What are the uses, indications, adverse effects, and contraindications of artificial blood?

Artificial Blood: Uses, Indications, Adverse Effects, and Contraindications

Currently, there are no FDA-approved artificial blood products available for routine clinical use, though several hemoglobin-based oxygen carriers have shown promise in clinical trials. 1 While development continues, understanding the potential applications and limitations of artificial blood technologies is important for clinical decision-making.

Types of Artificial Blood

Two main categories of artificial blood substitutes have been developed:

1. Hemoglobin-Based Oxygen Carriers (HBOCs)

   • Derived from outdated human or bovine blood
   • Function: Transport and deliver oxygen

2. Perfluorocarbons (PFCs)

   • Synthetic compounds
   • Function: Dissolve and carry oxygen

Potential Indications

Artificial blood substitutes would be most beneficial in the following scenarios:

• Major hemorrhage situations where rapid volume and oxygen-carrying capacity restoration is needed 2
• Emergency trauma settings where blood typing is not immediately available 3
• Military or disaster medicine where blood storage and transport is challenging
• Patients who refuse blood transfusions for religious reasons (e.g., Jehovah's Witnesses) 4, 1
• Surgical procedures with anticipated significant blood loss 3
• Remote locations without access to blood banking facilities
• Situations with blood supply shortages or compatibility issues

Advantages Over Traditional Blood Products

• No compatibility testing required 3
• Free from blood-borne infections 3
• Extended shelf life without refrigeration 3
• Immediate availability without cross-matching
• Potential for use in patients who refuse blood products for religious reasons 4

Adverse Effects

Based on clinical trials of artificial blood products, potential adverse effects include:

• Cardiovascular effects: Hypertension, vasoconstriction
• Renal dysfunction: Increased risk of acute kidney injury
• Gastrointestinal symptoms: Nausea, abdominal pain
• Immune reactions: Allergic responses, complement activation
• Limited oxygen-carrying capacity: Studies of Fluosol-DA (a perfluorocarbon) showed minimal increase in arterial oxygen content (only 0.7 ml/dL) 5
• Short half-life: Some products like Fluosol-DA demonstrated a brief half-life (24.3 hours), limiting clinical utility 5

Contraindications

While specific contraindications would depend on the particular artificial blood product, general contraindications might include:

• Known hypersensitivity to components of the artificial blood product
• Severe liver or kidney dysfunction (based on elimination pathways)
• Pregnancy and lactation (insufficient safety data)
• Conditions where vasoconstriction would be harmful (certain cardiovascular conditions)

Current Status and Limitations

The search for ideal blood substitutes continues with no truly safe and effective artificial blood product currently marketed 6. Clinical evidence shows significant limitations:

• In a study of severely anemic patients (mean Hb 3.0 g/dL) who received Fluosol-DA, there were no appreciable beneficial effects, possibly due to the small increase in arterial oxygen content, brief half-life, and limited total dose 5
• Six of eight severely anemic patients receiving Fluosol-DA died in this study 5

Practical Considerations for Clinical Use

If artificial blood products become available:

1. Patient selection should focus on those with clear indications and without contraindications
2. Monitoring should include vital signs, renal function, and signs of adverse reactions
3. Dosing limitations must be strictly observed based on clinical trial data
4. Integration with blood conservation strategies like cell salvage techniques when appropriate 7, 2

Cell Salvage as Current Alternative

While waiting for artificial blood development, cell salvage techniques represent a current alternative for certain patients:

• Indications: Clean surgical wounds in procedures like open heart surgery, vascular surgery, joint replacements, spinal surgery, liver transplantation, and ruptured ectopic pregnancy 7
• Contraindications: Bacterial contamination of operative field, blood containing fat or amniotic fluid (risk of embolism and DIC), and caution in sickle cell disease 7
• Acceptability: Some Jehovah's Witnesses may accept transfusion of autologous cells salvaged by a continuous circuit device 7

Conclusion

While artificial blood remains a promising concept with significant potential benefits, current evidence does not support its routine clinical use. Ongoing research and development may eventually yield products that can effectively supplement or replace traditional blood transfusions in specific clinical scenarios.