Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
2000-06-08
2002-07-30
Shaver, Kevin (Department: 3736)
Surgery
Diagnostic testing
Liquid collection
C606S009000, C606S017000, C607S089000, C128S898000, C604S020000
Reexamination Certificate
active
06425873
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of medical procedures, namely, procedures facilitated primarily by laser medical equipment used in the delivery of pharmaceuticals or the removal of biomolecules, fluids or gases.
BACKGROUND
The traditional method for the collection of small quantities of fluids or gases from a patient utilizes mechanical perforation of the skin with a sharp device such as a metal lancet or needle. Additionally, the typical method of administering local anesthetic is through the use of a needle. These procedures have many drawbacks, two of which are the possible infection of health-care workers or the public at large with the device used to perforate the skin, and the costly handling and disposal of biologically hazardous waste.
When skin is perforated with a sharp device such as a metal lancet or needle, biological waste is created in the form of the “sharp” which is contaminated by the patient's blood and/or tissue. If the patient is infected with any number of blood-born agents, such as human immunodeficiency virus (HIV) which causes acquired immune deficiency syndrome (AIDS), hepatitis virus or the etiological agent of other diseases, the contaminated sharp can pose a serious threat to others who come in contact with it. There are many documented instances of HIV infection of medical workers who were accidentally stabbed by a contaminated sharp.
Disposal of sharps is also a major problem. Disposal of contaminated materials poses both a logistic and a financial burden on the end user such as the medical institution. In the 1980s, numerous instances of improperly disposed biological wastes being washed up on public beaches occurred. The potential for others, such as intravenous drug users, to obtain improperly disposed needles is also problematic.
There exists additional drawbacks to the traditional method of stabbing a patient with a sharp instrument for the purpose of delivering pharmaceutical agents or for drawing fluids or gases. Often, the stabbing procedure must be repeated, often resulting in significant stress and anxiety in the patient. The pain associated with being stabbed by a sharp instrument can be a traumatizing procedure, especially in pediatric patients. This can cause significant stress and anxiety in the patient.
Clearly the current procedure for puncturing skin for the purpose of drawing fluids or gases has significant inherent problems. These problems arise because a sharp instrument is used in the procedure. Thus, a need exists for techniques to remove biomolecules, fluids or gases, and to administer pharmaceutical agents, which do not use a sharp instrument. Such methods would obviate the need for disposal of contaminated instruments, and reduce the risk of cross infection.
The current technology for applying pharmaceutical substances without the use of needles typically involves: (a) drug mixtures in creams, lotions or gels; (b) iontophoresis; (c) carriers or vehicles which are compounds that alter the chemical properties of either the stratum corneum or the pharmaceutical; (d) sonophoresis which involves altering the barrier function of stratum corneum by ultrasound; or (e) drug patches which attach to the skin to effect transdermal administration. For example, lidocaine is commonly used as a local anesthetic, especially in pediatric patients, but requires a cream to be applied for up to 60 minutes, and anesthesia is produced to a depth of only about 4 mm. The lack of penetration is a consequence of the barrier function of the stratum corneum. Inherent problems with iontophoresis include the complexity of the delivery system, cost, and unknown toxicology of prolonged exposure to electrical current. Additionally, the use of carriers or vehicles involves the use of an additional compound which right alter the pharnacokinetics of the pharmaceutical of interest. Finally, most patch applications are insufficient because many drugs do not easily traverse the stratum corneum.
Clearly a need exists for a means to apply pharmaceutical substances without the use of a needle. The current procedure for applying pharmaceuticals without the use of a needle puncture has inherent problems. The discoveries disclosed herein reduce or eliminate the problems associated with disposal of contaminated needles or sharps, reduce or eliminate the pain associated with being stabbed by a sharp instrument, and improve transdermal delivery of drugs.
Lasers have been used in recent years as a very efficient and precise tool in a variety of surgical procedures. Among potentially new sources of laser radiation, the rare-earth elements are of major interest for medicine. The most promising of these is a YAG (yttrium, aluminum, garnet) crystal doped with erbium (Er) ions. With the use of this crystal, it is possible to build an Erbium: YAG (Er:YAG) laser which can be configured to emit electromagnetic energy at a wavelength (2.94 microns) which is strongly absorbed by water. When tissue, which consists mostly of water, is irradiated with radiation at or near this wavelength, it is rapidly heated. If the intensity of the radiation is sufficient, the heating is rapid enough to cause the vaporization of tissue. Some medical uses of Er:YAG lasers have been described in the health-care disciplines of dentistry, gynecology and ophthalmology. See, e.g., Bogdasarov, B. V., et al., “The Effect of YAG:Er Laser Radiation on Solid and Soft Tissues,” Preprint 266, Institute of General Physics, Moscow, 1987; Bol'shakov, E. N. et al., “Experimental Grounds for YAG:Er Laser Application to Dentistry,” SPIE 1353:160-169, Lasers and Medicine (1989).
Er:YAG lasers, along, with other solid state lasers often employ a polished barrel crystal element such as a polished rod. A laser built with such a polished element maximizes the laser's energy output. Other lasers employ an entirely frosted element, normally with matte of about 50-55 microinch. However, in both cases, the energy output is typically separated into a central output beam surrounded by halo rays, or has an otherwise undesirable mode. Since it is extremely difficult to focus halo rays to a specific spot, the laser output may be unacceptable for specific applications.
Solid state lasers also typically employ two optic elements in connection with the crystal element. The optic elements consist of the rear (high reflectance) mirror and the front partial reflectance mirror, also know as an output coupler. The crystal element and the optic elements are rigidly mounted in order to preserve the alignment between them. However, changes in temperature, such as that caused by expansion of the crystal rod during flash lamp exposure, also cause shifts in alignment between the mirrors and the crystal. The misalignment of the mirrors and the crystal element results in laser output energy loss. Thus, the rigidly mounted elements require constant adjustment and maintenance. Moreover, thermal expansion of the crystal element during lasing can cause the crystal to break while it is rigidly -attached to a surface with different expansion characteristics.
SUMMARY OF THE INVENTION
The present invention primarily employs a laser to perforate, ablate or alter one or more layers of the skin of a patient in order to remove biomolecules, fluids or gases, or to administer pharmaceutical substances. Alteration of a patient's skin is produced by irradiating the surface of the skin by a pulse of electromagnetic energy emitted by a laser. Such irradiation may merely enhance the permeability of the stratum corneum without causing ablation (vaporization) or perforation of tissue; alternatively, it may enhance the skin's permeability by ablating or perforating the stratum corneum, or it may enhance the permeation of molecules by altering such intercellular or intracellular molecules. It is possible to very precisely alter skin or permeability to a selectable extent without causing clinically relevant damage to healthy proximal tissue; the depth and extent of alteration may be accomplished by a judicious selection of
Flock Stephen T.
Marchitto Kevin S.
Astorino Michael C
Irell & Manella LLP
Shaver Kevin
Transmedica International, Inc.
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