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Needle-less Injection with a Degassed Fluid

IP.com Disclosure Number: IPCOM000009712D
Publication Date: 2002-Sep-12
Document File: 71 page(s) / 6M

Publishing Venue

The IP.com Prior Art Database

Abstract

Apparatuses and methods are described for administering a needle-less injection of a degassed fluid. Prior to filling, or after filling but prior to administration of a needle-less injection, gas is removed from the fluid. A needle-less injection may then be performed with a reduced risk of discomfort to the recipient of the injection and with lower potential for the creation of a subdermal hematoma as a result of the injection. A wide variety of needle-less injectors may be used in accordance with various embodiments of the present invention.

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NEEDLE-LESS INJECTION WITH A DEGASSED FLUID

ABSTRACT:

Apparatuses and methods are described for administering a needle-less injection of a degassed fluid. Prior to filling, or after filling but prior to administration of a needle-less injection, gas is removed from the fluid. A needle-less injection may then be performed with a reduced risk of discomfort to the recipient of the injection and with lower potential for the creation of a subdermal hematoma as a result of the injection. A wide variety of needle-less injectors may be used in accordance with various embodiments of the present invention.

BACKGROUND:

    Subdermal hematomas, tissue damage, and scarring from mechanical force injury may result from the use of needle-less injectors when pockets of gas are present in the injector ampoule prior to dispensing the medication contained therein. Within the 800 to 1200 foot per second range, optimal for acceleration of liquid medication through the skin via a needle-less injector, liquid readily penetrates the skin while air does not. Thus, gas pockets accelerated against the skin lead to the formation of a bruise and can be quite painful for the recipient, whereas liquid medication passes into and/or through the skin without discomfort.

    In general, the gas pocket is found at the dispensing terminus of the ampoule, which is proximate to the skin, though this can change depending on the orientation of the ampoule during storage. Further, when a cap is removed from the end of a needle-less injector, exposing the dispensing area for application to the skin surface, any gas pocket not already situated at the dispensing end may tend to migrate toward that end, due to the pressure change caused by cap removal. This motion of the gas pocket often forces some liquid from the ampoule, thereby diminishing the volume of liquid that will be injected into the recipient. This renders the dosage level inaccurate, as a nontrivial volume of medication is lost from the injector prior to use.

    Gas pockets may be present from the outset, resulting from improper filling of an ampoule. Filling the ampoule with an insufficient amount of liquid clearly leaves such a pocket. However, overfilling the ampoule and removing any excess to arrive at the desired volume is generally not a practical alternative, since it is likely that a small amount of liquid will remain on the outer surface of the ampoule. In the medical context, any such liquid is likely to foster the

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growth of bacteria, which is unacceptable in a scenario where sterile conditions are imperative. Any ampoule with such bacterial growth must be disposed of, and is therefore wasteful.

    Even in a perfectly filled ampoule, where no cognizable gas pockets are present immediately following loading, pockets may still develop over time as the dissolved gases present in the liquid separate out from solution. Dissolved gases are present in the liquids filled into ampoules under normal conditions...