Haemodilutional effect of standard fluid management limits the effectiveness of acute normovolaemic haemodilution in AAA surgery--results of a pilot trial.
OBJECTIVE
To evaluate the impact of standard fluid management on the effectiveness of ANH as a blood conservation method in elective open AAA repair.


METHODS
Prospective randomised controlled study.


METHODS
Thirty-four patients undergoing elective AAA repair were randomised to have ANH (16) or act as controls (18). Intra-operative cell salvage was permitted in both groups. Haemoglobin (Hb) concentrations were determined at variable intervals peri-operatively. Blood loss and the use of heterologous blood were recorded.


RESULTS
The pre- and post-operative Hb concentrations, surgical blood loss and the use of cell salvage were similar in both groups. Hb concentration (median, range) decreased significantly from pre-operative to aortic clamping (with blood loss <100 ml) in ANH patients from 8.8 (7.5-10.2) to 5.7 (4.2-6.6)mmol/l following ANH but also in controls from 8.6 (7.5-9.7) to 7.0 (4.5-9.0)mmol/l due to fluid infusion (P<0.01 for every comparison). Bank blood requirements were similar: median 2 units in ANH and 2.5 units in control patients (P=0.68).


CONCLUSIONS
Large volumes of fluids infused during AAA repair already conserve blood by the mechanism of hypervolaemic haemodilution. When cell salvage is used with standard fluid management during AAA repair, additional ANH is ineffective in saving blood.
D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D016063:Blood Loss, Surgical; D001803:Blood Transfusion; D001804:Blood Transfusion, Autologous; D001810:Blood Volume; D000077324:Crystalloid Solutions; D005260:Female; D006438:Hemodilution / Q000379:methods; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D010952:Plasma Substitutes / Q000008:administration & dosage*; D011446:Prospective Studies
D000077324:Crystalloid Solutions; D006454:Hemoglobins; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D010952:Plasma Substitutes