Appropriate Needle Insertion Depth for Intramuscular Injection Based on Assessment of BMI

Abstract

Aim: e present study was conducted to clarify the appropriate needle insertion depth for intramuscular injection based on assessment of BMI.Methods: e 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 clari ed the association between BMI and subcutaneous tissue thickness, with reference to muscle thickness, we clari ed 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. erefore, 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. erefore, the appropriate needle length was 1.5 cm for BMI<18.5, and 2.0 cm for BMI≥18.5 <30.0.Conclusion: e 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.

Explanatory Variables as Evidence for Precision in Intramuscular Long-Acting Injections of Patients with Schizophrenia

“…Although the research result of Takahashi et al [18] is very useful in that the injection-needle penetration depth can be easily selected, it is different from this research in that it targeted healthy people, and all deltoid-muscle injection sites were unified to 5 cm below acromion. It is also required to examine the influence caused by the difference in BMI to multiple-regression equation in our research.…”

“…As being discussed in preceding research [18], BMI was an explanatory variable useful for the prediction equation from the epidermis to the upper-arm bone. However, as shown in Figure 1 and Figure 2, in this prediction equation, when the value of BMI becomes larger, predicted DEB is sometimes calculated longer than DEB measured by ultrasonography.…”

“…The correlation with DEUF of which is recognized, is a BMI showing the degree of obesity obtained from body weight and body height [18]. This was considered to be useful as explanatory variables.…”

“…Takahashi et al [18] recommend that in the case of 5 cm below the acromion of the deltoid muscle, if 18.5 ≤ BMI < 30.0, injection insertion length is 1.5 cm, if BMI ≥ 30.3, injection insertion length is 2.0 cm and encourage to discuss the other site if BMI < 18.5. However, there may be differences in injection-needle penetration depth by individuals.…”

“…Kikuchi et al [17] developed a formula to assess the subcutaneous tissue thickness from the BMI which was in association with the BMI that was identified. Takahashi et al [18] reported that in the case of IM injection into the site 5 cm below the acromion of the deltoid muscle, if the needle insertion depth is 15 mm for those with BMI from 18.5 to 30 kg/m 2 and 20 mm for those with BMI of more than 30.0 kg/m 2 , the needle reaches the under-fascia and is in the position where it does not touch the upper-arm bone in both males and females. As the method of objectively assessing the distance from the epidermis of the deltoid muscle to the muscle layer or upper-arm bone, there are measuring methods such as using ultrasonography, BMI, and adipometers (fat measuring calipers) [19].…”