Increased tissue PO2 and decreased O2 delivery and consumption after 80% exchange transfusion with polymerized hemoglobin.
The O2-carrying blood substitute based on polymerized bovine hemoglobin (PBH) was used to determine efficacy in maintaining tissue Po2 after an 80% isovolemic blood exchange leading to a hematocrit of 19% [5.4 g Hb/dl from red blood cells (RBCs) and 6.3 g Hb/dl from PBH]. Effects were studied in terms of O2 delivery, O2 extraction, and tissue Po2 at the microcirculatory level at 1, 12, and 24 h after exchange transfusion in awake hamsters prepared with a window chamber model. At 1 h after exchange, arteriolar and venular diameters were decreased compared with baseline. Arteriolar diameter did not fully recover at 12 h after exchange, but venular diameter returned to normal. At 24 h after exchange, arteriolar and venular diameters were not different from baseline. Combining diameter and flow velocity data allowed us to calculate arteriolar and venular flows. At 1 h after exchange, arteriolar and venular flow was reduced compared with baseline. Arteriolar flow was lower at 12 h after exchange and recovered after 24 h. The number of capillaries with RBC passage [functional capillary density (FCD)] at 1 h after exchange with PBH was significantly lower than baseline. FCD remained decreased at 12 h; at 24 h after exchange transfusion, FCD was fully recovered. Tissue Po2 was maximal at 1 h after exchange and decreased progressively at 12 and 24 h after exchange. O2 release to the tissue was minimal at 1 h and increased at 12 and 24 h after exchange. These results suggest the impairment of tissue O2 metabolism after introduction of PBH into the circulation, which is mitigated as PBH concentration declines.
Cabrales
Pedro
P
Dept. of Bioengineering, 0412, Univ. of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0412, USA. pcabrales@ucsd.edu
Tsai
Amy G
AG
Intaglietta
Marcos
M
D000818:Animals; D001160:Arterioles; D001802:Blood Substitutes / Q000493:pharmacokinetics*; D001803:Blood Transfusion; D002245:Carbon Dioxide / Q000097:blood; D006224:Cricetinae; D006400:Hematocrit; D006454:Hemoglobins; D008647:Mesocricetus; D008706:Methemoglobin / Q000494:pharmacology; D010100:Oxygen / Q000493:pharmacokinetics*; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure
D001802:Blood Substitutes; D006454:Hemoglobins; C079129:hemoglobin polymer; D002245:Carbon Dioxide; D008706:Methemoglobin; D010100:Oxygen