Laser perforator.

This application is a continuation-in-part of pending US Serial No. 07 / 968,862, filed October 28, 1992.

Field of the invention

This invention relates to the field of medical equipment, in particular laser medical equipment.

background

The traditional method of collecting small amounts of blood from a patient uses the mechanical perforation of the skin by means of a sharp object such as a metallic lancet or needle. This method has many disadvantages, two of which are the potential infection of healthcare workers or the general public with a device used to perforate the skin and the costly handling and disposal of biohazardous waste.

When skin is perforated with a pointed device such as a metallic lancet or needle, biological waste is produced in the shape of the "tip" which is contaminated with the patient's blood and / or tissue. If the patient is infected with any hematogenous pathogen, such as the AIDS virus (HIV), which causes the autoimmune disease syndrome (AIDS), the hepatitis virus, or the etiological pathogen of other diseases, the contaminated tip can pose a serious threat to those who which could come into contact with this. There are many documented cases of HIV infection from medical workers who happen to be stung by a contaminated tip.

The removal of tips is also a big problem. The disposal of contaminated material charges the end user, such as the medical institution, both a logistical and a financial burden. In the 1980s, numerous cases of improperly disposed biowaste were washed up on public beaches. In addition, the potential for others, such as users of intravenous drugs, to problematically dispose of needles is problematic.

There is another disadvantage of the traditional method of pricking by means of a pointed instrument for the purpose of blood collection. Often, the lancing must be repeated before enough blood has been obtained. This can cause significant stress and anxiety for the patient.

Obviously, the current method of puncturing skin for purposes of blood sampling has significant inherent problems. These problems occur because the method uses a pointed instrument. Therefore, there exists a need for a technique for puncturing skin that does not use a pointed instrument. This method would avoid the need for disposal of contaminated instruments and reduce the risk of cross-infection.

In recent years, lasers have been used as a very efficient and precise tool in various surgical procedures. Among the potentially new sources of laser radiation, the rare earth elements are of great interest to medicine. The most promising of these is a YAG (yttrium aluminum garnet) crystal doped with erbium (Er) ions. By using this crystal, it is possible to construct an erbium-YAG (Er: YAG) laser which can be arranged to emit electromagnetic energy at a wavelength (2.94 μm) which is strongly absorbed by water. When tissue consisting essentially of water is irradiated with radiation at or near that wavelength, it is rapidly heated. When the intensity of the radiation is sufficient, the heating is fast enough to produce vaporization of the tissue. Some medical applications of the Er: YAG laser have been described in the health care disciplines of dentistry, gynecology and ophthalmology. See, for example, B. Bogdasarov, BV, et al., The Effect of YAG: He Laser Radiation on Solid and Soft Tissues, Preprint 266, Institute of General Physics, Moscow, 1987; Bol'shakov, EN et al., "Experimental Grounds for YAG: Er Laser Application to Dentistry", SPIE 1353: 160-169, Lasers and Medicine (1989).

Summary of the invention

This invention uses a laser beam to perforate the skin of a patient. The perforation is created by irradiating the surface of the skin with a focused pulse of electromagnetic energy emitted by a laser. It is possible by means of a judicious choice of the following irradiation parameters to perforate the skin very precisely to a selectable depth without causing clinically relevant damage to healthy adjacent tissue: wavelength, energy flux (determined by dividing the pulse energy by the irradiated area), temporal Pulse width and irradiation spot size.

A device is provided which emits a pulsed laser beam which is focused on a small spot of light for the purpose of perforating tissue. By adjusting the output power of the laser, the depth, width and length of the perforation can be controlled to suit the purpose for which the perforation is needed. This method can be used to create a small, relatively shallow hole in the skin which penetrates into the capillary bed, thereby enabling the withdrawal of blood for various purposes. Optionally, a tissue preheater may be added to increase blood flow prior to laser perforation. Advantageously, safety interrupters are incorporated in the device to avoid hazardous operation and accidental laser irradiation.

This device may be further modified to include a container. Such a container may be added to: (1) increase the efficiency of blood and serum collection; (2) reduce the noise generated while the laser beam perforates the patient's tissue; and (3) to collect the ablated tissue. The container is optionally evacuated to accelerate the collection of blood and serum. In one embodiment, the container collects only removed tissue. The noise generated by the interaction of the laser beam with the patient's skin may potentially trigger anxiety in the patient. The optional container reduces the noise intensity and thus alleviates anxiety and stress in the patient. The container also minimizes the risk of cross-contamination and guarantees the sterility of the collected sample. The placement of the container in the device of the present invention is unique in that it covers the tissue to be punctured during the time of laser beam puncturing and thus can collect the blood sample and / or ablated tissue when puncturing occurs.

This invention also provides a unit for puncturing the skin of a patient in such a manner that no bleeding results. The created perforation typically passes through the keratin layer or through both the keratin layer and the epidermis.

This allows the administration of pharmaceuticals through the skin. There are some advantages to, for example, administering drugs in this way: drugs can be administered continuously over a long period of time on the basis of an outpatient, and the rate and / or efficiency of drug delivery can be increased for drugs that are either slow or unable are to penetrate the skin. In addition, this delivery method provides an alternative delivery route for drugs that would otherwise need to be injected.

This invention avoids the use of tips. The absence of contaminated tips eliminates the risk of accidental injury and the associated risks to the healthcare worker, the patient, and anyone who might come into contact with the top, whether accidentally or by necessity.

The absence of tips thus avoids the need to dispose of biologically hazardous waste. Thus, the invention provides an ecologically sound method of perforating skin.

The device according to the invention requires no special knowledge about its use. It is small, lightweight and can be powered by rechargeable batteries. This portability and ease of use allows the use of this device in a variety of environments, such as hospital rooms, clinics or at home.

The security features incorporated into this device do not require that any special safety eye shield be worn by the device operator, the patient, or anyone else in the vicinity of the device while the device is in operation. This is a significant improvement over prior art laser devices which require such special protection.

Esterowitz et al., "Mid-IR Solid State Laser with Fiber Optics as to Ideal Medical Scalpel", in Proceedings Intern. Conference on Lasers, Las Vegas, 1985, pp. 68-71, describes the use of an Er: YAG laser emitting at 2.94 μm as a medical scalpel for irradiating biological samples. Also described is the use of flexible ZrF 4 fibers to transmit the laser radiation to the biological sample. This device described therein has the features according to the preamble of claim 1.

U.S. Patent 4,710,940 issued December 1, 1984 to Sipes Jr. describes an optically pumped Nd: YAG laser.

European Patent Application A-0 214 712, "Infrared Catheter System", describes mid-infrared laser catheter systems incorporating Er: YAG lasers, and fiber optic systems for generating and transmitting energy to an operating theater for purposes of tissue removal and repair ,

Brief description of the figures

With reference to the attached drawings, the present invention may be better understood and its advantages appreciated by those skilled in the art

Fig. 1 shows a laser device with its power source, high voltage pulse forming network, flash lamp, laser rod, mirror, housing and focusing lens;

Figure 2 shows an optional spring-assisted circuit breaker and an optional heat applicator;

Fig. 3 shows an alternative unit for exciting the laser rod using a diode laser;

Fig. 4 shows an alternative focusing mechanism;

Figure 5A shows optional multiple beam splitters for generating multiple simultaneous perforations, such as partially silvered mirrors, dichroic mirrors, or beam splitting prisms;

Fig. 5B shows an optional acousto-optic modulated high voltage modulator for operating the modulator and deflecting the beam to create multiple simultaneous perforations;

Fig. 6 shows a flap which can be used to sterilize the perforation site;

Fig. 7A shows a tab for sterilizing and / or delivering pharmaceuticals;

Figure 7B shows a tab with an optional laser-transparent material, such as mica, quartz or sapphire, transparent to the laser beam in the center of the tab;

Figure 8 shows an optional container for collecting blood and ablated tissue and reducing noise resulting from the interaction between the laser and the patient's tissue;

Figure 9 shows a plug and stopper perforation center;

Figure 10 shows an optional container for collecting ablated tissue and reducing noise resulting from the interaction between the laser and the patient's tissue; and

Figure 11 shows an optional version of the collection container which is particularly useful when the container includes a reactant for mixing with the sample.

Detailed Description of the Preferred Embodiments

This invention provides a method and apparatus for perforating skin for either the collection of blood or the administration of pharmaceuticals. The device uses a laser beam, in particular focused, and lasing at a suitable wavelength, preferably between 2 μm and 7 μm, to create small holes in the skin of a patient. The laser beam is focused by means of a lens to produce on the skin an irradiated light spot with a size of about 0.1 ... 1 mm in diameter and an energy flux in the range of 10 ... 100,000 J / cm². Optionally, the light spot may be slit-shaped with a width of 0.05 to 0.5 mm and a length of up to 2.5 mm.

contraption

As shown in the figures, the device has a power connection, which is either a standard electrical supply 10 or optionally a rechargeable battery pack 12, optionally with a circuit breaker switch 14 for safety purposes; a high voltage pulse forming network 16; a laser pump cavity 18 including a laser rod 20, preferably Er: YAG; a unit for exciting the laser rod, preferably a flashlamp 22, disposed within the laser pumping cavity; an optical resonator comprising a high-reflectance mirror 24 positioned behind the laser rod and an outcoupling mirror 26 positioned in front of the laser rod; a transmission focusing lens 28 positioned beyond the outcoupling mirror; optionally, a second focusing cylindrical lens 27 positioned between the outcoupling mirror and the transmission focusing lens; an applicator 30 for positioning the skin to be examined at the focal point of the laser beam, which may optionally be heated, for example, by means of a thermoelectric heater 32 mounted on the laser housing 34; a circuit breaker 36 positioned between the applicator and the power supply; and optionally, a jet absorber 38 attached to the applicator with a fingerprint access port 40.

Figs. 1 and 2 are diagrammatic representations of a preferred embodiment of the device according to the invention. The device preferably draws power from a 110V or 220V standard power line 10 (a single phase, 50 or 60 Hz) which is rectified and used to charge a capacitor bank contained within the high voltage pulse forming network 16. Optionally, a rechargeable battery pack 12 may be used instead. The capacitor bank generates a DC high voltage applied to a high power flash lamp 22. Optionally, a circuit breaker 14, such as a key switch, may be provided which avoids accidental charging of the capacitors and thus accidental laser excitation. An additional interrupter may be added to the device at the applicator, such as a spring assisted circuit breaker 36, such that discharging the capacitors requires enabling both interrupters.

By depressing a switch, a voltage pulse may be superimposed on the voltage already applied to the flash lamp to cause the flash lamp to fire and, as a consequence, to initiate the flash of light. The light of the flashlamp is located in the laser cavity 18, which has a shape such that most of the light is efficiently directed to the laser rod 20 which absorbs the light and subsequently to deenergize. The laser cavity mirrors with low 26 and high 24 reflectivity, which are positioned collinear with the longitudinal axis of the laser rod, serve to amplify and align the laser beam.

Optionally, as shown in Figure 3, a diode laser 42 which generates a pump beam collinear with the laser axis's longitudinal axis may be used in place of the flash lamp to excite the crystal. The pump beam of this laser is collimated with a collimator lens 44 and transmitted through the high-reflectance infrared mirror 45 to the primary laser rod. This highly reflective mirror allows the transmission of the diode-pumped laser beam while reflecting infrared light from the primary laser.

The Er: YAG lasing material is the preferred material for the laser rod since the wavelength of the electromagnetic energy emitted by this laser is 2.94 μm, very close to the maximum absorption wavelength (about 3 μm) of water , Consequently, this wavelength is very strongly absorbed by water. The rapid heating of water causes perforation of the skin.

Another useful lasing material is any material which, when excited to emit, emits a wavelength which is strongly absorbed by the tissue, such as by absorption of water, nucleic acids or proteins, and thus causes the necessary perforation of the skin. A laser can effectively cut tissue to create the desired perforations where the tissue exhibits an absorption coefficient of 10 ... 10,000 cm-1. Examples of useful lasing elements are pulsed CO 2 lasers, Ho: YAG (Holmium: YAG), Er: YAP, Er / Cr: YSGG (erbium / chromium: yttrium scandium gallium garnet; 2.796 μm), Ho: YSGG (Holmium: YSGG, 2.088 μm), Er: GGSG (erbium: gadolinium gallium scandium garnet), Er: YLF (erbium: yttrium lithium fluoride, 2.8 μm), Tm: YAG (thulium: YAG; 2.01 μm), Ho: YAG (Holmium: YAG, 2.127 μm), Ho / Nd: YAlO & sub3; (Holmium / Neodymium: yttrium aluminate: 2.85-2.92 μm), cobalt: MgF & sub2; (Cobalt: magnesium fluoride, 1.75 ... 2.5 μm), HF chemical (hydrogen fluoride, 2.6 to 3 μm), DF chemical (deuterium fluoride, 3.6 to 4 μm), carbon monoxide (5 to 6 μm), deep ultraviolet laser and Frequency-tripled Nd: YAG (Neodymium: YAG, where the laser beam passes through crystals causing a trebling of the frequency).

Using current technology, some of these laser materials provide the added benefit of a small size, making the laser perforator easy and portable. In addition to Er: YAG, Ho: YAG lasers offer this advantage.

The emitted laser beam is down-focused by using the focusing lens 28 to a spot size of one millimeter or less than one millimeter. The consideration of laser safety conditions suggests that a short focus focusing lens be used to ensure that the energy flow rate (W / cm²) is low except at the focal point of the lens where the tissue sample to be perforated is positioned. Consequently, the danger of the laser beam is minimized.

The beam may be focused using a cylindrical focusing lens 27 such that it is narrower along one axis than along the other, thereby creating a slot-shaped perforation. This lens, which focuses the beam along an axis, is placed in series with the transmission focusing lens 28. If the perforations are slit-shaped, the pain associated with the perforation is considerably reduced.

Optionally, the beam may be broadened prior to focusing by the focusing lens 28, for example by using a concave diverging lens 46 (see Fig. 4). This broadening of the beam results in a laser beam with a correspondingly lower energy flow rate a short distance behind the focal point, thus reducing the hazard level. Further, this optical arrangement reduces the optical aberrations in the laser light spot at the treatment position, resulting in a much more precise perforation.

Optionally, the beam can also be divided by means of beam splitters for generating a plurality of beams which can perforate at different locations simultaneously or almost simultaneously. Fig. 5 provides two variations of useful beam splitters. In one version, multiple beam splitters 48, such as partially silvered mirrors, dichroic mirrors, or beam splitting prisms, may be provided after the beam has been focused. Alternatively, a modulated high voltage acousto-optic modulator 52 may be used to drive the modulator 52 and deflect the beam. This modulator is located outside the laser cavity. It works by sequentially and quickly deflecting the laser beam to different angles to simulate the production of multiple beams.

A small heating element, such as a thermoelectric heating element 32, is optionally located at the end of the laser applicator near the location of the perforation. The heating element raises the temperature of the skin and the capillaries in the tissue to be perforated before the laser irradiation. This increases blood flow, thereby increasing the volume of blood to be collected when the device is used for this purpose. A suggested range for skin temperature is between 36 ° C and 45 ° C, although any other temperature is suitable which causes vasodilation and the consequent increase in blood flow without altering blood chemistry.

A container 68 is optionally fitted in the laser housing and is positioned proximate to the perforation site.

The container reduces the intensity of the noise generated when the laser beam perforates the patient's tissue, increases blood collection efficiency, and collects the removed tissue. The container is shaped to allow easy insertion into the laser housing and to provide a friction fit within the laser housing. Fig. 8 shows the inserted into the laser housing and arranged above the perforation container.

The shape and size of the container are such as to allow insertion into the applicator and to allow the collection of the blood sample and / or the removed tissue. Preferably, the container is spherical with a volume of approximately 1.5 ml.

In the preferred embodiment, the container is made of glass or plastic. In one embodiment, the container is evacuated. The optional vacuum in the container creates a negative pressure above the perforation site, thereby increasing blood collection efficiency. The container is optionally coated with anti-coagulant and / or preservative chemicals. Examples of preservatives include ethylenediaminetetraacetic acid (EDTA) or sodium benzoate. Examples of anticoagulant chemicals are sodium heparin and sodium citrate.

The closest to the perforation point end of the container is optionally sealed airtight with a plug 70. The plug is made of a material with suitable flexibility so that it adapts to the contours of the perforation (for example, the finger). The desired perforation is pressed firmly against the plug. The plug material is impermeable to gas flow. Furthermore, the plug material is thin enough to permit the perforation of both the material and the skin by the laser. In the preferred embodiment, the plug is made of rubber.

The plug perforation center 74 as shown in Fig. 9 is preferably made of a thin rubber material. The thickness of the stopper is such that the stopper can maintain the vacuum prior to perforation and the laser can perforate both the stopper and the tissue adjacent the stopper. For use with an Er: YAG laser, the plug should be in the range of about 100 ... 500 μm thick, but not more than 1 mm thick.

The plug perforation center 74 is large enough to cover the perforation site. Optionally, the perforation site is a round hole with an approximate diameter of 0.1 ... 1 mm or slot-shaped with an approximate width of 0.05 ... 0.5 mm and an approximate length of up to 2.5 mm. Thus, the plug perforation center is sufficiently large to cover the perforation sites of these sizes.

The perforation is pressed firmly against the rubber material. Optionally, a circular ring of adhesive may be applied to the rubber plug to provide an airtight seal between the perforation site and the container. Preferably, the perforation site on the stopper is stretched as the tissue is pressed against the stopper. This stretching of the plug material causes the hole created in the plug to be enlarged beyond the size of the hole created in the fabric. As a result, the blood and / or serum may flow unhindered into the reservoir 68.

The container 68 includes a window 72 made of an infrared transparent material and positioned in the beam path of the laser beam, at the end of the container closest to the beam. The laser beam passes through the window through the container, perforates the plug perforation center 74, and perforates the patient's tissue. In the preferred embodiment, the infrared transparent material is quartz, but other examples of suitable infrared material include rock salt, germanium, and polyethylene.

In a second embodiment of the container, as shown in Fig. 10, the container 68 includes a hole 76 through which the laser passes. In this second embodiment, the container collects only removed tissue. As in the first embodiment, the perforation site is pressed firmly against the container. The container may optionally include a plug closest to the perforation site, but this is not essential since a vacuum need not be maintained in the second embodiment. Both embodiments of the container reduce the noise generated due to the interaction between the laser beam and the tissue of the patient and thus alleviate patient anxiety and stress.

Optionally, the container is a disposable item so that the container and stopper can be thrown away after use. In addition, the container may contain reagents for different tests to be performed on the collected blood. Examples of such reagents are sodium heparin and other reagents known in the art for use in standard chemical blood tests. For example, see D. Garza et al. Phlebotomy Handbook (3rd Edition), Appleton and Lang Pub. Co., Norwalk, CT, 1993, which is hereby incorporated by reference. The reagents are positioned so that they are not in the beam path of the laser light. The reagents are preferably in dry form, coating the inner walls of the container and thus are readily available for interaction with the blood sample as it has been collected. A preferred embodiment for the container is when it contains a reagent shown in Fig. 11. In this embodiment, the container has a notch 78 at the base such that any liquid reagent present in the container does not fall into the beam path of the laser beam when the container is held either vertically or horizontally. The vertex of the notched portion is made of infrared transparent substance such as quartz.

If reagents are contained in the container before the blood sample is collected, it is advantageous to characterize the container in some way as to which reagents are contained in the container or as to what test to run on the sample using these reagents , A preferred method for such labeling is by using color-coded stoppers. For example, a blue plug may indicate the existence of a reagent A, whereas a red plug may indicate the presence of reagents B plus C within the container.

To sterilize the skin prior to perforation, a sterile alcohol-impregnated rag or paper or other thin material may optionally be placed over the site to be perforated. This material may also prevent the escape of potentially infected tissue in the plume of vapor released by the perforation. The material must be permeable to the laser beam. Examples of such materials are a thin layer of quartz, mica or sapphire. Alternatively, a thin layer of plastic such as a layer of polyvinyl chloride may be placed over the skin. Although the laser beam will perforate the plastic, the plastic prevents most of the detachments from flying away, thus reducing any potential risk of contamination from infected tissue. In addition, a layer of a viscous sterile substance, such as petroleum jelly, the permeable material, or the plastic layer may be added to increase the adhesion of the material or plastic to the skin, and further reduce contamination of the vapor plume. Additionally, such a patch may be used to deliver allergens, local anesthetics, or other pharmaceuticals, as described below.

Examples of such a tab are provided in FIGS. 6 and 7. In Fig. 6, an alcohol-impregnated paper 54 is surrounded by a temporarily adhesive strip 58. Side views of two alternative flaps are shown in Figs. 7a and 7b, in which sterilizing alcohol, antibiotic ointment, allergen or a pharmaceutical is present in the central region of the flap 60. This material is held in place by means of a paper or plastic layer 62, optionally with a laser-transmissive material 64 (shown in Fig. 7b), such as mica, quartz or sapphire, which is transparent to the laser beam in the center of the lobe. The flap may be placed on the skin using an adhesive 66.

Factors to consider when defining the laser beam are wavelength, energy flux, temporal pulse width, and beam spot size. The wavelength is determined by the laser material, such as Er: YAG, used in the device. The temporal pulse width is a consequence of the width of the pulse generated by the capacitor bank, the flash lamp and the laser rod material. The pulse width is optimally between 1 μs and 1000 μs. The laser beam is focused exactly on the skin, producing a slit-shaped focal point with a width of 0.05 ... 0.5 mm and a length of up to 2.5 mm or an ellipsoidal focal point of 0.2 ... 0, 3 mm by 1 ... 2 mm. The energy density, which is a function of the laser output energy (in joules) and the size of the beam at the focal point (cm²), should be in the range of 10 ... 100,000 J / cm². The focal length of the lens may be arbitrarily large, but in one embodiment of the device is 30 mm. The energy flow rate is preferably in a range of 1.3 x 10 & sup4; ... 6.4 · 10¹ & sup0; W / cm 2, and at the same time, the energy flow rate is preferably in the range of 1.3 × 10 11 to 6.4 × 10 7. W / cm².

The device operates as follows: The circuit breaker is initiated, thus starting the charging of the capacitors. The device is manipulated in a manner that positions a portion of the patient's skin at the location of the laser focus within the applicator. For collecting blood, the perforation site is optimal at a position where the blood flow is high. Examples of such areas of the skin are on a fingertip, or the heel of a foot. For the perforation for delivery of anesthetics or pharmaceuticals or for immunization, a region of the skin which has less contact with hard objects or with contamination sources is preferred. Examples are the skin on the arm, leg, abdomen or back. Optionally, the skin heating element is activated at this time.

Preferably, a holding element is provided with a hole which coincides with the focal plane of the optical system. Optionally, a spring assisted circuit breaker 36 may be attached to the support member such that in the event that the patient exerts a small amount of pressure on the circuit breaker, it is led down to the focal point, a switch is closed and the laser initiates a radiation pulse. In this structure, the focal point of the beam is not in line with the end of the holding member as long as this end is depressed. In the extremely unlikely event of parasitic discharge of the laser prior to proper positioning of the tissue at the end of the laser applicator, this situation results in an energy flow rate which is significantly low in the optical arrangement, thus causing a negligible effect on unwanted targets.

For certain purposes it is useful to create a variety of perforations on the skin simultaneously or in rapid succession. To achieve this, a beam splitter can optionally be added to the device.

Collection of blood or serum

The device can be used to perforate the skin to the capillary layer to allow the collection of blood. The blood can be used for a large number of different tests, such as for determining blood chemistry (blood sugar, CBC, urea, electrolytes, creatinine, cholesterol, etc.) and / or it can be broken down into its components, such as serum and Cells for a variety of purposes, such as determining the number of red blood cells. The blood may also be used for purposes such as genetic analysis for genetic counseling.

With the other parameter setting, the intensity of the laser pump source determines the intensity of the laser pulse, which in turn determines the depth of the resulting perforation. Therefore, different settings of the device may be provided to allow penetration of different skin thicknesses.

As described above, the skin may be preheated to dilate the capillaries and increase blood flow prior to perforation. The increased blood flow allows the collection of increased blood volume and avoids the need for a variety of perforations. Preheating may be accomplished by adding a preheat element as described above or by other means for preheating the skin before positioning it on the laser applicator portion of the device.

Optionally, a beam absorber is positioned in such a way that the use of the laser to puncture fingertips is not hindered. The beam absorber absorbs any scattering of electromagnetic radiation of the beam that is not absorbed by the tissue, thereby preventing any stray radiation from causing damage. The beam absorber is easily removable for situations in which the presence of the beam absorber would hinder the placement of a body part on the applicator.

This blood collection procedure creates a very small zone where tissue is vaporized and only an extremely small zone of thermal necrosis. A substantially round hole may have a diameter in a range of 0.1... 1 mm, whereas a slot-shaped hole has a width in a range of about 0.05... 0.5 mm and a length of up to about 2.5 mm can have. As a result, healing is faster or as fast as healing after skin puncture with a sharp instrument.

The blood may be collected in a suitable vessel, such as a small test tube or capillary tube, or in a container placed between the laser and the tissue as described above. The laser of this invention is particularly suitable for collecting blood because it does not allow the blood to clot after penetration of the skin. Furthermore, the method is non-contacting and thus neither the patient, the blood to be sampled nor the instrument performing the perforation are contaminated.

Supplying pharmaceuticals

By means of a suitable modification of the energy level and / or the spot size of the laser beam, perforations can be produced which do not penetrate the skin as deeply as described above. These perforations can only be made through the upper surfaces, such as the keratin layer or both the keratin layer and the epidermis. Optionally, an optical beam splitter may be used so that either single perforations or a number of perforations may be made within a desired range. After perforation, the pharmaceuticals may be delivered to the skin in the form of a cream, lotion or rag.

immunization

As with delivery of the pharmaceuticals, antigens can be administered through the skin for immunization purposes. The perforations are made either alone or in a plurality through the outer layers of the skin and the immunogen is provided in a suitable form. For booster immunizations, where the delivery over a period of time increases the immune response, the immunogen may be provided in a form which penetrates the perforations slowly, but at a rate greater than that afforded by unperforated skin.

Feeding anesthetics

Localized anesthetics may be delivered using the method and apparatus of the invention. Locally applied anesthetics must penetrate the keratin layer to work. Currently, compounds acting as drug carriers are used to facilitate the transdermal diffusion of some drugs. These carriers sometimes alter the behavior of the drugs or are themselves toxic. The energy level of the device can be suitably adjusted so that the keratin layer is penetrated without penetrating the capillary layer. Anesthetics can then be delivered to the perforations, for example in a rag impregnated with an ointment.

Feeding allergens

This apparatus and method may also be applied to the delivery of allergens, for example for an allergy test. A variety of perforations can be realized which, although permeating the outer skin layer, do not penetrate the capillary layer. A variety of different allergens can then be delivered to the skin, as in a patch-skin test.

The following examples are descriptions of the use of the device of this invention for the purpose of blood sampling. These examples are not to be considered as limiting the scope of the invention and are merely an embodiment.

example 1

An infrared laser beam pulse was formed using a pulsed multimode solid state Er: YAG laser consisting of two flat resonator mirrors, an Er: YAG crystal as an active medium, a power supply and a means for focusing the laser beam. The wavelength of the laser beam was 2.94 μm. The duration of the pulse was about 100 ms. The elliptical spot size was about 0.2 ... 0.3 mm by 1 ... 2 mm. The pulse energy used was 0.7 J, 0.9 J or 2.0 J for each thin to thick skin. Single pulses were used, but in one test, 6 pulses per minute were used, each irradiating a separate piece of tissue.

The operating parameters were as follows: The energy per pulse was 2 J, the size of the beam at the focal point being 0.2 mm, thus producing an energy flux of 10 3 J / cm 2. The temporal pulse width was 100 μsec, thus providing an energy flow rate of 1 x 10 & sup7; W / cm² was generated.

Each finger of the patient was treated with 96% ethyl alcohol prior to perforation to remove bacteria. The finger was placed at the focal point of the laser and the laser was discharged. The blood was removed from the perforation with a glass capillary tube. The volume of the withdrawn blood (without squeezing the finger) varied from 0.5 ... 1.0 ml. This blood did not differ in chemical composition from comparable samples obtained by lancing puncture during control tests. The pain induced by the laser perforation was estimated to be about equal to or less than the pain caused by puncture of a lancet.

Morphological analysis of the effect of laser perforation on the skin tissue revealed a minimal range of thermal destruction (less than 20 ... 40 μm beyond the edge of the perforation produced) without any sign of charring. The wounds were conically shaped. It was found that the depth and width of the wounds were proportional to the energy flux and approximately related to the inverse of the duration of the laser pulse.

Example 2

The laser perforator includes a flash lamp (PSC Lamps, Webster, NY), an Er: YAG crystal (Union Carbide Crystal Products, Washagoul, WA), optical resonator mirrors (CVI Laser Corp., Albuquerque, NM), an infrared transmissive lens (Esco Products Inc., Oak Ridge, NJ), as well as a number of standard electrical components such as capacitors, resistors, inductors, transistors, diodes, silicon controlled rectifiers, fuses and switches, which can be obtained from any distribution company for distribution of electrical components, such as Newark Electronics, Little Rock, AR.

Example 3

An infrared laser beam pulse was formed using a pulsed multimode solid-state Er: YAG laser consisting of two flat resonator mirrors, an Er: YAG crystal as an active medium, a power supply and a means for focusing the laser beam. The wavelength of the laser beam was 2.94 μm. The duration of the pulse was about 100 ms. The elliptical spot size was about 0.2 ... 0.3 mm by 1 ... 2 mm. The pulse energy used was 0.7 J, 0.9 J or 2.0 J each for thin to thick skin. Single pulses were used, but in one test, 6 pulses per minute were used, each irradiating a separate piece of tissue.

The operating parameters were as follows: the energy per pulse was 2.0 J, the size of the laser beam at the focal point being 0.2 mm by 1 mm, producing an energy flux of 10 3 J / cm 2. The temporal pulse width was 100 μsec, thus providing an energy flow rate of 1 x 10 & sup7; W / cm² was generated.

Each finger of the patient was treated with 96% ethyl alcohol prior to perforation to remove bacteria. The finger was placed at the focal point of the laser and the laser was discharged. The blood was removed from the perforation with a glass capillary tube. The volume of blood drawn (without squeezing the finger) varied from 0.5 to 1.0 ml. This blood did not differ in its chemical composition from comparable samples obtained by lancet puncture during control tests. The pain induced by the laser perforation was estimated to be approximately equal to the pain caused by the puncture of a lancet.

Morphological analysis of the effect of laser perforation on the skin tissue revealed a minimal range of thermal destruction (less than 20 ... 40 μm beyond the edge of the perforation produced) without any sign of charring. The wounds were slit-shaped. It was found that the depth and width of the wounds were proportional to the energy flux and that they were approximately related to the inverse of the duration of the laser pulse.

Example 4

The perforation is performed as in Example 1 or 3 except that the device is modified to include a blood collection tube tightly fitted between the leading end of the laser device and the focal point of the laser through which the laser beam passes is. The tube is 2.0 cm long and has a diameter of 1.0 cm, has a notch in the bottom which pushes the bottom 1.0 cm into the center of the tube. As a result, no liquid or crystallized additive, such as the sodium heparin anticoagulant, will fall into the beam path of the laser beam when the tube is held either vertically or horizontally. The apex of the notched portion is made of a quartz disk permeable to the laser beam.

The far end of the tube is covered with a rubber stopper. The plug is externally coated with an adhesive to effect adhesion of the plug to the skin to be perforated. In the tube itself, an internal vacuum is maintained before the perforation. The tube is also internally coated with sodium heparin to act as an anticoagulant to form a blood count on the resulting sample.

Subsequently, the laser is ignited, whereby the laser beam is passed through the tube and only the distal end (the plug) of the tube and the skin are perforated. A blood sample of approximately 1 cc then flows into the tube and mixes with the sodium heparin. The entire blood sample and any exploded / ablated tissue is thus captured within the tube, thus preventing contamination and the spread of disease.

While embodiments and applications of this invention have been shown and described, it would be obvious to those skilled in the art that many more variations are possible without departing from the inventive concept as defined in the appended claims.