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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 5  |  Issue : 1  |  Page : 29-32

Outcomes in obese patients undergoing rib stabilization at a single institution over 9 years


Division of Trauma, Critical Care and General Surgery, Mayo Clinic College of Medicine and Science, Rochester, MN, USA

Date of Web Publication24-Dec-2020

Correspondence Address:
Nathaniel Robinson
Mayo Clinic College of Medicine and Science, 200 1st Street SW, Rochester, MN
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jctt.jctt_8_20

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  Abstract 


Background: We hypothesized that obese patients undergoing rib stabilization would have a smaller ratio of ribs repaired to those fractured, increased days to operation, increased length of operation, were mechanically ventilated longer, required a longer stay in the intensive care unit (ICU) and hospital, and had an increased risk of developing pneumonia.
Materials and Methods: This was a retrospective evaluation of patients who underwent surgical rib stabilization after trauma at a single institution over 9 years. Two hundred and seventy-three patients were divided according to body mass index (BMI) into three groups: group 1 (BMI: 15–29, n = 149), Group 2 (BMI: 30–35, n = 80), and Group 3 (BMI: 35–48, n = 44). Analysis of variance was performed to evaluate differences in outcomes in association with BMI. Two-tail t-tests were further utilized to compare Group 1 and Group 3. Results are reported in P values, with P < 0.05 being significant.
Results: Sixty-eight percent were male, the mean age was 61, and 96% were Caucasian. Comorbidities: asthma (15%), chronic obstructive pulmonary disease (12%), smokers (22%), hypertension (40%), and type 2 diabetes mellitus (15%). Patients with a higher BMI had a longer average hospital length of stay (12.0, 13.4, and 15.6 days, P < 0.05). The incidence of postoperative pneumonia was increased in those with a higher BMI (10%, 12%, and 30%, P < 0.05). The remaining variables were not significant.
Conclusion: Those with a higher BMI had a longer hospital stay and were at increased risk for developing pneumonia after rib stabilization. BMI did not have a significant effect on the ratio of ribs stabilized, time to operation, length of operation, days on mechanical ventilation, or ICU length of stay.

Keywords: Fixation, fracture, obesity, rib, stabilization


How to cite this article:
Robinson N, Stinson W, Zielinski M, Stephens D, Kim B. Outcomes in obese patients undergoing rib stabilization at a single institution over 9 years. J Cardiothorac Trauma 2020;5:29-32

How to cite this URL:
Robinson N, Stinson W, Zielinski M, Stephens D, Kim B. Outcomes in obese patients undergoing rib stabilization at a single institution over 9 years. J Cardiothorac Trauma [serial online] 2020 [cited 2021 Dec 6];5:29-32. Available from: https://www.jctt.org/text.asp?2020/5/1/29/304870




  Introduction Top


Chest wall stabilization reduces ventilator days, overall intensive care unit (ICU) length of stay and cost, and risk of developing pneumonia compared to those patients treated nonoperatively.[1],[2],[3] Demographic factors have previously been studied as a metric to help stratify the risks associated with chest wall stabilization.[4] Further investigation into the demographic of obesity is necessary. The National Center for Health Statistics estimates that 39.6% of Americans are obese.[5] With little information present in the current literature regarding the outcomes of obese patients who undergo chest wall stabilization, we hope that this analysis will improve management of these patients in the future.


  Materials and Methods Top


Study design

The aim of this analysis is to review the outcomes of obese patients who underwent chest wall stabilization at a single institution. After approval was obtained from the institutional review board, a retrospective evaluation of 273 patients was conducted. The analysis was performed on patients who underwent rib stabilization after a trauma at our institution between 2009 and 2017. General demographic information was obtained including gender, age, and race. Relevant past medical history including asthma, chronic obstructive pulmonary disease (COPD), smoking, hypertension, and type 2 diabetes mellitus was recorded. The National Institute of Health, Centers for Disease Control and Prevention, and World Health Organization define body mass index (BMI) as follows: normal range is 18.5–24.9, overweight is 25.0–29.9, obesity is 30.0–34.9, and severe obesity is 35 or higher.[6] Accordingly, we utilized patient weight and height to determine the BMI and used it as a metric of organization into three groups as follows: group 1 with a BMI between 15 and 29.9, Group 2 with a BMI between 30–34.9, and Group 3 with a BMI of ≥35.

Data collection

Within these three groups, patient outcomes were selected to consider the effect of BMI on patients who underwent rib stabilization and included: average hospital length of stay, ICU length of stay, incidence of postoperative pneumonia, ratio of ribs repaired to those fractured, days to operation, length of operation, and days mechanically ventilated. We hypothesized that obese patients had a longer hospital and ICU length of stay, an increased risk of postoperative pneumonia, a decreased ratio of ribs repaired to ribs fractured, increased number of days before operation, an increased length of operation, and were mechanically ventilated longer after rib fixation, compared to their nonobese counterparts.

Statistical analysis

An analysis of variance (ANOVA) was performed to evaluate differences in quantitative outcomes between BMI groups. Two-tail t-tests were further utilized to compare differences in quantitative outcomes between Group 1 and Group 3 in order to assess the statistical significance between those with the lowest BMI and those with the highest BMI. Chi-square analysis was utilized to compare our one categorical outcome (incidence of postoperative pneumonia) and its association with BMI. Continuous variables were expressed in averages. Categorical data were expressed in percentages. Statistical significance was expressed in P values, with P < 0.05 being significant.


  Results Top


A total of 273 patients who underwent rib stabilization were divided into three BMI groups. Group 1 consisted of 149 (55%) patients with a BMI of 15–29.9. Group 2 consisted of 80 (29%) patients with a BMI of 30–34.9. Group 3 consisted of 44 (16%) patients with a BMI of ≥35. Of the 273 patients studied, 68% were male, the mean age was 61, and 96% were Caucasian. Demographic averages and percentages are further broken down by group in [Table 1].
Table 1: Demographics

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Regarding comorbid conditions, overall, 16% had asthma, 12% had COPD, 22% were smokers, 40% had hypertension, and 15% had type 2 diabetes mellitus. These data were further broken down into the prevalence of the comorbidity by group, as shown in [Table 2]. Asthma, COPD, and smoking were found to decrease in prevalence as BMI increased. Diabetes type 2 and hypertension increased in prevalence as would be anticipated with increasing obesity.
Table 2: Comorbidities

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Patients with a higher BMI were found to have a longer average hospital length of stay (12.0, 13.4, and 15.6 days, P < 0.05 with ANOVA analysis). The incidence of postoperative pneumonia was increased in those with a higher BMI (10%, 12%, and 30%, P < 0.05 with Chi-square analysis).

Comparisons of averages between BMI groups for the remaining variables (ratio of ribs repaired to those fractured, days to operation, length of operation, days mechanically ventilated, and ICU length of stay) were not significant, as shown in [Table 3].
Table 3: Variables

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  Discussion Top


Obesity is becoming more prevalent in the population, and it can be assumed that an increasing number of obese patients are being evaluated in trauma centers. We set out to evaluate multiple variables present before and after chest wall stabilization between groups of patients with an increasing BMI in efforts to improve the understanding of the relationship between obesity and chest wall stabilization.

Patients with a higher BMI were found to have a longer average hospital length of stay and were more likely to develop postoperative pneumonia. The observation that obesity leads to a longer length of hospital stay is not new. An epidemiologic study performed by Zizza et al. in 2004 demonstrated that obese patients had length-of-stay rates greater than those of normal-weight patients.[7] Second, multiple studies have identified that obese patients are more likely to develop pneumonia following thoracic operations. Ghanta et al. identified that morbidly obese patients developed pneumonia at a higher rate (4.3% vs. 3.0%; P < 0.05) compared to normal-weight patients after cardiac surgery.[8] Simonsen et al. demonstrated that obesity carried an odds ratio of 1.91 for developing a postoperative pneumonia following any thoracic operation to address lung cancer.[9] The findings in our analysis are consistent with previous findings that obesity is associated with a longer hospital stay and the development of postoperative pneumonia following thoracic surgery compared to nonobese patients.

More interesting, however, is the data analysis evaluating the other variables of interest which include length of ICU stay, ratio of ribs repaired to ribs fractured, days from hospital admission to chest wall stabilization, length of operative time of chest wall stabilization, and postoperative mechanical ventilator days. None of these variables were found to influence rib stabilization in any significant way when comparing each BMI group. Phrased another way, being obese, did not negatively affect the majority of the studied variables in relation to chest wall stabilization. However, when observing the trends in [Table 3], it can be observed that all the variables with P > 0.05 (with the exception of length of operation) displayed an increasing trend with increasing BMI.

All the variables associated with technical issues of surgical rib fixation and increasing BMI were insignificant. The ratio of ribs repaired to ribs fractured was found to be the same across each BMI group. As many would agree, operative exposure of the chest wall in the nonobese patient is easier compared to the obese patient. However, once adequate exposure was obtained, the ratio of ribs repaired to ribs fractured is nearly identical. Days from hospital admission to chest wall stabilization were not found to be significant between any of the groups. It was hypothesized that obesity would significantly delay chest wall stabilization. This hypothesis was based on the thought that surgeons would give obese patients a much longer trial of nonoperative intervention compared to their nonobese counterparts in efforts to avoid the morbidity of operating on an obese patient. The data presented here demonstrate that taking an obese patient to the operating room shortly after injury was not associated with worse outcomes when comparing outcomes to nonobese patients. Finally, it is well known that increased operative times, for any procedure, lead to increased patient morbidity. Although analysis of the data demonstrates no significant increase in operative times when comparing each BMI group that underwent chest wall stabilization, operative times were not corrected for number or ribs repaired. The lack of information regarding this correlation may have influenced the significance of this finding.

The nontechnical variables associated with rib fixation and increasing obesity found to be insignificant are described as follows: the average of postoperative ventilator days approached significance when comparing each group but ultimately was not statistically significant. This association would suggest that there should not be an increased concern for multiple ventilator days leading to ventilator-associated morbidity (ventilator-associated pneumonia, the need for tracheostomy, etc.) when performing chest wall stabilization on obese patients. Many patients are admitted to the ICU postoperatively after chest wall stabilization to ensure pain control and that oxygenation and ventilation are adequate. Data presented here do not demonstrate a significantly longer ICU stay for obese patients undergoing chest wall stabilization compared to nonobese patients.

The main limitation of this analysis is that this study is a retrospective review. Only associations between each BMI group and the variables studied can be made. Further prospective randomized studies detailing the outcomes of obese patients undergoing chest wall stabilization compared to nonoperative treatment would better define which obese patient would most benefit from rib fixation. Second, the prevalence of three comorbidities (asthma, COPD, and smoking) was less in the obese population compared to the nonobese population in this review. It is unknown if these trends would remain the same when looking at a larger sample size. A trend toward a higher prevalence of comorbid conditions in the obese population may cause additional variables evaluated in this study to become clinically significant.

Overall, the data presented in this study demonstrate that obesity is not associated with a clinically significant effect on ratio of ribs undergoing fixation to ribs fractured, days from hospital admission to chest wall stabilization, length of operative during chest wall stabilization, postoperative mechanical ventilator days, and ICU length of stay. Clinically significant associations identified were that obese patients were found to have a longer hospital stay and were more likely to develop postoperative pneumonia. As stated above, chest wall stabilization has proven to be beneficial in many aspects when treating traumatic chest wall injuries. The data presented here suggest that chest wall stabilization is safe for and should be offered to obese patients with the knowledge that there is an associated risk for developing pneumonia and having a longer hospital course. Further prospective studies will be needed to fully solidify these associations and determine the effects of obesity on operative rib fixation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
1. Uchida K, Nishimura T, Takesada H, Morioka T, Hagawa N, Yamamoto T, et al. Evaluation of efficacy and indications of surgical fixation for multiple rib fractures: A propensity-score matched analysis. Eur J Trauma Emerg Surg 2017;43:541-7.  Back to cited text no. 1
    
2.
2. Swart E, Laratta J, Slobogean G, Mehta S. Operative treatment of rib fractures in flail chest injuries: A meta-analysis and cost-effectiveness analysis. J Orthop Trauma 2017;31:64-70.  Back to cited text no. 2
    
3.
3. Kocher GJ, Sharafi S, Azenha LF, Schmid RA. Chest wall stabilization in ventilator-dependent traumatic flail chest patients: who benefits? Eur J Cardiothorac Surg 2017;51:696-701.  Back to cited text no. 3
    
4.
4. Fitzgerald MT, Ashley DW, Abukhdeir H, Christie DB 3rd. Rib fracture fixation in the 65 years and older population: A paradigm shift in management strategy at a Level I trauma center. J Trauma Acute Care Surg 2017;82:524-7.  Back to cited text no. 4
    
5.
5. Hales CM, Carroll MD, Fryar CD, Ogden CL. Prevalence of obesity among adults and youth: United States, 2015-2016. NCHS Data Brief 2017;228:1-8.  Back to cited text no. 5
    
6.
6. “NIH Study Identifies Ideal Body Mass Index. Nih.gov, U.S. Department of Health and Human Services. Available from: https://www.nih.gov/news-events/news-releases/nih- study-identifies-ideal-body-mass-index. [Last accessed on 2020 Dec 01].  Back to cited text no. 6
    
7.
7. Zizza C, Herring AH, Stevens J, Popkin BM. Length of hospital stays among obese individuals. Am J Public Health 2004;94:1587-91.  Back to cited text no. 7
    
8.
8. Ghanta RK, LaPar DJ, Zhang Q, Devarkonda V, Isbell JM, Yarboro LT, et al. Obesity increases risk-adjusted morbidity, mortality, and cost following cardiac surgery. J Am Heart Assoc 2017;6:3.  Back to cited text no. 8
    
9.
9. Simonsen DF, Søgaard M, Bozi I, Horsburgh CR, Thomsen RW. Risk factors for postoperative pneumonia after lung cancer surgery and impact of pneumonia on survival. Respir Med 2015;109:1340-6.  Back to cited text no. 9
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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