Comparing the Effect of Duration and Site of Subcutaneous Injection of Enoxaparin on Pain Intensity and Bruising Size in Patients Admitted to Cardiac Care Units

Aims: Pain and bruise are the most common side effects of subcutaneous injection of enoxaparin sodium and the injection technique is responsible for 90% of these complications. Therefore, this study aimed to compare the effect of duration and site of subcutaneous injection of enoxaparin on pain intensity and bruise size in patients admitted to cardiac care units. Methods & Materials: This study was a clinical trial that was performed on 60 patients admitted to the cardiac care unit. The participants were selected by convenience sampling method and were randomly assigned into the two groups of 30-s and 15+5-s injection techniques. Pain intensity was measured immediately after injection by VAS (visual analog scale). Bruise size was measured 24 and 48 hours after each injection with a clear millimeter ruler. The obtained data were analyzed in SPSS version 21 at the significant level of 0.05. Findings: The results showed a significant decrease in pain intensity and bruise size 24 and 48 hours after the injection in the 30-s injection group compared to the 15+5-s injection group (P<0.001). The mean and standard deviation of pain reduction was 2.9±0.6 in the 30-s injection group and 3.53±0.5 in the 15+5- s injection group. The results also showed that mean and standard deviation of abdominal bruise size (15.76±3.07 mm) was significantly lower than arm (20.46 ±6.30 mm) in the 3-s injection group compared to the 15+5-s injection group (0.001). Conclusion: The 30-s injection technique resulted in a significant decrease in pain intensity and bruise size due to the subcutaneous injection of enoxaparin. It was also found that the extent of bruising in the abdominal site was less than the arm in the 30-s injection group compared to the 15+5-s injection, so the abdomen is recommended for subcutaneous injection of enoxaparin.