Hemodilution in Clinical Surgery: State of the Art 1996

Abstract

Acute normovolemic hemodilution entails removal of blood from a patient either immediately before or shortly after induction of anesthesia and simultaneous replacement with cell-free fluid. Nowadays, because of their predictable volume effects, the synthetic colloids (6% dextran 60/70, 6% hydroxyethyl starch 200,000) are preferred as volume substitutes; albumin should be avoided because of its high cost. Hemodilution has experienced a renaissance in recent years, mainly due to the evolving discussion of legal aspects, immunologic changes, viral infections, and a potentially higher cancer recurrence rate associated with the transfusion of homologous blood. Hemodilution should be considered for elective surgical patients free of contraindications and presenting with an initial hemoglobin concentration >/= 12 g/dl and an anticipated blood loss of >/= 1500 ml. The efficacy of this method (judged by the need to give homologous blood transfusion) depends on the preoperative (initial) hematocrit, the target hematocrit (to which hemodilution is performed), and the preset intra- and postoperative transfusion trigger. In the past, data from clinical trials showed that in healthy subjects a target hematocrit of 20% to 25% (hemoglobin 7.0-8. 0 g/dl) is feasible and safe for the patient. The lower the target hematocrit accepted, the more extensive is the monitoring required: Intraoperative target hemoglobin concentrations of 5.0 g/dl and less have been tolerated by surgical patients without adverse effects. The safety and efficacy of acute normovolemic hemodilution in terms of reducing homologous blood transfusion requirements has been demonstrated in various clinical studies. Hemodilution therefore is regarded an integral part of programs aimed at reducing the need for homologous blood and can thus be successfully combined with preoperative autologous blood deposition, intraoperative blood salvage, and carefully adjusted surgical techniques. Hemodilution is feasible and relatively cost-effective, and it minimizes adverse effects associated with transfusion of homologous blood, particularly transmission of viral diseases, immunosuppression, and infectious complications.

Case report: The management of advanced oral cancer in a Jehovah's Witness using the Ultracision Harmonic Scalpel

“…In the preoperative and intra-operative periods hypervolameic/normovolemic hemodiltion [9], hypotensive anaesthesia [10] and cell scavenging [11] have all been described to minimize blood loss. Acute normovolemic hemodilution is the process of removing one or more units of blood before the operation for transfusion to the patient either during or at the end of the operation.…”

“…The hematocrit is restored with a postoperative diuresis. This strategy is not suitable for patients with cardiovascular or renal dysfunction [9]. We also used controlled hypotension with a mean arterial pressure of 65 mmHg maintained with an opiate infusion.…”

Prolonged hypervolemic hemodilution decreases functional capillary density of ileal mucosa in pigs revealed by sidestream dark-field imaging

“…Acute normovolemic hemodilution (ANH) involving withdrawal of whole blood with parallel infusion of fluids maintaining normovolemia was introduced into clinical practice in the 1970s (Messmer et al, 1972;Laks et al, 1973) and was accepted as an appropriate alternative to reduce the need for allogeneic transfusion during surgery (Bryson et al, 1998). Recent meta-analysis concerning ANH in 42 trials has shown only modest benefits from preoperative ANH mainly due to methodological differences and the lack of properly designed controlled trials (Kreimeier and Messmer, 1996;Segal et al, 2004). Some previous clinical trials have used acute preoperative volume expansion without any blood removal and established this relatively new technique as hypervolemic hemodilution (HHD) (Trouwborst et al, 1990a;1990b;Mielke et al, 1997).…”

The use of a volatile anesthetic regimen protects against acute normovolemic hemodilution induced myocardial depression in patients with coronary artery disease

“…[12] With this technique, the adequacy of tissue oxygenation and organ function is maintained by compensatory increases in cardiac output, improved blood flow distribution, and higher oxygen extraction ratios. [3–5] In the myocardium, hemodilution-induced lowering of blood viscosity is thought to facilitate blood flow through stenotic and collateral vessels, thereby counteracting the reduced blood oxygen-carrying capacity. [6] However, a previous study[7] indicated that acute normovolemic hemodilution (ANH) was associated with a depression of myocardial function in coronary surgery patients with baseline heart rate faster than 90 bpm.…”