Changes in circulating blood volume after cardiac surgery measured by a novel method using hydroxyethyl starch

Objective: To determine the incidence and extent of postoperative blood vol ume (BY) changes in patients after elective cardiac surgery using a new met hod based on dilution of hydroxyethylstarch. Design: Prospective, clinical, and laboratory investigation, Setting: University hospital intensive care unit. Patients: A total of thirty-five patients undergoing cardiac surgery requir ing cardiopulmonary bypass (CPB), Interventions: Perioperative measurements of circulating BY, systemic hemod ynamics, lactate, and collection of clinical data. Measurements and Main Results: Measurements were made before and 1 to 72 hr s after CPB, The majority of patients undergoing cardiac surgery showed pos toperative BV deficits compared with preoperative BV despite marked positiv e fluid balances after CPB, At 1 hr and 5 hrs after GPB, 18% and 33% of the patients, respectively, had BV deficits in the range of 0.5 L and 1,5 L, a nd in 3% to 10% of the cases, postoperative BY deficits exceeded 1.5 L, Con comitantly, at 5 hrs after CPB, mean arterial pressure was maximally reduce d, and heart rate and lactate levels were maximally elevated. Thereafter, B V began to normalize, and at 24 hrs after GPB, pre- and postoperative mean BV were no longer significantly different. At 48 hrs and 72 hrs, even a BV surplus of more than 1 L could be observed in 6% and 14% of the patients, r espectively. Conclusions: During the first hours after GPB, a high percentage of patient s had significantly reduced BV and, concomitantly, showed cardiovascular dy sfunction and hyperlactemia. Because hypovolemia is associated with increas es of perioperative morbidity and mortality, rapid determination of BV is w arranted to guide fluid therapy and optimize treatment in patients undergoi ng cardiac surgery.