[Protective effect of tetramethylpyrazine on red blood cells during autotransfusion]

To evaluate the protective effect of tetramethylpyrazine (TMPZ) on red blood cells (RBCs) during autotransfusion.

Sixty patients undergoing autotransfusion were randomly divided into 2 groups, 30 in each. In group I TMPZ with the dose of 4 mg/kg was injected intravenously to the patients before their blood was collected and put into the washing fluid consisting of heparinized normal saline with the end concentration of 5%. In group II TMPZ of the same dose was given to the patients too but no TMPZ was put into the washing fluid. The retrieval rate of RBC was calculated according to formula. The morphology of RBCs was observed by microscopy. Fluorescence spectrometry was used to examine the free calcium concentration in RBCs ([Ca(2+)]i) in the venous blood before anesthesia and the retrieved blood of the same patients.

There was no difference in the [Ca(2+)]i in RBCs before ther were washed between the two groups (P > 0.05). After the RBCs were washed, the [Ca(2+)]i increased in both groups (34 nmol/L +/- 10 nmol/L vs 48 nmol/L +/- 17 nmol/L in group I, P < 0.05; and 38 nmol/L +/- 9 nmol/L vs 76 nmol/L +/- 23 nmol/L in group II, P < 0.01), and the difference between the two groups were statistically significant (P < 0.05 approximately 0.01). The retrieval rate of RBCs was 69% +/- 8% in group I, higher than that in group II (50% +/- 16%, P < 0.05). Abnormal RBCs and fragments of RBCs were less in group I than in group II.

RBCs undergo destruction to a certain degree during retrieval and washing. TMPZ protects RBCs from destruction through its calcium block, negative charge, and antioxidation effects. Pretreatment of the patients with TMPZ and addition of TMPZ into the washing fluid improve the quality of retrieved blood, increase the retrieval rate of blood, and decrease the destruction of RBCs.