Renal medullary hypoxia may contribute to the pathophysiology of acute kidney injury, including that associated with cardiac surgery requiring cardiopulmonary bypass (CPB). When performed under volatile (isoflurane) anesthesia in sheep, CPB causes renal medullary hypoxia. There is evidence that total intravenous anesthesia (TIVA) may preserve renal perfusion and renal oxygen delivery better than volatile anesthesia. Therefore, we assessed the effects of CPB on renal perfusion and oxygenation in sheep under propofol/fentanyl-based TIVA. Sheep ( n = 5) were chronically instrumented for measurement of whole renal blood flow and cortical and medullary perfusion and oxygenation. Five days later, these variables were monitored under TIVA using propofol and fentanyl and then on CPB at a pump flow of 80 mL·kg−1·min−1 and target mean arterial pressure of 70 mmHg. Under anesthesia, before CPB, renal blood flow was preserved under TIVA (mean difference ± SD from conscious state: −16 ± 14%). However, during CPB renal blood flow was reduced (−55 ± 13%) and renal medullary tissue became hypoxic (−20 ± 13 mmHg versus conscious sheep). We conclude that renal perfusion and medullary oxygenation are well preserved during TIVA before CPB. However, CPB under TIVA leads to renal medullary hypoxia, of a similar magnitude to that we observed previously under volatile (isoflurane) anesthesia. Thus use of propofol/fentanyl-based TIVA may not be a useful strategy to avoid renal medullary hypoxia during CPB.

Aim Blood transfusion may improve renal oxygenation during cardiopulmonary bypass (CPB). In an ovine model of experimental CPB, we tested whether increasing blood haemoglobin concentration [Hb] from ~7 g dL−1 to ~9 g dL−1 improves renal tissue oxygenation. Methods Ten sheep were studied while conscious, under stable isoflurane anaesthesia, and during 3 hours of CPB. In a randomized cross‐over design, 5 sheep commenced bypass at a high target [Hb], achieved by adding 600 mL donor blood to the priming solution. After 90 minutes of CPB, PlasmaLyte® was added to the blood reservoir to achieve low target [Hb]. For the other 5 sheep, no blood was added to the prime, but after 90 minutes of CPB, 800‐900 mL of donor blood was given to achieve a high target [Hb]. Results Overall, CPB was associated with marked reductions in renal oxygen delivery (−50 ± 12%, mean ± 95% confidence interval) and medullary tissue oxygen tension (PO2, −54 ± 29%). Renal fractional oxygen extraction was 17 ± 10% less during CPB at high [Hb] than low [Hb] (P = .04). Nevertheless, no increase in tissue PO2 in either the renal medulla (0 ± 6 mmHg change, P > .99) or cortex (−19 ± 13 mmHg change, P = .08) was detected with high [Hb]. Conclusions In experimental CPB blood transfusion to increase Hb concentration from ~7 g dL−1 to ~9 g dL−1 did not improve renal cortical or medullary tissue PO2 even though it decreased whole kidney oxygen extraction.

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Background TEG6S ® and TEG5000 ® (Haemonetics Corp, USA) are haemostasis analysers that measure viscoelasticity properties of whole blood. Both use different mechanisms to assess similar components of the coagulation process. The aim of this study was to assess agreement and interchangeability between the TEG6S and TEG5000 analysers. Methods 3.5 mL whole blood was collected from 25 adult patients in a tertiary intensive care unit (ICU). Analysis was performed using TEG6S and TEG5000 haemostatic platforms. Agreement between platforms was measured using Lin’s concordance coefficient (Lin’s CC), further validated using intraclass correlation coefficients and reduced major axis regression (RMAR). Results Sixteen (64%) patients were male; mean (range) age: 59yo (23–86). TEG6S and TEG5000 systems were broadly interchangeable. The majority of TEG variables demonstrated almost perfect or substantial agreement and minimal proportional bias (maximum amplitude demonstrated a fixed bias). LY30%, however, demonstrated poor agreement and a proportional bias. Lin’s CC coefficients (95% CI, RMAR slope, intercept) between TEG6S and TEG5000 variables were: R time: 0.78 (0.64–0.92, 0.76, 0.92); K time: 0.82 (0.69–0.94, 1.30, − 0.93); alpha angle: 0.79 (0.64–0.95, 1.04, − 1.43); maximum amplitude (MA): 0.90 (0.83–0.96, 0.99, − 5.0); LY30%: 0.34 (0.1–0.58, 0.43, 0.04). Conclusions Adult patients with critical illness demonstrate almost perfect agreement in the R time and MA, substantial agreement in K time and alpha angle, but poor agreement in LY30%, as measured by the TEG6S and TEG5000 analysers. With the exception of LY30%, the TEG6S and TEG5000 platforms appear interchangeable. This has important implications for use in clinical practice and multi-site research programs. Trial registration ANZCRT number: 12617000062325 , registered 12/Jan17. Retrospectively registered. Electronic supplementary material The online version of this article (10.1186/s12871-019-0717-7) contains supplementary material, which is available to authorized users.

Purpose:There are an increasing number of anecdotal reports and trials of recombinant activated factor VII (rFVIIa) for bleeding during surgery. The reports of rFVIIa during cardiac surgery are limited. We report our experience using rFVIIa, in the operating room; to treat bleeding that prevented chest closure, despite appropriate conventional treatment, following complex cardiac surgery.Methods: Retrospective chart review, at an Australian University hospital and associated private hospital, of cardiac surgery patients given rFVIIa (usual dose 90 μg·kg -1 ). We used rFVIIa for bleeding that prevented closure of the chest despite administration of blood products, protamine, and surgical attempts to secure hemostasis.Results: Recombinant activated factor VII was administered on 55 occasions to 53 patients. Most patients had complex aortic or valve surgery. Median bypass time was 266 min. Before administering rFVIIa, patients received (median): packed red cells four units; platelets 15 units; fresh frozen plasma eight units; and cryoprecipitate ten units. After administering rFVIIa the median doses of donor blood products up to 12 hr after intensive care unit admission were: packed red cells one unit; platelets zero units; fresh frozen plasma zero units; and cryoprecipitate zero units. The decrease in doses of all blood products was significant (P < 0.001). We could not determine if rFVIIa played a role in significant mortality (19%) and morbidity (17%). Conclusion:Use of rFVIIa in cardiac surgery may be effective, but definitive clinical trials are needed to clarify its role in clinical practice and safety. We present an rFVIIa guideline developed during the audit period. Objectif