Hydropneumothorax

Simultaneous air and fluid in the pleural space, producing an air fluid level on an upright chest X-ray. The fluid may be serous, blood (haemopneumothorax), pus (pyopneumothorax), chyle or gastric content.

• Causes: after thoracentesis or other pleural procedure (iatrogenic pneumothorax with an existing effusion), trauma, spontaneous pneumothorax with a reactive effusion, bronchopleural fistula, tuberculosis (rupture of a subpleural focus or cavity), lung abscess, malignancy (pleural metastases or necrotic tumour), pleural infection with gas forming organisms, oesophageal rupture, rupture of a hydatid cyst, and subphrenic abscess communicating through the diaphragm.
• Trapped lung with pneumothorax ex vacuo develops when fluid is drained and a non-expandable lung leaves a space filled with air.
• It is not a disease on its own: prognosis depends on the cause, and delay in treating pleural infection and oesophageal rupture increases mortality (oesophageal rupture mortality is about 20 to 40%, rising steeply after 24 hours).

• Sudden or progressive breathlessness, chest pain, cough, fever if infected, and a recent chest procedure or trauma.
• Signs: succussion splash on shaking the patient, a horizontal level of dullness with tympany over it, reduced breath sounds, tachycardia, tachypnoea, reduced expansion. Tension features (hypotension, tracheal deviation) when air is trapped.
• Differential diagnosis: loculated pleural effusion with a hiatus hernia or elevated hemidiaphragm, lung abscess with an air fluid level, bulla with fluid, diaphragmatic hernia, pneumatocele, hydatid cyst, subphrenic abscess and pleural empyema with gas.
• Complications: respiratory failure, tension pneumothorax, empyema, bronchopleural fistula, mediastinitis (oesophageal rupture), haemorrhagic shock, trapped lung, fibrothorax and death.

• Erect chest X-ray: horizontal air fluid level with a visceral pleural line, absent lung markings in the air space. A lateral decubitus film or ultrasound confirms free fluid. CT chest with contrast defines the cause (cavity, tumour, fistula, retained collection, oesophageal perforation).
• Pleural fluid (from the drain): appearance, haematocrit (haemothorax is fluid haematocrit more than half of blood), pH, protein, LDH, glucose, cell count with differential, triglycerides, amylase (raised in oesophageal rupture, pancreatic disease), Gram stain, culture, acid fast smear, Xpert MTB/RIF, adenosine deaminase (greater than 40 U/L suggests tuberculosis), and cytology.
• Blood tests: full blood count, urea and electrolytes, coagulation, CRP, glucose, group and crossmatch if bloody, HIV test.
• Contrast swallow or CT with oral contrast when oesophageal rupture is suspected (sudden chest pain after vomiting, subcutaneous emphysema, pleural fluid with food and low pH).

• Resuscitate first: oxygen to SpO2 94 to 98% (88 to 92% in COPD with retention), IV access, analgesia (paracetamol 1 g four times daily, morphine 2.5 to 5 mg IV titrated), and enoxaparin 40 mg SC daily when stable.
• Drainage is the first treatment:
  • Insert an intercostal drain under ultrasound or CT guidance: 12 to 14 French for serous fluid and air, 24 to 28 French when blood, pus or thick fluid is expected, connected to an underwater seal; apply suction at 10 to 20 cmH2O if the lung does not re-expand within 24 to 48 hours. Drain fluid slowly (no more than 1.5 L at a time) to avoid re-expansion pulmonary oedema.
• Cause directed treatment:
  • Simple serous (iatrogenic or spontaneous): drainage; most settle in days; talc slurry pleurodesis (4 to 5 g in 50 mL saline after intrapleural lidocaine 3 mg/kg, maximum 250 mg) for recurrent or persistent disease.
  • Traumatic haemopneumothorax: large bore drain (28 to 32 French); thoracotomy for initial drainage greater than 1500 mL, ongoing loss greater than 200 mL/h for 2 to 4 hours, or instability; retained clot is treated by early thoracoscopic evacuation (within 3 to 7 days), and intrapleural alteplase 10 mg with dornase alfa 5 mg twice daily for 3 days is an option when surgery is not possible.
  • Infection (pyopneumothorax): IV antibiotics with drainage, with ceftriaxone 2 g daily plus metronidazole 500 mg every 8 hours, or piperacillin tazobactam 4.5 g every 6 to 8 hours; add vancomycin 15 to 20 mg/kg every 8 to 12 hours for methicillin resistant Staphylococcus aureus) for at least 2 to 4 weeks IV and 4 to 6 weeks in total, with surgical decortication for failed drainage.
  • Tuberculosis: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg (maximum 2 g), ethambutol 15 mg/kg (maximum 1.2 g) daily for 2 months, then rifampicin and isoniazid for 4 months (extend to 9 months with empyema), with pyridoxine 25 to 50 mg daily, plus drainage; start antiretroviral therapy within 2 to 8 weeks in HIV.
  • Oesophageal rupture: nil by mouth, IV piperacillin tazobactam 4.5 g every 6 hours plus fluconazole 400 mg daily, omeprazole 40 mg IV daily, large bore chest drainage, and urgent surgical repair or stenting within 24 hours with enteral feeding by jejunostomy or parenteral nutrition.
  • Malignant: drain, then talc pleurodesis or an indwelling pleural catheter, and treatment of the primary tumour.
  • Trapped lung with pneumothorax ex vacuo: no further suction; observe; decortication or indwelling pleural catheter only if symptoms are significant.
  • Hydatid cyst rupture: albendazole 400 mg twice daily with praziquantel as advised, drainage and surgery by specialists.
• Surgery (thoracoscopy or thoracotomy) for persistent air leak beyond 5 to 7 days, retained haemothorax or loculated pus, bronchopleural fistula, or failure of drainage.
• Supportive care: nutrition, physiotherapy, early mobilisation, and avoidance of positive pressure ventilation without a drain.
• Special groups:
  • Children: small bore drains sized by age, with early surgical referral for empyema.
  • Pregnancy: place a chest drain and give ceftriaxone 2 g daily with metronidazole 500 mg every 8 hours; avoid fluoroquinolones and tetracyclines.
  • HIV and immunosuppression: test for tuberculosis and Pneumocystis infection, and use broader antibiotics.
  • Renal impairment: adjust antibiotic doses; avoid NSAIDs.
• Red flags: shock, subcutaneous emphysema, sudden large air leak, severe pain after vomiting, fever with rigors, drainage greater than 200 mL/h of blood.
• Follow up: daily review until the drain is removed (output less than 100 mL/day, no air leak, lung expanded); chest X-ray at 1 to 2 weeks and 6 weeks; treatment of the cause.