Adverse effects of intrapleural instillation of tissue plasminogen activator in a horse: Suspected re‐expansion pulmonary oedema

This case report describes a 5‐year‐old pregnant Warmblood mare that was being treated for fibrinous bacterial pleuropneumonia. Since initial attempts to drain and lavage both pleural cavities were ineffective due to the presence of extensive intrapleural fibrin loculations, recombinant human tissue plasminogen activator (tPA) was instilled into both pleural cavities, to promote fibrinolysis and improve drainage. Within 1–2 h of instilling tPA, the horse became distressed, with increasing dyspnoea, tachycardia, pleurodynia and hypoxaemia. At 4 h post tPA instillation, diffuse bilateral pulmonary oedema was evidenced by the onset of widespread audible inspiratory crackles and ultrasonographic ring‐down artefacts. Ultrasonography demonstrated that tPA had induced pleural fibrinolysis, thereby removing the restrictive effects of pleural adhesions on lung motion and facilitating lung re‐expansion. Re‐expansion pulmonary oedema was suspected, although an adverse drug reaction could not be excluded. The complication resolved with nasal oxygen supplementation, and administration of frusemide, meloxicam, morphine and hydroxyethyl starch. Subsequent repetition of intrapleural tPA instillation and thoracic drainage had no apparent adverse effect. The mare was discharged from the hospital and subsequently foaled successfully. The pathogenesis, diagnosis and management of re‐expansion pulmonary oedema are reviewed.