Skin to Intramuscular Compartment Thigh Measurement by Ultrasound in Pediatric Population

INTRODUCTION: Pediatric obesity threatens the efficacy of medications given intramuscularly. In anaphylactic patients, epinephrine auto-injector needle lengths are potentially too short to reach the muscle compartment in patients with elevated body habitus. The objective of the study was to determine needle-length requirements for intramuscular injections in pediatric patients. METHODS: We used ultrasound to measure the distance from skin to muscle compartment of the thigh in 200 pediatric patients of various weight and body mass index who presented to the emergency department. RESULTS: Patients with higher body mass index had an increased distance to muscle and bone. If current recommendations were followed, 5% of patients within the EpiPen adult weight category and 11% of patients within the Centers for Disease Control and Prevention weight category would have potentially used a needle inadequate in length for intramuscular injections. CONCLUSION: With the increase in childhood obesity, needle lengths may be too short to effectively deliver medications to the intramuscular compartment. Needle length should be evaluated to accommodate pediatric patients with increased skin to muscle distance.