Prevalence of obesity and the effect on length of mechanical ventilation and length of stay in intensive care patients: A single site observational study

Goals of Care, Critical Care Utilization and Clinical Outcomes in Obese Patients Admitted under General Medicine

Obesity is associated with long-term morbidity and mortality, but it is unclear if obesity affects goals of care determination and intensive care unit (ICU) resource utilization during hospitalization under a general medicine service. In a cohort of 5113 adult patients admitted under general medicine, 15.3% were obese. Patients with obesity were younger and had a different comorbidity profile than patients who were not obese. In age-adjusted regression analysis, the distribution of goals of care categories for patients with obesity was not different to patients who were not obese (odds ratio for a lower category with more limitations, 0.94; 95% confidence interval [CI]: 0.79-1.12). Patients with obesity were more likely to be directly admitted to ICU from the Emergency Department, require more ICU admissions, and stayed longer in ICU once admitted. Hypercapnic respiratory failure and heart failure were more common in patients with obesity, but they were less likely to receive mechanical ventilation in favor of non-invasive ventilation. The COVID-19 pandemic was associated with 16% higher odds of receiving a lower goals of care category, which was independent of obesity. Overall hospital length of stay was not affected by obesity. Patients with obesity had a crude mortality of 3.8 per 1000 bed-days, and age-adjusted mortality rate ratio of 0.75 (95% CI: 0.49-1.14) compared to patients who were not obese. In conclusion, there was no evidence to suggest biased goals of care determination in patients with obesity despite greater ICU resource utilization.

The association between BMI trajectories and bronchopulmonary dysplasia among very preterm infants

OBJECTIVE

To investigate the association between change in body mass index (BMI) from birth to 36 weeks gestation (ΔBMI) and bronchopulmonary dysplasia (BPD) among infants born <30 weeks gestation.

METHODS

This was a multicenter retrospective cohort study (2015-2018) of infants born <30 weeks gestation and alive at ≥34 weeks corrected. Main exposure was a change in BMI z score from birth to 36 weeks corrected age grouped into quartiles of change. Association between ΔBMI z scores and BPD was assessed using generalized linear mixed models.

RESULTS

Among 772 included infants, 51% developed BPD. From birth to 36 weeks CGA, the weight z score of infants with BPD decreased less than for BPD-free infants, despite a greater decrease in length z score and similar caloric intake resulting in increases in BMI z score (median [IQR], 0.16 [-0.64; 1.03] vs -0.29 [-1.03; 0.49]; P < 0.01). In the adjusted analysis, higher ΔBMI z score quartiles were associated with higher odds of BPD (Q3 vs Q2, AOR [95% CI], 2.02 [1.23; 3.31] and Q4 vs Q2, AOR [95% CI], 2.00 [1.20; 3.34]).

CONCLUSION

Among preterm infants, an increase in BMI z score from birth to 36 weeks corrected is associated with higher odds of BPD.

IMPACT

Preterm infants with evolving lung disease often experience disproportionate growth in the neonatal period. In this multicenter cohort study, increases in BMI z score from birth to 36 weeks CGA were associated with higher odds of BPD. Despite similar caloric intake, infants with BPD had a higher weight- but lower length-for-age, resulting in higher BMI z score compared to BPD-free infants. This suggests that infants with evolving BPD may require different growth and nutritional targets compared to BPD-free infants.

Postoperative Complications in Obese Patients After Tracheostomy

OBJECTIVE

To determine the prevalence of varying classes of obesity in patients undergoing tracheostomy and the associated complication rates as compared with nonobese patients.

STUDY DESIGN

A retrospective chart review was performed from 2012 to 2018 on all patients who underwent open tracheostomy by the Department of Otolaryngology-Head and Neck Surgery.

SETTING

All tracheostomies were performed at a single tertiary care center.

METHODS

Patients were classified by body mass index (BMI) according to the World Health Organization classification system: underweight (<18.5), normal-overweight (18.5-29.9), class I (30-34.9), class II (35-39.9), and class III (>40). Charts were reviewed for patient demographic information, Charlson Comorbidity Index score, surgical indication, operative time, tracheostomy tube type, and postoperative complications.

RESULTS

A total of 387 patients (mean ± SD BMI, 31.3 ± 14.2) were identified per the inclusion/exclusion criteria. Of patients with BMI >30 (n=153), 34.6% were categorized as obesity class I, 29.4% as class II, and 35.9% as class III. The most common indication for tracheostomy was malignancy in nonobese patients (41.5%) and respiratory failure for obese patients (58.2%). Operative time was significantly longer in obese patients, and most of these patients required an extended-length tracheostomy tube. Patients with a BMI >40 had higher rates of multiple postoperative complications or death (P = .009). Underweight patients also had a higher rate of complication than normal-overweight patients (P = .016).

CONCLUSION

Class III and underweight patients had higher rates of postoperative complications, which should be taken into consideration during perioperative counseling.

Dose-Response Meta-Analysis of the Impact of Body Mass Index on Mortality in the Intensive Care Unit

INTRODUCTION

Both low and high body mass index (BMI) are associated with mortality in the intensive care unit (ICU). Although many studies have been done to determine the relationship between BMI and risk of mortality in the ICU, their results were inconsistent. This study aimed to conduct a dose-response meta-analysis of published observational studies to assess the effect of BMI on the risk of mortality in patients admitted to the ICU.

METHODS

PubMed, Scopus, and Google Scholar were searched to identify articles up to May 2019. A total of 31 relevant articles, with 238,961 patients and a follow-up period of 1 month to 11 years, were analyzed.

RESULTS

Linear analysis showed a 0.6% decrease in mortality rate per unit (kg/m² ) increase in BMI (odds ratio: 0.99; 95% CI, 0.98-0.99). In addition, nonlinear analysis showed a decrease in risk of mortality for a BMI of 35 (P < .001) and then increased the risk of mortality with a BMI > 35 (P < .001).

CONCLUSION

This dose-response meta-analysis revealed that a BMI ≤ 35 can be a protective agent against mortality, but a BMI > 35 is a life-threatening factor in patients admitted to the ICU.

The Effects of Obesity on Outcome in Preclinical Animal Models of Infection and Sepsis: A Systematic Review and Meta-Analysis

BACKGROUND

Clinical studies suggest obesity paradoxically increases survival during bacterial infection and sepsis but decreases it with influenza, but these studies are observational. By contrast, animal studies of obesity in infection can prospectively compare obese versus nonobese controls. We performed a systematic review and meta-analysis of animal investigations to further examine obesity's survival effect in infection and sepsis.

METHODS

Databases were searched for studies comparing survival in obese versus nonobese controls. We performed a systematic review and meta-analysis of animal investigations to further examine obesity's survival effect in infection and sepsis. Methods. Databases were searched for studies comparing survival in obese versus nonobese animals following bacteria, lipopolysaccharide, or influenza virus challenges.

RESULTS

Twenty-one studies (761 obese and 603 control animals) met the inclusion criteria. Obesity reduced survival in 19 studies (11 significantly) and the odds ratio (95% CI) of survival (0.21(0.13, 0.35); I ² = 64%, p < 0.01p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 31%, p=0.20 and n = 5, 0.22(0.13, 0.36); I ² = 0%, p=0.59, respectively), (2) not significantly with cecal ligation and puncture (n = 4, 0.72(0.08, 6.23); I ² = 75%, p < 0.01), and (3) significantly with influenza but with high heterogeneity (n = 6, 0.12(0.04, 0.34); I ² = 73%, p < 0.01). Obesity's survival effects did not differ significantly comparing the four challenge types (p=0.49). Animal models did not include antimicrobials or glycemic control and study quality was low.

CONCLUSIONS

Preclinical and clinical studies together emphasize the need for prospective studies in patients accurately assessing obesity's impact on survival during severe infection.

Impact of obstructive sleep apnea on the obesity paradox in critically ill patients

OBJECTIVE

Patients admitted to an intensive care unit (ICU) frequently suffer from multiple chronic diseases, including obstructive sleep apnea (OSA). Until recently OSA was not considered as a key determinant in an ICU patient's prognosis. The objective of this study was to document the impact of OSA on the prognosis of ICU patients.

METHODS

Data were retrospectively collected concerning adult patients admitted to ICU at two university hospitals. In a nested study OSA status was checked using the hospital electronic medical records to identify exposed and unexposed cases. The following outcomes were considered: length of stay in the ICU, ICU mortality, in-hospital mortality, ventilator-associated pneumonia (VAP).

RESULTS

Out of 5146 patients included in the study, 289 had OSA at ICU admission (5.6%). After matching, the overall impact of OSA on length of ICU stay was not significant (p = .24). In a predefined subgroup analysis, there was a significant impact of OSA on the length of ICU stay for patients with BMI over 40 kg/m² (IRR: 1.56 [1.05; 2.32], p = .03). OSA status had no impact on ICU or hospital mortality and VAP.

CONCLUSION

In general, known OSA did not increase the ICU stay except for patients with both OSA and morbid obesity.

Male patients with diabetes undergoing coronary artery bypass grafting have increased major adverse cerebral and cardiovascular events

OBJECTIVES

The role of body mass index (BMI) in the prognosis of patients with diabetes undergoing coronary artery bypass grafting (CABG) has been of great interest for a long time. However, the precise relationship between BMI and major adverse cerebral and cardiovascular events (MACCEs) in these patients is still unclear. The goal of this study was to investigate the outcome of patients with diabetes with different BMIs undergoing CABG and the results from the 5-year follow-up.

METHODS

This study included 771 patients with diabetes undergoing CABG from 1 January 2003 to 31 December 2009. They were classified based on the Chinese standard for BMI as follows: underweight: <18.5 kg/m2; normal weight: 18.5-23.9 kg/m2; overweight: 24-27.9 kg/m2; and obese: >28 kg/m2. Short-term outcomes and 5-year MACCEs were compared among various BMI groups after surgery.

RESULTS

Obese and overweight patients with diabetes tended to be younger than normal weight patients [57 years (49-64) vs 62 years (54-68) and 64 years (59-69); P < 0.001]. There were fewer male patients (25.20% vs 17.78% and 16.54%, P = 0.041). More smokers were in the 2 groups (38.8% vs 51.55% and 57.14%, P < 0.001). Glucose concentration was highest in the overweight group [6.40 (5.40-7.80) vs 6.96 (5.69-8.22) and 6.80 (5.90-8.40); P = 0.041)]. Cox regression analysis of the 5-year follow-up data indicated that various BMI groups were not associated with significant differences in 5-year MACCEs; however, male sex was the risk factor for MACCEs (hazard ratio 1.83, 95% confidence interval 1.11-3.04; P = 0.019).

CONCLUSIONS

The BMI of the patients with diabetes undergoing CABG had no effect on MACCEs. Male sex was the risk factor in these patients.

A latent class analysis of prolonged mechanical ventilation patients at a long-term acute care hospital: Subtype differences in clinical outcomes

RATIONALE

Patients on prolonged mechanical ventilation (PMV) at Long-Term Acute Care Hospital's (LTACHs) are clinically heterogeneous making it difficult to manage care and predict clinical outcomes.

OBJECTIVES

Identify and describe subgroups of patients on PMV at LTACHs and examine for group differences.

METHODS

Latent class analysis was completed on data obtained during medical record review at Midwestern LTACH.

MAIN RESULTS

A three-class solution was identified. Class 1 contained young, obese patients with low clinical and co-morbid burden; Class 2 contained the oldest patients with low clinical burden but multiple co-morbid conditions; Class 3 contained patients with multiple clinical and co-morbid burdens. There were no differences in LTACH length of stay [F(2,246) = 2.243, p = 0.108] or number of ventilator days [F(2,246) = 0.641, p = 0.528]. Class 3 patients were less likely to wean from mechanical ventilation [χ2(2, N = 249) = 25.48, p < 0.001] and more likely to die [χ2(2, N = 249) = 23.68, p < 0.001].

CONCLUSION

Patient subgroups can be described that predict clinical outcomes. Class 3 patients are at higher risk for poor clinical outcomes when compared to patients in Class 1 or Class 2.

Controversies when using mechanical ventilation in obese patients with and without acute distress respiratory syndrome

INTRODUCTION

As the prevalence of obesity increases, so does the number of obese patients undergoing surgical procedures and being admitted into intensive care units. Obesity per se is associated with reduced lung volume. The combination of general anaesthesia and supine positioning involved in most surgeries causes further reductions in lung volumes, thus resulting in alveolar collapse, decreased lung compliance, increased airway resistance, and hypoxemia. These complications can be amplified by common obesity-related comorbidities. In otherwise healthy obese patients, mechanical ventilation strategies should be optimised to prevent lung damage; in those with acute distress respiratory syndrome (ARDS), strategies should seek to mitigate further lung damage. Areas covered: This review discusses non-invasive and invasive mechanical ventilation strategies for surgical and critically ill adult obese patients with and without ARDS and proposes practical clinical insights to be implemented at bedside both in the operating theatre and in intensive care units. Expert opinion: Large multicentre trials on respiratory management of obese patients are required. Although the indication of lung protective ventilation with low tidal volume is apparently translated to obese patients, optimal PEEP level and recruitment manoeuvres remain controversial. The use of non-invasive respiratory support after extubation must be considered in individual cases.

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.