ARDIAC SURGERY IS ASSOCIATED with a high rate of allogeneic bloodtransfusion,varyingfrom 40% to 90% in most reports. 1-3 The rationale for perioperative red blood cell (RBC) transfusion is based on the observation that anemia is an independent risk factor for morbidity and mortality after cardiac operations. 4,5 However, transfusions have been associated with high rates of morbidity and mortality in critically ill patients, 6 and some recent studies have shown worse outcomes, including increased occurrence of renal failure and infection, as well as respiratory, cardiac , and neurologic complications, in transfused compared with nontransfused patients after cardiac surgery. 7,8 There is a lack of evidence regarding optimal blood transfusion practice in patients undergoing cardiac surgery. 9 On See also pp 1568 and 1610.

Background Vasoplegic syndrome is a common complication after cardiac surgery and impacts negatively on patient outcomes. The objective of this study was to evaluate whether vasopressin is superior to norepinephrine in reducing postoperative complications in patients with vasoplegic syndrome. Methods This prospective, randomized, double-blind trial was conducted at the Heart Institute, University of Sao Paulo, Sao Paulo, Brazil, between January 2012 and March 2014. Patients with vasoplegic shock (defined as mean arterial pressure less than 65 mmHg resistant to fluid challenge and cardiac index greater than 2.2 l · min−2 · m−2) after cardiac surgery were randomized to receive vasopressin (0.01 to 0.06 U/min) or norepinephrine (10 to 60 μg/min) to maintain arterial pressure. The primary endpoint was a composite of mortality or severe complications (stroke, requirement for mechanical ventilation for longer than 48 h, deep sternal wound infection, reoperation, or acute renal failure) within 30 days. Results A total of 330 patients were randomized, and 300 were infused with one of the study drugs (vasopressin, 149; norepinephrine, 151). The primary outcome occurred in 32% of the vasopressin patients and in 49% of the norepinephrine patients (unadjusted hazard ratio, 0.55; 95% CI, 0.38 to 0.80; P = 0.0014). Regarding adverse events, the authors found a lower occurrence of atrial fibrillation in the vasopressin group (63.8% vs. 82.1%; P = 0.0004) and no difference between groups in the rates of digital ischemia, mesenteric ischemia, hyponatremia, and myocardial infarction. Conclusions The authors’ results suggest that vasopressin can be used as a first-line vasopressor agent in postcardiac surgery vasoplegic shock and improves clinical outcomes.

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In critically ill patients, it is important to predict which patients will have their systemic blood flow increased in response to volume expansion to avoid undesired hypovolemia and fluid overloading. Static parameters such as the central venous pressure, the pulmonary arterial occlusion pressure, and the left ventricular end-diastolic dimension cannot accurately discriminate between responders and nonresponders to a fluid challenge. In this regard, respiratory-induced changes in arterial pulse pressure have been demonstrated to accurately predict preload responsiveness in mechanically ventilated patients. Some experimental and clinical studies confirm the usefulness of arterial pulse pressure as a useful tool to guide fluid therapy in critically ill patients.