Liver transplant outcomes using late allocation grafts

Post-cross clamp late allocation (LA) liver allografts are at increased risk for discard for many reasons including logistical complexity. Nearest neighbor propensity score matching was used to match 2 standard allocation (SA) offers to every 1 LA liver offer performed at our center between 2015 and 2021. Propensity scores were based on a logistic regression model including recipient age, recipient sex, graft type (donation after circulatory death vs. donation after brain death), Model for End-stage Liver Disease (MELD), and DRI score. During this time, 101 liver transplants (LT) were performed at our center using LA offers. In comparing LA and SA offers, there were no differences in recipient characteristics including indication for transplant ( p = 0.29), presence of PVT ( p = 0.19), TIPS ( p = 0.83), and HCC status ( p = 0.24). LA grafts came from younger donors (mean age 43.6 vs. 48.9 y, p = 0.009) and were more likely to come from regional or national Organ Procurement Organizations (OPOs) ( p < 0.001). Cold ischemia time was longer for LA grafts (median 8.5 vs 6.3 h, p < 0.001). Following LT, there were no differences between the 2 groups in intensive care unit ( p = 0.22) and hospital ( p = 0.49) lengths of stay, need for endoscopic interventions ( p = 0.55), or biliary strictures ( p = 0.21). Patient (HR 1.0, 95% CI, 0.47-2.15, p = 0.99) and graft (HR 1.23, 95% CI, 0.43-3.50, p = 0.70) survival did not vary between the LA and SA cohorts. One-year LA and SA patient survival was 95.1% and 95.0%; 1-year graft survival was 93.1% and 92.1%, respectively. Despite the additional logistical complexity and longer cold ischemia time, LT outcomes utilizing LA grafts are similar to those allocated by means of SA. Improving allocation policies specific to LA offers, as well as the sharing of best practices between transplant centers and OPOs, are opportunities to further help minimize unnecessary discards.

Association of DGF and Early Readmissions on Outcomes Following Kidney Transplantation

Concerns regarding outcomes and early resource utilization are potential deterrents to broader use of kidneys at risk for delayed graft function (DGF). We assessed outcomes specific to kidneys with DGF that required early readmission following transplant. Three groups were identified: 1) recipients with DGF not requiring readmission, 2) recipients with DGF having an isolated readmission, and 3) recipients with DGF requiring ≥2 readmissions. Most recipients either required a single readmission (26.8%, n = 247) or no readmission (56.1%, n = 517); 17.1% (n = 158), had ≥2 readmissions. Recipients requiring ≥2 readmissions were likely to be diabetic (53.8%, p = 0.04) and have longer dialysis vintage (p = 0.01). Duration of DGF was longer with increasing number of readmissions (p < 0.001). There were no differences in patient survival for those with DGF and 0, 1 and ≥2 readmissions (p = 0.13). Graft survival, however, was lower for those with ≥2 readmissions (p < 0.0001). This remained true when accounting for death-censored graft loss (p = 0.0012). Additional subgroup analysis was performed on mate kidneys with and without DGF and mate kidneys, both with DGF, with and without readmissions. For these subgroups, there were no differences in patient or graft survival. As a whole, patients with DGF have excellent outcomes, however, patients with DGF requiring ≥2 readmissions have lower graft survival. A better understanding of recipient variables contributing to multiple readmissions may allow for improvements in the utilization of DGF at-risk kidneys.

Effect of aging on cerebral autoregulation during cardiopulmonary bypass. Association with postoperative cognitive dysfunction

BACKGROUND

Age is a predictor of cognitive dysfunction after cardiac surgery, but the mechanism is unknown. The purpose of our study was to determine whether age-related decrements in cognition are associated with cerebral blood flow (CBF) autoregulation during cardiopulmonary bypass (CPB).

METHODS AND RESULTS

Cognitive function testing was completed before surgery and before hospital discharge in 215 patients undergoing elective coronary artery bypass grafting (CABG) surgery. The battery consisted of seven tests with nine measures designed to evaluate memory, mood changes, and visuomotor speed and function. Pressure-flow and metabolic-flow cerebral autoregulation during hypothermic cardiopulmonary bypass were determined using the 133Xe clearance CBF method and radial artery and jugular bulb effluent to calculate cerebral metabolic rate (CMRO2) and cerebral AV difference (C[AV]O2). Pressure-flow autoregulation was tested by using two CBF measurements at stable hypothermia: one at stable mean arterial pressure (MAP) and the second 15 minutes later when MAP had increased or decreased > or = 20%. Metabolism-flow autoregulation was tested by varying the temperature (CMRO2) and measuring the coupling of CBF and CMRO2. Individual patient autoregulation was correlated with changes in cognitive measures. Cognitive performance declined in 6 of 9 measures after CABG surgery. Age predicted cognitive decline in 7 of 9 measures; short-term memory showed the greatest effect of age. Pressure-flow autoregulation during hypothermic CPB showed a small but significant (P < .0001) effect of pressure on CBF. There was no effect of age on the slope of CBF response to changes in MAP (pressure-flow autoregulation). There was a major effect of temperature on CBF during CPB (P < .0001). Coupling CBF and CMRO2 with changing temperature was unaffected by age. Changes in cognition were not associated with measures of cerebral autoregulation. However, increasing C(AV)O2 is associated with cognitive deficits in 5 of 9 measures; these associations were independent of age.

CONCLUSIONS

Increased age predisposes to impaired cognition after cardiac surgery. This decline in cognitive function in the elderly is not associated with age-related changes in cerebral blood flow autoregulation. The association of increased oxygen extraction with decline in some measures of cognitive function suggests that an imbalance in cerebral tissue oxygen supply, which is unrelated to age, contributes to acute cognitive dysfunction after cardiac surgery. Cognitive dysfunction after CPB in the elderly cannot be explained by impaired CBF autoregulation.

Warming during cardiopulmonary bypass is associated with jugular bulb desaturation

The objective of this study was to characterize cerebral venous effluent during normothermic nonpulsatile cardiopulmonary bypass. Thirty-one (23%) of 133 patients met desaturation criteria (defined as jugular bulb venous oxygen saturation less than or equal to 50% or jugular bulb venous oxygen tension less than or equal to 25 mm Hg) during normothermic cardiopulmonary bypass (after hypothermic cardiopulmonary bypass at 27 degrees to 28 degrees C). Cerebral blood flow, calculated using xenon 133 clearance methodology, was significantly (p less than 0.005) higher in the saturated group (33.7 +/- 10.3 mL.100 g-1.min-1) than in the desaturated group (26.2 +/- 6.9 mL.100 g-1.min-1), whereas the cerebral metabolic rate for oxygen was significantly lower (p less than 0.005) in the saturated group (1.28 +/- 0.39 mL.100 g-.min-1) than in the desaturated group (1.52 +/- 0.36 mL.100 g-1.min-1) at normothermia. The arteriovenous oxygen difference at normothermia was lower in the saturated group (3.92 +/- 1.12 mL/dL) than in the desaturated group (5.97 +/- 1.05 mL/dL). Neuropsychological testing was performed in 74 of the 133 patients preoperatively and on day 7 postoperatively. There was a general decline in mean scores of all tests postoperatively in both groups with no significant difference between the groups. We conclude that cerebral venous desaturation represents a global imbalance in cerebral oxygen supply-demand that occurs during normothermic cardiopulmonary bypass and may represent transient cerebral ischemia. These episodes, however, are not associated with impared neuropsychological test performance as compared with the performance of patients with no evidence of desaturation.