Trauma is the leading cause of death worldwide among young people [1]. Chest trauma is widespread, with a very high morbidity and mortality rate reaching 25% [2], making it the second cause of mortality in terms of trauma after head trauma [3]. Traumatic Pneumothorax [TPT] is a diagnostic and therapeutic emergency which may threaten the patient’s life if not treated immediately. The management depends on the mechanism of the traumatism, the stability of the patient and the severity of the injuries. The causes of death are mainly late pulmonary complications [4]. Many factors make the management problematic, especially in persistent air leaks [PAL]. Not many studies have mainly focused on these factors after a TPT. Our study aims to identify the predictors of PAL in TPT to set a strategy for managing this type of Pneumothorax.

Clinical settings

We conducted a retrospective study in the Thoracic and Cardiovascular Department of the Habib BOURGUIBA’s University Hospital in Sfax, Tunisia, over 12 years from January 2010 to December 2021, including patients who were hospitalized for a traumatic Pneumothorax.

Patients who underwent an iatrogenic Pneumothorax or were hospitalized in other departments during the management period have been excluded from our study.

Definitions

PAL is an air leak lasting more than 5 to 7 days. These air leaks may be continuous during forced expiration, normal expiration, or inspiration [5].

Current management

Management began in the pre-hospital setting for patients brought to the emergency room by medical transport. A brief assessment of vital signs was performed for patients seen in the emergency room. Unstable patients were admitted directly to the emergency medical service [EMS]. Stable patients were admitted to the thoracic and cardiovascular surgery department or other departments depending on the chief complaint and then transferred to our department for further management.

The respiratory assessment was based on clinical findings (respiratory rate, presence of penetrating wounds, signs of struggle, measurement of O2 saturation...) and imaging data: mainly standard chest X-ray and chest CT scan. The hemodynamic evaluation was based on the search for signs of shock, heart rate measurement, blood pressure, and paraclinical data, essentially electrocardiogram and haemoglobin level. The neurological evaluation is based mainly on calculating the Glasgow score [GCS]. Unstable patients admitted to the intensive care units had a rapid evaluation with filling, drugs, and sometimes transfusions. Simple monitoring was indicated for stable patients with minimal pleural effusion. Chest drainage was performed for large pneumothoraxes or those associated with a hemothorax. Surgical treatment was considered for patients not stabilized or for specific indications.

Data collected were about patient profiles, the type of accident, the nature of the traumatism, clinical data, paraclinical data, management data and the progression data (Length of stay in the ICU, Length of hospital stay, Duration of chest tube, Complications of Chest tube insertion, Postoperative follow-up for operated patients...)

Our analytic study has focused on PAL's predictive factors after chest tube insertion. The factors studied were: age, sex, and smoking, type of trauma, drainage technique and associated thoracic lesions.

Statistical study

The collected data were explored and analyzed by the statistical software SPSS version 20. The statistical analysis consisted of the search for correlation between the different variables of the study by Chi2, Fischer and Student tests. A multi-variate study by logistic regression was also performed to determine the predictive and prognostic factors. A result was defined as significant if p < 0.05.

During our study, 823 patients were hospitalized for chest trauma, and 375 patients (45.56%) presented a traumatic pneumothorax, so they have been included in our study. The average age was 40 years (+/-17.24). Three hundred and thirty-four men (89%) and 41 women (11%) with a sex ratio of 8.14 have been included. A history of active smoking was noted in 159 patients (42.4%). Twenty-two of the 159 patients who were smokers had quit. Two hundred and sixty-nine patients were free of any known pathology or allergy. Road accidents were the most common cause of post-traumatic pneumothorax, with 198 cases (53%), followed by assaults in 77 cases (20%). Seventy (19%) patients were victims of a domestic accident, and 24 (6%) had a work accident. Six patients (2%) were self-assaulted, with a suicide attempt in 3 cases. The direct shock was the most common mechanism. It was noted in 309 patients (82.4%). PPT was due to a penetrating wound in 63 patients (16.8%). Deceleration was noted in 2 cases (0.5%) and a blast effect in one case (0.3%). Open trauma was noted in 63 cases (16.8%). Polytrauma was noted in 179 cases (47.7%). The pneumothorax was classified as unilateral in 340 cases (90.7%): left in 175 cases (46.66%) and right in 165 cases (44%). It was bilateral in 35 cases (9.3%). Because of polytrauma or vital distress, 190 patients were initially admitted to an intensive care unit. Conservative treatment was the option for 164 patients (43.7%). Placement of a chest tube was indicated in 207 cases (55.2%). Chest drainage was subsequently indicated in 14 cases after the failure of conservative treatment. Among these patients, 89 (43%) underwent a chest tube in the intensive care unit, while the 104 other patients (50.24%), who were already stable, were managed by thoracic surgeons. Fourteen patients (6.76%) underwent a chest tube in other regional hospitals and were referred to us. The average drainage time was four days (+/- 3 days). PAL was found in 36 cases (16.2% of patients managed by chest tube). A correlation was found between the number of Packet-years (PY) and the PAL after chest tube placement with p=0.03 < 0.05. Indeed, PY >10 is a risk factor for prolonged air leaks (Fig 1).

Fig1: Impact of Smoking on PAL after a TPT

It was shown in our study that chest tube placement, if done in the emergency room, under non-optimal conditions, exposed 2.6 times to prolonged air leaks with P=0.014 (<0.05) [OR=2.687, CI=95%, 1.226-5.889]. No influence was noted between the gender, age, the existence or not of a penetrating wound or the existence or not of associated chest injuries on the duration of air leaks when a chest tube was put in: P>0.05 (not significant) (Tab 1).

Tab 1: Persistent air leaks studied Factors.

The TPT is the 2nd most common injury in thoracic trauma. According to the literature, its incidence in thoracic trauma reaches 55% [6]. The mean age of the patients in our series was 40 years, with extremes ranging from 3 years to 90 years? In the literature, the average age varies from 26 to 44 years. A male predominance is described in the literature with percentages higher than 65% of male victims, representing 89% of patients in our series. Respiratory pathologies such as pulmonary tuberculosis, bullous emphysema and pulmonary neoplasia are described in the literature as risk factors for pneumothorax [7]. This remains applicable to TPT. In our study, most patients were young, with an average age of 40 years and free of previous pulmonary pathologies.

In our study, road traffic accidents were the leading cause of TPP (53%), and assaults were responsible for 20% of the TPT, which is in line with the literature where the most frequent causes of PPT are public road accidents (69%) followed by assaults (16%) and falls from a height (11%) [8].

 Penetrating wounds are 15 times more likely than falls to cause TBI, according to Alghnam et al.'s study [8]. The direct shock was the main trauma mechanism in 82.4% of patients, followed by penetrating wounds in 16.8% of patients. Deceleration and electrocution were responsible for only 0.8% of PPT.

 The literature defines four mechanisms involved in thoracic trauma: direct shock, thoracic compression, deceleration and blast effect [9]. Open chest trauma can cause pneumothorax by air entering the pleural cavity through the chest wall or injury to the visceral pleura. In closed chest trauma, laceration of the visceral pleura against fractured ribs may cause air leakage into the pleural cavity and PPT following a sudden increase in intra-alveolar pressures with PPT alveolar rupture, as is the case with blast injuries. Chest trauma is closed in 70% of cases. However, the extent of the injuries may be underestimated [10].

The TPT was 90.7% unilateral, which agrees with the literature results. The diagnosis of TPT is clinical. Imaging confirms the diagnosis in case of doubt and allows the choice of therapeutic option. In the case of suffocating TPT, needle exsufflation is recommended [9, 10].

In our study, 190 patients were initially hospitalized in an intensive care unit due to hemodynamic, respiratory or neurological instability and then referred to us after stabilization. Conservative treatment was the option in 164 cases (43.7%). In the literature, conservative treatment has increasingly become the rule in TP management. In the face of a partial anterior TP, a conservative attitude can be satisfactory in 81% of cases [11]. Failure of conservative treatment, thus the necessitating placement of a pleural drain, has been observed in several studies with a rate of 6 to 8% [12,13]. In our study, 14 patients (8.5% of the patients in whom conservative treatment was indicated) had pleural drainage, which aligns with the data in the literature.

For patients requiring positive pressure ventilation, the risk of increased pneumothorax and progression to a compressive state reaches 20% [14]. Chest drainage in these patients remains questionable.

In the Ball et al. [6] series, 35% of patients required ventilation. Chest drainage was performed in 76% of these patients, 23% of whom had a drainage complication. Lu et al. [15] showed that the incidence of TPT in the first 48 h after chest trauma with minimal rib fractures is 5.4. This may be explained by minimal air leakage caused by pulmonary laceration against fractured ribs.

According to the literature, complications of drainage are frequent. They occur in 10.2% of drained patients [6]

Regarding mortality, we noted only one death (0.0027%) after thoracic drainage in our department following acute pulmonary re-expansion oedema. Chest Tube increases the risk of infectious complications and mortality.

PAL was noted in 16.2% of the patients who underwent chest tube in our study, and if they persist for some more days of drainage, surgery is questionable [16].

Several factors are involved in complications during the chest tube's placement. Indeed, a correlation between the resident's specialty and pleural drainage complications has been noted in several studies [17]: residents from surgical specialties have a lower risk of complications (OR=0.4, 95%; CI=0.16-0.96) than residents from non-surgical specialties (notably emergency physicians) (OR=2.49, 95%, 1.11-5.56).

Ball et al. also showed that the location of the chest tube placement was an independent predictor of complications; indeed, a tube placed in the emergency room in the shock room or the intensive care unit was at a higher risk of complication and PAL (P=0.04).

Dugan et al. [18] showed that a history of COPD, female gender, smoking, diabetes and use of steroidal corticosteroids are predictive factors of prolonged air leaks.

In our study, only smoking [OR=2.4, IC=95%, 1.427-5.641] and drainage technique [OR=2.687, IC=95%, 1.226-5.889] were noted as predictors of prolonged air leaks.

Traumatic Pneumothorax is a diagnostic and therapeutic emergency. The management depends on the patient and the evolution. This work has proven that smoking and the conditions, especially the operator of the chest tube placement, are predictors of PAL. These factors can be considered to define a strategy for managing this kind of injury.

Competing interests

The authors declare no competing interest.

1. Alberdi F, Garcia I, Atutxa L, Zabarte M. Epidemiology of severe trauma. Medicina Intensiva (English Edition). 2014; 38: 580?588.
2. O’Connor JV, Adamski J. The Diagnosis and Treatment of Non-Cardiac Thoracic Trauma. Journal of the Royal Army Medical Corps. 2010; 156: 514.
3. Sauaia A, Moore FA, Moore EE, Moser KS, Brennan R, Read RA, et al. Epidemiology of Trauma Deaths: A Reassessment. The Journal of Trauma: Injury, Infection, and Critical Care. 1995; 38: 185-193.
4. Simon BJ, Cushman J, Barraco R, Lane V, Luchette FA, Miglietta M, et al. Pain Management Guidelines for Blunt Thoracic Trauma. The Journal of Trauma Injury, Infection, and Critical Care. 2005; 59: 1256-1267.
5. Dugan KC, Laxmanan B, Murgu S, Hogarth DK. Management of Persistent Air Leaks. Chest. 2017; 152: 417-423.
6. Ball CG, Kirkpatrick AW, Laupland KB, Fox DI, Nicolaou S, Anderson IB, et al. Incidence, Risk Factors, and Outcomes for Occult Pneumothoraces in Victims of Major Trauma. Journal of Trauma and Acute Care Surgery. 2005; 59: 917-925.
7. MacDuff A, Arnold A, Harvey J, on behalf of the BTS Pleural Disease Guideline Group. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax. 2010; 65; ii 18?31.
8. Alghnam S, Aldahnim MH, Aldebasi MH, Towhari JA, Alghamdi AS, Alharbi AA, et al. The incidence and predictors of pneumothorax among trauma patients in Saudi Arabia: Findings from a level-I trauma center. SMJ. 2020; 41: 247?252.
9. Oikonomou A, Prassopoulos P. CT imaging of blunt chest trauma. Insights Imaging. 2011; 2: 281?295.
10. Marts B, Durham R, Shapiro M, Mazuski JE, Zuckerman D, Sundaram M, et al. Computed tomography in the diagnosis of blunt thoracic injury. The American Journal of Surgery. 1994; 168: 688?692.
11. Ball CG, Kirkpatrick AW, Feliciano DV. The occult pneumothorax: What have we learned? Canadian Journal of Surgery. 2009; 52: E173-E179.
12. Zhang M, Teo LT, Goh MH, Leow J, Go KTS. Occult pneumothorax in blunt trauma: is there a need for tube thoracostomy? Eur J Trauma Emerg Surg. 2016; 42: 785-790.
13. Moore FO, Goslar PW, Coimbra R, Velmahos G, Brown CVR, Coopwood TBJ, et al. Blunt Traumatic Occult Pneumothorax: Is Observation Safe?—Results of a Prospective, AAST Multicenter Study. Journal of Trauma and Acute Care Surgery. 2011; 70: 1019-1025.
14. Reddy VS. Minimally invasive techniques in thoracic trauma. Semin Thorac Cardiovasc Surg. 2008; 20: 72-77.
15. Lu MS, Huang YK, Liu YH, Liu HP, Kao CL. Delayed pneumothorax complicating minor rib fracture after chest trauma. Am J Emerg Med. 2008; 26: 551-554.
16. Esme H, Solak O, Yurumez Y, Yavuz Y. The factors affecting the morbidity and mortality in chest trauma. Ulus Travma Acil Cerrahi Derg. 2006; 12: 305-310.
17. Ball CG, Lord J, Laupland KB, Gmora S, Mulloy RH, Ng AK, et al. Chest tube complications: How well are we training our residents? 2007; 50: 450-458.
18. Dugan KC, Laxmanan B, Murgu S, Hogarth DK. Management of Persistent Air Leaks. Chest. 2017; 152: 417-423.