The Need for Standardizing the Index of Hemolysis

Abstract

Hemolysis is one of the most important performance parameters of blood pumps. However, comparative in vitro evaluation of the reported hemolysis effect is difficult owing to the lack of uniformity in the test methods used. Currently, three types of formulas are generally accepted and widely used for the index of hemolysis: the traditionally used index of hemolysis (defined as grams of plasma free hemoglobin released per 100 L of blood pumped); the normalized index of hemolysis (normalized by hematocrit); and the modified index of hemolysis (taking into account not only hematocrit but also hemoglobin). In addition, the tested blood conditions are often not indicated in the reports. To address this confusing situation, all three indices of hemolysis were routinely derived in our laboratory. To avoid further confusion, the tested blood conditions and test loop were defined in each study in our laboratory. If we limit the acceptable range of hemoglobin in human blood, the normalized index of hemolysis is sufficient. Furthermore, using milligrams as the unit of expression would be easier and reasonable for comparing the less hemolytic blood pumps, such as the centrifugal pumps that are currently available clinically. We would like to propose this value of a normalized index of hemolysis in milligrams as the most useful formula for the index of hemolysis in the assessment of various types of rotary blood pumps.

Bomba sangüínea espiral: concepção, desenvolvimento e aplicação clínica de projeto original

“…Factors such as age, clinical conditions, type of heart disease, and the presence of comorbidities, different surgical and myocardial protection techniques, oxygenator, tubes, cannulas, and different perfusates can influence the hemolytic indexes [3,20,21]. The amount of Free Hemoglobin in the plasma depends on both the velocity and the capacity of removal of the pigment by the body of each individual.…”

“…The hemolysis is the motive of extensive researches in the development of devices of blood propulsion [20][21][22][23][24][25] by starting from the presupposed that it is impossible to avoid the mechanical hemolysis caused by a propulsion device and, besides that it has been checked through different indexes making comparisons often difficult [21]. The definition of the "in vitro" Hemolysis index was established by the amount of Free Hemoglobin per 100 liters of pumped blood with fresh blood and hemoglobin e" 14 g/dL and if its deposit was located 140 cm above the pump [26,27].…”

“…The characteristics of a mechanic device of blood propulsion are important to verify its hydrodynamic effectiveness and the intensity of trauma imposed to the blood-formed elements [13]. Therefore, the same pump model can present different degrees of cellular trauma many times related to small changes in the "design", what have demonstrated through studies and evaluation of the pump flow with the same diameter, but with varied positions of the wings in relation to the axis, observing a difference as to the movement of the particles in its interior [14].…”

Modelagem matemática da fluidodinâmica não-newtoniana e bifásica simplificada da hemólise induzida mecanicamente em sistemas de bombeamento centrífugo de sangue

“…O índice normalizado de hemólise (Naito et al, 1994) é calculado pela fórmula (1.9) e multiplicado por um fator de normalização baseado no valor do hematócrito , dado em escala percentual…”

“…O índice modificado de hemólise (Naito et al, 1994) consiste em um valor adimensional obtido pela fórmula = × 1000 (1.11) onde é a concentração total de hemoglobina no sangue ( / ).…”