The effect of PAC use on patient outcome is controversial. Several large trials did not confer a definite benefit to PAC use. One multi-institutional study examined the association of PAC placement within the first 24 hours of hospital stay and its associated outcomes. They found a higher mortality rate in patients who received a PAC than those who did not have a PAC (212). The study was limited because it was retrospective and not randomized. A randomized controlled trial of 1,994 high-risk (American Society of Anesthesiologists class III or IV risk) patients age 60 or older undergoing urgent or elective major noncardiac surgery compared outcomes of those who underwent PAC placement versus standard care. Results analyzed by a blinded assessor revealed no benefit of PAC over standard care with central venous catheters (213). Another randomized controlled trial enrolling 65 intensive care units in the United Kingdom found no difference in mortality among critically ill patients managed with or without a PAC (214). A meta-analysis of 13 randomized controlled trials of PAC use found no significant difference in mortality rates and an increased use of ionotropes and intravenous vasodilators (215). Routine preoperative use of PAC in noncardiac surgery patients is no longer indicated. Use of PAC in critically ill patients postoperatively remains controversial.
Hematologic Disorders The presence of hematologic disorders, although uncommon in gynecologic patients, significantly affects operative morbidity and mortality and should be considered routinely in preoperative evaluation. Preoperative assessment should include consideration of anemia, platelet and coagulation disorders, white blood cell function, and immunity.
Anemia Moderate anemia is not in itself a contraindication to surgery because it can be corrected by transfusion. If possible, surgery should be postponed until the cause of the anemia can be identified and the anemia corrected without resorting to transfusion. By tradition, anesthetic and surgical practice recommended a hemoglobin level of greater than 10 g/dL or a hematocrit of greater than 30%. Data suggest a lower tolerance for pre-and intraoperative transfusion threshold to improve intra-and postoperative morbidity and mortality (216–219). It remains that no universal “transfusion threshold” is agreed upon, but that a hematocrit of less than 24% should prompt strong consideration (219). The circulating blood volume provides oxygen-carrying capacity and tissue oxygenation. Usually this capacity is reﬂected by the hemoglobin level and hematocrit. Under certain circumstances this is not the case. After an acute blood loss or before plasma expansion by extracellular ﬂuid occurs, hematocrit measurements may be normal despite a low circulating blood volume. Conversely, overhydration may result in low hematocrit and hemoglobin levels despite adequate red blood cell mass.
Individual tolerance of anemia depends on overall physical fitness and cardiovascular reserve. The effects of anemia depend on its magnitude, the rate at which it occurs, the oxygen requirement of the patient, and the ability of physiologic mechanisms to compensate (220). Maintenance of adequate tissue perfusion requires an increase in cardiac output as hemoglobin concentration falls (193). In the healthy patient, oxygen delivery is unchanged when it falls below 7 g/dL (221). In contrast, a patient with ischemic heart disease will not tolerate anemia as well (222). The presence of cardiac, pulmonary, or other serious illness justifies a more conservative approach to the management of anemia. Patients with longstanding anemia may have normal blood volume levels and tolerate surgical procedures well. There is no evidence that mild to moderate anemia increases perioperative morbidity or mortality (222).