To determine if endobronchial (topical) tranexamic acid used prophylactically prior to performing transbronchial biopsies in lung transplant recipients reduces bleeding risk.

Tranexamic acid (TXA) is an antifibrinolytic agent. It forms a reversible complex that displaces plasminogen from fibrin resulting in inhibition of fibrinolysis. It also inhibits proteolytic activity of plasmin. TXA is frequently used in clinical practice and can be administered via multiple delivery methods, including intravenous, nebulized, and topical. It has been shown to reduce blood loss in a variety of clinical settings without significant adverse effects. It has also been evaluated for prophylactic use with mixed results in reducing bleeding. In our current general pulmonary practice, topical TXA is used variably by pulmonologists during bronchoscopy for post-biopsy bleeding or pulmonary hemorrhage.

The purpose of this research study is to determine if prophylactic topical TXA can reduce bleeding risk in lung transplant patients who undergo transbronchial biopsies. A finding of reduced bleeding would be significant as it could improve clinical outcomes, allow for improved diagnostic yield of biopsy samples, and improve patient experience. It therefore has the potential to change clinical practice and standardize bronchoscopy procedures.

Inclusion Criteria:

1. Single or double lung transplant recipients
2. Patients >18 years old
3. Willingness and ability to sign an informed consent for study participation

Exclusion Criteria:

1. Platelet count (<50k/uL)
2. INR (>1.6)
3. Active bleeding
4. Decompensated liver disease
5. History of uremic bleeding or BUN >50
6. Severe pulmonary hypertension (mean PA pressure >40 mmHg on RHC or estimated PA systolic pressure >62 mmHg on TTE within one year of procedure)
7. Known bleeding disorder
8. Allergy to TXA
9. Prior history of severe TBBx-related airway bleeding requiring admission or advanced maneuvers for hemostasis (examples including intubation, bronchial artery embolization, surgical intervention)
10. Contraindications to topical TXA
11. Pregnancy
12. Vulnerable populations
13. Adults of limited English proficiency/non-English speakers

The investigational pharmacist will be responsible for randomizing on the day of bronchoscopy to placebo or Tranexamic acid in a 1:1 fashion using REDCap software. The pharmacist will be the only individual aware of the randomization assignment. All other study personnel will be blinded to the randomization assignment.