SummaryVasodilatory shock after cardiopulmonary bypass is a common complication requiring treatment with high doses of inotropes and prolonged stays in the intensive care unit. The vasodilatory shock is initiated by an inflammatory response to the extracorporeal circuit. The inflammatory response results in endothelial synthesis and release of nitric oxide resembling the clinical features observed in vasodilatory shock caused by septicaemia. During vasodilatory shock, the inhibition of nitric oxide synthase and the nitric oxide ⁄ cyclic guanylyl monophosphate pathway is an attractive adjunct to therapy with traditional inotropes. Methylthioninium chloride inhibits nitric oxide ⁄ cyclic guanylyl monophosphate mediated vasodilation and can successfully be used as a supplement in the treatment of vasodilatory shock associated with cardiopulmonary bypass. The application of methylthioninium chloride in septicaemia has not produced comparable positive clinical results. During the last decade, many reports and more letters but few studies have commented on clinical experience with methylthioninium chloride (MB), formerly known as methylene blue, in the treatment of vasodilatory shock during and after surgery requiring cardiopulmonary bypass (CPB). Peri-operative vasodilatory shock accompanied by tachycardia and increased cardiac output has, in the absence of other causes of hypotension, been termed vasoplegic syndrome [1] or low systemic vascular resistance syndrome [2]. It is widely recognised that these features are the results of CPB initiating an inflammatory response clinically indistinguishable from that observed in septicaemia [3]. A result of the CPB-associated inflammatory response is an increased endothelial production and release of nitric oxide (NO), causing profound hypotension. Methylthioninium chloride, being a potent inhibitor of NO-mediated vasodilation, offers an attractive proposition as an adjunct in the treatment of vasodilatory shock. These characteristics of MB have been reported in many observational studies and case reports. However, no reports have concurrently reviewed the pharmacology and clinical applications of MB in the treatment of vasoplegic syndrome. Therefore, the aim of this review is to summarise the current knowledge and application of MB with special emphasis on vasodilatory shock associated with CPB.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether use of thromboelastography could predict and decrease bleeding and blood and blood product requirements in adult patients undergoing cardiac surgery. Altogether 170 papers were identified using the reported search strategy of which 14 represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that thromboelastography may be useful in predicting patients who are likely to bleed postoperatively but more importantly, it can guide transfusion therapy algorithms in the bleeding cardiac surgical patient resulting in significant decreases in blood and blood component transfusion requirements. However, the technique remains unvalidated in the eyes of many haematologists and further large studies involving them are required to fully validate its use and to define the 'ideal' treatment algorithm.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether use of the Hepcon point-of-care coagulation monitor (Medtronic, Minneapolis, MN) to optimise and monitor heparin and protamine dosage for cardiopulmonary bypass could decrease bleeding and blood and blood product requirements in adult patients undergoing cardiac surgery. Altogether 680 papers were identified on Medline, and 879 on Embase using the reported search strategy. Two further relevant papers were found by hand-searching of reference lists. Fourteen papers represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that in patients undergoing cardiac surgery, use of the Hepcon coagulation monitor will increase the dose of heparin but decrease the dose of protamine administered compared to more empirical ACT-based dosing regimes. There is some evidence that this leads to less activation of the coagulation system and may be associated with decreased postoperative bleeding and blood product requirements but more work is required to quantify the magnitude of this effect.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the Allen's test, plethysmography, Doppler ultrasound or MRI imaging was the best method of assessing the presence of adequate collateral blood flow in the arm preoperatively prior to radial artery harvest for conduits during CABG surgery. Altogether 176 papers were identified using the reported search of which 15 represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that whilst there are theoretical limitations with the Allen's test, for most patients it is an adequate method of assessing collateral arm flow prior to radial artery harvest and several large studies have confirmed the absence of neurological and vascular adverse outcome with a modified Allen's test cut-off point of up to 12 s. However, if there are concerns about collateral flow then a second confirmatory test such as dynamic Doppler ultrasound or measurement of digital pressure changes with radial artery occlusion can also be used prior to harvest. Newer techniques such as Gadolinium-enhanced magnetic resonance angiography have also been described to confirm adequate collateral circulation prior to radial artery harvest for CABG conduit and whilst in time they might come to represent an ultimate 'gold standard' they are clearly too expensive and impracticable for everyday use.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether methylene blue (MB) is of benefit in treating adult patients who develop catecholamine-resistant vasoplegic syndrome (VPS) during cardiac surgery. Altogether 47 papers were found in Medline and 107 in Embase using the reported search. A further five papers were found by hand-searching reference lists. Four papers represented the best evidence on the subject and details of authors, journal, date and country of publication, patient group, relevant outcomes and weaknesses were tabulated. In addition, a further 14 papers are referenced to aid the discussion. We conclude that MB may provide an interesting and novel therapeutic option for adult patients who develop catecholamine-resistant VPS during cardiac surgery. Whilst there is currently insufficient evidence to advocate its use as first-line therapy it should be considered as a possible 'rescue therapy' in catecholamine-resistant VPS and some work has suggested that it may have a prophylactic role in preventing VPS. However, further large well-controlled studies are required before its routine use can be recommended.