Estimation of supernatant hemoglobin in red cell units with and without temperature interruptions

Red cell units issued to patient and returned back unused, are visually inspected for hemolysis before releasing them for reissue. A study was conducted to find out effect of temperature interruptions in the red cell units, during transport. The aims were to find out hemolysis in units with temperature interruptions and its relationship to the duration and also to compare actual hemolysis with visible hemolysis, if any. Thirty samples with different duration of temperature interruptions were evaluated for actual hemolysis. Fifteen samples of similar shelf-age but without temperature interruptions were included in the study as controls. Low hemoglobin photometer was used to measure supernatant hemoglobin. Despite temperature interruptions, almost all red cell units had acceptable level of hemolysis and this was similar to the red cell units without temperature interruption. The difference between the units with or without temperature interruption was not statistically significant (p > 0.05). Red cell units with smaller duration of temperature interruptions had lesser hemolysis than in those with longer temperature interruptions (p < 0.05). Red cell units younger than 7 days had lesser hemolysis than the units older than 8 days in both categories of units with and without temperature interruptions (p < 0.05). The units without visible hemolysis had lower hemolysis than units with visible hemolysis (p < 0.05). It can be concluded that temperature interruptions have a very minor role in hemolysis, younger units have lesser hemolysis than older units and visual assessment is subjective and tend to overestimate hemolysis.