Safety of Transbronchial Biopsies in Patients with Pulmonary Hypertension: Systematic Review and Meta-Analysis

Rationale: Transbronchial lung biopsies (TBLBs) are commonly performed by pulmonologists. Most providers consider pulmonary hypertension to be at least a relative contraindication to TBLB. This practice is based primarily on expert opinion, as there are very few patient outcomes data backing it. Objectives: We performed a systematic review and meta-analysis of previously published studies to determine the safety of TBLB in patients with pulmonary hypertension. Methods: The MEDLINE, Embase, Scopus, and Google Scholar databases were searched for pertinent studies. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Meta-analysis was performed using MedCalc version 20.118 to calculate the weighted pooled relative risk of complications in patients with pulmonary hypertension. Results: Nine studies with a total of 1,699 patients were included in the meta-analysis. On the basis of the Newcastle-Ottawa Scale, the risk of bias was low in the included studies. The overall weighted relative risk of bleeding with TBLB in patients with pulmonary hypertension was 1.01 (95% confidence interval, 0.71-1.45) compared with patients without pulmonary hypertension. Heterogeneity was low; therefore, the fixed-effects model was used. In a subgroup analysis of three studies, the overall weighted relative risk of significant hypoxia in patients with pulmonary hypertension was 2.06 (95% confidence interval, 1.12-3.76). Conclusions: Our results show that the patients with pulmonary hypertension do not have a significantly elevated risk of bleeding with TBLB compared with control subjects. We hypothesize that significant postbiopsy bleeding might be preferentially originating from bronchial artery circulation as opposed to pulmonary artery circulation, much like episodes of massive spontaneous hemoptysis. This hypothesis can explain our results, as in this scenario, elevated pulmonary arterial pressure would not be expected to have a bearing on the risk of post-TBLB bleeding. Most of the studies in our analysis included patients with mild to moderate pulmonary hypertension and it is not clear if our results can be extrapolated to patients with severe pulmonary hypertension. We noted that the patients with pulmonary hypertension were at a higher risk of developing hypoxia and needing a longer duration of mechanical ventilation with TBLB compared with control subjects. Further studies are needed to better understand the origin and pathophysiology of post-TBLB bleeding.