The successful use of jet anesthetic injections with childhood lacerations

Efficacy and safety of needle-free jet injector-assisted intralesional treatments in dermatology-a systematic review

Needle-free jet injectors are used for the intralesional treatment of various dermatological indications. However, a systematic review that evaluates the efficacy and safety of these treatments has not been published. The objectives of this study are to evaluate the efficacy and safety of needle-free jet injections for dermatological indications and to provide evidence-based treatment recommendations. An electronic literature search was conducted in April 2022. Two reviewers independently selected studies based on predefined criteria and performed a methodological quality assessment using the Cochrane Collaborations risk-of-bias 2.0 assessment tool and Newcastle-Ottawa Scale. Thirty-seven articles were included, involving 1911 participants. Dermatological indications included scars, alopecia areata, hyperhidrosis, nail diseases, non-melanoma skin cancer, common warts, local anesthesia, and aesthetic indications. Keloids and other types of scars (hypertrophic, atrophic, and burn scars) were investigated most frequently (n = 7). The included studies reported favorable efficacy and safety outcomes for intralesional jet injector-assisted treatment with triamcinolone acetonide/hexacetonide, 5-fluorouracil, bleomycin, or hyaluronic acid. Two high-quality studies showed good efficacy and tolerability of intralesional jet injections with a combination of 5-fluorouracil and triamcinolone acetonide in hypertrophic scars and with saline in boxcar and rolling acne scars. No serious adverse reactions and good tolerability were reported in the included studies. Overall, the methodological quality of the included studies was low. Limited evidence suggests that needle-free jet injector-assisted intralesional treatment is efficacious and safe for hypertrophic and atrophic acne scars. More well-powered RCTs investigating the efficacy and safety of jet injector treatment in dermatology are warranted to make further evidence-based recommendations.

'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.

Fluid mechanics analysis of a spring-loaded jet injector

A syringe jet injector is a device designed to administer a drug quickly and painlessly through the skin. Though syringe jet injectors have been in use for almost 50 years, current designs still suffer from inconsistent performance. To better understand the fluid mechanics of jet injection and gain insight into how the design might influence performance, two theoretical analyses to determine the fluid pressure profile at the exit orifice were conducted. The first was a continuum analysis assuming static incompressibility. Results demonstrated that the maximum jet pressure was highly sensitive to the spring constant, initial piston velocity, and piston cross-sectional area while the time to achieve the maximum pressure was most sensitive to the injection chamber length, initial piston velocity, bulk modulus of the injectant, and the piston cross-sectional area. The second analysis was a shock wave analysis. Results demonstrated a stepwise pressure-time plot that was similar in magnitude to that for the continuum analysis assuming static incompressibility. Results from these two investigations are useful for design modification of the jet injector to achieve desired pressure-time profiles at the orifice. Control of pressure-time profiles may help to achieve a more consistent and effective injection process.

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.