Hematologic challenges in ICU patients with cardiovascular disease

Restrictive blood transfusion strategies, with a hemoglobin transfusion threshold of 70 g/L, are safe for the majority of critically unwell patients in the ICU. However, patients with cardiovascular disease have a myocardium that is vulnerable to injury at rest. Critical illness may both decrease oxygen supply to and increase oxygen demand from the myocardium increasing the risk of myocardial infarction. Anemia may exacerbate this oxygen supply-demand imbalance. In the absence of high-quality evidence, guidelines for patients with acute coronary syndromes, and for patients with acute illness and coexisting chronic cardiovascular disease, currently recommend more liberal transfusion strategies although the optimum transfusion threshold and hemoglobin are uncertain. However, a restrictive hemoglobin transfusion threshold of 75 g/L appears safe for patients undergoing cardiac surgery.

This chapter will discuss the diagnosis of myocardial infarction in critical illness and the evidence for transfusion strategies for patients with acute coronary syndrome and chronic coexisting cardiovascular disease and for patients undergoing cardiac surgery.