Purpose Severe Pulmonary hypertension (PHTN) is defined as the mean pulmonary artery pressure (mPAP) greater than 40 mmHg at rest. Lung transplantation is often the common treatment pathway for end-stage pulmonary hypertension. Anesthetic management of lung transplantation in a patient with severe PHTN can be challenging. The intraoperative period during the induction, initial one lung ventilation, and clamping of the pulmonary artery is particular dangerous as vasodilation, myocardial depression, initiation of positive pressure ventilation, acute increase in RV afterload can lead to systemic hypotension and acute RV failure leading to cardiac arrest. Our aim is review patients with severe PHT undergoing their first double lung transplantation over the last 10 year period. Methods and Materials We investigated the role of the severity of PHT in predicting the need for mechanical support (VA-ECMO, or CPB) prior to first lung pneumonectomy. We retrospectively reviewed 88 cases of sequential double lung transplants, between 2007 and September 2009, who had a mean pulmonary pressure greater (mPA) 40 mmHg on their preoperative right heart catheterization. Results Our results show a clear dose response relationship between mPA and need for MCS: for patients with mPA between 40-49 (45/59 patient done under support, with 19/45 needing support unplanned), 50-60 (21/22 with support, 9/21 unplanned), 60-70 (8/9, and 1/8 unplanned), and >70 (1/1, 0/1 unplanned). Moreover, examining all 88 patients, patients needing support 75/88 vs 13/88 done without support, the average mean PA was 50 vs 45, PVR (7.7 vs 4.6), and 6 minute walk distance (161 vs 221 meters). In conclusion, we show that mean pulmonary artery pressure shows a dose response relationship with need for MCS. Conclusions The incidence of hemodynamic instability requiring resuscitation and emergency institution of cardiopulmonary bypass or extracorporeal life support is very high (26%) in severe PHT and future studies should focus on the prediction and management.