Abstract: Objective To investigate the effect of low molecular weight heparin injection mode to the incidence of adverse drug reactions in patients with acute myocardial infarction.Methods From March to April in 2016, 72 patients were randomly assigned to receive low molecular weight heparin injection in our hospital and divided into 6 groups: group A, B, C: injection for 10 s and pressing for 0, 5, 10 min. Group D, E, F: injection for 30 s and pressing for 0, 5, 10 min. The original grade 4 pain was changed to grade 3 (no pain, mild pain and moderate pain) according to the 4 point verbal rating scale. The degree of local pain of injection was evaluated and the patient’s bleeding (mild, moderate, severe) was recorded.Results Under the same injection length, subcutaneous bleeding rate on group pressing 5 min and pressing 10 min was less than non-compression (P < 0.05), group between pressing 5 min and pressing 10 min blood had no significant difference (P > 0.05). There was no statistically significant difference on pain degree among pressing 0, 5, 10 min (P > 0.05). Under the same pressing time, bleeding amount and local pain degree in patients injecting 30 s was lower than 10 s, the difference was statistically significant (P < 0.05).Conclusion To reduce subcutaneous hemorrhage and local pain caused by injection, the subcutaneous injection of low molecular weight heparin lasting 30 s and pressing for 5 min after injection should be conducted.

Key words: low molecular heparin, local pain, four points oral grading pain score, amount of bleeding