Technique, Weight Should Dictate Needle Length

CHICAGO — When immunizing adolescents, body weight and injection technique should guide the choice of needle length, according to a poster study presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

“We looked at the performance of a 5/8-inch vs. a 1-inch needle—using both pinching and flattening of the injection site—in relation to the recipient's body weight,” said Dr. Michael Koster.

A needle that is too short might result in reduced immunogenicity and more adverse reactions to vaccines intended for intramuscular injection, whereas a needle that is too long may strike bone and injure underlying neurovascular structures, he said in an interview.

With use of the pinching technique on adolescents weighing 88–155 pounds, a 1-inch needle is appropriate. For those weighing less than 88 pounds, the shorter needle is best, said Dr. Koster, who conducted the study at Schneider Children's Hospital at North Shore in Manhasset, New York.

With use of the muscle-flattening technique, the longer needle likewise is recommended when body weight is 88–155 pounds, and the 5/8-inch needle is appropriate for adolescents weighing less than 88 pounds, said Dr. Koster, who is now a pediatric infectious disease fellow at Hasbro Children's Hospital in Providence, R.I.

The study included 141 participants. They were aged 11–15 years, with 87% of them aged 12–13 years. Of the total, 28% weighed less than 88 pounds, and about 20% weighed more than 132 pounds.

The researchers noted subjects' height, weight, and arm circumference, and conducted upper-arm ultrasonography during both muscle pinching and skin flattening of the participants' nondominant arms. The measurements were duplicated by a second researcher and averaged for analysis.

“When injecting someone [using] the pinching technique, you increase muscle and subcutaneous tissue layers, in which case you'll want a little longer needle. When flattening, typically using the forefinger and thumb, you can go up to [a weight of] about 50 kilos [110 pounds] and be safe in terms of getting the vaccine into the muscle without striking bone,” Dr. Koster said at the meeting, which was sponsored by the American Society for Microbiology.

As a general rule, with the pinching technique, a 1-inch needle is appropriate most of the time, and the shorter needle is appropriate only for patients who weigh less than 88 pounds.

With the flattening technique, the shorter length is appropriate only three-quarters of the time and only on patients weighing less than 110 pounds. “Independent of technique, it would be appropriate to use a 5/8-inch needle on subjects less than 88 pounds,” he said.

Although females had a larger subcutaneous layer than did males of the same body weight, the difference did not result in the use of a different needle length, Dr. Koster said, adding that body weight was a better predictor of required needle size than was arm circumference.

The American Academy of Pediatrics Red Book makes needle length recommendations for adolescents only in terms of body weight and sex. For example, both sizes of needles are advised for girls and boys who weigh less than 132 pounds. The 1-inch needle is recommended for girls who weigh 132–198 pounds and boys who weigh 132–260 pounds. The AAP recommends an even longer (11/2-inch) needle for females over 198 pounds and males over 260 pounds. Only 2 of the 141 subjects were that heavy, and the data on these two still are being analyzed.

Data from previous studies have suggested obese teens who are immunized with 1-inch needles develop lower hepatitis B virus (HBV) vaccine titer levels, compared with those vaccinated with 11/2-inch needles. In one study, 24 obese subjects aged 14–24 years were randomized to 1-inch and 11/2-inch needle groups, and the subjects (girls over 198 pounds and boys over 265 pounds) were given an HBV vaccination using a 0, 1-, and 4-month schedule. HBV surface antibody was obtained 2 months after the third vaccination, and data showed that the final titer levels in the 11/2-inch needle group were significantly higher than those in the 1-inch needle group (J. Adol. Health 2006;38:101).

Dr. Koster said he hoped his findings would be included in the 2009 Red Book, especially since meningococcal conjugate vaccine and human papillomavirus vaccine have been recommended for all adolescents.

If a needle is too short, it may cut immunogenicity; if it's too long, it may injure underlying structures. DR. KOSTER

CHICAGO — When immunizing adolescents, body weight and injection technique should guide the choice of needle length, according to a poster study presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

“We looked at the performance of a 5/8-inch vs. a 1-inch needle—using both pinching and flattening of the injection site—in relation to the recipient's body weight,” said Dr. Michael Koster.

A needle that is too short might result in reduced immunogenicity and more adverse reactions to vaccines intended for intramuscular injection, whereas a needle that is too long may strike bone and injure underlying neurovascular structures, he said in an interview.

With use of the pinching technique on adolescents weighing 88–155 pounds, a 1-inch needle is appropriate. For those weighing less than 88 pounds, the shorter needle is best, said Dr. Koster, who conducted the study at Schneider Children's Hospital at North Shore in Manhasset, New York.

With use of the muscle-flattening technique, the longer needle likewise is recommended when body weight is 88–155 pounds, and the 5/8-inch needle is appropriate for adolescents weighing less than 88 pounds, said Dr. Koster, who is now a pediatric infectious disease fellow at Hasbro Children's Hospital in Providence, R.I.

The study included 141 participants. They were aged 11–15 years, with 87% of them aged 12–13 years. Of the total, 28% weighed less than 88 pounds, and about 20% weighed more than 132 pounds.

The researchers noted subjects' height, weight, and arm circumference, and conducted upper-arm ultrasonography during both muscle pinching and skin flattening of the participants' nondominant arms. The measurements were duplicated by a second researcher and averaged for analysis.

“When injecting someone [using] the pinching technique, you increase muscle and subcutaneous tissue layers, in which case you'll want a little longer needle. When flattening, typically using the forefinger and thumb, you can go up to [a weight of] about 50 kilos [110 pounds] and be safe in terms of getting the vaccine into the muscle without striking bone,” Dr. Koster said at the meeting, which was sponsored by the American Society for Microbiology.

As a general rule, with the pinching technique, a 1-inch needle is appropriate most of the time, and the shorter needle is appropriate only for patients who weigh less than 88 pounds.

With the flattening technique, the shorter length is appropriate only three-quarters of the time and only on patients weighing less than 110 pounds. “Independent of technique, it would be appropriate to use a 5/8-inch needle on subjects less than 88 pounds,” he said.

Although females had a larger subcutaneous layer than did males of the same body weight, the difference did not result in the use of a different needle length, Dr. Koster said, adding that body weight was a better predictor of required needle size than was arm circumference.

The American Academy of Pediatrics Red Book makes needle length recommendations for adolescents only in terms of body weight and sex. For example, both sizes of needles are advised for girls and boys who weigh less than 132 pounds. The 1-inch needle is recommended for girls who weigh 132–198 pounds and boys who weigh 132–260 pounds. The AAP recommends an even longer (11/2-inch) needle for females over 198 pounds and males over 260 pounds. Only 2 of the 141 subjects were that heavy, and the data on these two still are being analyzed.

Data from previous studies have suggested obese teens who are immunized with 1-inch needles develop lower hepatitis B virus (HBV) vaccine titer levels, compared with those vaccinated with 11/2-inch needles. In one study, 24 obese subjects aged 14–24 years were randomized to 1-inch and 11/2-inch needle groups, and the subjects (girls over 198 pounds and boys over 265 pounds) were given an HBV vaccination using a 0, 1-, and 4-month schedule. HBV surface antibody was obtained 2 months after the third vaccination, and data showed that the final titer levels in the 11/2-inch needle group were significantly higher than those in the 1-inch needle group (J. Adol. Health 2006;38:101).

Dr. Koster said he hoped his findings would be included in the 2009 Red Book, especially since meningococcal conjugate vaccine and human papillomavirus vaccine have been recommended for all adolescents.

If a needle is too short, it may cut immunogenicity; if it's too long, it may injure underlying structures. DR. KOSTER

CHICAGO — When immunizing adolescents, body weight and injection technique should guide the choice of needle length, according to a poster study presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

“We looked at the performance of a 5/8-inch vs. a 1-inch needle—using both pinching and flattening of the injection site—in relation to the recipient's body weight,” said Dr. Michael Koster.

A needle that is too short might result in reduced immunogenicity and more adverse reactions to vaccines intended for intramuscular injection, whereas a needle that is too long may strike bone and injure underlying neurovascular structures, he said in an interview.

With use of the pinching technique on adolescents weighing 88–155 pounds, a 1-inch needle is appropriate. For those weighing less than 88 pounds, the shorter needle is best, said Dr. Koster, who conducted the study at Schneider Children's Hospital at North Shore in Manhasset, New York.

With use of the muscle-flattening technique, the longer needle likewise is recommended when body weight is 88–155 pounds, and the 5/8-inch needle is appropriate for adolescents weighing less than 88 pounds, said Dr. Koster, who is now a pediatric infectious disease fellow at Hasbro Children's Hospital in Providence, R.I.

The study included 141 participants. They were aged 11–15 years, with 87% of them aged 12–13 years. Of the total, 28% weighed less than 88 pounds, and about 20% weighed more than 132 pounds.

The researchers noted subjects' height, weight, and arm circumference, and conducted upper-arm ultrasonography during both muscle pinching and skin flattening of the participants' nondominant arms. The measurements were duplicated by a second researcher and averaged for analysis.

“When injecting someone [using] the pinching technique, you increase muscle and subcutaneous tissue layers, in which case you'll want a little longer needle. When flattening, typically using the forefinger and thumb, you can go up to [a weight of] about 50 kilos [110 pounds] and be safe in terms of getting the vaccine into the muscle without striking bone,” Dr. Koster said at the meeting, which was sponsored by the American Society for Microbiology.

As a general rule, with the pinching technique, a 1-inch needle is appropriate most of the time, and the shorter needle is appropriate only for patients who weigh less than 88 pounds.

With the flattening technique, the shorter length is appropriate only three-quarters of the time and only on patients weighing less than 110 pounds. “Independent of technique, it would be appropriate to use a 5/8-inch needle on subjects less than 88 pounds,” he said.

Although females had a larger subcutaneous layer than did males of the same body weight, the difference did not result in the use of a different needle length, Dr. Koster said, adding that body weight was a better predictor of required needle size than was arm circumference.

The American Academy of Pediatrics Red Book makes needle length recommendations for adolescents only in terms of body weight and sex. For example, both sizes of needles are advised for girls and boys who weigh less than 132 pounds. The 1-inch needle is recommended for girls who weigh 132–198 pounds and boys who weigh 132–260 pounds. The AAP recommends an even longer (11/2-inch) needle for females over 198 pounds and males over 260 pounds. Only 2 of the 141 subjects were that heavy, and the data on these two still are being analyzed.

Data from previous studies have suggested obese teens who are immunized with 1-inch needles develop lower hepatitis B virus (HBV) vaccine titer levels, compared with those vaccinated with 11/2-inch needles. In one study, 24 obese subjects aged 14–24 years were randomized to 1-inch and 11/2-inch needle groups, and the subjects (girls over 198 pounds and boys over 265 pounds) were given an HBV vaccination using a 0, 1-, and 4-month schedule. HBV surface antibody was obtained 2 months after the third vaccination, and data showed that the final titer levels in the 11/2-inch needle group were significantly higher than those in the 1-inch needle group (J. Adol. Health 2006;38:101).

Dr. Koster said he hoped his findings would be included in the 2009 Red Book, especially since meningococcal conjugate vaccine and human papillomavirus vaccine have been recommended for all adolescents.

If a needle is too short, it may cut immunogenicity; if it's too long, it may injure underlying structures. DR. KOSTER