) died within 90 days. The deceased group had higher Acute Physiology Score (APS III), Sequential Organ Failure Assessment (SOFA), and Simplified Acute Physiology Score II (SAPS II). In multivariate logistic regression model, independent risk factors for mortality in ARDS patients included age ([odds ratio] OR, 1.035; 95% confidence interval [CI], 1.020–1.049), body mass index (OR, 0.957; 95% CI, 0.926–0.989), red blood cell distribution width (OR, 1.283; 95% CI, 1.141–1.443), hematocrit (OR, 1.055; 95% CI, 1.017–1.095), lactate (OR, 1.226; 95% CI, 1.127–1.334), blood urea nitrogen (OR, 1.025; 95% CI, 1.007–1.044), acute kidney failure (OR, 1.875; 95% CI, 1.188–2.959), sepsis (OR, 1.917; 95% CI, 1.165–3.153), type of admission (emergency vs. elective [OR, 2.822; 95% CI, 1.647–4.837], and urgent vs. elective [OR, 5.156; 95% CI, 1.896–14.027]). The area under the curve (AUC) of the model was 0.826, which was superior than the SAPS II (0.776), APS III (0.718), and SOFA (0.692). In the cross‐validation model, the accuracy of the test set was 0.823, the precision was 0.643, and the AUC was 0.813.

Conclusions

We established a prediction model using data commonly used in the clinic, which has high accuracy and precision and is worthy of use in clinical practice.

The Impact of Obesity on Renal Trauma Outcome: An Analysis of the National Trauma Data Bank from 2013 to 2016

BACKGROUND

The obesity paradox has been recently demonstrated in trauma patients, where improved survival was associated with overweight and obese patients compared to patients with normal weight, despite increased morbidity. Little is known whether this effect is mediated by lower injury severity. We aim to explore the association between body mass index (BMI) and renal trauma injury grade, morbidity, and in-hospital mortality.

METHODS

A retrospective cohort of adults with renal trauma was conducted using 2013-2016 National Trauma Data Bank. Multiple regression analyses were used to assess outcomes of interest across BMI categories with normal weight as reference, while adjusting for relevant covariates including kidney injury grade.

RESULTS

We analyzed 15181 renal injuries. Increasing BMI above normal progressively decreased the risk of high-grade renal trauma (HGRT). Subgroup analysis showed that this relationship was maintained in blunt injury, but there was no association in penetrating injury. Overweight (OR 1.02, CI 0.83-1.25, p = 0.841), class I (OR 0.92, CI 0.71-1.19, p = 0.524), and class II (OR 1.38, CI 0.99-1.91, p = 0.053) obesity were not protective against mortality, whereas class III obesity (OR 1.46, CI 1.03-2.06, p = 0.034) increased mortality odds. Increasing BMI by category was associated with a stepwise increase in odds of acute kidney injury, cardiovascular events, total hospital length of stay (LOS), intensive care unit LOS, and ventilator days.

CONCLUSIONS

Increasing BMI was associated with decreased risk of HGRT in blunt trauma. Overweight and obesity were associated with increased morbidity but not with a protective effect on mortality. The obesity paradox does not exist in kidney trauma when injury grade is accounted for.

Image-based assessment of sarcopenic obesity predicts mortality in major trauma

BACKGROUND

Patients with obesity are also at risk for sarcopenia, which is difficult to recognize in this population. Our study examines whether sarcopenic-obesity (SO) is independently associated with mortality in trauma.

METHODS

Using a retrospective database, we performed logistic regression analysis. . Admission CT scans were used to identify SO by calculating the visceral fat to skeletal muscle ratio >3.2.

RESULTS

Of 883 patients, the prevalence of SO was 38% (333). Patients with SO were more likely to be male (79% versus 43%, p < 0.001), older (mean 66.5 years versus 46.3 years, p < 0.001), and less likely to have an injury severity score (ISS) ≥ 24 (43% versus 55%, p = 0.0003). Using multivariable logistic regression analysis, SO was independently associated with mortality (OR 2.8; 95% CI 1.6-4.8, p < 0.001). Causal mediation analysis found admission hyperglycemia as a mediator for mortality.

CONCLUSIONS

Sarcopenic obesity is an independent predictor of mortality in major trauma.

Association of Body Mass Index on Injuries and Outcomes After Ground-Level Falls

BACKGROUND

The impact of body mass index (BMI) on trauma severity after ground-level falls (GLF) is currently unclear. This study aimed to examine the associations between BMI, injuries, and outcomes after GLF.

STUDY DESIGN

All patients ≥16 years of age injured by GLF were queried from the TQIP database (2013-2017). Exclusions were transfers, emergency department death, AIS 6 in any region, and missing data. Body mass index defined study groups: Underweight (BMI<18.5), Normal (BMI 18.5-24.9), Overweight (25.0-29.9), and Obese (≥30).

RESULTS

After exclusions, 131 570 patients remained for analysis. Most patients had a normal BMI (n = 58 503, 44%). Median ISS was 9 [IQR 9-10] in all groups. The Obese group had significantly lower rates of fractures than the Normal group, particularly femur fractures (53% vs. 64%, P < .001), but required orthopedic surgical intervention more frequently (45% vs. 41%, P < .001). On multivariate analysis, being overweight was protective against mortality (OR .881, P = .005), while obesity was not associated with mortality (OR 1.012, P = .821).

CONCLUSION

Increasing BMI may be protective against both fracture risk and mortality after GLF. However, obese patients require operative fixation more frequently. Particularly as fracture diagnosis may be more challenging in the obese, special care should be taken during their tertiary surveys after GLF to ensure injuries are not missed.

Isolated severe blunt traumatic brain injury: effect of obesity on outcomes

OBJECTIVE

Obesity has been widely reported to confer significant morbidity and mortality in both medical and surgical patients. However, contemporary data indicate that obesity may confer protection after both critical illness and certain types of major surgery. The authors hypothesized that this "obesity paradox" may apply to patients with isolated severe blunt traumatic brain injuries (TBIs).

METHODS

The Trauma Quality Improvement Program (TQIP) database was queried for patients with isolated severe blunt TBI (head Abbreviated Injury Scale [AIS] score 3-5, all other body areas AIS < 3). Patient data were divided based on WHO classification levels for BMI: underweight (< 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), obesity class 1 (30.0-34.9 kg/m2), obesity class 2 (35.0-39.9 kg/m2), and obesity class 3 (≥ 40.0 kg/m2). The role of BMI in patient outcomes was assessed using regression models.

RESULTS

In total, 103,280 patients were identified with isolated severe blunt TBI. Data were excluded for patients aged < 20 or > 89 years or with BMI < 10 or > 55 kg/m2 and for patients who were transferred from another treatment center or who showed no signs of life upon presentation, leaving data from 38,446 patients for analysis. Obesity was not found to confer a survival advantage on univariate analysis. On multivariate analysis, underweight patients as well as obesity class 1 and 3 patients had a higher rate of mortality (OR 1.86, 95% CI 1.48-2.34; OR 1.18, 95% CI 1.01-1.37; and OR 1.41, 95% CI 1.03-1.93, respectively). Increased obesity class was associated with an increased risk of respiratory complications (obesity class 1: OR 1.19, 95% CI 1.03-1.37; obesity class 2: OR 1.30, 95% CI 1.05-1.62; obesity class 3: OR 1.55, 95% CI 1.18-2.05) and thromboembolic complications (overweight: OR 1.43, 95% CI 1.16-1.76; obesity class 1: OR 1.45, 95% CI 1.11-1.88; obesity class 2: OR 1.55, 95% CI 1.05-2.29) despite a decreased risk of overall complications (obesity class 2: OR 0.82, 95% CI 0.73-0.92; obesity class 3: OR 0.83, 95% CI 0.72-0.97). Underweight patients had a significantly increased risk of overall complications (OR 1.39, 95% CI 1.24-1.57).

CONCLUSIONS

Although there was an obesity-associated decrease in overall complications, the study data did not demonstrate a paradoxical protective effect of obesity on mortality after isolated severe blunt TBI. Obese patients with isolated severe blunt TBI are at increased risk of respiratory and venous thromboembolic complications. However, underweight patients appear to be at highest risk after severe blunt TBI, with significantly increased risks of morbidity and mortality.

The effect of perturbations of the glycocalyx on microvascular perfusion in the obese trauma population: an in vitro study

Objectives

Patients with morbid obesity have impaired responses to resuscitation following severe injury, which may contribute to adverse outcomes. Obesity is associated with microvascular dysfunction and metabolic changes associated with altered hemorheological profiles. These include decreased red blood cell (RBC) deformity associated with increased aggregation and adhesion. These RBC changes may be impacted by the glycocalyx layer of the endothelial cell (EC) and RBC. Degradation of either or both glycocalyx layers may impair microvascular perfusion. This was studied from blood obtained from patients with obesity and in an in vitro microfluidic device to mimic the microvascular environment.

Methods

RBCs were obtained from fresh whole blood from normal controls and patients with obesity (body mass index 37.6–60.0). RBC glycocalyx was indexed by fluorescent intensity and shedding of EC glycocalyx components into the serum was determined by measurement of syndecan-1 and hyaluronic acid. In a second set of experiments, human umbilical vein endothelial cell monolayers (HUVEC) were perfused with RBC suspensions from control and patients with obesity using a microfluidic device and RBC adherence under normoxic or shock conditions (hypoxia+epinephrine) was determined using confocal microscopy. HUVEC glycocalyx thickness and shedding were also measured.

Results

Microfluidic studies demonstrated that RBC obtained from subjects with obesity had increased adhesion to the endothelial layer, which was more profound under shock conditions versus normal subjects. This appeared to be related to increased shedding of the endothelial glycocalyx following shock as well as a diminished RBC glycocalyx layer in the obese population.

Conclusion

Blood from patients with obesity have decreased RBC glycocalyx thickness accompanied by evidence of increased EC glycocalyx shedding. In vitro adhesion to the endothelium was more pronounced with RBC from patients with obesity and was significantly greater under ‘shock conditions’. Hemorheological properties of RBC from patients with obesity may account for failure of standard resuscitation procedures in the trauma patient.

Level of evidence

Increasing BMI is associated with higher mortality, worsening outcomes and highly specific injury patterns following trauma: A multi-institutional analysis of 191,274 patients

BACKGROUND

As the prevalence of obesity has increased, trauma centers are faced with managing this expanding demographics' unique care requirements. Research on the effects of body mass index (BMI) in trauma patients remains conflicting. This study aims to evaluate the impact of BMI on patterns of injury and patient outcomes following trauma.

METHODS

Patients from 87 hospitals' trauma registries were selected. Those missing height, weight, disposition, or who died in the emergency department were excluded. The BMI categories were calculated from admission height and weight and verified against the electronic medical records. Patients were grouped by the National Institutes of Health-defined obesity class and compared by rate of mortality and in-hospital complications. Logistic regression was used to estimate associations, adjusting for age, gender, race, Injury Severity Score, and number of comorbidities.

RESULTS

There were 191,274 patients, 53% male; mean age was 60.4 years, mean Glasgow Coma Scale score 14.4, mean Injury Severity Score of 8.8, and 40.4% normal weight. Increased BMI was associated with an injury pattern of increased rates of extremity fractures (humerus, femur, tibia/fibula) and decreased rates of hip fractures and head injuries. Compared with the normal weight group, patients were more likely to die if they were Underweight (adjusted odds ratio [AOR], 1.18; 95% confidence interval [CI], 1.01-1.38), obese class II (AOR, 1.24; 95% CI, 1.07-1.45), or obese class III (AOR, 1.55; 95% CI, 1.29-1.87). Obese class III was associated with higher odds of a National Trauma Data Standard complication (AOR, 1.20; 95% CI, 1.11-1.30).

CONCLUSION

In this large multicenter study, increasing BMI and lower than normal BMI were strongly associated with higher mortality. Increasing BMI was also associated with longer length of stay, increased complications, and unique injury patterns. These untoward outcomes, coupled with a distinct injury pattern, warrant care guidelines specific to trauma patients with higher BMI, as well as those with BMI lower than normal.

LEVEL OF EVIDENCE

Epidemiological, Level III.

The Obesity Paradox in the Trauma Patient: Normal May not Be Better

Objective

The obesity paradox is the association of increased survival for overweight and obese patients compared to normal and underweight patients, despite an increased risk of morbidity. The obesity paradox has been demonstrated in many disease states but has yet to be studied in trauma. The objective of this study is to elucidate the presence of the obesity paradox in trauma patients by evaluating the association between BMI and outcomes.

Methods

Using the 2014–2015 National Trauma Database (NTDB), adults were categorized by WHO BMI category. Logistic regression was used to assess the odds of mortality associated with each category, adjusting for statistically significant covariables. Length of stay (LOS), ICU LOS and ventilator days were also analyzed, adjusting for statistically significant covariables.

Results

A total of 415,807 patients were identified. Underweight patients had increased odds of mortality (OR 1.378, p < 0.001 95% CI 1.252–1.514), while being overweight had a protective effect (OR 0.916, p = 0.002 95% CI 0.867–0.968). Class I obesity was not associated with increased mortality compared to normal weight (OR 1.013, p = 0.707 95% CI 0.946–1.085). Class II and Class III obesity were associated with increased mortality risk (Class II OR 1.178, p = 0.001 95% CI 1.069–1.299; Class III OR 1.515, p < 0.001 95% CI 1.368–1.677). Hospital and ICU LOS increased with each successive increase in BMI category above normal weight. Obesity was associated with increased ventilator days; Class I obese patients had a 22% increase in ventilator days (IRR 1.217 95% CI 1.171–1.263), and Class III obese patients had a 54% increase (IRR 1.536 95% CI 1.450–1.627).

Conclusion

The obesity paradox exists in trauma patients. Further investigation is needed to elucidate what specific phenotypic aspects confer this benefit and how these can enhance patient care.

Level of evidence

Level III, prognostic study

Obesity and impaired barrier function after shock: A biomimetic in vitro model using microfluidics

BACKGROUND

Impaired microvascular perfusion in the obese patient has been linked to chronic adverse health consequences. The impact on acute illnesses including trauma, sepsis, and hemorrhagic shock (HS) is uncertain. Studies have shown that endothelial glycocalyx and vascular endothelial derangements are causally linked to perfusion abnormalities. Trauma and HS are also associated with impaired microvascular perfusion in which glycocalyx injury and endothelial dysfunction are sentinel events. We postulate that obesity may impact the adverse consequences of HS on the vascular barrier. This was studied in vivo in a biomimetic model of HS using microfluidic technology.

METHODS

Human umbilical vein endothelial cell monolayers were established in a microfluidic device. Cells were exposed to standard or biomimetic shock conditions (hypoxia plus epinephrine) followed by perfusion from plasma obtained from obese or nonobese subjects. Endothelial glycocalyx and endothelial cellular injury were then determined.

RESULTS

Plasma from nonobese patients completely reversed glycocalyx and endothelial vascular barrier injury. Plasma from obese patients was only partially protective and was associated with differences in adipokines and other substances in the plasma of these patients.

CONCLUSION

Our study supports that obesity impairs HS resuscitation. This may be due to microrheological differences between nonobese and obese individuals and may contribute to the poorer outcome in this patient population.

Severe burn injury: Body Mass Index and the Baux score

OBJECTIVE

The revised Baux score (age total body surface area (TBSA) burned and inhalation injury)) is predictive of mortality in burn patients. Our study objective was to assess whether the addition of body mass index (BMI) to the revised Baux score would be of value. We posited that increasing BMI follows a pattern similar to age and TBSA in the revised Baux score after severe burn injury.

METHODS

Patient data from the burn registry was queried for patients admitted between 1/1/2013 to 8/31/2019. Patients 12 years or older with a TBSA of 20% or greater burn were included. Inpatient outcomes were analyzed based on BMI.

RESULTS

56 of 1365 patients met inclusion criteria. Mean age of the study population was 48.25 years and 64.3% of patients were male. Median BMI was 25.8 and median TBSA was 26.5. Inhalation injury was present in 44.6% (25/56) of patients. Median hospital length of stay (LOS) and ICU LOS were 21.5 and 17 days respectively. On bivariate analysis, non-survivors had higher TBSA (41.5% vs 25.5%, p = 0.034), more inhalation injury (83.3%, 10/12 vs 34.8%, 15/43 p = 0.003) and higher complication rates (91.6%, 11/12 vs 59.1 %, 25/43, p = 0.043). Survivors also had higher BMI (28.2 vs 23, p = 0.003) and increased hospital LOS (24 vs 5.5, p = 0.003). Automatic model fit in binary logistic regression showed a negative relationship between BMI and mortality.

CONCLUSION

We found a negative relationship between BMI and mortality. Pre-obesity appears to have a protective role, but BMI was not found to be a useful addition to the revised Baux score. Larger sample sizes may be of benefit a for a for a more definitive understanding of the role of BMI with regards to burn survival.

The effect of body mass index on outcomes following severe blunt chest trauma

INTRODUCTION

Obesity has been described as a significant risk factor for adverse outcomes in hospitalized patients. However, recent literature reports an "obesity paradox", suggesting that obesity may have a protective effect in a subset of surgical and critically ill patients. The present study assesses the effect of body mass index (BMI) on outcomes following severe isolated blunt chest trauma.

METHODS

This was a TQIP database study including patients with severe isolated blunt chest injury (chest AIS 3-5, extrathoracic AIS <3). Patients were excluded for age <20 or >89, death on arrival, facility transfer, or BMI <10 or >55. Patients were divided into five groups according to BMI: underweight (BMI <18.5), normal weight (18.5-24.9), overweight (25.0-29.9), obesity class 1 (30.0-34.9), obesity class 2 (35.0-39.9) and obesity class 3 (≥40.0). Logistic regression models were constructed to evaluate the effect of BMI on outcomes.

RESULTS

28,820 patients met criteria for inclusion in the analysis. After multivariable analysis, underweight patients as well as obesity class 2 and 3 patients had a significantly higher mortality (OR 1.86 [95% CI, 1.12-3.10], OR 1.48 [95% CI, 1.02-2.16], and OR 1.60 [95% CI, 1.03-2.50]), respectively. Underweight patients had significantly higher risk of overall complications as compared to normal weight patients (OR 1.58 [95% CI, 1.34-1.88]). Obesity class 2 and 3 were independently associated with increased respiratory complications (OR 1.60 [95% CI, 1.27-2.01] and OR 1.58 [95% CI, 1.20-2.09], respectively) and all classes of overweight and obese patients were associated with increased risk of VTE complications (OR 1.68 [95% CI, 1.23-2.27], OR 1.98 [95% CI, 1.42-2.77], OR 2.32 [95% CI, 1.55-3.48], OR 2.02 [95% CI, 1.23-3.33], respectively for overweight and obesity class 1, 2, 3).

CONCLUSIONS

The obesity paradox does not extend to severe blunt chest trauma. Underweight and obesity class 2 and 3 patients have worse mortality than normal weight patients. Obesity was independently associated with an increased risk of pulmonary and VTE complications.

Is There an Obesity Paradox in Critical Illness? Epidemiologic and Metabolic Considerations

PURPOSE OF REVIEW

Obesity represents a global epidemic with serious implications in public health due to its increasing prevalence and its known association with a high morbidity and mortality burden. However, a growing number of data support a survival benefit of obesity in critical illness. This review summarizes current evidence regarding the obesity paradox in critical illness, discusses methodological issues and metabolic implications, and presents potential pathophysiologic mechanisms.

RECENT FINDINGS

Data from meta-analyses and recent studies corroborate the obesity-related survival benefit in critically ill patients as well as in selected populations such as patients with sepsis and acute respiratory distress syndrome, but not trauma. However, this finding warrants a cautious interpretation due to certain methodological limitations of these studies, such as the retrospective design, possible selection bias, the use of BMI as an obesity index, and inadequate adjustment for confounding variables. Main pathophysiologic mechanisms related to obesity that could explain this phenomenon include higher energy reserves, inflammatory preconditioning, anti-inflammatory immune profile, endotoxin neutralization, adrenal steroid synthesis, renin-angiotensin system activation, cardioprotective metabolic effects, and prevention of muscle wasting. The survival benefit of obesity in critical illness is supported from large meta-analyses and recent studies. Due to important methodological limitations, more prospective studies are needed to further elucidate this finding, while future research should focus on the pathophysiologic role of adipose tissue in critical illness.

The effect of cirrhosis on trauma outcomes: A systematic review and meta-analysis

BACKGROUND

The negative effect of cirrhosis on mortality following traumatic injury has been quantified in multiple observational studies. However, to our knowledge, the information contained in these studies has never been synthesized. The aims of this study were: (1) to determine the magnitude of the effect of liver cirrhosis on mortality, morbidity, and hospital course among trauma patients and (2) to analyze sources of study heterogeneity that may lead to differing estimates in the observed mortality rate among patients with cirrhosis.

METHODS

A systematic search of EMBASE and PubMed was conducted. Data were extracted from eligible studies and analyzed using a random-effects model to compare trauma outcomes in cirrhotic and noncirrhotic patients (PROSPERO Registration CRD42018088464). Mortality was the primary outcome. Secondary outcomes included complication rate, length of hospital stay, length of intensive care unit stay, and mechanical ventilation days.

RESULTS

Title and abstract review of 15,958 articles led to the identification of 31 relevant articles. Ultimately, 18 observational studies were included in this meta-analysis. The pooled effect sizes for mortality (odds ratio [OR], 4.52; 95% confidence interval [CI], 3.13-6.54) and complication rate (OR, 1.92; 95% CI, 1.30-2.85) were higher in the cirrhotic group than the noncirrhotic group. Trauma patients with cirrhosis also incurred longer hospital stays (mean difference, 3.81 days; 95% CI, 1.22-6.41) and longer ICU stays (mean difference, 2.40 days; 95% CI, 0.65-4.15). There was no difference in days spent on mechanical ventilation.

CONCLUSION

Preexisting liver cirrhosis is associated with increased mortality rate, complication rate, and length of hospitalization among trauma patients, even after adjusting for confounding factors and potential sources of between-study heterogeneity. Trauma patients with cirrhosis would benefit from heightened surveillance and injury prevention interventions.

LEVEL OF EVIDENCE

Systematic review and meta-analysis, level III.

Sex-Based Differences in Inpatient Burn Mortality

BACKGROUND

Among burn patients, research is conflicted, but may suggest that females are at increased risk of mortality, despite the opposite being true in non-burn trauma. Our objective was to determine whether sex-based differences in burn mortality exist, and assess whether patient demographics, comorbid conditions, and injury characteristics explain said differences.

METHODS

Adult patients admitted with burn injury-including inhalation injury only-between 2004 and 2013 were included. Inverse probability of treatment weights (IPTW) and inverse probability of censor weights (IPCW) were calculated using admit year, patient demographics, comorbid conditions, and injury characteristics to adjust for potential confounding and informative censoring. Standardized Kaplan-Meier survival curves, weighted by both IPTW and IPCW, were used to estimate the 30-day and 60-day risk of inpatient mortality across sex.

RESULTS

Females were older (median age 44 vs. 41 years old, p < 0.0001) and more likely to be Black (32% vs. 25%, p < 0.0001), have diabetes (14% vs. 10%, p < 0.0001), pulmonary disease (14% vs. 7%, p < 0.0001), heart failure (4% vs. 2%, p = 0.001), scald burns (45% vs. 26%, p < 0.0001), and inhalational injuries (10% vs. 8%, p = 0.04). Even after weighting, females were still over twice as likely to die after 60 days (RR 2.87, 95% CI 1.09, 7.51).

CONCLUSION

Female burn patients have a significantly higher risk of 60-day mortality, even after accounting for demographics, comorbid conditions, burn size, and inhalational injury. Future research efforts and treatments to attenuate mortality should account for these sex-based differences. The project was supported by the National Institutes of Health, Grant Number UL1TR001111.

Obesity is associated with postinjury hypercoagulability

BACKGROUND

Obesity is linked to hypercoagulability with an increased risk of venous thromboembolic events (VTE) in the uninjured population. Therefore, we hypothesize that obesity (body mass index [BMI] ≥30 kg/m [BMI30]) is associated with a hypercoagulable state postinjury characterized by increased clot strength and resistance to fibrinolysis.

METHODS

Our prospective Trauma Activation Protocol database includes all trauma activations patients for whom a rapid thrombelastography is obtained within 60 minutes postinjury prior to any transfusions. The data set was then stratified by BMI and subjects with BMI30 were compared with those with BMI less than 30 kg/m). The following thrombelastography measurements were obtained: activated clotting time, clot formation rate (angle), maximum clot strength (MA), and % clot lysis 30 minutes after MA (LY30, %). Fibrinolysis shutdown (SD) was defined as LY30 < 0.6% and hyperfibrinolysis (HF) as LY30 greater than 7.6%. Continuous variables are expressed as median (interquartile range).

RESULTS

Overall, 687 patients were included of whom 161 (23%) had BMI30. The BMI30 group was older, had a lower proportion of males and of blunt trauma, and was less severely injured. After adjustment for confounders, BMI30 was independently associated with lower odds of MA less than 55 mm (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.13-0.60) and of HF (OR, 0.31; 95% CI, 0.10-0.97) and higher odds of SD (OR, 1.82; 95% CI, 1.09-3.05). No independent association was observed with angle less than 65° (OR 0.57 95% CI 0.30-1.05). While VTEs were more frequent among BMI30 patients (5.0 vs. 3.3%), this did not reach significance after confounding adjustment (p = 0.11).

CONCLUSION

Obesity was protective against diminished clot strength and hyperfibrinolysis, and obesity was associated with an increased risk of fibrinolytic SD in severely injured patients. These findings suggest a relative hypercoagulability. Although no difference in VTEs was noted in this study, these findings may explain the higher rate of VTEs reported in other studies.

LEVEL OF EVIDENCE

Prognostic and Epidemiological, level III.

A retrospective analysis of associations between BMI and days spent on mechanical ventilation in a level 1 trauma facility

OBJECTIVE

To examine whether BMI impacts the outcomes of mechanically ventilated patients.

METHODS

Data was collected retrospectively among patients involved in motor vehicle accidents in intensive care at a major trauma center in Atlanta, GA. Patients were categorized into five BMI groups: underweight (BMI < 18.5), normal weight (BMI of 18.5-24.9), overweight (BMI of 25-29.9), obese (BMI of 30-39.9), and morbidly obese (BMI of >40).

RESULTS

Among all patients (n=2,802), 3% of patients were underweight, 34% were of normal weight, 30% were overweight, 27% were obese, and 6% were morbidly obese. The mean number of ventilator days for normal weight patients was 4.6, whereas the mean number of ventilator days for underweight and morbidly obese patients were higher (10.3 and 7.4, respectively).

CONCLUSIONS

Underweight and morbidly obese populations may require additional interventions during their ICU stays to address the challenges presented by having an unhealthy BMI.

Obesity associated with increased postoperative pulmonary complications and mortality after trauma laparotomy

Background

Patient-related risk factors for the development of postoperative pulmonary complications (PPCs) include age ≥ 60-years, congestive heart failure, hypoalbuminemia and smoking. The effect of obesity is unclear and has not been shown to independently increase the likelihood of PPCs in trauma patients undergoing trauma laparotomy. We hypothesized the likelihood of mortality and PPCs would increase as body mass index (BMI) increases in trauma patients undergoing trauma laparotomy.

Methods

The Trauma Quality Improvement Program (2010–2016) was queried to identify trauma patients ≥ 18-years-old undergoing trauma laparotomy within 6-h of presentation. A multivariable logistic regression analysis was used to determine the likelihood of PPCs and mortality when stratified by BMI.

Results

From 8,330 patients, 2,810 (33.7%) were overweight (25–29.9 kg/m²), 1444 (17.3%) obese (30–34.9 kg/m²), 580 (7.0%) severely obese (35–39.9 kg/m²), and 401 (4.8%) morbidly obese (≥ 40 kg/m²). After adjusting for covariates including age, injury severity score, chronic obstructive pulmonary disease, smoking, and rib/lung injury, the likelihood of PPCs increased with increasing BMI: overweight (OR = 1.37, CI 1.07–1.74, p = 0.012), obese (OR = 1.44, CI 1.08–1.92, p = 0.014), severely obese (OR = 2.20, CI 1.55–3.14, p < 0.001), morbidly obese (OR = 2.42, CI 1.67–3.51, p < 0.001), compared to those with normal BMI. In addition, the adjusted likelihood of mortality increased for the morbidly obese (OR = 2.60, CI 1.78–3.80, p < 0.001) compared to those with normal BMI.

Conclusion

Obese trauma patients undergoing emergent trauma laparotomy have a high likelihood for both PPCs and mortality, with morbidly obese trauma patients having the highest likelihood for both. This suggests obesity should be accounted for in risk prediction models of trauma patients undergoing laparotomy.

Electronic supplementary material

The online version of this article (10.1007/s00068-020-01329-w) contains supplementary material, which is available to authorized users.

The relationship between weight indices and injuries and mortalities caused by the motor vehicle accidents: a systematic review and meta-analysis

BACKGROUND

The relationship between weight indices and injuries and mortality in motor vehicle accidents is unknown. Systematic review studies addressing the collection and analysis of the relationship in investigations are very limited. The purpose of this systematic review is to determine the relationship between BMI, obesity and overweight with mortality and injuries and their severity and vulnerable organs after the motor vehicle accident.

METHODS

The databases (MEDLINE/PUBMED, EMBASE, Web of Science, etc) were searched for relevant abstracts using certain keywords. Of all the articles, similar ones were removed considering different filters. The collected data were entered into the STATA SE v 13.1. The heterogeneity of the data was analyzed using i2 statistics. In addition, the estimates of the study were done based on the age group (children and adults) and the impact of obesity on different regions of the body.

RESULTS

A direct relationship was observed between the overall BMI and the degrees of injuries (CI=0.503-1.139), and mortality due to motor vehicle accident (CI=1.267-1.471). A positive relationship was found between obesity and AIS+2 (CI=0.653-1.426), and AIS+3 (CI=1.184-1.741), and ISS (CI=1.086-1.589). Also, a negative relationship between overweight and injuries rates, and a direct relationship between overweight and mortality (CI=0.979-1.167), and injuries with index of AIS+2 (CI=1.178-0.768) and AIS+3 (CI=0.48-2.186) were found.

CONCLUSIONS

The prediction of injury, mortality and severity of injuries in the motor vehicle accident by the variable of obesity and overweight determines the need to design prevention programs for this vulnerable group at all levels.

Impact of pathologic body composition assessed by CT-based anthropometric measurements in adult patients with multiple trauma: a retrospective analysis

PURPOSE

In recent years, there has been mounting evidence on the clinical importance of body composition, particularly obesity and sarcopenia, in various patient populations. However, the relevance of these pathologic conditions remains controversial, especially in the field of traumatology. Computed tomography-based measurements allow clinicians to gain a prompt and thorough assessment of fat and muscle compartments in trauma patients. Our aim was to investigate whether CT-based anthropometric parameters of fat and muscle tissues show correlations with key elements of pre-hospital and clinical care in an adult population with multiple trauma.

METHODS

In this retrospective analysis we searched our institutional records of the German Trauma Registry (TraumaRegister DGU^®) from January 2008 to May 2014. Included were 297 adult trauma patients with multiple trauma who underwent a whole-body CT-scan on admission and were treated in an ICU. We measured anthropometric determinants of abdominal core muscle and adipose tissue using the digital imaging software OsiriX™. Multivariate linear and logistic regression analyses were conducted to unveil potential correlations.

RESULTS

None of the obesity-linked anthropometric parameters were associated with longer pre-hospital or initial ED treatment times. Obese patients were less frequently intubated at the site of the accident. Patients with increased abdominal fat tissue received on average lower volumes during fluid resuscitation in the pre-hospital phase but were not more often in shock on admission. During ED treatment, fluid resuscitation and transfusion volumes were not affected by abdominal fat tissue, although transfusion rates were higher in the obese. Furthermore, damage control surgeries took place less frequently in patients with increased abdominal fat tissue markers. Obesity parameters did not affect the prevalence of sepsis, although increased abdominal fat was associated with higher white blood cell counts on admission. Finally, there was no statistically significant correlation between sarcopenia or obesity markers and duration of mechanical ventilation, ICU length of stay or neurologic outcome.

CONCLUSION

CT-based assessment of abdominal fat and muscle mass is a simple method in revealing pathologic body composition in trauma patients. Our study suggests that obesity influences pre-hospital and ED treatment and early immune response in multiple trauma. Nevertheless, we could not demonstrate any significant effect of abdominal fat and muscle tissue parameters on the course of treatment, in particular the duration of mechanical ventilation, ICU length of stay and neurologic outcome.

Open Abdomen in Obese Patients: Pay Attention! New Evidences from IROA, the International Register of Open Abdomen

BACKGROUND

Open abdomen is the cornerstone of damage control strategies in acute care and trauma surgery. The role of BMI has not been well investigated. The aim of the study was to assess the role of BMI in determining outcomes after open abdomen.

METHODS

This is an analysis of patients recorded into the International Register of Open Abdomen; patients were classified in two groups according to BMI using a cutoff of 30 kg/m². The primary outcome was in-hospital mortality; secondary outcomes were primary fascia closure rate, length of treatment, complication rate, entero-atmospheric fistula rate and length of ICU stay.

RESULTS

A total of 591 patients were enrolled from 57 centers, and obese patients were 127 (21.5%). There was no difference in mortality between the two groups; complications developed during the open treatment were higher in obese patients (63.8% vs. 53.4%, p = 0.038) while post-closure complications rate was similar. Obese patients had a significantly longer duration of the open treatment (9.1 ± 11.5 days vs. 6.3 ± 7.5 days; p = 0,002) and lower primary fascia closure rate (75.5% vs. 89.5%; p < 0,001). No differences in fistula rate were found. There was a linear correlation between the duration of open abdomen and the BMI (Pearson's linear correlation coefficient = 0,201; p < 0,001).

CONCLUSIONS

Open abdomen in obese patients seems to be safe as in non-obese patients with similar mortality; however, in obese patients the length of open abdomen is significantly higher with higher complication rate, longer ICU length of stay and lower primary fascia closure rate.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, Identifier: NCT02382770.

Medical Versus Surgical ICU Obese Patient Outcome: A Propensity-Matched Analysis to Resolve Clinical Trial Controversies

OBJECTIVES

To determine the short- and long-term mortality of obese ICU patients following medical as opposed to surgical admission and the relation between obesity and mortality.

DESIGN

Retrospective analysis of prospectively collected data, using a propensity score-matched analysis of patients with medical or surgical admission.

SETTING

One French mixed medical-surgical ICU.

PATIENTS

Critically ill obese patients (body mass index ≥ 30 kg/m) and nonobese patients admitted during a 14-year period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Seven-hundred ninety-one obese patients and 4,644 nonobese patients were included, 338 (43%) and 2,367 (51%) medical and 453 (57%) and 2,277 (49%) surgical obese and nonobese patients, respectively. Mortality was significantly higher in medical than in surgical obese patients in ICU (25% vs 12%; p < 0.001) and up to 365 days (36% vs 18%; p < 0.001) post ICU admission. One-to-one propensity score matching generated 260 pairs with well-balanced baseline characteristics. After matching on propensity score, mortality was still significantly higher in medical patients both in the ICU (21% vs 13%; p = 0.03) and up to 365 days (30% vs 20%; p = 0.01) post ICU admission. Obesity was not significantly associated with mortality both in univariate analysis (140 obese patients [15%] in the dead group vs 651 [14%] in the alive group; p = 0.72) and multivariate analysis (odds ratio, 1.09 [95% CI, 0.86-1.38]; p = 0.49) after adjustment for Simplified Acute Physiology Score II, age, category of admission, history of cardiac disease, and history of respiratory disease.

CONCLUSIONS

After careful matching, the data suggest that ICU mortality in obese population was higher in the medical group than in the surgical group and remains significantly higher 365 days post ICU admission.

[Effects of front-of-package nutritional labeling of food and beverages: synopsis of systematic reviewsEfeitos da rotulagem nutricional frontal de alimentos e bebidas: sumário de estudos de revisão sistemática]

Objetivos.

Sintetizar la información disponible sobre el efecto del etiquetado nutricional frontal en la elección, compra y consumo de alimentos y bebidas, y el estado nutricional de los consumidores, e identificar los factores que influyen en su efectividad.

Métodos.

Se realizó una sinopsis de revisiones sistemáticas (RS) conforme a las recomendaciones PRISMA. La búsqueda bibliográfica se realizó en Medline (Pubmed), The Cochrane Library, LILACS, EBSCOhost y Scopus, limitada a estudios publicados en español o inglés sin restricción por fecha de publicación. La calidad metodológica se evaluó utilizando la herramienta AMSTAR 2.

Resultados.

Se incluyeron siete RS. El etiquetado frontal facilitó la elección de alimentos saludables y tuvo un efecto variable sobre las dimensiones de consumo y compra. Ninguna RS evaluó el efecto sobre el estado nutricional. El costo y sabor, los hábitos alimentarios, el nivel educativo y los sistemas dominantes de procesamiento de información en el consumidor influyeron en su efectividad. La mayoría de RS mostraron limitaciones metodológicas y un nivel de confianza críticamente bajo.

Conclusiones.

El etiquetado frontal tuvo efecto positivo en la elección de alimentos saludables, con resultados variables en las dimensiones de compra y consumo. Se necesitan estudios locales con una adecuada calidad metodológica para identificar el formato de etiquetado más efectivo en cada país. Su implementación como política de salud pública debe acompañarse de estrategias para mejorar el acceso a alimentos saludables, promover la actividad física y brindar educación nutricional a los consumidores.

Obese trauma patients have increased need for dialysis

PURPOSE

Obesity is a risk factor for the development of acute kidney injury but its effect on the need for dialysis in trauma has not been elucidated. Additionally, the contribution that obesity has towards risk of mortality in trauma is unclear. We hypothesized that patients with a higher body mass index (BMI) will have a higher risk for need of dialysis and mortality after trauma.

METHODS

This is a retrospective analysis using the National Trauma Data Bank. All patients ≥ 8 years old were grouped based on BMI: normal (18.5-24.99 kg/m²), obese (30-34.99 kg/m²), severely obese (35-39.99 kg/m²) and morbidly obese (≥ 40 kg/m²). The primary outcome was hemodialysis initiation. The secondary outcome was mortality during the index hospitalization.

RESULTS

From 988,988 trauma patients, 571,507 (57.8%) had a normal BMI, 233,340 (23.6%) were obese, 94,708 (9.6%) were severely obese, and 89,433 (9.0%) were morbidly obese. The overall rate of hemodialysis was 0.3%. After adjusting for covariates, we found that obese (OR 1.36, CI 1.22-1.52, p < 0.001), severely obese (OR 1.89, CI 1.66-2.15, p < 0.001) and morbidly obese (OR 2.04, CI 1.82-2.29, p < 0.001) patients had a stepwise increased need for hemodialysis after trauma. Obese patients had decreased (OR 0.92, CI 0.88-0.95, p < 0.001), severely obese had similar (OR 1.02, CI 0.97-1.08, p = 0.50) and morbidly obese patients had increased (OR 1.06, CI 1.01-1.12, p = 0.011) risk of mortality after trauma.

CONCLUSIONS

Obesity was associated with an increased risk for dialysis after trauma. Mortality risk was reduced in obese, similar in severely obese, and increased in morbidly obese trauma patients suggesting an inflection threshold BMI for risk of mortality in trauma.

Early treatment with GLP-1 after severe trauma preserves renal function in obese Zucker rats

Early posttrauma hyperglycemia (EPTH) is correlated with later adverse outcomes, including acute kidney injury (AKI). Controlling EPTH in the prehospital setting is difficult because of the variability in the ideal insulin dosage and the potential risk of hypoglycemia, especially in those with confounding medical comorbidities of obesity and insulin resistance. Glucagon-like peptide-1 (GLP-1) controls glucose levels in a glucose-dependent manner and is a current target in antidiabetic therapy. We have shown that after orthopedic trauma, obese Zucker rats exhibit EPTH and a later development of AKI (within 24 h). We hypothesized that GLP-1 treatment after trauma decreases EPTH and protects renal function in obese Zucker rats. Obese Zucker rats (~12 wk old) were fasted for 4 h before trauma. Soft tissue injury, fibula fracture, and homogenized bone component injection were then performed in both hind limbs to induce severe extremity trauma. Plasma glucose levels were measured before and 15, 30, 60, 120, 180, 240, and 300 min after trauma. GLP-1 (3 μg·kg^-1·h^-1, 1.5 ml/kg total) or saline was continuously infused from 30 min to 5 h after trauma. Afterwards, rats were placed in metabolic cages overnight for urine collection. The following day, plasma interleukin (IL)-6 levels, renal blood flow (RBF), glomerular filtration rate (GFR), and renal oxygen delivery (Do₂) and consumption (V̇o₂) were measured. EPTH was evident within 15 min after trauma but was significantly ameliorated during the 5 h of GLP-1 infusion. One day after trauma, plasma IL-6 was markedly increased in the trauma group and decreased in GLP-1-treated animals. RBF, GFR, and Do₂ all significantly decreased with trauma, but renal V̇o₂ was unchanged. GLP-1 treatment normalized RBF, GFR, and Do₂ without affecting V̇o₂. These results suggest that GLP-1 decreases EPTH and protects against a later development of AKI. Early treatment with GLP-1 (or its analogs) to rapidly, effectively, and safely control EPTH may be beneficial in the prehospital care of obese patients after trauma.

Obesity and hospital outcomes following traumatic injury: Associations in 9 years of patient data from a single metropolitan area

Traumatic injury is a leading cause of death and disability worldwide. Obesity may put trauma patients at risk for complications leading to negative clinical outcomes. Data on all hospital admissions due to traumatic injury in the Detroit metropolitan area between 2006 and 2014 were obtained from the Michigan State Inpatient Database. Generalized linear modelling was used to compare patients with and without obesity on three outcomes: mortality, length of hospital stay and total charges for care. Adjusting for demographics, patients with obesity had 26% longer hospitalization. Adjusting for demographics and length of stay, charges were 8% higher. Obesity was unrelated to mortality. Obesity had greater impact on length of stay among younger adults; its relationship with charges emerged only among older adults. Obesity has significant clinical implications for trauma care. Demands for trauma care resources, and the charges associated with providing care, are likely to increase as obesity rates rise.

Impact of body mass index on outcomes after thoracic trauma-A matched-triplet analysis of the TraumaRegister DGU®

INTRODUCTION

Chest trauma and obesity are both associated with increased risks for respiratory complications (e.g. hypoxia, hypercarbia, pneumonia), which are frequent causes of posttraumatic morbidity and mortality. However, as there is only limited and inconsistent evidence, the aim of our study was to analyse the effect of body mass index (BMI) on patient outcomes after thoracic trauma.

PATIENTS AND METHODS

We screened 50.519 patients entered in TraumaRegister DGU^®, between 2004-2009, when the BMI was part of the standardized dataset. After matching for injury patterns and severity of trauma we performed a matched tripled analysis with regard to the BMI (group 1: <25.0 kg/m²; group 2: 25.0-29.9 kg/m²; group 3: >30.0 kg/m²). Data are shown as percentages and mean values with standard deviation.

RESULTS

The matching process yielded a cohort of 828 patients with serious blunt thoracic trauma, evenly distributed over the 3 BMI groups (276 triplets). BMI did not have an impact on the need for prehospital or emergency department interventions. There was a trend towards more liberal use of whole-body-CT scanning with increasing BMI (group 1: 68.8%; group 2: 73.2%; group 3: 75.0%). Additional abdominal injuries were more common in normal weight patients (Group 1: 28.3%; Group 2: 14.9%; Group 3: 17.8%). Obesity (BMI > 30.0 kg/m²) had a significant impact on the duration of mechanical ventilation (in days; group 1: 6.5 (9.4); group 2: 6.4 (8.9); group 3: 9.1 (14.4); p = 0.002), ICU days (in days; group 1: 11.5 (11.5); group 2: 10.9 (9.6); group 3: 14.1 (16.7); p = 0.005) and hospital length of stay (in days; group 1: 27.8 (19.3); group 2: 27.4 (19.2); group 3: 32.2 (25.9); p = 0.009). There were no significant differences regarding overall mortality (group 1: 3.6%; group 2: 1.8%; group 3: 4.0%; p = 0.26).

CONCLUSIONS

Obesity has a negative impact on outcomes after blunt chest trauma, as it is associated with prolonged duration of mechanical ventilation, ICU and hospital length of stay. Mortality did not seem to be affected, yet, further research is required to confirm these results in a larger cohort.

The Effect of Age upon the Interrelationship of BMI and Inpatient Health Outcomes

OBJECTIVES

There is growing evidence that the relationship between body mass index (BMI - defined as weight in kilograms divided by height in metres squared) and patient outcomes is age-dependent; specifically, a raised BMI may have a protective effect in older adults. This has been demonstrated clearly in the community setting; less clear is the effect of age on this relationship in the inpatient setting.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Retrospective analysis of 22,903 electronic records for patients discharged from two large public hospitals in South Australia between January 2015 and September 2018 inclusively. Records were retained if the patient's height and weight had been recorded during the admission, BMI was between 10-99 kg/m2 and it was the patient's first admission during that time. Patients were grouped by BMI (<18.5 kg/m2 ("underweight"), 18.5-24.9 kg/m2 ("normal weight"), 25-29.9 kg/m2 ("overweight"), >30 kg/m2 ("obese")) and age (18-59 years, 60-79 years, > 80 years); for each group we measured the relative stay index (RSI) (actual length of stay divided by predicted length of stay), death in hospital and composite adverse outcome after discharge (unplanned readmission within 30 days and/or death within 30 days).

RESULTS

Underweight patients across all age groups generally experienced significantly poorer outcomes compared to those not underweight. In those aged 18-59 years there were no significant differences in outcomes between the normal weight, overweight and obese groups. In those aged 60-79 years overweight patients had a significantly reduced risk of RSI > 2 compared to those of normal weight (p=0.014), and both overweight and obese patients had a significantly reduced risk of adverse outcome after discharge when compared to those of normal weight (p=0.028 and p=0.009 respectively). In those aged 80 years or older, both overweight and obese patients had a significantly reduced risk of adverse outcome after discharge when compared to those of normal weight (p=0.028 and p=0.013 respectively), and obese patients had a significantly reduced risk of inpatient mortality and RSI >2 when compared to those of normal weight (p=0.027 and p=0.037 respectively).

CONCLUSION

A BMI > 25 kg/m2 in older patients is associated with reduced risk of prolonged admission, inpatient mortality and adverse outcomes following discharge. This adds to growing evidence that age-specific BMI guidelines are required for adults because the healthiest BMI in the older hospital patient is seemingly not in the range 18.5-24.9 kg/m2.

High volume crystalloid resuscitation adversely affects pediatric trauma patients

BACKGROUND

Aggressive fluid resuscitative strategies have been the cornerstone of early trauma management for decades. However, recent prospective adult studies have challenged this practice, underlining the detrimental effect of positive fluid balance on cardiopulmonary function. Fluid overload has been associated with impaired oxygenation and morbidity in critically ill adults, but data is lacking in pediatric trauma patients.

METHODS

We completed a retrospective chart review of all pediatric trauma patients 0-18 years old admitted to a level 1 trauma center from January 2013 to December 2015. Four patient cohorts were established based on volume of fluid administered: <20 ml/kg/day, 20-40 ml/kg/day, 40-60 ml/kg/day, and > 60 ml/kg/day. The primary outcome was death. Secondary outcomes included the number of days on the ventilator, intensive care unit length of stay (ICU LOS), overall length of stay (LOS), number of days nil per os (NPO) as an indicator of ileus, and incidence of bloodstream infection and/or surgical site infection.

RESULTS

The mean volume of fluid administered over the first 24 h was 41 ml/kg/day, and 28 ml/kg/day over the first 48 h. ICU length of stay and overall length of stay were increased in patients who received more than 60 ml/kg/day in the first 24 h of their hospitalization. Furthermore, ventilator use, ICU length of stay, overall length of stay, and time to resumption of a regular diet were all increased in patients who received >60 ml/kg/day over 48 h.

CONCLUSIONS

Early administration of high volumes of crystalloid fluid greater than 60 ml/kg/day significantly correlates with pulmonary complications, days NPO, and hospital length of stay. These results span the first 48 h of a patient's hospital stay and should encourage surgical care providers to exercise judicious use of crystalloid fluid administration in the trauma bay, ICU, and floor.

TYPE OF STUDY

Therapeutic.

LEVEL OF EVIDENCE

Level III.

Obesity in the Polytrauma Patient

The rates of obesity continue to increase in the United States and the overall impact of obesity on health care spending and patient outcomes after trauma is considerable. The unique physiology of the obese places them at higher risk for complications, including infection, failure of fixation, nonunion, multiorgan failure, and death. These physiologic differences and overall patient size can make orthopedic care in obese patients with trauma more difficult, but appropriate initial resuscitation, careful preoperative planning, meticulous surgical technique, diligent postoperative medical management, and specialized rehabilitation give these patients their best opportunity for a good outcome.