Kidney international
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Kidney international · Jun 2019
CommentAdjusting cardiopulmonary bypass flow or arterial pressure to maintain renal medullary oxygen.
Cardiopulmonary bypass leads to renal hypoperfusion, resulting in medullary hypoxia and acute kidney injury. In instrumented sheep subjected to cardiopulmonary bypass, Lankadeva et al. found that medullary perfusion and tissue oxygen tension (PO2) was maintained at low-dose metaraminol, an α1-adrenoceptor agonist, because low-dose metaraminol increased perfusion pressure without affecting renal vascular resistance. ⋯ Urine PO2 tracks medullary PO2, and low urine PO2 predicts acute kidney injury. Adjusting cardiopulmonary bypass to maintain urine PO2 may help avoid acute kidney injury.
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Kidney international · Jun 2019
Comparative StudyComparison of organ donation and transplantation rates between opt-out and opt-in systems.
Studies comparing opt-out and opt-in approaches to organ donation have generally suggested higher donation and transplantation rates in countries with an opt-out strategy. We compared organ donation and transplantation rates between countries with opt-out versus opt-in systems to investigate possible differences in the contemporary era. Data were analysed for 35 countries registered with the Organisation for Economic Co-operation and Development (17 countries classified as opt-out, 18 classified as opt-in) and obtained organ donation and transplantation rates for 2016 from the Global Observatory for Donation and Transplantation. ⋯ In a multivariate linear regression model, an opt-out system was independently predictive of fewer living donors but was not associated with the number of deceased donors or with transplantation rates. Apart from the observed difference in the rates of living donation, our data demonstrate no significant difference in deceased donation or solid organ transplantation activity between opt-out versus opt-in countries. This suggests that other barriers to organ donation must be addressed, even in settings where consent for donation is presumed.
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Kidney international · Jun 2019
Strategies that improve renal medullary oxygenation during experimental cardiopulmonary bypass may mitigate postoperative acute kidney injury.
Renal medullary hypoxia may contribute to cardiac surgery-associated acute kidney injury (AKI). However, the effects of cardiopulmonary bypass (CPB) on medullary oxygenation are poorly understood. Here we tested whether CPB causes medullary hypoxia and whether medullary oxygenation during CPB can be improved by increasing pump flow or mean arterial pressure (MAP). ⋯ Increasing pump flow from 80 to 100 mL kg-1min-1 increased RBF (17%) and medullary Po2 from 20 to 29 mm Hg. Metaraminol (0.2 mg/min) increased MAP from 63 to 90 mm Hg, RBF (47%), and medullary Po2 from 19 to 39 mm Hg. Thus, the renal medulla is susceptible to hypoxia during CPB, but medullary oxygenation can be improved by increasing pump flow or increasing target MAP by infusion of metaraminol.
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Kidney international · Apr 2019
Disparate outcomes observed within Kidney Disease: Improving Global Outcomes (KDIGO) acute kidney injury stage 1.
The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline classifies acute kidney injury (AKI) into 3 stages defined by serum creatinine elevation or urine output decline. We evaluated the potential impact of further categorizing AKI stage 1 into two stages based on serum creatinine criteria, with a focus on how the resulting 4-stage classification would affect the association of AKI stages with clinical outcomes. We defined AKI stage 1a as an absolute increase in serum creatinine of 0.3 mg/dl within 48 hours and stage 1b as a 50% relative increase in serum creatinine within 7 days. ⋯ Compared to patients with no AKI, the odds of in-hospital mortality were progressively higher for patients with higher AKI stages (odds ratio 4.3 for patients with stage 1a, 10.9 for stage 1b, 40.6 for stage 2, and 60.0 for stage 3 AKI). Patients with AKI stages 1a and 1b experienced clinically meaningful and statistically significant differences in length of stay and mortality. This study suggests that a modified 4-stage version of the KDIGO AKI classification may provide additional prognostic information.