Application of a versatile instrument for production of cutaneous anesthesia without needle penetration of the skin

'Needle-free' delivery of local anesthesia: a valuable option in pediatrics

Needleless injection or jet injection of medication has had a rather limited clinical use in children's healthcare beyond mass vaccinations. Medications injected into children with a needle-free system include local anesthetic agents, sedatives (midazolam), and anesthetic induction agents (ketamine). Reports suggest that local discomfort is often negligible and costs are often minimal. Risks associated with this simple and flexible technique are considered to be markedly less than alternative approaches, such as syringe and needle. Further investigations are needed to confirm initial reports and establish current and other uses of jet injectors in children.

Potential for cross-contamination from use of a needleless injector

BACKGROUND

Medical devices that are used on patients in fields containing potentially infectious body fluids can become contaminated and transmit infectious agents to other sites on the patient or to other patients if the devices are not properly cleaned and decontaminated after use on each patient treatment site. One such device is the needleless or jet injector, which is widely used in medicine and dentistry to deliver local anesthetic in procedures such as bone marrow aspirations, lumbar punctures, and cutaneous and intraoral injections. This study was conducted to determine whether cross-contamination can occur on in vitro reuse of a needleless injector and whether a manufacturer's recommended method of injector decontamination (ie, immersion sterilization) is effective in the prevention of cross-contamination.

METHODS

The study was performed with new autoclaved injectors, fluorescein dye, and Streptococcus crista (the bacteria commonly found in saliva) in the field of use to determine whether these devices can become contaminated during use and carry over the contamination to other sites during immediate reuse.

RESULTS

Fluorescein dye and bacteria tests with the needleless injectors showed that contamination or carryover does occur. It appeared to reduced to a minimum when a autoclaved, sterile rubber cap used over the head of the device during injection was replaced between each use, although replacement of the rubber cap alone did not prevent carryover. Immersion of the head of the injector in a 2% glutaraldehyde solution for 30 minutes followed by a sterile water rinse and the replacement of the rubber cap with a sterile cap between uses was shown to curtail bacterial growth and prevent cross-contamination on immediate reuse of the device.

CONCLUSION

This study demonstrated that needleless injectors become contaminated during in vitro use and direct contact with contaminated surfaces and that needless injectors carry over the contamination to subsequent sites of release. The replacement of the injector's rubber cap with a new one after initial discharge or the removal of an exposed rubber cap and immersion of the head of the injector in 2% glutaraldehyde followed by a rinse of the head in sterile water, as recommended by one injector manufacturer, can minimize or eliminate the carryover.

The efficacy and acceptability of using a jet injector in performing digital blocks

This prospective, nonblinded study, comparing jet injection with needle-syringe injection of lidocaine in performing digital blocks, tested the hypothesis that jet injection can be used effectively as a less painful way to perform digital blocks. Twenty-four adult patients with injuries of the middle or distal phalanges of the fingers received digital blocks using a jet injector on one side of the finger and a needle-syringe on the other side; pain was assessed at 0, 1, 3, 6, 12, and 24 hours using visual analog scales. Differences in pain scores for the two procedures (jet injector vs needle) were tested at each time period using nonparametric statistical procedures for paired or matched data (paired Wilcoxon). At the time of injection (time 0) and at 12 hours, the jet had a significantly lower pain score than the needle. Comparisons made at the other points were statistically nonsignificant at .05. The anesthesia achieved using the jet injector was considered adequate in 23 of 24 patients. We conclude that the jet injector can be used effectively in performing digital blocks and is less painful than standard needle-syringe methods.