Facilitating ventilator weaning through rib fixation combined with video-assisted thoracoscopic surgery in severe blunt chest injury with acute respiratory failure

Severe blunt chest trauma can cause multiple rib fractures accompanied by hemothorax or pneumothorax [1, 2] and lung contusions, compromising the facility for gas exchange in the lung parenchyma. Together with severe pain, all these complications can induce acute respiratory failure (ARF)—oximeter saturation of less than 90% and PaO₂ level of less than 60 mmHg, as determined through a Venturi mask with 100% FiO₂, such that mechanical ventilation is required—the most serious posttrauma complication, which may induce high mortality.

Intubation with positive pressure ventilation is widely accepted as an initial treatment for ARF [3, 4]. This method can be rapidly applied to provide sufficient tissue oxygenation in patients with lung contusion as well as rib fracture, contributing to impaired gas exchange in the lungs. However, long-term ventilator use should be avoided because ventilator-acquired pneumonia can become another contributor to increased morbidity and length of hospital stay. Therefore, reducing ventilator dependence following major complications is crucial.

Studies have demonstrated that early video-assisted thoracoscopic thoracic surgery (VATS) can decrease the rate of posttrauma pneumonia and empyema in blunt chest trauma [5, 6]. Some studies have claimed that rib fixation can also decrease ventilator dependence [7, 8], but others have considered this claim to be controversial [9, 10]. The results might vary depending on the surgical approach used during rib fixation. In our hospital, we combine VATS and rib fixation in severe blunt chest injuries with ARF. In our previous study, we found that rib fixation exhibited some benefits in patients without respiratory failure [11]. In this study, we hypothesize that rib fixation with VATS could provide a better outcome in intubated patients with ARF. The two study periods overlapped. However, the patient groups were not the same. The main purpose of this study was to evaluate the effects of this approach on the length of ventilator use and length of hospital stay.

During the study period, a total of 61 patients were enrolled. All patients had ARF and received emergent endotracheal tube insertions and positive pressure ventilator support within 24 h after trauma. These patients all had pneumothorax and hemothorax, resulting in tube thoracostomy being performed in the ED. Twenty-one patients receiving rib fixation with VATS were included in group 1, and the other 40 patients receiving VATS only belonged to group 2. The collection was terminated after statistical power reached 0.8.

Table 1 presents the basic demographic characteristics of the two groups. The means of age and the distribution of sex between the two groups had no statistically significant differences. Factors that could affect the ventilator dependence—including consciousness levels, number of fractured ribs, percentage of flail chest, lung contusion scores, AISs, and ISSs—all exhibited no statistically significant differences. All patients were evaluated for pain levels in the ED initially, and the 10-point pain scores between the two groups exhibited no differences. Thus, the two groups were satisfactorily matched and could be compared on the basis of their similar characteristics.

All patients in this study received VATS within 6 days after trauma [19]. The time periods from trauma to operation were equal between the two groups, without statistical significance. In this study, a total of 17 (27.9%) patients received lung repair during VATS. The proportions of patients receiving lung repair in the two groups were similar (Table 1). Lobectomy procedures were not performed in this study. After rib fixations, most patients with ARF could be weaned off the ventilator within 4 days or much faster than VATS-only patients (3.19 ± 3.37 days vs. 8.05 ± 8.23, P = 0.002). The total ventilator-dependence time durations were also much shorter in the rib fixation group (7.71 ± 3.65 days vs. 12.55 ± 8.22, P = 0.002). A patient was defined as having high PEEP if pressure was greater than 5 cmH₂O. Patients in group 2 required significantly more days of total ventilator use (5.71 ± 3.65 vs. 10.55 ± 8.22, P = 0.013). Eight patients had prolonged ventilations that required a tracheostomy; all these patients belonged to group 2 (0 vs. 20.0%, P = 0.042). Because of early weaning from the ventilator in the rib fixation group, the rate of pneumonia was also much lower (38.1% vs. 75.0%, P = 0.005). The time of chest tube use after the operation was also shorter in the rib fixation group (6.33 ± 2.13 days vs. 8.75 ± 4.04, P = 0.003). Because of early weaning from the ventilator and shortened periods of chest tube use, the LOSs in the ICU and hospital were both shorter in group 1, with statistical significance (8.81 ± 3.40 days vs. 12.08 ± 4.95, P = 0.008; 17.76 ± 8.38 days vs. 24.13 ± 9.80, P = 0.011). In this study, all patients had normal consciousness upon discharge. The pain scores at discharge were much lower in the rib fixation group (3.57 ± 1.03 vs. 5.18 ± 1.40, P = 0.001). Table 2 illustrates all clinical outcomes after operations on patients with ARF.

We applied binary logistic regression to test the parameters, and the results are displayed in Table 3. According to the multivariate logistic regression, the only independent clinical outcome determinant of the two groups was the time periods of ventilator use (aOR, 3.411; 95% CI 1.214–9.585, P = 0.020). These results indicate a strong association between rib fixation and ventilator dependence. Calibration of the final model was assessed using the Hosmer–Lemeshow goodness of fit test. A P value of 0.726 (χ² = 5.290) suggested that the model was accurate.

ARF is a dangerous posttraumatic complication that occurs mainly when both chest wall and lung parenchyma are destroyed in severe blunt chest injuries [20]. This emergency situation requires rapid resuscitation through the immediate insertion of an endotracheal tube with ventilator support. The primary treatment goal for these patients is early weaning from the ventilator. In this study, rib fixation with VATS in patients with such severe blunt chest trauma and ARF could greatly decrease the length of ventilator dependence.

Other studies have usually targeted treatments of severe blunt chest trauma by managing the hemothorax or pneumothorax [21‐23]. Initially, fractured ribs were not the main target of treatment in our hospital [23]. In fact, fractured ribs, especially the bicortical fractured type, can produce an unstable thoracic cage that might not support the full expansion of lung parenchyma. Although positive pressure ventilation can provide a supporting force for lung expansion, long-term ventilator dependence may be required to wait for the chest wall to heal. Many orthopedic materials have been designed specifically for fractured ribs. Several studies have successfully proven that reconstruction of a chest wall using rib fixation could reduce ventilator dependence [16, 24, 25]. In contrast with other studies, we performed rib fixation combined with VATS to completely manage chest wall injury, lung laceration, and pleural collections. These two procedures can be performed simultaneously to accelerate ventilator weaning. The rate of ventilator-acquired pneumonia subsequently decreases, which may also shorten the whole course of treatment.

The timing of the operation is another influential factor in blunt chest trauma. Early VATS may decrease the rate of pleural infection. Our previous studies have demonstrated that VATS should be performed within 1 week after trauma [19]. We thus adhered to this principle in this study. All patients received VATS within 6 days after trauma. The rates of empyema for the two groups are similar without statistical significance. Group 1 patients had rib fixation added during VATS to enable the reconstructed chest wall to maintain a firm structure. A stable chest wall can allow patients with lung parenchyma to retain full lung capacity without long-term use of the high PEEP ventilator mode. This benefit could decrease the probability of barotrauma for alveoli. The earlier the expansion of lung parenchyma occurs, the earlier the ventilator weaning can occur.

Fractured ribs not only make the chest wall unstable but also result in the persistence of pleural collection, especially bicortical fractures [26, 27]. The fractured ends of ribs can produce an ooze from the bone marrow [28]. The fractured ribs could also scrub lung surfaces, which may induce persistent microair leakage. These complications both lengthen the usage time of chest tubes, which is another major factor that lengthens the total course of admission. In this study, rib fixation was observed to prevent these complications. Chest tube usage time after rib fixation was much shorter than in the VATS-only group.

In this study, the pain score was difficult to estimate because all patients had endotracheal insertions with sedation during ventilator dependence. Only one pain evaluation was conducted, upon initial arrival at the ED, and all patients had similar pain scores. During ventilator-dependent periods, pain agents were administered continuously. The longer the period was for ventilator dependence, the more analgesics and sedative agents were required. In this study, after patients were weaned from the ventilator, they all regained normal consciousness. The pain scores upon discharge were evaluated again and had decreased compared with initial admission scores. In the rib fixation group, the pain score upon discharge was lower than in the other group. Therefore, pain can be greatly reduced for patients undergoing rib fixation compared with those who do not receive rib fixation.

Although VATS combined with rib fixation has many advantages in patients with ARF, this study has several limitations. The numbers of patients with ARF are small for thoracic injuries because only 5 to 10% experience incidences after blunt chest trauma. However, in this study, we attempted to include a sufficient number of patients for the calculation power to reach 0.8. The other limitation of the study was that patient selection was not randomized, although the study protocol was designed prospectively. Because all patients were initially intubated and sedated after trauma, all decisions regarding operation were made by patients’ families. We considered that all patients in this study should receive fixation but that consent should be obtained from families. Although we provided detailed information regarding rib fixation, some family members did not understand our explanations. Therefore, we could only provide their families with choices to inform their final decisions. However, this condition provided a comparison group for the study. Although the two groups were not matched initially, which may have caused selection bias, the demographic characteristics of the two groups exhibited no statistically significant differences. The binary logistic regression examination also indicated a high correlation between rib fixation and the length of ventilation use after adjustment for other variances. Another limitation of the observation-based data was that different staff members recorded the observations. To mitigate this limitation, a senior surgeon reviewed all data for accuracy and consistency. All surgical procedures were performed by the same team, and the same surgeons were responsible for all decisions to perform rib fixation to avoid surgical confounding bias. The pain score evaluation comparison between the two groups was also a limitation in this study. In addition to the subjectivity of pain sensation, group 2 patients had longer ICU stays that may have interfered with pain scores. Fortunately, all patients in this study were lucid and conscious, decreasing the potential for such bias.

The combination of rib fixation with VATS may provide complete treatment of chest wall deformity and of lung and pleural lesions in severe blunt chest injuries. This combination surgery may decrease ventilator dependence, lower the rate of pneumonia, and shorten the course of admission.