Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Anesthesia/OR Economics
Introduction: Acute normovolemic hemodilution (ANH), in which blood for autologous use is collected immediately before the onset of surgical blood loss, is a recommended autologous blood procurement technique. [1,2] Little data is available to support the use of a particular replacement fluid during ANH. Therefore, we designed a prospective, randomized study to determine if the iv replacement fluid choice influences intraoperative hemodynamic stability and cost of hemodilution.
Methods: Following IRB approval, 40 consenting adult patients, ASA 1-3, scheduled for ANH during radical prostatectomy were randomly assigned to one of four replacement fluid groups: 1) Ringer's lactate (LR) solution, 2) 5% albumin (ALB), 3) 6% dextran 70 (DEX), or 4) 6% hetastarch (HES). After induction of a standardized general anesthetic, all patients underwent ANH to a final hemoglobin (Hb) level of 9 gm/dl. Colloids (ALB, HES, DEX) were simultaneously administered in a 1:1 volume replacement ratio for the blood removed and LR was administered in a 3:1 ratio. ECG leads II and V5, heart rate (HR), radial mean arterial blood pressure (MAP), central venous (CVP) and pulmonary capillary wedge (PCWP) pressures, cardiac index (CI), and arterial and mixed venous blood gases were monitored. Serial Hb levels, blood gases, and vital sign determinations were performed immediately before ANH, after the removal of each unit (475 ml) of blood, and at the end of ANH. Data were analyzed using ANOVA, Chi-square, and t-tests with p<0.05 considered significant. Data are expressed as mean +/- S.D.
Results: Demographic data, volume of blood removed during ANH, and baseline vital signs, were similar among all groups (Table 1). CI and O2 consumption index were stable during ANH in all groups while O2 extraction (O2 Ex) increased (Table 1). ANH resulted in no change in HR or PCWP, although a greater decline in MAP occurred with LR and ALB. Cost was lowest for LR compared to the other fluids studied (Table 1).
Discussion: During hemodilution, anesthetized patients maintain whole body oxygenation by increasing O2 Ex. The administration of HES or DEX during ANH is associated with a more stable MAP, but overall, ANH is well tolerated irrespective of the replacement fluid. Total fluid cost may be the most significant difference between the groups, thereby making LR the most cost-effective replacement fluid choice.