title: Determination of deltoid fat pad thickness. Implications for needle length in adult immunization.
abstract: OBJECTIVE
  To measure deltoid fat pad thickness and determine the optimal needle length for deltoid intramuscular immunization in healthy adults.
  
  
  METHODS
  Prospective study of 220 healthy health care workers (126 women, 94 men) at the Mayo Medical Center, Rochester, Minn.
  
  
  METHODS
  Deltoid fat pad thickness determined by high-resolution ultrasound scanning, weight, height, and mid-deltoid arm circumference.
  
  
  RESULTS
  We found a highly significant difference between women and men in deltoid fat pad thickness, with women having a thicker deltoid fat pad (11.7 vs 8.3 mm; P<.001). Women had a greater deltoid skin-fold thickness than men (34.7 vs 17.2 mm, P<.001) and an equal body mass index. According to the ultrasound findings, a standard 16-mm (5/8-in) needle would not have reached 5 mm into muscle in 17% (16/94) of men and 48.4% (61/126) of women in this study.
  
  
  CONCLUSIONS
  Among healthy adults of the age range we studied, the following needle lengths appear to be appropriate for true deltoid intramuscular immunization: For men across the weight ranges we studied (59-118 kg), use of a 25-mm (1-in) needle would result in at least 5 mm of muscle penetration in all subjects. For women who weighed less than 60 kg, a 16-mm (5/8-in) needle would be sufficient to achieve muscle penetration of 5 mm. For women between 60 and 90 kg, a 25-mm (1-in) needle would be sufficient, and women greater than 90 kg would require a 38-mm (1.5-in) needle to ensure intramuscular administration.
authors.affiliation: Mayo Vaccine Research Group, Clinical Pharmacology Unit, Rochester, MN 55905, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Poland
authors.forename: A
authors.initials: A
authors.lastname: Borrud
authors.forename: R M
authors.initials: RM
authors.lastname: Jacobson
authors.forename: K
authors.initials: K
authors.lastname: McDermott
authors.forename: P C
authors.initials: PC
authors.lastname: Wollan
authors.forename: D
authors.initials: D
authors.lastname: Brakke
authors.forename: J W
authors.initials: JW
authors.lastname: Charboneau
mesh_terms: D000328:Adult; D000886:Anthropometry; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal; D009339:Needles; D011446:Prospective Studies; D012016:Reference Values; D012885:Skinfold Thickness; D014611:Vaccination