Sickle red blood cells are more susceptible to in vitro haemolysis when exposed to normal saline versus Plasma-Lyte A.
BACKGROUND
Normal saline has been the fluid of choice for resuscitation, rehydration and fluid replacement during plasma or red cell exchange/cytapheresis. There are increased concerns about its clinical effects and data showing it causes more haemolysis in vitro than buffered solutions such as Plasma-Lyte A.


METHODS
We investigated whether normal saline or Plasma-Lyte A was associated with greater haemolysis during hours of in vitro incubation with both normal red cells and samples from patients with sickle cell anaemia.


RESULTS
Sickle red cells haemolysed more than normal red cells did in both crystalloid solutions. The results of 24-hour exposure to saline were particularly striking (median of 163 mg/dl (IQ range 105-247) for sickle red cells vs. 53 (48-92) for normal red cells (P < 0·0001). In patient samples containing variable quantities of haemoglobin S red cells, increased haemoglobin S was associated with increased haemolysis. This effect was greater for normal saline than Plasma-Lyte A (P = 0·12).


CONCLUSIONS
These in vitro models demonstrate that short-term ex vivo exposure of sickle red cells to normal saline leads to greater haemolysis than short-term exposure of normal red cells, and this effect is exacerbated by normal saline. Whether use of normal saline causes increased haemolysis in vivo is unknown. Given recent evidence that normal saline increases renal failure and mortality in critically ill patients, further studies are urgently needed.
['Blumberg|Neil|N|https://orcid.org/0000-0002-2011-5652', 'Henrichs|Kelly|K|', 'Cholette|Jill|J|', 'Pietropaoli|Anthony|A|', 'Spinelli|Sherry|S|', 'Noronha|Suzie|S|', 'Phipps|Richard|R|', 'Refaai|Majed A|MA|https://orcid.org/0000-0001-8491-0279']
D000755:Anemia, Sickle Cell D000925:Anticoagulants D001803:Blood Transfusion D016638:Critical Illness D004573:Electrolytes D004906:Erythrocyte Count D004912:Erythrocytes D005440:Fluid Therapy D006403:Hematologic Tests D006451:Hemoglobin, Sickle D006461:Hemolysis D006801:Humans D061214:Patient Safety D010949:Plasma D012151:Resuscitation D000077330:Saline Solution D012965:Sodium Chloride
haemolysis sickle cell anaemia crystalloid solutions