3.6.5 Therapeutic agents and techniques for managing anaemia

Read through these techniques. Then have a look at the map at the foot of the page and see how they fit into the context of blood conservation.

        Stop any bleeding

An obvious, but vital, step in blood conservation.

        Oxygen support

During surgery the anaesthetist can change the method and amount of oxygen given to a patient. Normally a small amount of oxygen (1.5%) is carried in the plasma.  The anaesthetist can use a ventilator to deliver higher concentrations in the plasma.  In combination with other methods of oxygen delivery this can mean a blood transfusion is avoided.

        Haemoglobin solutions (when available)

Crit Care Med. 2003 Dec;31(12 Suppl):S698-707:

Hemoglobin solutions.

Creteur J, Vincent JL.

Department of Intensive Care, Erasme University Hospital, Free University of Brussels, Belgium.

OBJECTIVE: To review current knowledge about cell-free hemoglobin solutions. DATA SOURCE: A computerized MEDLINE search was used to retrieve all studies concerning cell- free hemoglobin solutions from 1990 to 2003. The reference lists of all available review articles and primary studies were also reviewed to identify references not identified in the computerized search. STUDY SELECTION: All clinical and experimental studies involving cell-free hemoglobin solutions were included. DATA EXTRACTION: From the selected studies, information was obtained regarding the experimental model or the study population in which cell-free hemoglobin solutions were investigated, the type of cell-free hemoglobin solution used, their deleterious or beneficial effects, and their possible indications. DATA SYNTHESIS:In many studies, hemoglobin solutions were considered as efficient resuscitative agents and good alternatives to red blood cell transfusion, owing to their marked vasopressor effect, coupled with their capacity to improve the microcirculation and rapidly restore metabolic parameters. The main problems identified include excessive systemic vasoconstriction and oxidative damage.  Initial enthusiasm in the development of hemoglobin solutions has been tempered recently by the negative results of a U.S. multicenter trial studying the early infusion of diaspirin cross-linked hemoglobin in trauma patients. Nevertheless, the properties of diaspirin cross- linked hemoglobin (and particularly the strong vasopressor effects) cannot be attributed to all hemoglobin solutions, and results of new clinical studies are eagerly awaited to evaluate the potential benefit of such solutions in the management of trauma patients. CONCLUSIONS: Today, we are aware of the effects of the first generation of blood substitutes. Further research is ongoing into newer solutions. One area of interest is the development of new molecular structures to decrease nitric oxide binding, thus minimizing any adverse events and maximizing potential benefits. Nevertheless, possible adverse effects need to be carefully evaluated before these agents can be widely administered.

        Perfluorcarbon-based oxygen-carriers (when available)

Intravenous fluids that have the ability to carry oxygen. Sometimes referred to as "oxygen-carrying blood substitutes." Currently being assessed in clinical trials. Perflubron is the generic name of one of the more versatile PFCs.

        Maintain intravascular volume

The human body needs the right proportions of water in 3 compartments:

1. in the interior of cells (intracellular)
2. in the interior of blood vessels (intravascular, in the plasma)
3. in the space between cells (interstitial, outside the blood vessels)

Intravascular volume can be maintained by volume expanders

        Haematinics

Agents that increase the amount of haemaglobin in the blood.

·        Iron

A nutrient that is required by red blood cells for good oxygen-carrying capacity. Iron is important for bloodless surgery and can be obtained from dietary sources like red meat or through supplements, such as ferrous sulfate or ferrous gluconate.

·        Folic acid

A member of the VitaminB complex

·        Vitamin B12

Essential for the formation of red blood cells

        Erythropoietin (rHuEPO)

Erythropoietin is the name of a chemical normally produced by the body, primarily by the kidneys. Erythropoietin stimulates the bone marrow to produce red blood cells. Laboratory-made synthetic erythropoietin (e.g., Procrit, Epoetin alfa, or Epogen) may be administered prior to a bloodless surgery procedure in order to maximize the bone marrow's production of red blood cells.

        Nutritional support

Enteral tube nutrition may be used in patients with a functioning GI tract to supplement oral feeding or to replace it entirely

Parenteral nutrition is administered intravenously.

        Immunosuppressive agents if indicated

A substance that suppresses or interferes with normal immune response.  Used in controlling autoimmune diseases and in enhancing the chances for survival of foreign tissue grafts and transplants.  A wide variety of drugs are used as immunosuppressive agents.

        Hyperbaric oxygen therapy

Hyperbaric means to be at higher-than-normal atmospheric pressure. Hyperbaric oxygen therapy is used in some facilities to assist bloodless medicine in certain situations. The patient enters a chamber and breathes pressurized oxygen, which concentrates oxygen in the blood.

See The Healing Powers of Hyperbaric Oxygen Treatment

        Tolerate lower degree of normovolemic anaemia (10/30 rule has no scientific basis)

Most patients can tolerate  much lower haemoglobin levels as long as normal volume is maintained.  The decision to transfuse a should be based, not on a single haemoglobin figure, but rather on clinical indicators unique to each patient.