The effect of storage on the P₅₀ of feline blood

Abstract

Objective: To determine the effect of storage on the P50 of feline hemoglobin. Design: Prospective, in vitro, laboratory study. Subjects: Venous blood from 4 clinically healthy cats. Measurements: Blood was collected into CPDA‐1 anticoagulant/preservative and maintained at 4°C for 5 weeks. Measurements were made on Days 0, 2, 4, 7, 14, 21, 28, and 35. The blood samples were equilibrated in a tonometer to gas mixtures containing 2.5%, 4%, 5%, or 8% oxygen, with 5% carbon dioxide balance nitrogen; pH was adjusted to 7.4. Chloride, partial pressure of oxygen, and hemoglobin saturation were measured; P50 was calculated. Results: Chloride decreased from 124.3±2.1 to 88.5±1.9 mEq/L immediately after dilution with CPDA‐1, and did not change for the 5 weeks thereafter. The P50 decreased from an average of 35.0±1.2 to between 31 and 32 mmHg after 7 days, and did not change further for 4 weeks thereafter. Conclusions: The decrease in P50 of feline hemoglobin was minor compared with that of blood from species in which 2,3‐diphosphoglycerate (2,3‐DPG) is a major modifier of hemoglobin affinity for oxygen. The decrease in P50 in the present study was attributed to an initial decrease in chloride and a subsequent loss of modest quantities of red cell 2,3‐DPG.

Red blood cell storage lesion

“…Furthermore, this mechanism may be even less important in species that do not depend on 2,3‐DPG to modify Hb oxygen affinity. For example, the feline Hb P50 is only slightly reduced after 35 days of storage suggesting that the storage lesion does not have a major impact on Hb oxygen affinity in this species …”

Haematological and morphological evaluation of feline whole blood units collected for transfusion purposes

“…7,8 To date, a limited number of studies have been performed on feline blood units collected and stored for transfusion purposes; all have documented biochemical changes consistent with anaerobic metabolism in a closed system: decreased glucose, increased lactate and increased ammonia. [9][10][11][12] The feline haemoglobin (Hb) P50 is only slightly reduced after FWB storage for 35 days in CPDA solution, suggesting that the storage lesion does not have a major impact on Hb-oxygen affinity in this species. 9 In addition, once collected, feline blood undergoes significant haematological changes between circulation in feline blood donors and in FWB donated units at time of collection.…”

“…[9][10][11][12] The feline haemoglobin (Hb) P50 is only slightly reduced after FWB storage for 35 days in CPDA solution, suggesting that the storage lesion does not have a major impact on Hb-oxygen affinity in this species. 9 In addition, once collected, feline blood undergoes significant haematological changes between circulation in feline blood donors and in FWB donated units at time of collection. 13 However, to our knowledge, the haematological and morphological changes in a limited number of FWB units collected with a closed system and stored for transfusion purposes have only recently been reported.…”

Canine and feline blood transfusions: controversies and recent advances in administration practices

“…Cat RBC rely on chloride for oxygen affinity and 2,3‐DPG concentrations are naturally low (Bunn ; Taketa et al. ); the P 50 of stored haemoglobin in cats decreases relatively little (Wong & Haskins ) compared to that of dogs (Ou et al. ) in which 2,3‐DPG is the major modifier of haemoglobin affinity for oxygen.…”