Donor preoperative oxygen delivery and post-extubation hypoxia impact donation after circulatory death hypoxic cholangiopathy.

ABSTRACT

AIM: To evaluate donation after circulatory death (DCD) orthotopic liver transplant outcomes [hypoxic cholangiopathy (HC) and patient/graft survival] and donor risk-conditions. METHODS: From 2003-2013, 45 DCD donor transplants were performed. Predonation physiologic data from UNOS DonorNet included preoperative systolic and diastolic blood pressure, heart rate, pH, SpO2, PaO2, FiO2, and hemoglobin. Mean arterial blood pressure was computed from the systolic and diastolic blood pressures. Donor preoperative arterial O2 content was computed as [hemoglobin (gm/dL) × 1.37 (mL O2/gm) × SpO2%) + (0.003 × PaO2)]. The amount of preoperative donor red blood cell transfusions given and vasopressor use during the intensive care unit stay were documented. Donors who were transfused ≥ 1 unit of red-cells or received ≥ 2 vasopressors in the preoperative period were categorized as the red-cell/multi-pressor group. Following withdrawal of life support, donor ischemia time was computed as the number-of-minutes from onset of diastolic blood pressure < 60 mmHg until aortic cross clamping. Donor hypoxemia time was the number-of-minutes from onset of pulse oximetry < 80% until clamping. Donor hypoxia score was (ischemia time + hypoxemia time) ÷ donor preoperative hemoglobin. RESULTS: The 1, 3, and 5 year graft and patient survival rates were 83%, 77%, 60%; and 92%, 84%, and 72%, respectively. HC occurred in 49% with 16% requiring retransplant. HC occurred in donors with increased age (33.0 ± 10.6 years vs 25.6 ± 8.4 years, P = 0.014), less preoperative multiple vasopressors or red-cell transfusion (9.5% vs 54.6%, P = 0.002), lower preoperative hemoglobin (10.7 ± 2.2 gm/dL vs 12.3 ± 2.1 gm/dL, P = 0.017), lower preoperative arterial oxygen content (14.8 ± 2.8 mL O2/100 mL blood vs 16.8 ± 3.3 mL O2/100 mL blood, P = 0.049), greater hypoxia score >2.0 (69.6% vs 25.0%, P = 0.006), and increased preoperative mean arterial pressure (92.7 ± 16.2 mmHg vs 83.8 ± 18.5 mmHg, P = 0.10). HC was independently associated with age, multi-pressor/red-cell transfusion status, arterial oxygen content, hypoxia score, and mean arterial pressure (r(2) = 0.6197). The transplantation rate was greater for the later period with more liberal donor selection [era 2 (7.1/year)], compared to our early experience [era 1 (2.5/year)]. HC occurred in 63.0% during era 2 and in 29.4% during era 1 (P = 0.03). Era 2 donors had longer times for extubation-to-asystole (14.4 ± 4.7 m vs 9.3 ± 4.5 m, P = 0.001), ischemia (13.9 ± 5.9 m vs 9.7 ± 5.6 m, P = 0.03), and hypoxemia (16.0 ± 5.1 m vs 11.1 ± 6.7 m, P = 0.013) and a higher hypoxia score > 2.0 rate (73.1% vs 28.6%, P = 0.006). CONCLUSION: Easily measured donor indices, including a hypoxia score, provide an objective measure of DCD liver transplantation risk for recipient HC. Donor selection criteria influence HC rates.