Proposed management algorithm for severe hypoxemia after liver transplantation in the hepatopulmonary syndrome

Abstract

The hepatopulmonary syndrome (HPS) is defined as the triad of liver disease, intrapulmonary vascular dilatation, and abnormal gas exchange, and is found in 10-32% of patients with liver disease. Liver transplantation is the only known cure for HPS, but patients can develop severe posttransplant hypoxemia, defined as a need for 100% inspired oxygen to maintain a saturation of ≥85%. This complication is seen in 6-21% of patients and carries a 45% mortality. Its management requires the application of specific strategies targeting the underlying physiologic abnormalities in HPS, but awareness of these strategies and knowledge on their optimal use is limited. We reviewed existing literature to identify strategies that can be used for this complication, and developed a clinical management algorithm based on best evidence and expert opinion. Evidence was limited to case reports and case series, and we determined which treatments to include in the algorithm and their recommended sequence based on their relative likelihood of success, invasiveness, and risk. Recommended therapies include: Trendelenburg positioning, inhaled epoprostenol or nitric oxide, methylene blue, embolization of abnormal pulmonary vessels, and extracorporeal life support. Availability and use of this pragmatic algorithm may improve management of this complication, and will benefit from prospective validation.

Figure 1

Proposed management algorithm for severe post–liver transplant hypoxemia in patients with hepatopulmonary syndrome. Response is defined as a 20% improvement in P/F ratio (and deterioration a 20% drop in P/F ratio), as measured at 30 min for all other interventions, and at 5 h for methylene blue (MB) (MB response can be seen as early as 30 min, but peak effect is at 5 h). ^‡If feeding in this position, ensure that patient has a post‐pyloric feeding tube. ^*If ventilated with high frequency oscillatory ventilation (HFOV), skip this step and go directly to inhaled nitric oxide. ^†In accordance with the modified University Health Network Inhaled Pulmonary Vasodilator Policy (see Supporting Information 1). ^‡MB 3 mg/kg in 50–100cc's normal saline IV over 15 min; change to reverse Trendelenburg for MB (if not possible, place supine). Hold MB after every 3 doses to assess ongoing need. Maximum recommended duration: 24–48 h (effects of larger cumulative doses unknown) 15, 16. Notes: hold any selective serotonin reuptake inhibitor (SSRI) and await appropriate washout if using MB (risk of serotonin toxicity) 17; MB can cause spuriously low pulse oximetry (verify oxygenation with ABG). Algorithm should be adapted in accordance with any available pre‐operative testing results of Trendelenburg positioning, inhaled nitric oxide and/or IV MB, and any prior pulmonary angiography identifying embolizable pulmonary vessels. FiO₂ denotes fraction on inspired oxygen; DO₂ denotes systemic oxygen delivery; SVO₂ denotes mixed venous oxygen saturation; HFOV denotes frequency oscillatory ventilation. See Supporting Information 2 for figure References.