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Abstract

Introduction: The incidence of pulmonary hypertension (PH) following hematopoietic stem cell transplant (SCT) is unknown. We have observed PH in multiple cases of critically ill SCT patients, especially those with transplant associated thrombotic microangiopathy (TA-TMA). Hence, we sought to determine the incidence of PH in SCT patients admitted to our pediatric intensive care unit (PICU). Hypothesis: PH is an important cause of morbidity in SCT patients admitted to the PICU. Methods: A multi-disciplinary practice guideline was implemented in January 2012 requiring screening for PH in SCT patients admitted to the PICU who had known PH or TA-TMA, and those presenting with respiratory failure or cardiovascular failure. Children underwent echocardiography on admission and every 1-2 weeks thereafter to screen for PH. Patients were stratified as being “at risk” for, or having PH if their right ventricular (RV) pressure was estimated at 35-49% or >50% of systolic blood pressure, respectively. These estimates were compared to data from routine pre-transplant echocardiograms. Results: During an 8 month period, 25 SCT patients admitted to the PICU met our screening criteria. All patients had undergone an allogeneic transplant, with 15 (60%) transplanted for underlying immunodeficiency. None had evidence of elevated RV pressure prior to SCT. Seventeen (70%) were transferred to the PICU for respiratory deterioration. Fourteen of those patients (56%) required invasive mechanical ventilation, while 3 (16%) received non-invasive support. At PICU admission or during subsequent screening, 7 patients (28%) were determined to be “at risk” while 3 (12%) developed PH. One PH patient with systemic RV pressure and low cardiac output underwent a successful atrial septostomy. TA-TMA was present in 16 (64%) admissions; overall, the incidence of TA-TMA was even higher in the “at risk” and PH group (8 of 10; 80%). PICU survival for this cohort was 60%; 70% of patients who were “at risk” or with PH are still alive. Conclusions: PH is common in SCT patients requiring ICU admission for respiratory failure, especially in the setting of TA-TMA. Recognition and aggressive therapy of PH in these patients may have a positive impact on outcome.