Obesity and outcomes after blunt trauma

The effect of body mass index on the development of acute kidney injury and mortality in intensive care unit: is obesity paradox valid?

BACKGROUND

The conflicting results of studies on intensive care unit (ICU) mortality of obese patients and obese patients with acute kidney injury (AKI) reveal a paradox within a paradox. The aim of this study was to determine the effects of body mass index and obesity on AKI development and ICU mortality.

METHODS

The 4,459 patients treated between January 2015 and December 2019 in the ICU at a Tertiary Care Center in Turkey were analyzed retrospectively.

RESULTS

AKI developed more in obese patients with 69.8% (620). AKI development rates were similar in normal-weight (65.1%; 1172) and overweight patients (64.9%; 1149). The development of AKI in patients who presented with cerebrovascular diseases was higher in obese patients (81; 76.4%) than in normal-weight (158; 62.7%) and overweight (174; 60.8%) patients (p < 0.05). The risk of developing AKI was approximately 1.4 times (CI 95% = 1.177-1.662) higher in obese patients than in normal-weight patients. Dialysis was used more frequently in obese patients (24.3%, p < 0.001), who stayed longer in the ICU (p < 0.05). It was determined that the development of AKI in normal-weight and overweight patients increased mortality (p < 0.001) and that there was not a difference in mortality rates between obese patients with and without AKI.

CONCLUSION

The risk of AKI development was higher in obese patients but not in those who were in serious conditions. Another paradox was that the development of AKI was associated with a higher mortality rate in normal-weight and overweight patients, but not in obese patients. Cerebrovascular diseases as a cause of admission pose additional risks for AKI.

Dynamic Cushioning: Obesity and Trauma Patients Undergoing Exploratory Laparotomy

BACKGROUND

Traumatic injuries account for 10% of all mortalities in the United States. Annually the global estimated population of overweight and obese individuals rises in number. It is well established in the literature that obesity is associated with worse outcomes in trauma patients. While body mass index, or BMI is not an independent predictor of increased morbidity or mortality after trauma laparotomy, we hypothesized that it may place patients at increased risk of postoperative complications and have lasting significant negative effects on quality of life in a manner disproportionate to normal-weight patients.

METHODS

The trauma registry of an academic level 1 trauma hospital was queried for laparotomies following either blunt or penetrating traumatic injury from 2015 to 2019. Individual patient charts were reviewed. Patients were divided into three groups, according to Body Mass Index (BMI) cut-offs as normal weight (BMI < 25 kg/m²), overweight; BMI 25-29.9 kg/m²), and obese (BMI ≥ 30 kg/m²). Demographics, intraoperative management and outcomes were compared between groups, after which complications were regressed based on BMI to evaluate the impact BMI had on each.

RESULTS

Records of 197 trauma patients who underwent exploratory laparotomies were analyzed. There was no significant difference in demographics or injury severity score (ISS) between groups. BMI had a direct positive association with intensive care unit length of stay (r = 0.239 [0.103, 0.367]), P < 0.001), hospital length of stay (r = 0.197 [0.059, 0.328], P = 0.005) and return to OR (OR = 1.057, [1.010, 1.109], P = 0.017). There was no significant relationship between BMI and in-hospital or 90-d mortality.

CONCLUSIONS

Our findings show that with increasing BMI, postoperative complications increase following laparotomy for trauma. As rates of obesity increase, trauma surgeons must be prepared to anticipate plans of care from patient presentation to well beyond discharge to cope with more complex postoperative and post-hospital clinical courses.

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.

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.

Morbidity and Mortality in the Obese Trauma Intensive Care Unit Patient

INTRODUCTION

Obesity is an epidemic in the United States, known to be associated with comorbidities. However, some data show that obesity may be a protective factor in some instances. The purpose of this study is to determine if there are differences in morbidity and mortality when comparing the obese and non-obese critically ill trauma patient populations.

MATERIALS AND METHODS

This was a retrospective study conducted at Prisma Health Upstate in Greenville, South Carolina, an Adult Level 1 Trauma Center. Patients over the age of 18 years admitted due to trauma from February 6, 2016 to February 28, 2019 were included in this study. Burn patients were excluded. An online trauma database was used to obtain age, sex, body mass index, Glasgow coma score (GCS), injury severity score (ISS), revised trauma score (RTS), days on mechanical ventilation, hospital length of stay (LOS), and intensive care unit (ICU) LOS.

RESULTS

There were 2365 critically ill trauma patients who met inclusion criteria for this study. 1570 patients were men (66.38%) and mean age was 53.2 ± 20.9. Of the patients, 2166 patients had blunt trauma (91.59%). Median GCS was 15 (interquartilerange [IQR]: 12, 15), median RTS was 12 (IQR: 11, 12), and median ISS was 17 (IQR: 9, 22). Obese critically ill trauma patients had significantly lower odds of mortality than nonobese (OR .686, CI 0.473-.977). Penetrating traumas (OR: 4.206, CI: 2.478, 6.990), increased ISS (OR: 1.095, CI: .473, 1.112), and increased age (OR: 1.036, CI: 1.038, 1.045) were associated with significantly increased odds of mortality.

DISCUSSION

The obesity paradox is observed in the obese critically ill trauma patient population.

Impact of Obesity on Mortality in Adult Trauma Patients

Introduction

Trauma is a major cause of morbidity and mortality amongst all populations in the United States. With the widespread increase of obesity in the United States, studies have been conducted to compare different body mass index (BMI) groups and their clinical outcomes for traumatic injuries. The goal of this study was to retrospectively compare mortality between adult trauma patients with a high BMI to those with a lower BMI as well as investigate whether the mechanism of trauma had an effect on the outcome.

Methods

This study was a retrospective review of all adult trauma patients presented to the emergency department at Arrowhead Regional Medical Center (ARMC) between January 2014 and October 2019. The outcome was all-cause mortality. Patients were grouped according to BMI and mechanisms of injury, including blunt trauma, low velocity penetrating trauma, and high velocity penetrating trauma. Patients were also stratified by injury severity scores (ISS).

Results

Among the 9642 patients assessed in this study, majority (88%) of patients sustained blunt trauma. The number of patients among the three different BMI groups was appropriately equal with 34.4% of normal BMI, 34.6% overweight, and 31.1% obese. The overall mortality of all patients studied was 2.6% (n=248). There was no statistically significant difference in mortality among the three different BMI groups for blunt trauma, penetrating trauma, and subgroup analyses stratified by ISS score (ISS<16 or ISS ≥ 16).

Conclusion

Our study found no statistically significant differences in mortality among the three BMI groups in regard to mortality, even when stratified by ISS, or mechanism of injury, and traumatic velocities.

Bypassing TBI: Metabolic Surgery and the Link between Obesity and Traumatic Brain Injury-a Review

Obesity is a common outcome of traumatic brain injury (TBI) that exacerbates principal TBI symptom domains identified as common areas of post-TBI long-term dysfunction. Obesity is also associated with increased risk of later-life dementia and Alzheimer's disease. Patients with obesity and chronic TBI may be more vulnerable to long-term mental abnormalities. This review explores the question of whether weight loss induced by bariatric surgery could delay or perhaps even reverse the progression of mental deterioration. Bariatric surgery, with its induction of weight loss, remission of type 2 diabetes, and other expressions of the metabolic syndrome, improves metabolic efficiency, leads to reversal of brain lesions seen on imaging studies, and improves function. These observations suggest that metabolic/bariatric surgery may be a most effective therapy for TBI.

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.

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.

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.

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.

Is body mass index associated with outcomes of mechanically ventilated adult patients in intensive critical units? A systematic review and meta-analysis

BACKGROUND

Obesity paradox refers to lower mortality in subjects with higher body mass index (BMI), and has been documented under a variety of condition. However, whether obesity paradox exists in adults requiring mechanical ventilation in intensive critical units (ICU) remains controversial.

METHODS

MEDLINE, EMBASE, China Biology Medicine disc (CBM) and CINAHL electronic databases were searched from the earliest available date to July 2017, using the following search terms: "body weight", "body mass index", "overweight" or "obesity" and "ventilator", "mechanically ventilated", "mechanical ventilation", without language restriction. Subjects were divided into the following categories based on BMI (kg/m2): underweight, < 18.5 kg/m2; normal, 18.5-24.9 kg/m2; overweight, BMI 25-29.9 kg/m2; obese, 30-39.9 kg/m2; and severely obese > 40 kg/m2. The primary outcome was mortality, and included ICU mortality, hospital mortality, short-term mortality (<6 months), and long-term mortality (6 months or beyond). Secondary outcomes included duration of mechanical ventilation, length of stay (LOS) in ICU and hospital. A random-effects model was used for data analyses. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale.

RESULTS

A total of 15,729 articles were screened. The final analysis included 23 articles (199,421 subjects). In comparison to non-obese patients, obese patients had lower ICU mortality (odds ratio (OR) 0.88, 95% CI 0.0.84-0.92, I2 = 0%), hospital mortality (OR 0.83, 95% CI 0.74-0.93, I2 = 52%), short-term mortality (OR 0.81, 95% CI 0.74-0.88, I2 = 0%) as well as long-term mortality (OR 0.69, 95% CI 0.60-0.79, I2 = 0%). In comparison to subjects with normal BMI, obese patients had lower ICU mortality (OR 0.88, 95% CI 0.82-0.93, I2 = 5%). Hospital mortality was lower in severely obese and obese subjects (OR 0.71, 95% CI 0.53-0.94, I2 = 74%, and OR 0.80, 95% CI 0.73-0.89, I2 = 30%). Short-term mortality was lower in overweight and obese subjects (OR 0.82, 95% CI 0.75-0.90, I2 = 0%, and, OR 0.75, 95% CI 0.66-0.84, I2 = 8%, respectively). Long-term mortality was lower in severely obese, obese and overweight subjects (OR 0.39, 95% CI 0.18-0.83, and OR 0.63, 95% CI 0.46-0.86, I2 = 56%, and OR 0.66, 95% CI 0.57-0.77, I2 = 0%). All 4 mortality measures were higher in underweight subjects than in subjects with normal BMI. Obese subjects had significantly longer duration on mechanical ventilation than non-obese group (mean difference (MD) 0.48, 95% CI 0.16-0.80, I2 = 37%), In comparison to subjects with normal BMI, severely obese BMI had significantly longer time in mechanical ventilation (MD 1.10, 95% CI 0.38-1.83, I2 = 47%). Hospital LOS did not differ between obese and non-obese patients (MD 0.05, 95% CI -0.52 to 0.50, I2 = 80%). Obese patients had longer ICU LOS than non-obese patients (MD 0.38, 95% CI 0.17-0.59, I2 = 70%). Hospital LOS and ICU LOS did not differ significantly in subjects with different BMI status.

CONCLUSIONS

In ICU patients receiving mechanical ventilation, higher BMI is associated with lower mortality and longer duration on mechanical ventilation.

The role of increased body mass index in outcomes of sepsis: a systematic review and meta-analysis

Background

The role of increased body mass index (BMI) in sepsis is controversial. We aimed to evaluate the associations between overweight (25 kg/m² < BMI ≤ 29.9 kg/m²), obese (30 kg/m² < BMI ≤ 39.9 kg/m²) and morbidly obese (BMI > 40 kg/m²) BMIs and outcomes in septic patients.

Methods

We searched the PubMed, Embase, Web of Science, Cochrane Library and ClinicalTrials.gov databases for studies published by December 1, 2016. Electronic database searches yielded 3713 articles, eight of which were included in this meta-analysis. Data were independently extracted by two reviewers, and a third reviewer participated in making decisions as needed. We used Review Manager to conduct the analysis, and the outcomes were reported with odds ratios (ORs) or mean differences (MDs). The primary outcome was mortality, and the secondary outcome was length of stay (LOS) in the intensive care unit (ICU) or the hospital.

Results

Data from eight studies involving a total of 9696 patients were pooled in our final analysis. Compared with patients with normal BMI (18.5 kg/m² < BMI ≤ 24.9 kg/m²), patients with BMI ≥ 25 kg/m² exhibited decreased mortality (OR 0.81; 95% confidence interval (CI), 0.74–0.89, P < 0.0001). In subgroup analysis, compared with normal-weight patients, overweight patients had lower mortality (OR 0.87; 95% CI 0.77–0.97, P = 0.02), whereas obese (OR 0.89, 95% CI 0.72–1.10, P = 0.29) and morbidly obese (OR 0.64, 95% CI 0.38–1.08, P = 0.09) patients did not exhibit significantly reduced mortality.

Conclusions

In sepsis cases, overweight, but not obesity or morbid obesity, was associated with lower mortality. Further prospective studies are needed to clarify this relationship.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0405-4) contains supplementary material, which is available to authorized users.

Analysis of Mortality in Traumatically Injured Patients Based on Body Mass Index and Mechanism Reveals Highest Mortality among the Underweight in Comparison with the Ideal Weight Patients

The purpose of this study was to evaluate the effect of body mass index (BMI) on mortality after traumatic injury. The records of patients from 2012 to 2015 were retrospectively reviewed. The patients were stratified into the following groups based on admission BMI (kg/m2): underweight (UW) (BMI <19), ideal weight (IW) (BMI = 19–24.9), overweight (OW) (BMI = 25–29.9), obese (OB) (BMI = 30–39.9), and morbid obese (MO) (BMI >40). The groups were well matched with no significant differences in demographics and Injury Severity Score. Morality for the IW group was compared with the remaining BMI groups. A total of 6049 patients were identified. In comparison with IW group, the UW mortality was significantly higher (IW vs UW, 4.1% vs 8.8%, P = 0.001); however, the there was no significant difference with remaining groups. There was also no significant difference in mortality between IW and the remaining groups for patients that went directly to the operating room or for patients that had penetrating trauma (stab wounds and gunshot wounds). However, for blunt trauma, the mortality was significantly higher for UW (IW vs UW, 4.3% vs 9.4%, P = 0.001), no different for IW vs OW (4.3% vs 3.7%, P = 0.3), and significantly lower for IW vs OB (4.3% vs 2.8%, P = 0.04) and for IW vs MO (4.3% vs 1.0%, P = 0.03). After traumatic injuries, it is the underweight patients (BMI <19) and not the obese, that are at a significantly higher risk for overall mortality; this difference is especially evident after blunt trauma where obesity may actually confer a protective role.

Association of Injury Factors, Not Body Mass Index, With Hospital Resource Usage in Trauma Patients

BACKGROUND

Allocating resources appropriately requires knowing whether obese patients use more resources during a hospital stay than nonobese patients.

OBJECTIVES

To determine if trauma patients with different body mass indexes differed in use of resources measured as a multifaceted outcome variable.

METHODS

A trauma registry was used for a retrospective study of adult patients admitted to a midwestern level I trauma center. Patients were stratified into 3 groups: nonobese (normal weight, overweight), obese, and morbidly obese. Three canonical correlation analyses were used to determine the relationship between patient/injury characteristics and hospital resource usage.

RESULTS

In a sample of 9771 patients, 71.2% were non-obese, 23.8% obese, and 5.0% morbidly obese. For patient/injury characteristics, Injury Severity Score and physiological complications were significant variables for all 3 groups. Scores on the Glasgow Coma Scale were significant for nonobese patients only. For resource usage, intensive care unit length of stay and procedures were significant variables for all 3 groups.

CONCLUSIONS

Associations between body mass index and outcomes have been noted when assessed as independent variables. However, when resource usage was assessed as a multifaceted outcome variable, injury factors (higher Injury Severity Score, lower scores on the Glasgow Coma Scale, more physiological complications) were associated with resource usage (increased length of stay in the intensive care unit and increased number of procedures). These findings provide clinicians a new perspective for evaluating the complex relationship between patient/injury characteristics and hospital resource usage.

Body Morphology and Its Associations With Thoracolumbar Trauma Sustained in Motor Vehicle Collisions

OBJECTIVE

This study investigates the relationship between body mass index (BMI) and the patterns of thoracolumbar spinal fractures sustained by patients in motor vehicle collisions (MVCs).

DESIGN

The Crash Injury Research and Engineering Network (CIREN) database was used to analyze prospective data on patients involved in MVCs of moderate severity.

METHODS

Thoracolumbar fractures in 631 subjects were analyzed for patient-, vehicle-, and crash-related factors. Spine injuries were classified according to a modified Denis classification system. Subjects were stratified into BMI subgroups that were then analyzed by injury level, fracture pattern, associated systemic injury, and mortality.

RESULTS

Obesity (BMI ≥ 30.0) was found to be associated with a more cephalad level of injury. Mean BMI was higher in 67 patients with fatal outcomes compared with 557 survivors. Patients who sustained a thoracolumbar fracture and another system injury were more likely to be overweight and obese. Among the various fracture patterns analyzed, BMI was highest in patients with extension injuries.

CONCLUSION

This study characterizes the relationship between body morphology and the thoracolumbar injury patterns associated with MVC to improve understanding of the overall morbidity and mortality of these injuries. These results corroborate research demonstrating the unique relationships between patients who are obese and specific patterns of injury and higher injury severity caused by MVCs and establish a rationale for specifically including thoracolumbar spine parameters in crash safety standards.

Morbid obesity increases the risk for systemic complications in patients with femoral shaft fractures

OBJECTIVES

To determine whether morbidity and mortality were increased in morbidly obese patients who had reamed intramedullary nailing of closed femoral shaft fractures compared with similar patients of normal weight.

DESIGN

Retrospective case-control study.

SETTING

Level I trauma center.

PATIENTS/PARTICIPANTS

All patients with closed femoral shaft fractures treated with reamed intramedullary nailing over a 5-year period were identified. Normal-weight patients (BMI < 25) were compared with overweight (25 ≤ BMI < 30), obese (30 ≤ BMI < 40), and morbidly obese patients (BMI ≥ 40).

INTERVENTION

Reamed intramedullary nailing.

MAIN OUTCOME MEASUREMENTS

Occurrence of postoperative complications.

RESULTS

Of 507 patients with 526 femoral shaft fractures (AO/OTA-32), 184 (36.3%) were of normal weight, 170 (33.5%) were overweight, 114 (22.5%) were obese, and 39 (7.7%) were morbidly obese. There were no significant differences in complications when comparing normal-weight patients with overweight and obese patients. Systemic complications occurred in 23% of morbidly obese and 9% of normal-weight patients [odds ratio (OR) = 3.15, P = 0.013]. Morbid obesity increased odds of adult respiratory distress syndrome (OR = 35.38, P = 0.019) and sepsis (OR = 6.49, P = 0.0015). Overall, morbidly obese patients with a femoral fracture had a mortality rate of 10%, but a subset of polytraumatized patients (Injury Severity Score > 17) had a mortality rate of 20%. Morbid obesity significantly increased the odds of mortality (OR = 46.77, P = 0.01). Body mass index was found to be an independent predictor of adult respiratory distress syndrome, sepsis, and death.

CONCLUSIONS

Morbid obesity is a significant risk factor for systemic complications in patients with closed femoral shaft fractures, especially in polytraumatized patients. Patients and their families need to be counseled regarding the high risk of morbidity and mortality.

LEVEL OF EVIDENCE

Prognostic level II. See Instructions for Authors for a complete description of levels of evidence.

Impact of obesity on mortality and complications in trauma patients

OBJECTIVE

To examine the association between obesity and outcomes in injured patients.

BACKGROUND

The United States is facing an obesity epidemic affecting 1 in 3 adult Americans. Very little is known about the role of obesity in acute illness. Optimal care of obese trauma patients can only be achieved once we gain a better understanding of the impact of severe obesity on trauma outcomes.

METHODS

We conducted a retrospective cohort study of 147,680 patients admitted to 28 level I and level II Pennsylvania trauma centers between 2000 and 2009. Logistic regression was used to examine the association between obesity and in-hospital mortality and major complications, adjusting for injury severity, age, gender, mechanism of injury, systolic blood pressure, and the motor component of the Glasgow Coma Scale, comorbidities, and year of admission. Patients were grouped into predefined weight categories: underweight (<1st percentile), reference (1st-74th percentile), grade 1 obesity (75th-90th percentile), grade 2 obesity (91th-95th percentile), grade 3 obesity (96th-99th percentile), and grade 4 obesity (>99th percentile). Body mass index was not calculated because height data was not available.

RESULTS

After adjusting for injury severity and other risk factors, male patients with severe obesity-grade 3 obesity [adjusted odds ratio (AOR) 1.28; 95% confidence interval (CI): 1.00, 1.64; P = 0.052] or grade 4 obesity (AOR 2.30; 95% CI: 1.48, 3.58; P < 0.001)-were more likely to die than nonobese patients. Severe obesity was associated with an approximately twofold higher risk of major complications: male patients with grade 3 obesity (AOR 1.71; 95% CI: 1.48, 1.97; P < 0. 001) or grade 4 obesity (AOR 2.14; 95% CI: 1.83, 2.51; P < 0.001). Similar results were obtained for female patients. Male and female patients with severe obesity had a 2.5- to 4-fold higher risk of developing acute renal failure. Severely obese females had 2.5- to 4.5-fold higher risk of developing wound complications, and a 4-to 8-fold higher risk of developing decubiti.

CONCLUSIONS

Severely obese trauma patients were at least 30% more likely to die and approximately twice as likely to have a major complication compared with nonobese patients.

Crash characteristics and injury patterns of restrained front seat occupants in far-side impacts

OBJECTIVE

The study was conducted to determine the association between vehicle-, crash-, and demographic-related factors and injuries to front seat far-side occupants in modern environments.

METHODS

Field data were obtained from the NASS-CDS database for the years 2009-2012. Inclusion factors included the following: adult restrained front outboard-seated occupants, no ejection or rollovers, and vehicle model years less than 10 years old at the time of crash. Far-side crashes were determined by using collision deformation classification. Injuries were scored using the Abbreviated Injury Scale (AIS). Injuries (MAIS 2+, MAIS 3+, M denotes maximum score) were examined based on demographics, change in velocity, vehicle type, direction of force, extent zone, collision partner, and presence of another occupant in the front seat. Only weighted data were used in the analysis. Injuries to the head and face, thorax, abdomen, pelvis, and upper and lower extremity regions were studied. Odds ratios and upper and lower confidence intervals were estimated from multivariate analysis.

RESULTS

Out of 519,195 far-side occupants, 17,715 were MAIS 2+ and 4,387 were MAIS 3+ level injured occupants. The mean age, stature, total body mass, and body mass index (BMI) were 40.7 years, 1.7 m, 77.2 kg, and 26.8 kg/m2, respectively. Of occupants with MAIS 2+ injuries, 51% had head and 19% had thorax injuries. Of occupants with MAIS 3+ injuries, 50% had head and 69% had thorax injuries. The cumulative distribution of changes in velocities at the 50th percentile for the struck vehicle for all occupants and occupants with MAIS 2+ and MAIS 3+ injuries were 19, 34, and 42 km/h, respectively. Furthermore, 73% of MAIS 2+ injuries and 86% of MAIS 3+ injuries occurred at a change in velocity of 24 km/h or greater. Odds of sustaining MAIS 2+ and MAIS 3+ injuries increased with each unit increase in change in velocity, stature, and age, with one exception. Odds of sustaining injuries were higher with the presence of an occupant in the front seat at the MAIS 3+ level, although it was reversed at the lower level. The extent zone of 3+ increased the odds compared to the extent zones of 1 to 2 at both MAIS 2+ and MAIS 3+ injuries. Odds ratios and confidence intervals are given.

CONCLUSIONS

The findings are as follows: head and thorax are the more frequently injured body regions, and the prevalence of cranium injuries is similar at both injury severities; thoracic injuries are more prevalent at the MAIS 3+ level; the presence of another front seat occupant plays a role in MAIS 3+ trauma; injuries continue to occur at changes in velocity representative of side impact environments; and mean demographic factors are close to mid-size automotive anthropometry, indicating the need to pursue this line of study. Because data were gathered from only 4 years, it would be important to include additional NASS-CDS database years, rescore injuries from previous years, and analyze other international databases to reinforce these findings for advancing safety for far-side occupants.

Year in review 2012: Critical Care--Out-of-hospital cardiac arrest and trauma

In 2012 Critical Care published many articles pertaining to the resuscitation of out-of-hospital cardiac arrest and trauma. In this review, we summarize several of these articles, including those regarding advances in resuscitation techniques and methods. We examine articles pertaining to prehospital endotracheal intubation, the use of specialized devices for cardiopulmonary resuscitation and policies regarding transport destinations for both cardiac arrest and trauma patients. Articles on the predictors of outcome in both pediatric and adult populations are evaluated, including articles on the effects of obesity on survival from hemorrhage and pediatric outcomes from traumatic cardiac arrest. The effects of the type and volume of resuscitation fluids for both adult and pediatric patients are discussed, as are the factors contributing to hypothermia in trauma patients.

A novel experimental model of orthopedic trauma with acute kidney injury in obese Zucker rats

Obesity is associated with an increased risk of acute kidney injury (AKI) after blunt traumatic injury in humans. Because limitations exist in studying trauma in human patients, animal models are necessary to elucidate mechanisms of remote organ injury after trauma. We developed a model of severe orthopedic trauma in lean (LZ) and obese (OZ) Zucker rats, in which OZ develop greater kidney dysfunction after trauma than LZ. Orthopedic trauma was inflicted via bilateral hindlimb soft tissue injury, fibula fracture, and injection of homogenized bone components. Mean arterial pressure (MAP) and heart rate (HR) were measured for 6 h after trauma, and again at 24 h after trauma. Urine was collected for 24 h before and after trauma to measure urine albumin excretion. Glomerular filtration rate (GFR), renal plasma flow (RPF), plasma interleukin-6 (IL-6), and renal macrophage infiltration (ED-1 [CD68 Antibody] immunostaining) were measured in animals with and without trauma. MAP and HR were similar between LZ and OZ throughout the study, with the exception that OZ had a 18 mmHg lower pressure 24 h posttrauma. GFR and RPF were decreased significantly (∼50%), while urine albumin excretion, plasma IL-6, and renal ED-1-positive cells were increased in OZ 24 h after trauma compared to both OZ without trauma and LZ after trauma. In conclusion, these data are consistent with studies in humans that show that AKI develops more frequently in obese than in lean individuals. This model will be an important experimental tool to better understand the underlying mechanisms of poor outcomes after trauma in obese patients.

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

OBJECTIVE

This study aims to assess the effect of obesity on injury severity score (ISS), mortality and course of hospital stay among trauma patients.

METHOD

A systematic review of the literature was conducted by Internet search. Data were extracted from included studies and analysed using a random-effects model to compare outcomes in the obese (body mass index (BMI)≥30kgm(-2)) with the non-obese (BMI<30kgm(-2)) group.

RESULT

Eventually, 18 studies met our inclusion criteria with 7751 obese patients representing 17% of the pooled study population. The data revealed that obesity was associated with increased risk of mortality, longer stay in the intensive care unit and higher rates of complication. Additionally, obese patients seemed to have longer duration of mechanical ventilation and hospital length of stay but it did not reach statistical significance. No difference was observed in ISS between the two groups.

CONCLUSION

Evidence strongly supports the correlation of obesity with worse prognosis in trauma patients and further studies should target this kind of population for therapy and prevention.

Obesity Does Not Increase Morbidity and Mortality after Laparotomy for Trauma

Obesity has been suggested to be a risk factor for increase morbidity and mortality after trauma and surgery. Trauma laparotomy provides an opportunity to assess the effect of body mass index (BMI) on patients subjected to both trauma and surgery. We hypothesized that obesity would have a deleterious effect on outcomes. A retrospective review was conducted of all patients 18 years of age or older undergoing laparotomy for trauma between July 2001 and June 2011. Patients were stratified according to BMI into the following four groups: underweight (16 to 22 kg/m2), normal (23 to 27 kg/m2), overweight (28 to 34 kg/m2), and obese (35 kg/m2 or higher). Data on the patient's hospital course included length of stay, mortality, respiratory failure, infectious complications, wound dehiscence, and organ failure. A total of 1,297 patients underwent laparotomy. Seven per cent of the study group was obese and 24 per cent was underweight. There was no difference among mean Injury Severity Score, percent of patients arriving in shock, and mean number of units of packed red blood cells administered during their hospital stay. Obese patients had longer intensive care unit and hospital lengths of stay. There were no differences in ventilator days or mortality. Using univariate statistics, obese patients had increased rates of respiratory and renal failure, bacteremia with and without septic shock, and abdominal wound dehiscence. Subjecting the data to logistic regression analysis, BMI was no longer an independent predictor of any complication. Although obese trauma patients do have increased infectious morbidity, wound dehiscence, and a prolonged length of stay, increased BMI is not an independent predictor of increased morbidity or mortality after trauma laparotomy.

Thoraco-abdominal deflection responses of post mortem human surrogates in side impacts

The objective of the present study was to determine the thorax and abdomen deflections sustained by post mortem human surrogate (PMHS) in oblique side impact sled tests and compare the responses and injuries with pure lateral tests. Oblique impact tests were conducted using modular and non-modular load-wall designs, with the former capable of accommodating varying anthropometry. Tests were conducted at 6.7 m/s velocity. Deflection responses from chestbands were analyzed from 15 PMHS tests: five each from modular load-wall oblique, non-modular load-wall oblique and non-modular load- wall pure lateral impacts. The thorax and abdomen peak deflections were greater in non-modular load-wall oblique than pure lateral tests. Peak abdomen deflections were statistically significantly different while the upper thorax deflections demonstrated a trend towards significance. Deflection angulations were statistically significantly different between pure lateral and oblique tests at all regions indicating that it is important to characterize not only the amplitude but also the angle of the vector. Injuries were confined to skeletal regions in pure lateral tests and this was in contrast to the occurrence of both skeletal and soft tissue/organ injury in oblique loading tests, again emphasizing the role of obliqueness in side impacts. Furthermore, injuries in oblique tests were primarily unilateral, paralleling real-world trauma and confirming the applicability of the experimental design to field environments. Potential injury mechanisms are discussed based on anatomical considerations. These findings, albeit from a limited sample size, underscore the need for additional studies to derive human injury tolerance and criteria in oblique side impacts.

Does obesity impact the pattern and outcome of trauma in children?

PURPOSE/BACKGROUND

Childhood obesity is pandemic condition. The effect of obesity on trauma outcomes in children has been relatively understudied. We conducted this study to ascertain the effects of obesity on the hospital outcome of injured children.

METHODS

A retrospective cohort study of patients aged 2 to 18 years admitted to the King Abdul Aziz Medical City between May 2001 and May 2009 was conducted. Patients were categorized as lean (body mass index <95th percentile) and obese (body mass index ≥ 95th percentile). Groups were compared regarding admission demographics, mechanism of injury, pattern of injury, length of stay, intensive care unit admission, ventilation duration, types of procedures performed, injury severity score, and mortality.

RESULT

Nine hundred thirty-three patients were included, of those 55 (5.89%) children were obese. The obese children were older than nonobese (P = .001) and had a higher injury severity score (P = .001) and a lower pediatric trauma score (P = .00), heart rate (P = .0081), and respiratory rate (P = .000). There were no differences between groups with regard to sex, mechanism of injury, and surgical procedures. Obese children were more likely to have rib fractures (P = .02) and pelvic injuries (P = .033). There was no significant association between mortality and obesity (P = .42).

CONCLUSION

Obesity does not seem to impact the severity of injury, mortality rate, types of injury, and procedure outcomes in children. Obese patients are more likely to have rib and pelvic injuries.

Obese patients show a depressed cytokine profile following severe blunt injury

We hypothesized that severely injured obese patients would display increased concentrations of proinflammatory cytokines when compared with patients of normal body mass index (BMI) and that this would be associated with multiple organ failure (MOF). This was a retrospective review of prospectively collected data in the "Inflammation and the Host Response to Injury" trauma-related database. Data were collected prospectively from US level I trauma centers. The subjects were severely injured adult blunt trauma patients. Cytokine concentrations obtained within 12 h of injury and on days 1 and 4 were compared between subjects on the basis of BMI (normal, 18.5-24.9 kg/m, and obese, ≥30 kg/m). Demographic measures, injury severity, cytokine concentrations, and outcome measures were compared between groups. Seventy-four adult blunt trauma victims were evaluated. Relative to patients of normal BMI (n = 34), obese patients (n = 40) demonstrated an overall depressed cytokine response to severe injury, with significantly lower concentrations of several cytokines. Obese patients showed greater incidences of nosocomial infection (60 vs. 45%, not statistically significant) and MOF (63% vs. 44%, not statistically significant) and a later onset of maximum MOF score (5 vs. 3 days, P < 0.04) when compared with those of normal BMI. Despite prior reports suggesting a proinflammatory cytokine profile in obese individuals, obese patients sustaining severe injury show a depressed early cytokine response when compared with patients of normal BMI. This may confer increased susceptibility to nosocomial infection and later MOF. Further study of immune dysfunction in the postinjury obese patient should assess the possibility of early immune suppression.

Obese trauma patients are at increased risk of early hypovolemic shock: a retrospective cohort analysis of 1,084 severely injured patients

INTRODUCTION

Morbid obesity and its consequences are considered risk factors for adverse outcome in trauma, although the pathophysiologic mechanisms are incompletely understood. The aim of this study was to compare initial resuscitation, treatment, and short-term outcome of severely injured patients by body mass index (BMI).

METHODS

A total of 1,084 severely injured patients with an injury severity score of 16 or greater were enrolled between 1996 and 2009 and grouped according to BMI. Their course of treatment and in-hospital outcome were analyzed by univariate and multivariate comparison.

RESULTS

Of these patients, 603 (55.6%) were of normal weight with a BMI between 18.5 and 24.9, 361 (33.3%) had BMI values between 25 and 29.9, and 90 patients (8.3%) were obese (BMI ≥ 30). Thirty patients (2.8%) had BMI levels below 18.5. All groups were comparable with respect to injury severity, initial resuscitation, and time to ICU admission. There was a tendency towards higher mortality in obese patients (mortality 24.4%) and also overweight patients (mortality 18.8%) when compared with patients with a normal BMI (mortality 16.6%). Obese patients showed the highest mortality on day 0 (8.9% vs. 2.8% in the normal-weight group, P = 0.023), mostly due to persistent shock (6.7%). When corrected for BMI, obese patients are provided significantly lower volumes of intravenous fluids during the initial resuscitation period.

CONCLUSION

In contrast to the mostly American literature, only a low percentage of trauma patients at a European trauma center are obese. These patients are at risk of higher mortality from persistent hemorrhagic shock in the initial phase after trauma, which may potentially be related to relative hypovolemia during the resuscitation period. In the later course of treatment, no significant differences exist with respect to specific complications, hospital stay, or in-hospital mortality.

Prediction models for complications in trauma patients

BACKGROUND

Because the death rate among the total trauma population is low, other performance indicators in addition to the classical dependent variable mortality are required to assess the overall quality of trauma care. The aim of this study was to develop and validate a prediction model for the occurrence of complications that can be used to adjust a measure of quality of trauma care for case mix.

METHODS

Complications recorded in a trauma registry between 1997 and 2008 were analysed. Formulas for different types of complication (institution- or diagnosis-related) derived from logistic regression models were used to calculate the probability of absence of complications (PAC). Discriminative power was tested by calculating the area under the receiver operating characteristic curve (AUC) in test and validation samples. Calibration was tested using Hosmer and Lemeshow methodology.

RESULTS

Some 5944 surgical trauma admissions were included in the analysis. A significant association between both institution- and diagnosis-related complications and Injury Severity Score was found. Diagnosis-related complications were also associated with Glasgow Coma Score and age. The AUCs of the PACs for institution- and diagnosis-related complications were 0·64 and 0·75 respectively in the test sample, and 0·66 and 0·76 in the validation sample. The AUCs increased when the outcomes of the models were divided into subcategories of complications. Hosmer and Lemeshow tests were not significant for all models, except that for institutional complications.

CONCLUSION

To predict complications, a distinction should be made between institution- and diagnosis-related complications. The development of more detailed diagnosis-related prediction models is preferable because of better performance. The formulas predicting the PAC can be used to compare expected and observed complications.

Body adipose content is independently associated with a higher risk of organ failure and nosocomial infection in the nonobese patient postinjury

OBJECTIVE

Obesity defined by a body mass index (BMI) >30 kg/m is associated with increased morbidity and mortality following trauma. Evidence suggests that obesity represents a state of chronic inflammation and that the adipose tissue content may affect the intensity and resolution of inflammatory response. We sought to avoid the confounding effects attributable to obesity and determine the association of BMI and outcomes following injury in nonobese patients.

METHODS

Data were obtained from a multicenter prospective cohort study evaluating outcomes in blunt-injured adults with hemorrhagic shock. Only patients with a BMI≥18.5 and<30 were analyzed. Those with isolated traumatic brain injury and cervical cord injury and those who survived<24 hours were excluded. Logistic regression was used to evaluate the effects of BMI on mortality, multiple organ failure (MOF, multiple organs dysfunction score [MODS]>5), and nosocomial infection (NI) after adjusting for differences in demographics, injury severity, early resuscitation needs, shock parameters, and comorbidities.

RESULTS

Overall mortality, MOF, and NI rates for the study cohort (n=820) were 13%, 37%, and 46%, respectively. Median Injury Severity Score was 33 (interquartile range, 22-41). Median BMI for the study cohort was 25 (interquartile range, 23-27). As BMI increased, maximum organ dysfunction scores also significantly increased for cardiac, respiratory, and renal systems. Logistic regression revealed no significant association with mortality (odds ratio [OR]=0.95; 95% confidence interval [CI], 0.9-1.0); however, BMI was independently associated with a higher risk of MOF (OR=1.09; 95% CI, 1.02-1.06) and NI (OR=1.07; 95% CI, 1.01-1.13). For every single-point increase in BMI, the risk of MOF and NI increase by 9% and 7%, respectively.

CONCLUSION

The risk of MOF and NI increases as BMI increases in the nonobese injured patient. These results suggest that body adipose content may be associated with the magnitude of or extent of the inflammatory response postinjury. Further studies are needed to elucidate the mechanism responsible for this association.

Glucose Metabolism, Not Obesity, Predicts Mortality in Critically Ill Surgical Patients

Our hypothesis was to determine if insulin resistance and hyperglycemia, rather than obesity, are predictive of mortality in the surgically critically ill. An observational study of an automated protocol in surgical and trauma intensive care units was performed. Two groups were created based on body mass index (BMI): Obese (OB) defined as BMI ≥ 30 (n = 338) and nonobese defined as BMI < 30 (n = 885). Euglycemia was maintained using an automated protocol using an adapting multiplier, which we used as our marker of stress insulin resistance. The primary outcome was hospital mortality. One thousand, two hundred and twenty-three patients met criteria with 73,225 glucose values. The OB group required more insulin (4.5 U/hr vs 3.2 U/hr, P ≤ 0.01) and had a higher mean multiplier (0.07 vs 0.06, P < 0.01) reflecting insulin resistance. There was no difference in mortality between OB and nonobese (11.6% vs 11.5%, P = 0.96). Logistic regression showed that insulin dose (odds ratio 0.864; 95% confidence interval 0.772-0.967, P = 0.01), and not BMI, was an independent predictor of survival in this population. Obesity is not an independent risk factor for mortality in the surgical critical care population. Insulin resistance and subsequent hyperglycemia are increased in obesity and are independent predictors of mortality.

Traditional resuscitative practices fail to resolve metabolic acidosis in morbidly obese patients after severe blunt trauma

BACKGROUND

Obesity is a risk factor for postinjury complications; in particular, obese patients develop multiple organ failure (MOF) at a greater rate than do normal weight counterparts. Evaluation of differences in resuscitative practices altered by body mass index (BMI) might provide an explanation for the increased risk of MOF seen in these high-risk patients.

METHODS

We used prospectively collected multicenter data to retrospectively compare patients grouped by BMI with regard to resuscitation volumes and traditional end points during the first 48 hours after injury. Marshall MOF score was used as the primary outcome measure.

RESULTS

One thousand sixty-six patients were analyzed, with 877 meeting inclusion and exclusion criteria. All patients received similar volumes of resuscitation per kilogram lean and ideal body weight. Morbidly obese patients attained greater central venous pressures but otherwise differed little in attainment of standard cardiovascular end points. Despite this, morbidly obese patients resolved base deficit more slowly and remained in metabolic acidosis for 48 hours postinjury. Morbidly obese patients with persistent metabolic acidosis developed MOF at a significantly greater rate than did normal weight patients with or without persistent metabolic acidosis.

CONCLUSIONS

Morbidly obese trauma patients show prolonged metabolic acidosis despite receiving similar volumes and attaining similar end points of resuscitation when compared with patients in other BMI groups. Inadequate resuscitation based on inaccurate end points and metabolic disturbances associated with increased BMI are likely responsible; identification of the etiology, sources, and consequences of this acidosis may provide further insight into the susceptibility of the morbidly obese patient to develop postinjury organ failure.

Differences in outcome between obese and nonobese patients following severe blunt trauma are not consistent with an early inflammatory genomic response

OBJECTIVES

Obesity has been demonstrated to alter a number of acute and chronic medical conditions. The effect of obesity on severely injured patients, however, remains incompletely defined. We sought to unravel potential physiologic and genomic alterations induced by obesity in severely injured blunt trauma patients.

DESIGN

A retrospective review of clinical and genomic information contained in the Inflammation and the Host Response to Injury multicenter trauma-related database examining the relationship between body mass index and the early genomic response from peripheral blood leukocytes to patient outcome following severe blunt trauma was performed.

SETTING

Multicenter collaboration between university-based academic trauma centers.

PATIENTS

Severely injured blunt trauma patients enrolled in the database.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Univariate analysis of 455 severely injured trauma patients using the National Institutes of Health/World Health Organization body mass index classification system revealed significant increases in morbidity, including longer intensive care unit stays and a greater number of ventilator days, cardiac arrests, episodes of acute renal failure, and patients developing multiple organ failure. Regression modeling identified body mass index class as being independently associated with adverse outcomes and increased morbidity but an inverse relationship with mortality in patients who suffered severe blunt traumatic injury. Initial leukocyte genomic expression patterns between 163 patients in the four different body mass index groupings did not differ; however, analysis of gene differences between body mass index classes occurring over time demonstrated significant changes in 513 probe sets with significant pathway differences being related to cellular metabolism.

CONCLUSIONS

Increasing body mass index is associated with increased morbidity following severe blunt trauma. The initial blood leukocyte inflammatory response to blunt trauma does not appear to differ significantly between patients despite increasing body mass index. Resolution of the inflammatory response may differ between patients on the basis of body mass index; however, additional work is needed to clarify the potential causality of this finding.

Obesity and site-specific nosocomial infection risk in the intensive care unit

BACKGROUND

Obese patients are at higher than normal risk for postoperative infections such as pneumonia and surgical site infections, but the relation between obesity and infections acquired in the intensive care unit (ICU) is unclear. Our objective was to describe the relation between body mass index (BMI) and site-specific ICU-acquired infection risk in adults.

METHODS

Secondary analysis of a large, dual-institutional, prospective observational study of critically ill and injured surgical patients remaining in the ICU for at least 48 h. Patients were classified into BMI groups according to the National Heart, Lung and Blood Institute guidelines: <or= 18.5 kg/m(2) (underweight), 18.5-24.9 kg/m(2) (normal), 25-29.9 kg/m(2) (overweight), 30.0-39.9 kg/m(2) (obese), and >or= 40.0 kg/m(2) (severely obese). The primary outcomes were the number and site of ICU-acquired U.S. Centers for Disease Control and Prevention-defined infections. Multivariable logistic and Poisson regression were used to determine age-, sex-, and severity-adjusted odds ratios (ORs) and incidence rate ratios associated with differences in BMI.

RESULTS

A total of 2,037 patients had 1,436 infection episodes involving 1,538 sites in a median ICU length of stay of 9 days. After adjusting for age, sex, and illness severity, severe obesity was an independent risk factor for catheter-related (OR 2.2; 95% confidence interval [CI] 1.5, 3.4) and other blood stream infections (OR 3.2; 95% CI 1.9, 5.3). Cultured organisms did not differ by BMI group.

CONCLUSION

Obesity is an independent risk factor for ICU-acquired catheter and blood stream infections. This observation may be explained by the relative difficulty in obtaining venous access in these patients and the reluctance of providers to discontinue established venous catheters in the setting of infection signs or symptoms.

Childhood obesity: a risk factor for injuries observed at a level-1 trauma center

PURPOSE

Obesity is an independent risk factor in trauma-related morbidity in adults. The purpose of this study was to investigate the effect of obesity in the pediatric trauma population.

METHODS

All patients (6-20 years) between January 2004 and July 2007 were retrospectively reviewed and defined as non-obese (body mass index [BMI] <95th percentile for age) or obese (BMI > or =95th percentile for age). Groups were compared for differences in demographics, initial vital signs, mechanisms of injury, length of stay, intensive care unit stay, ventilator days, Injury Severity Score, operative procedures, and clinical outcomes.

RESULTS

Of 1314 patients analyzed, there were 1020 (77%) nonobese patients (mean BMI = 18.8 kg/m(2)) and 294 (23%) obese patients (mean BMI = 29.7 kg/m(2)). There was no significant difference in sex, heart rate, length of stay, intensive care unit days, ventilator days, Injury Severity Score, and mortality between the groups. The obese children were significantly younger than the nonobese children (10.9 +/- 3.3 vs 11.5 +/- 3.5 years; P = .008) and had a higher systolic blood pressure during initial evaluation (128 +/- 17 vs 124 +/- 16 mm Hg, P < .001). In addition, the obese group had a higher incidence of extremity fractures (55% vs 40%; P < .001) and orthopedic surgical intervention (42% vs 30%; P < .001) but a lower incidence of closed head injury (12% vs 18%; P = .013) and intraabdominal injuries (6% vs 11%; P = .023). Evaluation of complications showed a higher incidence of decubitus ulcers (P = .043) and deep vein thrombosis (P = .008) in the obese group.

CONCLUSION

In pediatric trauma patients, obesity may be a risk factor for sustaining an extremity fracture requiring operative intervention and having a higher risk for certain complications (ie, deep venous thrombosis [DVT] and decubitus ulcers) despite having a lower incidence of intracranial and intraabdominal injuries. Results are similar to reports examining the effect(s) of obesity on the adult population.

Impact of obesity in damage control laparotomy patients

BACKGROUND

Obesity is an independent predictor of increased morbidity and mortality in critically injured trauma patients. We hypothesized that obese patients in need of damage control laparotomy (DCL) will encounter an increase incidence of postsurgical complications with a concomitant increase mortality when compared with a cohort of nonobese patients.

METHODS

All adult trauma patients who underwent DCL during a 4-year period at a Level I Trauma Center were retrospectively reviewed. Patients were categorized into nonobese (body mass index [BMI] < or = 29 kg/m), obese (BMI 30-39 kg/m), and severely obese (BMI > or = 40 kg/m) groups. Outcome measures included the occurrence of postoperative infectious complications, failure of primary abdominal wall fascial closure, acute respiratory distress syndrome, acute renal insufficiency, multiple system organ failure, days of ventilator support, hospital length of stay, and death.

RESULTS

During a 4-year period, 12,759 adult trauma patients were admitted to our Level I Trauma Center of which 1,812 (14.2%) underwent emergent laparotomy. Of these, 104 (5.7%) were treated with DCL: nonobese, n = 51 (49%); obese, n = 38 (37%); and severely obese, n = 15 (14%). In a multivariate adjusted model, multiple system organ failure was 1.82 times more likely in severely obese (95% CI: 1.14-2.90) and 1.74 times more likely in the obese patients (95% CI: 1.14-2.66) when compared with patients with normal BMI after DCL (p < 0.01). In the severely obese patients undergoing DCL, significantly elevated prevalence ratios (PR) for development of postoperative infectious complications, acute renal insufficiency, and failure of primary abdominal wall fascial closure were 1.75, 3.07, and 2.62, respectively. Days of ventilator support, length of stay, and mortality rates were significantly higher in severely obese patients (24 days, 27 days, and 60%) compared with obese (14 days, 14 days, and 21%) and nonobese (9.8 days, 14 days, and 28%) patients.

CONCLUSION

Severe obesity was significantly associated with adverse outcomes and increased resource utilization in trauma patients treated with DCL. Measures to improve outcomes in this vulnerable patient population must be directed at multiple levels of health care.

The impact of obesity on outcomes after critical illness: a meta-analysis

PURPOSE

To assess whether obesity is associated with mortality or other adverse intensive care unit (ICU) and post-ICU outcomes.

METHODS

A meta-analysis of studies from PubMed and EMBASE databases.

RESULTS

Twenty-two studies (n = 88,051 patients) were included. Pooled analysis demonstrated no difference in ICU mortality, but lower hospital mortality for obese and morbidly obese subjects (RR 0.76; 95% CI 0.59, 0.92; RR 0.83; 95% CI 0.66, 1.04, respectively) versus normal weight subjects. There was no association between obesity and duration of mechanical ventilation or ICU stay. Morbidly obese versus normal weight patients had longer hospitalizations. No study reported physical function, mental health, or quality of life outcomes after discharge.

CONCLUSIONS

Obesity is not associated with increased risk for ICU mortality, but may be associated with lower hospital mortality. There is a critical lack of research on how obesity may affect complications of critical illness and patient long-term outcomes.

Obesity and vulnerability of the CNS

The incidence of obesity is increasing worldwide, and is especially pronounced in developed western countries. While the consequences of obesity on metabolic and cardiovascular physiology are well established, epidemiological and experimental data are beginning to establish that the central nervous system (CNS) may also be detrimentally affected by obesity and obesity-induced metabolic dysfunction. In particular, data show that obesity in human populations is associated with cognitive decline and enhanced vulnerability to brain injury, while experimental studies in animal models confirm a profile of heightened vulnerability and decreased cognitive function. This review will describe findings from human and animal studies to summarize current understanding of how obesity affects the brain. Furthermore, studies aimed at identifying key elements of body-brain dialog will be discussed to assess how various metabolic and adipose-related signals could adversely affect the CNS. Overall, data suggest that obesity-induced alterations in metabolism may significantly synergize with age to impair brain function and accelerate age-related diseases of the nervous system. Thus, enhanced understanding of the effects of obesity and obesity-related metabolic dysfunction on the brain are especially critical as increasing numbers of obese individuals approach advanced age.

Obesity and pulmonary complications in critically injured adults

BACKGROUND

Pulmonary complications following injury significantly contribute to subsequent mortality. Obese patients have preexisting risk factors for pulmonary complications, and are at risk for these complications following elective surgery. Whether or not obesity contributes to pulmonary complications after critical injury is poorly understood.

METHODS

A secondary analysis of a prospective cohort study of critically injured adults requiring at least 48 h of intensive care was performed. Patients were classified into the following body mass index groups: < or = 18.5 kg/m2 (underweight); 18.5 to 24.9 kg/m2 (normal); 25 to 29.9 kg/m2 (overweight); 30.0 to 39.9 kg/m2 (obese); and > or = 40.0 kg/m2 (severely obese). Outcomes included the rates of ARDS and pneumonia, the placement of a tracheostomy tube, and in-hospital mortality rate.

RESULTS

A total of 1,291 patients were available for analysis, and 30% of these patients were classified as either obese or severely obese. The age-, gender-, and severity-adjusted rate of ARDS was lower in severely obese patients (odds ratio, 0.36; 95% confidence interval [CI], 0.13 to 0.99) compared to normal weight patients. The rates of pneumonia (37%), tracheostomy (10%), and in-hospital mortality (11%) did not differ among the groups. Despite no difference in pulmonary complications, the severely obese group had an ICU length of stay that was 4.8 days (95% CI, 1.8 to 7.7 days) longer than the normal weight group.

CONCLUSION

Obesity does not appear to be an independent risk factor for increased pulmonary complications after critical injury, but severely obese patients are likely to require longer ICU stays.

Effect of obesity on intensive care morbidity and mortality: a meta-analysis

OBJECTIVE

To evaluate the effect of obesity on intensive care unit mortality, duration of mechanical ventilation, and intensive care unit length of stay among critically ill medical and surgical patients.

DESIGN

Meta-analysis of studies comparing outcomes in obese (body mass index of > or = 30 kg/m2) and nonobese (body mass index of < 30 kg/m2) critically ill patients in intensive care settings.

DATA SOURCE

MEDLINE, BIOSIS Previews, PubMed, Cochrane library, citation review of relevant primary and review articles, and contact with expert informants.

SETTING

Not applicable.

PATIENTS

A total of 62,045 critically ill subjects.

INTERVENTIONS

Descriptive and outcome data regarding intensive care unit mortality and morbidity were extracted by two independent reviewers, according to predetermined criteria. Data were analyzed using a random-effects model.

MEASUREMENTS AND MAIN RESULTS

Fourteen studies met inclusion criteria, with 15,347 obese patients representing 25% of the pooled study population. Data analysis revealed that obesity was not associated with an increased risk of intensive care unit mortality (relative risk, 1.00; 95% confidence interval, 0.86-1.16; p = .97). However, duration of mechanical ventilation and intensive care unit length of stay were significantly longer in the obese group by 1.48 days (95% confidence interval, 0.07-2.89; p = .04) and 1.08 days (95% confidence interval, 0.27-1.88; p = .009), respectively, compared with the nonobese group. In a subgroup analysis, an improved survival was observed in obese patients with body mass index ranging between 30 and 39.9 kg/m2 compared with nonobese patients (relative risk, 0.86; 95% confidence interval, 0.81-0.91; p < .001).

CONCLUSION

Obesity in critically ill patients is not associated with excess mortality but is significantly related to prolonged duration of mechanical ventilation and intensive care unit length of stay. Future studies should target this population for intervention studies to reduce their greater resource utilization.

Body Mass Index and Outcomes in Critically Injured Blunt Trauma Patients: Weighing the Impact

BACKGROUND

The influence of increased body mass index (BMI) on morbidity and mortality in critically injured trauma patients has been studied, with conflicting results. The objective of this study was to investigate the relationship between stratified BMI and outcomes in blunt injured patients.

STUDY DESIGN

Consecutive adult trauma patients from July 2001 to November 2005 with Injury Severity Score (ISS) > or = 16 and blunt mechanism were evaluated using the National Trauma Registry of the American College of Surgeons. Demographics, injury severity, hospital course, complications, and mortality were compared among standard BMI strata. Logistic regression was used to determine odds ratios (OR) with 95% confidence intervals and evaluate BMI as an independent risk factor for morbidity and mortality. Statistical significance was set at p < 0.05.

RESULTS

The study group consisted of 1,543 patients. Controlling for age, gender, Injury Severity Score, and Revised Trauma Score, and using BMI 18.5 to 24.9 kg/m(2) as the reference category, morbid obesity (BMI> or =40 kg/m(2)) was associated with acute respiratory distress syndrome (OR 3.675, 95% CI, 1.237 to 10.916), acute respiratory failure (OR 2.793, 95% CI, 1.633 to 4.778), acute renal failure (OR 13.506, 2.388 to 76.385), multisystem organ failure (OR 2.639, 95% CI, 1.085 to 6.421), pneumonia (OR 2.487, 95% CI, 1.483 to 4.302), urinary tract infection (OR 2.332, 95% CI, 1.229 to 4.427), deep venous thrombosis (OR 4.112, 95% CI, 1.253 to 13.496), and decubitus ulcer (OR 2.841, 95% CI, 1.382 to 5.841). Morbid obesity was not associated with increased mortality (OR 0.810, 95% CI, 0.353 to 1.856).

CONCLUSIONS

This is the largest study to date evaluating the relationship between BMI and outcomes in critically injured trauma patients. Increasing BMI increases morbidity while having no proved influence on mortality.