Incidence of clinically unsuspected pulmonary embolism in mechanically ventilated lung transplant recipients

BACKGROUND: The incidence of pulmonary embolism (PE) in lung transplant recipients has not been well established. The purpose of this study was to describe the incidence of clinically unsuspected PE in a cohort of lung transplant recipients requiring mechanical ventilatory support. These patients underwent surgical lung biopsy (SLBx) for progressive deterioration in the absence of a specific diagnosis. METHODS: We retrospectively reviewed all SLBx pathology reports for mechanically ventilated lung transplant recipients with clinical deterioration, progressive radiographic abnormalities, or both at any time after transplantation. Our objective was to determine the incidence of clinically unsuspected PE in this patient population during an 11-year period. RESULTS: Clinically unsuspected PE was identified in 8 (19.5%) of 41 mechanically ventilated lung transplant recipients after a median of 20 days (interquartile range: 16.3, 148.8 days) after transplantation. There was a tendency for clinically unsuspected PE to occur in the early postoperative period, with the majority of events (75%) occurring within 14 weeks of transplantation. Pulmonary infarction occurred in 37.5% of cases and occurred uniformly during the postoperative period. The finding of pulmonary emboli on SLBx lead to confirmatory investigations in five (62.5%) of eight patients and changed management in seven (87.5%) of eight patients. CONCLUSIONS: A high index of suspicion and reliance on ancillary diagnostic testing may be insufficient to establish the diagnosis of postoperative pulmonary emboli. PE is an underappreciated complication contributing to respiratory failure in the early postoperative period in lung transplant recipients, warranting identification of putative risk factors and consideration for prophylaxis.