Body size, gender, and transfusions as determinants of outcome after coronary operations.

Background: Small body size, female gender, and transfusions are traditionally considered morbidity and mortality risk factors in coronary surgery. Because these clinical conditions are interrelated, we designed a study to investigate their respective roles in determining adverse outcomes after coronary operations.

Methods: A retrospective study on 4,546 consecutive patients who underwent coronary surgery was performed. The outcome (hospital mortality and length of stay in the intensive care unit) was evaluated according to body surface area, gender, and the presence of allogeneic blood transfusions.

Results: Female gender is not a risk factor for hospital mortality or prolonged intensive care unit stay. Small body surface area in men and large body surface area in women are associated with a prolonged intensive care unit stay. Transfusions are independent risk factors for both mortality and prolonged intensive care unit stay. Fresh-frozen plasma and platelet transfusion carry a higher mortality risk (odds ratio, 12) than transfusions of packed red blood cells (odds ratio, 5).

Conclusions: Female gender and small body surface area are associated with severe intraoperative hemodilution, and this may trigger blood transfusions, which are true determinants of adverse outcomes. A large body surface area in women is frequently associated with obesity (68%) and may prolong the intensive care unit stay, whereas it is not a risk factor in men. Conversely, a small body surface area is accompanied by a prolonged intensive care unit stay in men but not in women.