Continuous bladder urinary oxygen tension as a new tool to monitor medullary oxygenation in the critically ill.

Acute kidney injury (AKI) is common in the critically ill. Inadequate renal medullary tissue oxygenation has been linked to its pathogenesis. Moreover, renal medullary tissue hypoxia can be detected before biochemical evidence of AKI in large mammalian models of critical illness. This justifies medullary hypoxia as a pathophysiological biomarker for early detection of impending AKI, thereby providing an opportunity to avert its evolution. Evidence from both animal and human studies supports the view that non-invasively measured bladder urinary oxygen tension (PuO2) can provide a reliable estimate of renal medullary tissue oxygen tension (tPO2), which can only be measured invasively. Furthermore, therapies that modify medullary tPO2 produce corresponding changes in bladder PuO2. Clinical studies have shown that bladder PuO2 correlates with cardiac output, and that it increases in response to elevated cardiopulmonary bypass (CPB) flow and mean arterial pressure. Clinical observational studies in patients undergoing cardiac surgery involving CPB have shown that bladder PuO2 has prognostic value for subsequent AKI. Thus, continuous bladder PuO2 holds promise as a new clinical tool for monitoring the adequacy of renal medullary oxygenation, with its implications for the recognition and prevention of medullary hypoxia and thus AKI.

Health-related quality of life after restrictive versus liberal RBC transfusion for cardiac surgery: Sub-study from a randomized clinical trial.

BACKGROUND: Transfusion Requirements in Cardiac Surgery III (TRICS III), a multi-center randomized controlled trial, demonstrated clinical non-inferiority for restrictive versus liberal RBC transfusion for patients undergoing cardiac surgery. However, it is uncertain if transfusion strategy affects long-term health-related quality of life (HRQOL). STUDY DESIGN AND METHODS: In this planned sub-study of Australian patients in TRICS III, we sought to determine the non-inferiority of restrictive versus liberal transfusion strategy on long-term HRQOL and to describe clinical outcomes 24 months postoperatively. The restrictive strategy involved transfusing RBCs when hemoglobin was <7.5 g/dl; the transfusion triggers in the liberal group were: <9.5 g/L intraoperatively, <9.5 g/L in intensive care, or <8.5 g/dl on the ward. HRQOL assessments were performed using the 36-item short form survey version 2 (SF-36v2). Primary outcome was non-inferiority of summary measures of SF-36v2 at 12 months, (non-inferiority margin: -0.25 effect size; restrictive minus liberal scores). Secondary outcomes included non-inferiority of HRQOL at 18 and 24 months. RESULTS: Six hundred seventeen Australian patients received allocated randomization; HRQOL data were available for 208/311 in restrictive and 217/306 in liberal group. After multiple imputation, non-inferiority of restrictive transfusion at 12 months was not demonstrated for HRQOL, and the estimates were directionally in favor of liberal transfusion. Non-inferiority also could not be concluded at 18 and 24 months. Sensitivity analyses supported these results. There were no differences in quality-adjusted life years or composite clinical outcomes up to 24 months after surgery. DISCUSSION: The non-inferiority of a restrictive compared to a liberal transfusion strategy was not established for long-term HRQOL in this dataset.

30-Day Outcomes Post Veno-Arterial Extra Corporeal Membrane Oxygenation (VA-ECMO) After Cardiac Surgery and Predictors of Survival.

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is sometimes needed for post-cardiotomy cardiogenic shock (PCCS). There is little data regarding outcomes in the Australian context, particularly in a non-cardiac transplant centre. Our aim was to report on 30-day outcomes after patients with PCCS treated with VA-ECMO in an Australian non-cardiac transplant tertiary centre, and to determine risk factors for non-survival in this population. METHODS: A retrospective analysis was performed on all adults treated with VA-ECMO for PCCS between August 2001 and September 2016 at our centre. Univariate analysis with adjustment for multiplicity identified risk factors for non-survival. Area under the receiver operating characteristics (AUROC) method was used to assess their predictive value. RESULTS: We identified 64 patients out of 5,502 open-heart surgery cases of which three patients did not meet inclusion criteria. Mean (SD) age was 63 (14) years. Survival to hospital discharge or 30 days post VA-ECMO occurred in 27/61 (44%) patients. VA-ECMO was able to be weaned in 44/61 patients (72%); 54/61 patients (89%) had at least one major complication. Prior to VA-ECMO initiation, no statistically significant differences between survivors and non-survivors could be determined. After VA-ECMO initiation, only 24-hour nadir lactate and 48-hour nadir lactate levels were significantly different between survivors and non-survivors (1.50 mmol/L vs 3.20 mmol/L p=0.001; and 1.20 mmol/L vs. 1.90 mmol/L p=0.001 respectively). For mortality prediction, 24- and 48-hour nadir lactate levels had AUROCs of 0.775 and 0.782, respectively. CONCLUSIONS: VA-ECMO is associated with acceptable survival rates but significant morbidity. Nadir lactate levels in the first 24 and 48 hours after VA-ECMO initiation may be useful in predicting early survival.