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Diaspirin cross-linked hemoglobin (DCLHb) ensures tissue oxygenation during hemodilution below the critical hematocrit

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Background

Normovolemic hemodilution (HD) is an effective blood sparing strategy in the perioperative setting. Despite physiologic compensation for reduced hematocrit (Hct) and O2 content (CaO2), tolerance to HD is limited. At a Hct called `critical' (Hctcrit), tissue hypoxia occurs.

Objective

To assess, whether HD can be extended below Hctcrit when using an hemoglobin-based O2 carrier as diluent.

Methods

Twelve anesthetized, mechanically-ventilated pigs were hemodiluted by 1:1 exchange of blood with either 10% DCLHb (DCLHb, n=6) or 8% albumin (HSA, n=6) oncotically matched to DCLHb (diluents were provided by Baxter Healthcare Inc., Boulder, CO). In both groups, measurements were performed at baseline and after HD to (1) preset Hct-values of 15%, 8%, 4% 2%, 1% or (2) until the individual Hctcrit, defined by the onset of myocardial ischemia (ST-segment depression), was reached. Total body O2-delivery and O2-uptake (DO2I, VO2I), as well as local tissue O2 partial pressure (tPO2, MDO-Electrode,Eschweiler, Kiel, Germany) on the surface of liver and skeletal muscle were assessed during every measurement (Median ± [Q1-Q3]/2; rANOVA, MWU-test P<0.05).

Results

In the HSA-group, Hctcrit was 6.1±0.9%, at which all animals died. In the DCLHb-group, Hctcrit was not reached despite hemodilution to Hct 1.2%. At Hct 4%in the DCLHb-group, all parameters (CaO2, DO2I, tPO2:P<0.05 vs HSA; VO2I n.s.) were less altered than at Hctcritin the HSA-group.

Conclusion

During HD with DCLHb, O2-transport and tissue oxygenation were fully preserved at Hct 4%, while all HSA-animals had died at Hct 6.1%. The difference is due to the O2 transporting capacity of DCLHb.

References

  1. Anesth Analg 1997, 85: 953. 10.1097/00000539-199711000-00001

  2. Adv Microcirc 1972, 4: 1-77.

  3. Anesth Analg 1992, 75: 818-821.

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Keywords

  • Public Health
  • Ischemia
  • Albumin
  • Skeletal Muscle
  • Partial Pressure