1. Acute normovolaemic haemodilution: a forgotten friend
Yves OZIER
Division of Anaesthesia, Critical Care and Emergency Medicine
Brest University Hospital, France

2. Acute normovolaemic haemodilution is NOT forgotten
Is Acute normovolaemic haemodilution
REALLY A GOOD FRIEND
or should we forget it ?

3. There are 2 types of acute isovolaemic haemodilution
Preop Intraop Postop
This is the one
we talk about

4. Acute normovolaemic haemodilution Theoretical benefits
Reduced total red cell loss
Supply of fresh autologous blood providing red cells, platelets and clotting factors near the end of surgery

5. Acute normovolaemic haemodilution A cost-effective alternative to autologous predonation ?
Less costly
More convenient for patients
Units collected / kept at the patient’s bedside
Less chance of a wrong unit error
Fresher blood

6. Acute isovolaemic haemodilution Which efficacy ?
Mathematical models
Simple exponential haemodilution equation
Brecher. Transfusion 1994;34:176-9
Feldman. Anesth Analg 1995;80:108-13
Weiskopf. Transfusion 1995;35:37-41

7. Acute isovolaemic haemodilution Theoretical efficacy
Weiskopf et al. Transfusion 1995;35:37-41 1 2 3 4 5
Initial Hct = 45%
Initial Hct = 40%
PRBCs saved (units)
Initial Hct = 35% 30 25 20 15
Final haematocrit (%)

8. Acute isovolaemic haemodilution Theoretical efficacy
PRBCs saved (units) 2
∆Hct = 45-25%
Male
∆Hct = 40-25%
Female 1 9 8 7 6 5 4 3
Weight (kg)

10. Acute isovolaemic haemodilution Theoretical conditions for efficacy
High preoperative haematocrit (40-45%)
Low target haematocrit (<30%)
High estimated total blood volume
Substantial amount of surgical blood loss
L’hémodilution isovolémique préopératoire est une technique d’intérêt très controversé
Déjà, on peut modéliser l’économie théorique que l’on peut en attendre
et il est facile de se rendre compte que pour espérer en obtenir quelque chose, le malade et l’opérations doivent satisfaire a certaines conditions
Hématocrite initial élevé (≥ 45%)
Hématocrite cible bas (< 30%)
Volume sanguin total estimé élevé
Saignement prévisible abondant
Feldman et al. Anesth Analg 1995;80:108-13
Weiskopf et al. Transfusion 1995;35:37-41

11. Nb allogeneic PRBCs units Nb whole-blood autologous units to collect
Acute isovolaemic haemodilution How many whole blood units to collect ?
Change in Hct
Nb allogeneic PRBCs units
Potentially saved
Nb whole-blood autologous units to collect
40-25 %
1.1 5
45-25 %
1.7
6-7
45-20 %
2.9 9
Calculations for a 70 kg man
Feldman et al. Anesth Analg 1995;80:108-13

12. Acute isovolaemic haemodilution Which efficacy ?
Mathematical models
Clinical trials

13. ANH Meta-analysis 2004 JB Segal, et al. Transfusion 2004;44:632-44
RR of allogeneic transfusion Haemodilution vs usual care

14. ANH Meta-analysis 2004 JB Segal, et al. Transfusion 2004;44:632-44
RR of allogeneic transfusion Haemodilution
vs another blood conservation
method

15. Transfusion 2004;44:632-44

16. ANH Meta-analysis 2015 X. Zhou, et al Anesth Analg 2015;121:1443–55
Haemodilution vs usual care
RR of allogeneic transfusion
0.74
95%CI =

17. ANH Meta-analysis 2015 X. Zhou, et al Anesth Analg 2015;121:1443–55
Haemodilution vs usual care
Allogeneic RBC units
WMD −0.94 units
95%CI, −1.27 to −0.61 units

18. Diverse surgical procedures and settings
Anesth Analg 2015;121:1443–55
Diverse surgical procedures and settings
Small sample size of most studies
Magnitude of haemodilution & transfusion triggers unknown in most studies
Considerable heterogeneity
Obvious publication biases, overestimation of benefit
Low rates of reported adverse events

19. Anesth Analg 2015;121:1443–55
Conclusion Although these results suggest that preoperative ANH is effective in reducing allogeneic blood transfusion, we identified significant heterogeneity and publication bias, which raises concerns about the true efficacy of preoperative ANH

20. Cardiac surgery Haemodilution vs usual care Allogeneic RBC units
L. Barile, et al. Anesth Analg 2017;124:743–52
Haemodilution vs usual care
Allogeneic RBC units
MD −0.79 units
95%CI, −1.25 to −0.34 units

21. Cardiac surgery Haemodilution vs usual care Allogeneic RBC units
L. Barile, et al. Anesth Analg 2017;124:743–52
Haemodilution vs usual care
Allogeneic RBC units
MD −0.79 units
95%CI, −1.25 to −0.34 units

22. Acute isovolaemic haemodilution Are there any drawbacks ?
Labor-intensive and time-consuming
Potential for added OR time
Invasive intravascular access required, potential for added cardiovascular monitoring
Reinfusion of anaesthetic agents with collected blood
Postoperative edema
Management of unecessary units ?
Profound haemodilution and oxygen supply ??

23. JP Mathew, et al. Anesthesiology 2007;107:577– 84

24. with increasing change in hematocrit from baseline
JP Mathew, et al. Anesthesiology 2007;107:577– 84
Decline in cognition
with increasing change
in hematocrit from baseline

25. In summary : Safety and efficacy of ANH still in question after 50 yrs of experience
Technique not standardized
Inconsistent data on efficacy
Lack of high level evidence of safety
Subpopulation likely to benefit uncertain
Surgical techniques and patient blood management methods have evolved - Is ANH useful to-day ?