Trauma is the leading cause of death in Taiwan in the adult population aged < 50 years.1 Occurring almost always as an unexpected affliction with very high mortality and morbidity, thoracic trauma is responsible for approximately 25% of trauma deaths. Thoracic trauma is also a contributing factor towards an additional 25% of trauma deaths worldwide.2–6 The incidence of rib fractures owing to thoracic trauma is in the range of 10–40% among all trauma cases.2,7,8 In studies focusing on blunt thoracic trauma, rib fractures were present in as many as 40–80% of thoracic trauma patients, who frequently require the care of an intensive care unit (ICU) and/or ventilator support.8–10 Contrary to the previous conception that most chest wall injuries are benign, rib fractures exist in 4.4% of patient mortality within 30 days and 55% of patient mortality within 24 hours because of their precarious nature, based on a nationwide population-based study using pooled data from the Taiwan's National Health Insurance Research Database.11
In the present study, our aims were to understand the clinical course following traumatic rib fractures and identify risk factors for mortality and morbidity. These results may help to prepare a trauma team with better treatment strategies in the initial encounter with patients with thoracic trauma at clinical presentation, especially elderly patients with rib fractures.
2.1. Study population
This retrospective cohort study included consecutive patients with blunt thoracic trauma who were admitted to the Department of Thoracic Surgery at Tungs’ Taichung Metro Harbor Hospital (Taichung, Taiwan, R.O.C.; a Level I trauma center) between March 1, 2005 and December 31, 2013. All data were obtained from electronic medical records. The exclusion criteria included:(1) patients treated only in an outpatient setting or transferred to another institution; (2) patients aged < 18 years; (3) patients admitted to the Department of Cardiovascular Surgery with cardiac or great vessel involvement whose care did not involve the Department of Thoracic Surgery; and (4) patients for whom the medical chart parameters under study could not be well determined.
Data such as sex, age, admission, and discharge dates, duration of hospital and ICU stay, ventilator support, injury severity score (ISS), type of injury (rib fractures were specifically identified by two independent licensed thoracic surgeons), associated injuries, treatments received, and mortality were collected from the medical records. Surgery and associated injuries were classified according to the body part involved, namely head injury, facial bone fracture, spine injury, clavicle fracture, extremity fracture, or abdomen injury. Soft tissue injuries were not included in this study.
The study protocol was approved by the Institutional Review Board of Tungs’ Taichung Metro Harbor Hospital, Taichung, Taiwan, R.O.C. (Approval Number, #102039).
2.2. Statistical analysis
We retrospectively performed statistical analysis on the database of all thoracic trauma patients admitted to the hospital. The χ2 test was employed for the statistical analysis of the variables. The relationships between the total number of rib fractures and various associated injuries were statistically analyzed using χ2 for trend and the t test for comparison. The Pearson correlation was calculated to determine the relationships between the total number of rib fractures in patients with thoracic trauma and prolonged hospital stay of ≥7 days, ICU stay, mechanical ventilator use, or mortality. Multivariate logistic regression was also performed to explore the relationship between rib fractures and patients’ age, sex, and comorbidities. All statistical results were significant when p < 0.05. Statistical analysis was performed using the SPSS statistical package (Version 17.0; SPSS, Inc., Chicago, IL, USA).
During the 9-year study period, there were 1621thoracic trauma patients, excluding eight patients who were younger than 18 years old. The majority (72.5%) of thoracic trauma patients were male (Table 1). The patients’ age ranged from 18 years to 95 years with a mean age of 51.2 years (standard deviation, 17.1 years).
When classified according to the type of injury the thoracic trauma patients had sustained, 1272 (78.5%) patients had rib fractures, 515 (31.8%) patients had traumatic hemothorax, 253 (15.6%) patients had pneumothorax, 156 (9.6%) patients had hemopneumothorax, and only 75 (4.6%) patients had lung contusions (Table 1). Extremity fracture was the most common site of injury, followed by head injury and clavicle fracture. As the most common treatment the patients received, chest tubes were placed in 368 (22.7%) thoracic trauma patients. The most common surgeries were for injuries to an extremity, followed by the clavicle and the head. Only 2.3% of all patients received thoracic surgery. Surgeries for facial bone fractures were the least common.
Approximately 11.7% of patients with thoracic trauma had an ISS of >16, indicating the severity of harm in thoracic trauma patients, which was further demonstrated by a mortality rate of 6.9% in this group of patients (Table 1).
To examine the impact of rib fractures in patients with thoracic trauma, we categorized patients by the location of fractured ribs (Fig. 1). These patients presented with a normal distribution in the location of fractured ribs, and the peak was at the 5th and 6th ribs bilaterally, with a trend of more fractured ribs on the left than on the right; this finding was not statistically significant. Patients with thoracic trauma were further grouped according to the total number of rib fractures, as illustrated in Fig. 2. Most (74.8%) thoracic trauma patients had three or fewer rib fractures.
We investigated the relationships between the number of rib fractures in patients with thoracic trauma and prolonged hospital stay of ≥7 days, ICU stay, mechanical ventilator use, and mortality. In patients with thoracic trauma with rib fractures, the relationship between prolonged hospital stay of ≥7 days and the number of rib fractures was statistically significant at p = 0.000 and r = 0.174 (Fig. 3). The relationship between the number of rib fractures and ICU stay was also statistically significant at p = 0.000 and r = 0.113 (Fig. 4). However, the relationship between the number of rib fractures and mechanical ventilator use was not statistically significant (p = 0.417). There was also no significant relationship between the number of rib fractures and mortality (p = 0.426).
We also examined the relationship between associated injuries and the number of rib fractures in patients with thoracic trauma (Table 2). We categorized patients with rib fractures into four groups: (1) 1–2 rib fractures; (2) 3–4 rib fractures; (3) 5–6 rib fractures, and (4) ≥7 rib fractures. Statistical analysis using the χ2 for trend showed that head injury and clavicle fracture were significantly associated with an increased number of rib fractures, whereas facial bone fracture, spine injury, extremity injury, and abdominal injury were not significantly associated (Table 2).
With regard to pulmonary complications, the number of rib fractures was positively associated with hemothorax, pneumothorax, and hemopneumothorax (all, p < 0.001; Table 2). The number of rib fractures was also significantly associated with ISS ≥ 16 (p < 0.001). Mortality was not significantly associated with an increased number of rib fractures, even though we observed a greater proportion of mortality in patients with ≥7 rib fractures (11.4%; Table 2).
Table 3 further shows the adjusted odds ratios for rib fracture, based on patient characteristics, using multivariate analysis. Correlation analysis revealed that old age and clavicle fracture were associated with rib fractures in patients with thoracic trauma (p < 0.001). Similar to results presented in Table 2, head injury and clavicle fracture were significant factors associated with rib fractures (p = 0.010 and p = 0.003, respectively). In addition, extremity fracture was a significant factor associated with rib fractures (p < 0.001).
The present study's results showed that most patients with thoracic trauma were men aged 18–95 years (mean age, 51.2 years). This finding is similar to trends reported by the National Trauma Data Bank and the statistics of the Department of Health that indicate that male individuals account for most thoracic trauma patients.1,12 Motor vehicle crash is the leading cause of rib fractures, but this problem cannot be easily solved because of the size of the motorcycling population in Taiwan and elsewhere.12,13
The incidence of rib fractures among all trauma cases is in the range of 10–40%.2,7,8 These patients frequently require the care of an ICU and/or ventilator support.8−10In the present study, approximately 11.7% of such patients had an ISS ≥ 16 and a mortality rate of 6.9%. Among these individuals, 1272 (78.5%) patients had a rib fracture; 31.8% of patients, traumatic hemothorax; 15.6% of patients, pneumothorax; 9.6% of patients, hemopneumothorax; and 4.6% of patients, lung contusion. The severity was associated with the number of rib fractures: 40.5% of the patients had a severe ISS (i.e., ≥16) with a number of rib fractures >7. In addition, associated injuries including head injury, extremity fracture, and clavicle fracture are common in motorcycle and motor vehicle accidents.14 These complications may have a significant clinical impact.
For treatment, extremity surgery (20.6% of patients) and chest tube therapy (22.7% of patients) were the two most common treatments patients with thoracic trauma received, followed by clavicle surgery (11.9% of patients) and head surgery (6% of patients). Chest tube placement is a common procedure used to treat traumatic chest injuries, although its complication may vary, depending on the severity of injury. Therefore, the severity of the thoracic injury, as measured by the Chest Abbreviated Injury Score and ISS, should be incorporated into the development of chest tube management guidelines for chest tube complications after thoracic trauma.15
In our study, the number of rib fractures was associated with prolonged hospital and ICU stays (≥7 days), but not with mechanical ventilator use. The number of rib fractures was also significantly associated with an ISS ≥ 16. In addition, old age was associated with rib fractures (p < 0.001) in patients with thoracic trauma. These results agreed with the findings in the literature for thoracic trauma with the precarious features of associated injuries, complications, mortality, and morbidity.16–20 Taken together, it is critical for a trauma team to accurately and efficiently detect and diagnose traumatic rib fractures and improve treatment strategies in the initial encounter with thoracic trauma patients.21,22
In conclusion, the severity of traumatic rib fractures was identified in this study. Therefore, a trauma team needs better preparation to respond to patients with thoracic trauma with effective treatment strategies, especially patients who are old and/or have rib fractures.
We thank Miss Chen-Fan Wen for her assistance in the statistical analysis. This study was supported by a grant from Tungs’ Taichung Metro Harbor Hospital (Taichung, Taiwan; grant no. TTMHH-103C008).
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