RESUMEN
Background: Pneumothorax following shoulder arthroscopy, although rare, is documented in over 30 PubMed case reports as occurring during or within 10 hours post-procedure. Case Presentation: A fit septuagenarian underwent a two-hour arthroscopic rotator cuff repair with IV anaesthesia and laryngeal mask airway, without a nerve block. With one hour remaining of the operation, the patient had desaturation and hypotension. Lung sliding was absent on ultrasound and x-ray confirmed left-sided tension pneumothorax. Successful thoracic drain insertion and lung re-expansion facilitated his recovery, allowing discharge after 24 hours and symptom-free status at 6 months. Interpretation: This case highlights pneumothorax as an uncommon yet possible post-arthroscopic event. The speculated aetiology is the surgical procedure, where pump-induced pressure fluctuations may displace air into surrounding tissue. Instances of pneumomediastinum and subcutaneous emphysema without pneumothorax suggest arthroscopic origin of air. Prompt perioperative ultrasound can aid in detecting such critical complications.