Abstract
Aim: The present study was conducted to clarify the appropriate needle insertion depth for intramuscular injection based on assessment of BMI.
Methods: The participants were 553 individuals more than 18 years old. We measured their height, weight, subcutaneous tissue thickness over the deltoid and gluteus medius, and muscle thickness of the deltoid. We clarified the association between BMI and subcutaneous tissue thickness, with reference to muscle thickness, we clarified the appropriate needle length for intramuscular injection.
Results: Subcutaneous tissue thickness over the deltoid was 0.04×BMI−0.25 in males, and 0.04×BMI−0.17 in females. However, in individuals with a BMI of <18.5, there was a risk of hitting the bone because the deltoid muscle was thin. Therefore, the appropriate needle length was 1.5 cm for BMI ≤18.5−<30.0, and 2.0 cm for BMI≥30.0. Subcutaneous tissue thickness over the gluteus medius was 0.05×BMI−0.38 in males, and 0.05×BMI−0.03 in females. However, in individuals with a BMI of ≥30.0, there was a risk of subcutaneous injection because of thick subcutaneous tissue over the gluteus medius. Therefore, the appropriate needle length was 1.5 cm for BMI<18.5, and 2.0 cm for BMI≥18.5−<30.0.
Conclusion: The appropriate needle insertion depth for intramuscular injection into the deltoid is 1.5 cm for BMI<18.5−<30.0 and 2 cm for BMI≥30.0, whereas that for the gluteus medius is 1.5 cm for BMI <18.5 and 2.0 cm for BMI≥18.5−<30.0.
