Effect of Cold Application on Bruising and Pain Following Heparin Subcutaneous Injection: A Systematic Review and Meta-Analysis

We performed this review systematically to assess the effect of cold application at the heparin subcutaneous injection site on incidence and size of bruising, hematoma, and pain intensity.

A systematic review and meta-analysis were utilized as the study design.

To retrieve the relevant randomized controlled trials (RCTs) published up to July 2019, the databases of PubMed, Scopus, Web of Science, ScienceDirect, Cochrane Library, Google Scholar, TRIP, and Elmnet.ir were searched.

Those RCTs were selected in which the participants had received any type of heparin via subcutaneous injections at least once a day, as were those comparing the effect of cold application (i.e., moist or dry ice packs or vapocoolant spray) on injection sites with no interventions or placebos. The types of outcomes measured included pain intensity, bruising, and hematoma at injection sites. Furthermore, odds ratios (ORs) and mean differences (MDs) with 95% confidence intervals (CIs) were employed to measure the pooled data.

A total of nine studies recruiting 896 patients with a mean age range of 37 to 62 years were ultimately included in this study. The findings revealed that eight studies had used low-molecular-weight heparin, but unfractionated heparin had been administered in one study. The quality of the studies was also assessed in seven domains. Overall, risk of bias in the included articles was low to moderate. Pooling data of six studies showed that the patients had experienced less pain intensity once cold had been applied at the heparin injection sites (MD = -1.67; 95% CI -3.03 to -0.31; p = .02; I² = 92%). Bruising had been correspondingly reported in eight and six studies in terms of size and incidence, respectively. In particular, the results had demonstrated no statistically significant difference between either group in terms of bruising size or incidence at 48 to 72 hr following heparin injection. Furthermore, hematoma incidence had been reported in two studies, and one trial had reported hematoma size only. The results had suggested that the patients had smaller hematomas (MD = -0.87; 95% CI -1.63 to -0.11; p = .03) and a lower incidence of hematomas (OR = 0.35; 95% CI 0.16 to 0.76; p = .008) in the cold application group 48 hr after injection.

The results of this systematic review and meta-analysis showed that patients could experience less pain and fewer hematomas once the cold had been applied for 3 to 5 min at the injection sites before or after subcutaneous heparin administration. During this period, clinicians should also consider the patient's comfort; if some patients feel discomfort at the cold application site, the minimum possible time should be considered.

This study's results could be used as evidence for all hospitalized and outpatients who need to receive any form of heparin and may suffer from local complications of this medicine.