Background: The dorsogluteal and ventrogluteal intramuscular injection sites both have their use in clinical practice; however, it has not been established in whom one or the other should be preferentially targeted or avoided. There is a need for an evidence-based approach towards site selection for a successful intramuscular injection outcome and to avoid unwanted injection outcomes of inadvertent subcutaneous injection or bone contact. Injection outcome is dependent on injection site subcutaneous fat thickness and muscle thickness; these are likely influenced by gender and anthropometry.
Objectives: To determine whether subcutaneous fat, muscle, and total tissue thicknesses differ between the dorsogluteal and ventrogluteal sites, and whether theoretical injection outcome (intramuscular, subcutaneous, or bone contact) can be predicted by demographic and anthropometric data and described by an algorithm.
Design: Cross-sectional study design.
Settings: University in Australia.
Participants: 145 volunteers (57% female) of at least 18 years of age recruited through the university community.
Methods: Anthropometric data was collected and subcutaneous fat and muscle thicknesses were quantified by ultrasonography. Anthropometric differences between theoretical injection outcome groups (bone contact versus intramuscular versus subcutaneous at the ventrogluteal and dorsogluteal sites) was determined for each gender (ANOVA). Multiple regression analysis was conducted to determine the influence of demographic and anthropometric data on theoretical intramuscular injection outcome. An algorithm to guide site selection was developed for each gender, based on the anthropometric measures that best discriminated between injection outcomes.
Results: Subcutaneous fat, muscle and total tissue were significantly thicker at the dorsogluteal site than the ventrogluteal site, and subcutaneous fat was significantly thicker in females than males at both sites (all p<0.001); there was no gender difference for muscle or total tissue thickness at either site. Female gender, and waist and hip circumference were significant predictors of subcutaneous fat thickness at both sites; male gender was a significant predictor of dorsogluteal site muscle thickness (all p<0.05). In the algorithm developed for site selection based on theoretical injection outcome, the best discriminators were: weight, BMI and waist circumference for females, and weight and distance between the iliac tubercle and anterior superior iliac spine for males.
Conclusions: The algorithm describes when each of the ventrogluteal and dorsogluteal sites is appropriate or should be avoided, based on easily obtained anthropometric data. This has direct relevance in clinical practice in evidence-based site selection for gluteal intramuscular injections for optimal medication and health outcomes.
Keywords: Dorsogluteal; Injection outcome; Intramuscular injection; Muscle; Subcutaneous fat; Ultrasound; Ventrogluteal.
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