The kinetics of sickle blood viscosity changes following rapid deoxygenation and reoxygenation

A technique is described in which alterations in sickle blood viscosity can be measured following rapid oxygenation or deoxygenation. The results for two SS blood samples and one SC sample indicate that no measurable rheological changes occur for 21 to 33 sec after partial deoxygenation. Viscosity changes following reoxygenation were too rapid to be accurately measured with this technique. Possible evidence that oxygen exchange may be impaired in sickle cells is also presented. The results suggest that sickle cell crisis may be initiated when the sickling delay time, following exposure to low oxygen tension, becomes shorter than the time required for most cells to return to the lungs, rather than the time needed to traverse a systemic capillary.