A Comprehensive Analysis of Traumatic Rib Fractures in an Acute General Hospital in Singapore.

BACKGROUND: Rib fractures are common sequelae after blunt chest wall trauma. They can occur in isolation or association with life-threatening injuries to the head, thorax, and abdomen and may be complicated by hemothorax, pneumothorax, or lung contusions. Contiguous rib fractures can result in flail chest, which is associated with increased morbidity and mortality. This study aims to compare the risk factors, treatment modalities, and outcomes between patients with flail chest and nonflail chest postblunt trauma. PATIENTS AND METHODS: Data were retrospectively collected from all patients admitted with rib fractures from January 2016 to December 2016 to the Department of General Surgery, Khoo Teck Puat Hospital, Singapore. The outcomes identified were mortality, pain scores on injury day 1, 3, 5, and 7, injury severity score, duration of mechanical ventilation, worst partial pressure arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, length of intensive care unit (ICU) stay, and pulmonary complications.
RESULTS: Motor vehicle accident was the most common cause of rib fractures (63.1%, n = 123). Patients with flail chest had more associated pneumothorax (53.8% vs. 35.2%) and lung contusions (53.8% vs. 30.2%) compared to those without flail chest and underwent more investigations such as inpatient-computed tomography scans (76.9% vs. 59.3%), interventions such as chest tube insertion (61.5% vs. 19.8%), and ICU admission (46.1 vs. 13.7%). Patients also had higher pain scores, used more analgesic modalities, and had increased inpatient mortality (30.8% vs. 4.4%).
CONCLUSION: Flail chest is associated with higher morbidity and mortality. Proactive management from a multidisciplinary team such as identification of high-risk patients in particular patients with flail chest, early admission to critical care, and protocols including multimodal pain management, respiratory support, and rehabilitation should be instituted.

INTRODUCTION

Rib fractures are the most common consequence of blunt chest wall trauma, which can result from various circumstances such as fall from a height, motor vehicle accidents (MVAs), workplace accidents, or interpersonal violence. Blunt trauma is the major mechanism of injury in Singapore, and rib fractures are frequently identified postthoracic trauma.[1]

Rib fractures may be associated with complications such as hemothorax, pneumothorax, lung contusions, as well as significant injuries to the head, thorax, and abdomen.[2] The majority of patients experience significant pain from rib fractures, which may hinder respiratory effort and lead to complications such as pneumonia, pleural effusion, or acute respiratory distress syndrome.

The clinical outcomes of patients with rib fractures depend on the location, number, and pattern of the fractures.[23] The presence of flail chest, with fractures of three or more contiguous ribs at more than one location per rib, is associated with severe pain and respiratory compromise with a 10%–20% increase in mortality.[245] MVAs are the most common cause of flail chest.[6]

In our institution, the emergency surgery and trauma (ESAT) team is responsible for the management of trauma patients admitted to the general surgery service. Early consultation with the ESAT team is performed for all patients identified to have three or more rib fractures on chest X-ray in the emergency department. Those with less than three rib fractures with no associated hemothorax, pneumothorax, or thoracoabdominal visceral injury are observed in the extended diagnostic treatment unit under the care of the emergency department and discharged after 24 h if there were no further complications.

In this study, we aim to identify epidemiological risk factors and evaluate clinical outcomes between rib fracture patients with and without flail chest. There is a paucity of local data on the incidence and sequelae of flail chest and limited guidelines on optimal treatment strategy for this vulnerable group of patients.

PATIENTS AND METHODS

We performed a retrospective descriptive study of patients admitted with rib fractures from January 2016 to December 2016 to the Department of General Surgery, Khoo Teck Puat Hospital, Singapore. Approval for the study was obtained from the institutional ethics review board. Data extracted from the trauma registry included patient demographics, mechanism of injury, injury characteristics, in-hospital interventions, admission to critical care, and inpatient mortality.

Inclusion criteria for the study were patients with injury severity score (ISS) ≥9. Patients who died in the emergency department and patients who were not admitted were excluded from the study. A total of 195 patients were identified within the study parameters. There were 13 cases of flail chest and 182 cases of rib fractures without flail chest.

Independent t- test was used to analyze continuous data, and Chi-square and Fisher's exact tests were used for categorical data.

The measured primary outcome was mortality and the secondary outcomes measured include primary disposition, pain scores on injury day 1, 3, 5, and 7, ISS, duration of mechanical ventilation, worst partial pressure arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, length of intensive care unit (ICU) stay, and pulmonary complications.

RESULTS

The mean age of the study group was 56 years (range 16–87). The incidences of rib fractures in male (80.5%) far outnumbered females (19.5%). Among the various injury types, MVAs were the most common cause of injury (63.1%). Same-level fall (defined as fall from a height <0.5 m) ranked second in frequency (24.6%) followed by fall from a height >0.5 m (7.2%) and assaults (1.5%) [Table 1].

Table 1

Comparison between patients with flail versus nonflail chest - demographics and injury mechanism

Characteristics	All patients, n (%)	Patients with flail ribs fracture, n (%)	Patients without flail ribs fracture, n (%)	P
n	195	13	182
Mean age (years)±SD	56±19	51±12	56±20	0.1
Male	157 (80.5)	13 (100)	144 (79.1)	0.05
Mean BMI±SD	24.8±4.3	26.9±5.6	24.7±4.2	0.3
Presence of smoking history	36 (18.5)	2 (15.4)	34 (18.7)	0.6
Injury mechanism
Motor vehicle accident	123 (63.1)	9 (69.2)	114 (62.6)	0.4
Same-level fall ≤0.5 m	48 (24.6)	2 (15.4)	46 (25.3)	0.3
Fall from height	14 (7.2)	0	14 (7.7)	0.4
Assault	3 (1.5)	0	3 (1.6)	0.8
Other*	6 (3.1)	2 (15.4)	4 (2.2)	0.05
Unknown	1 (0.5)	0	1 (0.6)	0.9
Medical comorbidity	59 (30.3)	3 (23.1)	56 (30.8)
Diabetes	44	2	42	0.4
Asthma	10	1	9	0.5
COPD	5	0	5	0.7
PTB	1	0	1	0.9

*Other refers to falling object, kicked by horse, injury due to machinery/tools, and likely fall following suffocation by hanging. SD: Standard deviation, BMI: Body mass index, COPD: Chronic obstructive pulmonary disease, PTB: Pulmonary tuberculosis

On comparing the patients who had MVAs and same-level fall, there was a difference in the age-wise distribution of the cases. Those who sustained rib fractures as a result of MVAs were generally younger (49 years) as compared to (76 years) for those from same-level falls [Figure 1].

Figure 1

Age comparison between patients who had motor vehicle accidents and same-level falls

Demographically, the two groups were similar with significant male preponderance as shown in the flail chest group. All the reported flail chest cases occurred in males, whereas males accounted for 79.1% of cases of nonflail chest rib fractures. The two groups were similar in distribution for mechanism of injury and medical comorbidities.

Pneumothorax, lung contusion, and hemothorax were the most frequent associated thoracic injuries identified. Spleen, liver, and kidney injuries accounted for the most common abdominal organ affected in sequential order [Table 2].

Table 2

Comparison between patients with flail versus nonflail chest - injury characteristics

Characteristics	All patients, n (%)	Patients with flail ribs fracture, n (%)	Patients without flail ribs fracture, n (%)	P
n	195	13	182
Associated thoracic injuries
Pneumothorax	71 (36.4)	7 (53.8)	64 (35.2)	0.3
Lung contusion	62 (31.8)	7 (53.8)	55 (30.2)	0.1
Hemothorax	35 (17.9)	7 (53.8)	28 (15.4)	<0.01
Cardiac injury	7 (3.6)	4 (30.8)	3 (1.6)	<0.01
Lung laceration	4 (2.1)	1 (7.7)	3 (1.6)	0.2
Injury to diaphragm	2 (1.0)	1 (7.7)	1 (0.5)	0.1
Aorta injury	1 (0.5)	1 (7.7)	0	0.07
Associated abdominal organ injuries
Spleen	14 (7.2)	0	14 (7.7)	0.4
Liver	12 (6.2)	2 (15.4)	10 (5.5)	0.2
Kidney	7 (3.6)	2 (15.4)	5 (2.7)	0.07
Adrenal	4 (2.1)	0	4 (2.2)	0.8
Mesentery	3 (1.5)	1 (7.7)	2 (1.1)	0.2
Small bowel	3 (1.5)	1 (7.7)	2 (1.1)	0.2
Large bowel	2 (1)	1 (7.7)	1 (0.5)	0.1
Bladder	2 (1)	1 (7.7)	1 (0.5)	0.1
Gallbladder	1 (0.5)	0	1 (0.5)	0.9
Omentum	1 (0.5)	0	1 (0.5)	0.9

Hemothorax (53.8% vs. 15.4%) and cardiac injuries (30.8% vs. 1.6%) were significantly higher in the flail chest group. The prevalence of pneumothorax in the flail chest group was 53.8% compared to 35.2% in the nonflail chest group. The percentage of lung contusions in the flail chest group was 53.8% compared to 30.2% in the nonflail chest group [Table 2]. However, both fail to show a significant difference despite showing a higher percentage in the flail chest group. No significant difference was shown in the associated abdominal organ injuries in both groups. Majority (97.4%) of the patients had chest X-ray. About 60.5% had computed tomography (CT) scans subsequently for further evaluation of suspected associated injuries. A nonsignificant higher percentage of patients in the flail chest group underwent CT scans compared to the nonflail chest group [Table 3].

Table 3

Comparison between patients with flail versus nonflail chest - medical and surgical management

Characteristics	All patients, n(%)	Patients with flail ribs fracture, n(%)	Patients without flail ribs fracture, n (%)	P
n	195	13	182
APS review	58 (29.7)	5 (38.5)	53 (29.1)	0.7
Investigations
Chest x-ray	190 (97.4)	11 (84.6)	179 (98.4)	0.04
CT scan	118 (60.5)	10 (76.9)	108 (59.3)	0.2
Number of patients requiring chest tube	44 (22.6)	8 (61.5)	36 (19.8)	<0.01
One chest drain	28	3	25	0.3
Two chest drains	12	3	9	0.04
>2 chest drains	4	2	2	0.02
Medication route
Oral	173 (88.7)	9 (69.2)	164 (90.1)	0.04
IV	67 (34.4)	7 (53.8)	60 (33.0)	0.2
PCA	32 (16.4)	5 (38.5)	27 (14.8)	0.07
Transdermal patch/ketoprofen gel	13 (6.7)	1 (7.7)	12 (6.6)	0.6
Regional block	9 (4.6)	1 (7.7)	8 (4.4)	0.5
IM	6 (3.1)	0	6 (3.3)	0.7
Subcutaneous	3 (1.5)	0	3 (1.6)	0.8
Surgical intervention
Thoracotomy	6 (3.1)	3 (23.1)	3 (1.6)	<0.01
Tracheostomy	10 (5.1)	0	10 (5.5)	0.5

CT: Computerized tomography, IV: Intravenous, PCA: Patient-controlled analgesia, IM: Intramuscular, APS: Acute pain service

Majority (61.5%) of the patients with flail chest required chest tube insertion compared to that in the nonflail chest group (19.8%). The percentage of patients requiring two or more chest drains in the flail chest group was also significantly higher than in the nonflail chest group [Table 3].

Oral analgesia was the primary modality of pain relief in both groups of patients. A significantly higher percentage of patients in the nonflail chest group were managed with oral analgesia, whereas the flail chest group showed a higher utilization of other analgesic methods such as intravenous and patient-controlled analgesia [Table 3].

A significantly higher percentage of patients in the flail chest group required ICU admission compared to the nonflail chest group (46.1% vs. 13.7%). Initial pain scores were similar in both groups of patients but a significantly higher score on day 3 in the flail chest group. The ISS of the flail chest group was significantly higher than the nonflail chest group [Table 4].

Table 4

Comparison between patients with flail versus nonflail chest - outcomes

Characteristics	All patients, n(%)	Patients with flail ribs fracture, n (%)	Patients without flail ribs fracture, n (%)	P
n	195	13	182
Disposition from ED
General ward	143 (73.3)	3 (23.1)	140 (76.9)	<0.01
HDU	21 (10.8)	4 (30.8)	17 (9.4)	0.04
ICU	31 (15.9)	6 (46.1)	25 (13.7)	<0.01
Pain assessment
Initial pain score	6±3 (MD=6)	5±3 (MD=5)	6±3 (MD=6)	0.3
Pain score - Day 1	2±2 (MD=2)	2±2 (MD=2.5)	2±2 (MD=2.0)	0.7
Pain score - Day 3	1±2 (MD=0)	2±3 (MD=2)	1±2 (MD=0)	0.04
Pain score - Day 5	1±1 (MD=0)	1±1 (MD=0)	0.5±1 (MD=0)	0.6
Pain score - Day 7	0±1 (MD=0)	1±1 (MD=0)	0.5±1 (MD=0)	0.7
Injury severity score	18±10	29±18	17±9	0.03
Mechanical ventilation - Mean days (n=32)	6.6±10.9 (MD=2)	1.8±1.8 (MD=1)	5.6±6.3 (MD=2)	0.02
Worst PaO2/FiO2 ratio	239.5±145.3	115.8±76.3	255.1±144.7	<0.01
Hospital days
Overall LOS	8.3±11.8 (MD=4)	4.8±8.4 (MD=2)	8.0±10.9 (MD=5)	0.2
HDU days	2.3±1.8 (n=37; MD=2)	2.8±2.2 (n=4; MD=2)	2.2±1.8 (n=33; MD=2)	0.6
ICU days	7.9±7.8 (n=35; MD=5)	2±2 (n=7; MD=1)	7.6±6.7 (n=28; MD=5)	<0.01
Complications	14 (7.2)	1 (7.7)	13 (7.1)	0.6
Pneumonia	12	1	11	0.6
Pleural effusion	1	-	1	0.9
ARDS	1	-	1	0.9
Discharge status
Alive	183 (93.8)	9 (69.2)	174 (95.6)	<0.01
Transferred to other acute hospital - CVTS unit	6	4	2
Dead	12 (6.2)	4 (30.8)	8 (4.4)

Data are n (%); mean±SD. MD: Median, HDU: High-dependency unit, ICU: Intensive care unit, PaO2: Partial pressure arterial oxygen, FiO2: Fraction of inspired oxygen, LOS: Length of stay, ARDS: Acute respiratory distress syndrome, CVTS: Cardiovascular and thoracic surgery, SD: Standard deviation, ED: Emergency department

Interestingly, the length of ICU stay and period of mechanical ventilation were significantly higher in the nonflail chest group. However, the flail chest group recorded significantly worse PaO2/FiO2 ratios during the ICU stay. No significant difference was noted in the pulmonary complication between the two groups [Table 4].

A significantly higher mortality rate (30.8%) was reported in flail chest compared to nonflail chest (4.4%) group [Table 4].

DISCUSSION

Majority of patients with flail chest are treated nonoperatively.[578] The current standard in nonoperative management includes early intubation, intermittent positive pressure ventilation, adequate analgesia, and pulmonary toilet. This mode of management has been around since the 1950s,[9] and the idea was strengthened by further studies done into the 1970s by Cullen et al.[10]

Our study demonstrates that patients with flail chest are more likely to have higher mortality, increased utilization of imaging, pain relief, and surgery. Selective management of specific traumatic conditions has been discussed before in literature.[11] This helps in early identification and timely management in this high-risk group to reduce morbidity and mortality.

A patient diagnosed with flail chest on imaging should be admitted to high-dependency unit or ICU for further management. The respiratory compromise that occurs with flail chest is not only due to the paradoxical movement of the ribs but also contributed by the pain and the underlying pulmonary contusions. The management of flail chest was first reported by Trinkle et al.[12] They recommended treatment of the underlying lung injury with a combination of fluid restriction, corticosteroids, aggressive pulmonary toilet, and pain control. It demonstrated a reduction in mortality rate from 21% to 0%, a 5-fold decrease in morbidity, and a nearly 3.5-fold reduction in hospital stay in these patients when compared with those undergoing mechanical ventilation alone. Our study shows that patients with flail chest have a higher risk of mortality from injuries than the nonflail chest group. The ISS correlates with these findings, and the higher mortality could also be due to other injuries secondary to the high-energy trauma.

Our study showed a significant difference in the incidence of hemothorax and >50% incidence in pneumothorax and lung contusion. The patients will benefit from the insertion of chest tubes when indicated at the time of diagnosis. As cardiac contusions were significantly higher in the flail chest group, these patients should have a low threshold for cardiac monitoring for arrhythmias or heart failure.

Optimal pain management of flail chest patients has shown to reduce the length of ICU stay, duration of intubation, and pulmonary complications.[13] Our study showed that intravenous analgesia and patient-controlled analgesia with oral analgesia were used preferentially in the flail chest group. The assistance of the acute pain service was obtained 38.5% of the time in the management of pain. However, our study does not show increased utilization of regional analgesia such as intercostal block and interfascial plane block. Studies have shown excellent results with the use of epidural block in the management of flail chest.[14] It aids in pulmonary toileting by enabling effective breathing, coughing, and improved participation in chest physiotherapy.

Although the overall length of mechanical ventilation and duration of ICU stay were higher in the nonflail group, flail chest group of patients recorded significantly worse PaO2/FiO2 ratios during ventilation. This observation is likely due to injuries in other organ systems in the nonflail chest group, resulting in a more extended ICU stay but better ventilatory parameters.

The limitations of the study include the retrospective nature of the study and comparatively small number of patients with flail chest. Based on our findings, patients with flail chest should be selectively managed as a select group of thoracic trauma patients. They should undergo comprehensive imaging to exclude other injuries. We recommend that they are managed early in a high-dependency or intensive care setting with close observation of respiratory parameters with optimal pain management. Intravenous methods of analgesia and regional blocks should be employed early to improve the patient's breathing, chest wall mechanics, and pulmonary toileting. Although our primary mode of management was nonsurgical, there are potential benefits of early surgical fixation in patients with severe flail chest requiring ventilation suggested by a recent meta-analysis.[15]

CONCLUSION

Flail chest is associated with higher morbidity and mortality. Proactive management from a multidisciplinary team such as identification of high-risk patients in particular patients with flail chest, early admission to critical care, multimodal pain management, respiratory support, and rehabilitation should be instituted.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest