Abstract
Transfusion medicine is a relatively novel facet of avian medicine. In transfusion studies using fresh whole blood, it has been found that heterologous transfusions do not last as long as homologous transfusions.1-3 Storage of avian whole blood could be useful so that hospitals would not have to maintain donor birds of many species. To date, there have been no studies in long-term storage of avian whole blood or its components. The shorter life span and higher metabolic rate of the nucleated avian erythrocyte is currently thought to make storage difficult, yet no controlled studies exist.4
The purpose of this study is to determine the effectiveness of three media: 0.9% citrate, acid-citrate-dextrose (ACD), and citrate-phosphate-dextrose with adenine (CPDA), in maintaining avian erythrocytes for 21 days. Ten milliliters of whole blood were collected from 10 healthy donor macaws (Ara spp.) monthly for 3 months. Aliquots of 2 ml were collected from each sample on days 0, 7, 14, and 21. Potassium, sodium, pH, glucose, uric acid, and packed cell volume (PCV) were measured at each time point. Subjective measurements of gross hemolysis and red cell morphology were also made at each sample day. Intracellular ATP was measured on days 0 and 7 for the ACD and CPDA samples.
In all media, serum potassium levels became significantly elevated (p=0.00025) by day 7. Sodium levels decreased in all samples (p=0.0001), but were not thought to be clinically significant. Similarly, pH levels were lower in the ACD and CPDA samples than in citrate (p<0.0001) because of the pH of the storage media, but were not thought to be of clinical relevance. Uric acid levels increased in all samples (p=0.0008). Glucose levels decreased in the citrate samples (p=0.042), but not in the ACD or CPDA samples (p=0.024). PCV decreased significantly in all samples. Hemolysis increased over time in all samples. Cell morphology showed variable cell size and shape, irregular cytoplasmic membranes, clumped chromatin, and refractile granules within the cytoplasm. ATP levels significantly decreased (p=0.011) in CPDA, but were not significantly different between days 0 and 7 in ACD.
The changes suggest a failure of the sodium-potassium exchange system within the erythrocyte during storage in the three media studied. The addition of dextrose and other cellular nutrients did not reverse or forestall this failure. It is thought that avian erythrocytes use lipid and protein degradation products for a significant energy source.5 The addition of these compounds to the storage media remains to be investigated. Because of the decrease in ATP and large increase in serum potassium, it is suggested that none of the three media maintained viable erythrocytes in a medium which could be safely transfused into a patient.
Literature Cited
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