Pulmonary barotrauma in a paratrooping accident

Introduction

Paratrooping is a challenging activity requiring a high degree of mental and physical fitness.¹ Injury rates varying from two to 20 per 1000 jumps have been documented, the wide variation being because of differences in the type of jump (training or tactical), timing (day or night), experience of the paratrooper and the type of terrain.¹ Lower extremity injuries are most common followed by spinal, head and neck and upper extremity injuries.^{1, 2} We report a case of a paratrooper who accidentally lost his parachute at an altitude of approximately 100 feet during a sea-landing jump. The pattern of injuries suffered and their successful conservative management have not been reported in literature until date.

Case report

A 21-year-old patient, a male paratrooper was brought to our hospital after a parachuting accident during a sea-landing jump. On arrival, he had a Glasgow Coma Score of 15. He complained of pain in chest during deep breathing which was more on the right side. He gave a history of accidentally losing his parachute at a height of approximately 100 feet above the sea during his sea-landing exercise and landing on sea from that height. On examination, his pulse was 92/min, blood pressure was 112/68 mm Hg, respiratory rate was 30/min and oxygen saturation was 90% on room air. He had bruises over the forehead, pectoral regions and epigastrium and chemosis of right eye. Chest examination revealed hyperresonant note with absence of breath sounds anteriorly in the patient in the supine position. Abdominal examination revealed a soft abdomen with the right hypochondrial tenderness. A chest radiograph revealed bilateral lower zone non-homogenous opacities which were more on the right side with a deep sulcus sign on the left side consistent with a pneumothorax (Fig. 1). A computerised tomography (CT) scan of the whole body was performed which revealed bilateral pneumothorax with features of bilateral lung contusion (Fig. 2), Grade III hepatic injury involving the segments VII and VIII with a thin rim of fluid in the right subhepatic space, a bilateral fracture of transverse process of the L5 vertebra and a bilateral undisplaced fracture of the anterior column of the acetabulum. There was a small air-fluid level in both the maxillary sinuses. The neuroparenchyma and cervical spine were normal. Arterial blood gas analysis revealed PaO₂/FiO₂ ratio of 220. He was started on oxygen using a mask with a PaO₂ rate maintained at more than 100 mm Hg. He was also started on injectable antibiotics as there was suspicion of sea water aspiration (intravenous ceftriaxone 1 g at 12 hourly interval and intravenous clindamycin 600 mg at 8 hourly interval) and medications for pain relief. It was decided to continue conservative management and closely monitor the patient. Intervention in the form of intercostal drainage of pneumothorax was planned if he developed clinical deterioration, desaturation/hypoxaemia or radiological increase in the size of pneumothorax. He was presented to the neurosurgeon, gastrointestinal surgeon, orthopaedic surgeon and ENT surgeon for associated injuries. All injuries were managed conservatively. He was under continuous monitoring of oxygen saturation. Arterial blood gas analysis was carried out daily for the first 3 days, and the chest radiograph was taken daily for 72 h followed by weekly for the next 4 weeks. His oxygen requirement gradually reduced over the next 4 weeks, and he was gradually weaned off oxygen. All his other injuries showed complete resolution before discharge. A chest radiograph, abdominal ultrasonograph and repeat CT scan taken at the fourth week were normal (Fig. 3). Spirometry and Diffusion Capacity of lung for Carbon Monoxide (DLCO) results at discharge were normal. He was kept under observation for 6 months after which he joined active duties.

Fig. 1.

A chest radiograph Antero Posterior (AP) view supine bedside film showing bilateral non-homogenous opacities (right > left).

Fig. 2.

A non-contrast computerised tomography (NCCT) scan of the thorax showing bilateral pneumothorax with bilateral diffuse areas of ground glass opacification suggestive of pulmonary contusions.

Fig. 3.

Repeat non-contrast computerised tomography (NCCT) chest scan which was normal.

Discussion

Risk of injury during paratrooping is well documented with an average of six injuries per 1000 jumps.³ Lower limbs followed by spinal injuries are most common.^{1, 2, 3} In our patient also, there was a bilateral fracture of transverse process of the L5 vertebra and bilateral undisplaced fracture of the anterior column of the acetabulum.

Mechanism of pneumothorax in a non-penetrating trauma is because of alveolar rupture from chest compression followed by dissection of released air along the interstitium to the mediastinal or visceral pleura and rupture of the mediastinal or visceral pleura.⁴ The supine chest radiograph is insensitive in early diagnosis in these patients.⁴ In our patient also, the initial chest radiograph did not reveal a pneumothorax. Most traumatic pneumothoraces require chest tube drainage, role of conservative management being limited to small pneumothorax.⁴ In our case also, we had planned for an early tube thoracotomy if the patient deteriorated clinically or had an increase in the size of pneumothorax. However, the patient showed progressive improvement with complete clinical and radiological resolution and normal pulmonary functions without any intervention.

Pattern of injuries, including those to chest, after a fall from height has been studied by various authors.^{5, 6, 7, 8} Robertson et al.⁶ studied lung injuries in 15 patients who attempted suicide by jumping into water from the Aurora Bridge in Seattle. The approximate height of jump was 50 m into the water. They noted that common signs in these patients were haemoptysis, crackles and hypotension. The authors also observed that although rib fractures were present only in four patients, pneumothorax was seen in 10 patients. The authors have proposed that the mechanism of barotraumas in patients without rib fractures could be pulmonary contusions followed by leakage of air along the pulmonary vasculature to the mediastinal pleura.⁵ The eventual rupture of the mediastinal pleura will lead to development of pneumothorax.⁵ In our patient also there was presence of bilateral lung contusions and pneumothorax without any rib fracture. Atanasijevic et al.⁶ studied the severity of injuries and the height of fall. The authors found that although there is an association between thoracic injury and fall height, the extensiveness of rib fractures is also dependent on the surface with which the patient makes impact.⁶ The authors also noted that sudden chest compression at the point of contact with surface would lead to pneumostatic pressure and lung rupture. The contact surface in our patient being water may have resulted in no rib fractures despite a fall from 100 feet. Lee et al.⁸ studied trauma patterns in 203 patients who jumped from bridges on the Han River. Among the patients who reached the emergency room (ER) alive, 26.9% required cardiopulmonary resuscitation (CPR). Of these 98% of patients died during the course of hospitalization. Among the patients not requiring CPR in the ER, the mortality was 0.7%.⁸ Our patient did not require CPR at any time which could explain the favourable outcome. In their study, chest injuries were most common, and spinal injuries were more common than abdominal injuries. Our patient had chest, abdominal and spinal injuries together which can be explained by the fact that he fell from a greater height than the patients included in the other study. A higher incidence of thoracic and spinal trauma in patients who fall from height into water can be explained by large surface areas and heavy weight of the trunk.

Conclusion

Paratrooping carries a high occupational risk of injury. Injuries in this subset can present with multiple system involvement simultaneously. Although it is generally the accepted norm to be aggressive in management of these patients, conservative management under controlled close monitoring may also play a role.

Conflicts of interest

The authors have none to declare.