Abstract:
A self-contained, sterilizable, compact light which does not include external wiring or power accessories is described herein. The lighting device is particularly useful in specialized lighting applications such as surgical applications. The lighting device preferably includes an LED and power source within a casing and can be attached in positions or on instruments within the surgical field. Alternately, the LED may be located on a suction tip while the power source and other electronics are located proximally on a handle of a suction device.

Description:
[0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 62/275,336, entitled “Lighting Device,” filed on Jan. 6, 2016, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    This disclosure pertains to compact, sterilizable, and easily positioned lighting devices having particular use in surgical applications. 
         [0003]    Sterile fields are of paramount importance to surgical operating rooms as post-surgical infections can be catastrophic to those affected. Breaks in sterile technique or field are not uncommon and can lead to changes/delays in surgery or postoperative infections. 
         [0004]    One issue that increases the risk of a break in sterile technique is wiring and tubing that passes onto and off of the surgical field. Examples include electrocautery, suction, arthroscopy lighting, suction, and similar items. 
         [0005]    Another common issue in the operating room is visualization of the operative field in a deep hole such as a hip, pelvis or abdomen. Typical overhead lights are employed in the operating room (OR), but sometimes there is a very limited window for visualization of the desired subject, or the surgeon&#39;s head will block the light while in the path to visualize the appropriate part of the wound. In this case an additional light can be placed on the surgeon&#39;s head (such as a headlight) but these can be heavy and cumbersome, and they do not always stay in place, leading to potential breaks as the light is adjusted. This can create visualization problems for both surgeon and assistants. Another way that increased illumination and lighting can be brought to the surgical field is through lighted retractors, or instruments with fiber optic cables that bring light through a cable from off the sterile field. This, however, leads back to the initial problem of increased risk for break in sterile field by having more tubing/wiring coming from nonsterile environment. 
       SUMMARY 
       [0006]    The present disclosure relates generally to an enclosed lighting source that can be easily mounted and removed in specialized applications such as surgical applications. The lighting device can be sterilized prior to use and can include a separate clip device for securing and positioning the lighting device. 
         [0007]    The present lighting device is designed to solve problems associated with lighting in surgical and other specialized applications. It is a free standing light source that is sterilized and can be opened directly onto the operative field. It has no wiring and is disposable. In a preferred embodiment it includes a light-emitting diode (LED) in a plastic casing that is sterilized, such as by gamma radiation, and can be attached to any retractor if desired, or can be placed directly into the wound and secured with a suture. It is locatable by x-ray so it will not be left within the surgical wound. In alternative embodiments, the light source may be attached to or held in place by a disposable suction tip such as a Yankauer suction tip. 
         [0008]    Generally speaking the lighting device includes an LED and associated electronics, such as a circuit board, power source, and heat sink, enclosed within a casing. The casing is preferably circular and plastic and may include holes or slots to facilitate attachment. In certain embodiments, a clip device accompanies the lighting device. The clip device may include a clip portion that can be attached to an item close to the area needing illumination, such as a surgical retractor, and may also include clip latches to hold the lighting device, and a front casing that will secure the lighting device within the clip. 
         [0009]    In alternative embodiments, the LED may be placed or held at a location that is removed from the electronics and circuitry. For example, the LED could be located at the end of a suction tip while the electronics and circuitry are located in the handle of the suction device. The modified suction tip could be hollow and attach to standard OR hosing for suction, with an LED built into the distal casing for lighting and illumination with all electronics and power sources located proximally in the handle portion of the device. The proximal area is also where the switch for turning the light source on and off would preferably be located. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows (A) a side view of an example of a lighting device and (B) a front view of an example of a lighting device. 
           [0011]      FIG. 2  shows (A) a side view of an example of a clip device including two separate portions and (B) a side view of an example of a clip device in which an example of a lighting device has been secured and in which the portions of the clip device have been engaged and connected. 
           [0012]      FIG. 3  shows a front view of a clip device in which an example of a lighting device has been secured. 
           [0013]      FIG. 4  shows a bottom view of a battery holder of an example of a lighting device and a bottom view of a LED casing in which the battery holder would be screwed into as part of the example lighting device. 
           [0014]      FIG. 5  shows an example circuit board found in an example of a lighting device. 
           [0015]      FIG. 6  shows (A) a top view of an example of a lighting device, with three LEDs visible through the surface of the casing, attached to or clipped onto a retractor with a clip attached to the bottom of the device and (B) a side view of an example lighting device and attached clip attached to or clipped onto a retractor. 
           [0016]      FIG. 7A  shows temperature of a chicken breast over time with an example of the lighting device placed 60 mm away from the chicken breast. 
           [0017]      FIG. 7B  shows temperature of a chicken breast over time with an example of the lighting device placed 30 mm away from the chicken breast. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0018]    The present disclosure relates to a lighting device for use in specialized applications, such as surgical applications, and a clip device that can be used therewith. 
         [0019]      FIG. 1A  shows a side view of an embodiment of the lighting device  10 . Casing  11  surrounds the internal light source and electronics and is preferably plastic and sterilizable. Casing  11  should be clear or translucent to allow light to pass, or in alternative embodiments will have slots or spaces to allow light from the LED to pass. Inside casing  11  is found a central mounting surface  12  on which other components may be mounted. In particular, in this example, LED  13  is mounted on central mounting surface  12 . LED  13  may be a single LED or multiple LEDs that provide the illumination or lighting. Reflectors  14  may help to direct the light from LED  13  out of the device in a forward direction, allowing for directed illumination of the field. The direction of illumination is shown in  FIG. 1A . Circuit board  15  is also mounted on central mounting surface  12  in proximity to LED  13  and is used to control LED  13 . Power source  16  used to provide power to LED  13  is also mounted on central mounting surface  12 . Heat sink  17  is also provided as a heat sink for LED  13  and, if applicable, any additional electronics. An example of a preferred power source is a battery, although additional sources of power and heat sink options may be used. One or more mounting holes  18  are also included in casing  11  to allow for attachment to a mounting device or to allow passage of a suture for direct mounting in or on a surgical field. Preferably these mounting holes pass through the body of the lighting device  10  but are surrounded by casing  11  so that the interior of casing  11  remains protected.  FIG. 1B  shows a front view of an embodiment of lighting device  10 . Again, casing  11  surrounds LED  13  and circuit board  15 . 
         [0020]    Some embodiments of the lighting device also include a clip device  20 , as shown in a side view in  FIG. 2A . Clip device  20  is made up of two separate portions—clip portion  28  and attachment portion  29 . Clip portion  28  includes clip  21  which allows for mounting of lighting device  10  to a variety of places, including most standard retractors used in an operating room (OR). On a portion of clip  21  is located one or more clip latches  23  that will allow lighting device  10  to be anchored within and secured to clip device  20 . In the embodiment seen in  FIG. 2A , clip  21  is bent, with clip latches  23  secured to a front clip portion  27 . Within attachment portion  29  is front casing  22  and inner contour  25 . Inner contour  25  is shaped to fit around lighting device  10  when it is placed within clip device  20  to hold it in a steady position. Lighting space  26  illustrates the preferred placement of lighting device  10 . Front casing  22  provides additional protection for lighting device  10 . Both inner contour  25  and front casing  22  should be clear or translucent to allow light to pass and are preferably made of plastic. Attachment portion  29  also includes one or more attachment latches  24  which engage clip latches  23  on clip portion  28  in order to secure attachment portion  29  to clip portion  28 , preferably with lighting device  10  located at lighting space  26 . This is also shown in  FIG. 2B , in which attachment latches  24  have moved past clip latches  23  and lighting device  10  is held in place by inner contour  25 . Front casing  22  is in the general direction of illumination provided by lighting device  10  and protects lighting device  10  while in use. Clip  21  allows mounting of clip device  20  and lighting device  10 , with clip space  37  providing an area where clip device  20  could be attached or clamped to a standard operative retractor, for example. 
         [0021]      FIG. 3  shows a front view of an embodiment of a lighting device  30  having a back clip portion  31  that will be utilized to affix lighting device  30  to an ideal mounting surface. In some embodiments, back clip portion  31  will reside posterior to a surgical retractor when secured to it. Front clip portion  32  of the lighting device  30  will face towards the surgical field, in the direction of illumination. Located on front clip portion  32  is a lighting element  35  that may have similar components as seen in  FIGS. 1A and 1B , including casing  36 , LED  37 , and circuit board  38 . Casing  33  helps secure lighting element  35  to the front portion  32  of the lighting device  30 . Locking clasps  34  can be used to secure casing  33  to front portion  32 . Casing  33  is preferably plastic and preferably clear or translucent, or in alternative embodiments the casing may have slots or spaces for permitting the light from the LED to pass through. 
         [0022]    In preferred embodiments, the light source is an LED or at least two LEDs that are a few millimeters in cross sectional diameter. The LEDs are powered by a battery and have required circuitry to maintain their function. There is a switch or button to turn on the illumination. The light source is attached to a clip that will secure onto a standard operative retractor, or will be imbedded within a disposable suction tip such as a Yankauer suction tip (already in common use) that will be modified in production to house the required LEDs and supporting electronics. The whole construct could be sterilized in a manner similar to other disposable instruments used within the operative theater such as arthroscopic or laparoscopic disposables such as shavers, endo loops, and similar instruments. The circuitry and electronics required for the light source, including the power source and the heat sink, may be modified according to need, so long as the light source remains compact, able to be securely positioned, and sterlizable or disposable. 
       EXAMPLE 1 
       [0023]    A preferred embodiment of the lighting device was investigated. Many deep cavity surgeries require retractors to hold open the operative field to reveal the targeted area. This embodiment of the lighting device uses a circular casing attached to a square clip that can be placed onto a retractor. Using a retractor as an anchor, rather than the patient&#39;s tissue, provides more certainty to the way it will be used, including a greater stability and a lower chance of damaging tissue. With few moving parts, the clip is also conceptually simple and sturdier. 
         [0024]    The circular casing in this example was slightly greater than the size of a quarter. It housed a lithium-ion battery, three LEDs, and a printed circuit board (PCB). Each LED was about half the size of a pencil eraser and produces natural white light. The device was turned on and off by rotating the casing around the clip. This movement was possible by introducing screw threads to the inside lining of the casing. The entire casing of the prototype and the clip was made by 3D printing. 
         [0025]    The main goal of this example was to establish feasibility to create a product solution for surgical lighting. The device must meet four essential feasibility criteria in order to achieve a minimal standard: non-obtrusive, cost-effective, sterilizable, and thermally benign. The device size must be small as to not obstruct to the physician during surgery. The cost of the device must be low to be disposed after a single use to minimize infection risks and eliminate the need for re-sterilization. Finally, the device must withstand the sterilization process and must be thermally benign as to not cause harm to the patient. Other needs that should be considered when designing a new surgical lighting device include: sufficiently illuminant, a fully self-contained system with all components in one unit, ease of setting up and using, versatile for different surgeries, adjustable from a fixed location, and adjustable from the operative field. Thus we can say that there exists a need for a supplemental surgical lighting option that is cost effective, independently portable, and minimally obtrusive, that accurately lights the field, which can be easily adjusted within operative field. 
         [0026]    Surgical lighting must provide accurate color so that surgeons have the visual acuity to accurately assess tissue oxygenation. If surgical lighting has too much of a blue hue, the tissue can falsely appear to be hypoxic. Parameters that affect the coloration of the LEDs from the surgical lighting device include the color rending index (CRI), and color correlated temperature (CCT). CRI is a measure of how well the light source renders the color of the object relative to a 3 reference light on a unitless scale of one to 100.7 CCT is a measure of the “warmth” or “coolness” of the light source color appearance. As CCT values decrease, red hues become more visible, i.e. the color temperature becomes “warmer”. Conversely, as CCT values increase, blue hues become more visible, i.e. the color temperature becomes “cooler”. Guidelines for these parameters are from the Department of Energy (DOE) and the International Electrotechnical Commission (IEC). The values given for CRI and CCT on the specification table are the average values found for the standard overhead lighting shown in Table 1 below. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Feature 
                 Value 
                 Unit 
               
               
                   
               
             
             
               
                 Color rendering index (CRI or R a ) 
                 85-100 
                 (unitless) 
               
               
                 Color correlated temperature (CCT) 
                 2700-6500; neutral 
                 degrees K 
               
               
                   
                 standard is 
               
               
                   
                 approximately 4000 
               
               
                 Efficacy 
                 no less than 16.7 
                 lumens/Watt 
               
               
                 Central illuminance (Ec) 
                 40,000-160,000; 
                 lux (at 1 m 
               
               
                   
                 standard is 
                 from the 
               
               
                   
                 approximately 
                 light 
               
               
                   
                 64,500 
                 emitting 
               
               
                   
                   
                 surface in 
               
               
                   
                   
                 the light 
               
               
                   
                   
                 field center) 
               
               
                 Beam uniformity characteristic 
                  0.5 
                 (unitless) 
               
               
                 Depth of illumination 
                 no less than 20 
                 cm 
               
               
                 Rated useful lifetime (hours 
                 no less than 3 
                 hours 
               
               
                 of operation at greater than 80 
               
               
                 percent of initial light output) 
               
               
                 Average cost of device &amp; 
                 no greater than 200 
                 USD 
               
               
                 maintenance 
               
               
                 Maximum tissue temperature (in 
                 43 
                 ° C. 
               
               
                 terms of device heat generation) 
               
               
                   
               
             
          
         
       
     
         [0027]    In addition to accurate coloring, the surgical light must meet specific requirements for the characteristics of the light itself including: efficacy, central illuminance (Ec), beam uniformity characteristic, and depth of illumination. Efficacy is the lumens of light produced per watt of input power. Central illuminance is defined as the illuminance at 1 m distance from the light source in the light field center. Beam uniformity characteristic is the ratio of the light field diameters d50 and d10, where the edge of the light field is defined where the illuminance is 50% and 10% Ec, respectively. The greater the value the of the beam uniformity characteristic, the sharper the edge of the lighted field. 
         [0028]    Depth of illumination is the distance between the point of maximum illumination intensity and the point of 60% illumination intensity. The values given for efficacy, central illuminance, and beam uniformity on the specification table (Table 1) are the average values found for the standard overhead lighting. Depth of illumination is estimated for an in-body placement lighting device. Guidelines for these parameters are also from the Department of Energy (DOE) and the International Electrotechnical Commission (IEC). 
         [0029]    Shown in  FIG. 4 , this example of the lighting device  40  consists of three surface-mounted LEDs (not shown), one lithium-ion coin cell battery (not shown), a circuit board (shown in  FIG. 5 ), an anchoring clip (shown in  FIGS. 6A and 6B ), and first portion of casing for the battery  41  and a second portion of casing for the LED  43 .  FIG. 4  shows the CR2032 battery holder casing  41  with a triangular thread profile  42 .  FIG. 4  also shows a bottom view of the LED casing  43  to which the battery holder would be connected or screwed into, also with a receiving triangular thread profile  45 . In this example, LED casing  43  has exterior slots  44  for receiving and mounting the LEDs and for permitting light from the LEDs to exit the device, rather than using a clear or translucent casing. The method of turning on the light is through a screw (twist) mechanism. The on/off capability allows for conservation of battery power and storage of the device in its deactivated state. This screw design was chosen for its simplicity and potential for a low profile. This would facilitate the manufacturing process, keeping the process time short and the cost low. Additionally, the screw mechanism is easy for surgeons to use. 
         [0030]    There are a variety of thread profiles, some of which are standardized and others are not. Potential thread profiles include: triangular, semicircular, rectangular, etc. The triangular thread profile was chosen and swept through a helical pattern, because this thread profile was easiest to design and 3D print. When manufacturing a final product, a standard thread profile could also be used. The common thread standards are described by the Unified Thread Standard (used in North America) and the ISO metric screw head (used worldwide). The major difference between these two profiles is the unit of measurement, either in inches or millimeters, respectively. Both profiles were in a trapezoidal shape and were cut at 30° to the vertical. The ACME thread profile is yet another standard that is similar to the two above but is used primarily for threads involved in heavy machinery. The profile is trapezoidal and is the standard because of its ease in manufacturing and utility effectiveness. 
         [0031]    The three LEDs that chosen were each rated at 25 lumens. Lumens are a unit of measure of the luminous power emitted from a light source. For reference, high quality bike lights are rated at about 300 lumens, and standard 60 Watt incandescent bulbs are rated at about 800 lumens. Surface-mounted LEDs (SMDs) were used because of their small size and ability to be easily incorporated into a custom-printed design. A single SMD measures only 2.80×3.50×0.81 mm. Furthermore, SMDs are relatively cheap with a relatively low cost, high lumen-to volume ratio, efficiency, and type of light emitted. 
         [0032]    The light emitted from the LEDs must qualify to certain specifications. The LED emits a natural white light with a CCT of 4000 K. As stated previously, reference values for the CCT are around 2700 K-6500 K with the high temperatures related to a blue or “cool” color and the low values related to a yellow or “warm” color. Therefore, a CCT of 4000 K indicates a relatively neutral color appearance. The LED used had a color rendering index (CRI) of 80. While a LED with a higher CRI value might be preferred, the positives of this LED significantly out-weigh this one downside. During the manufacturing process, another LED with a slightly higher price but a better CRI value may be suitable for use. 
         [0033]    The printed circuit board (PCB) was designed using EAGLE CAD software and is shown in  FIG. 5 . This PCB was simple, requiring only a voltage-in source, voltage-out source, and parallel wires to each of the three LEDs. 
         [0034]    The LED used can be activated in the range of 2.8 to 3.6 V with a 60 mA current, with its peak current at 180 mA. The CR2032 battery was tested on the SMD without a resistor and it was expected that the LED would blow out. However, in an informal experiment in which a single LED was connected directly to the battery, it was found that the setup lasted for more than a week. This prototype does not contain a resistor; as there is resistance already within the LED to draw the current. A resistor may be included in future iterations of the lighting device to lower the risk that the peak current of the LED will be exceeded, blowing out the LED. In the event the resistor value needs to be determined, the following equation can be used: 
         [0000]    
       
         
           
             
               R 
               LED 
             
             = 
             
               
                 
                   V 
                   B 
                 
                 - 
                 
                   V 
                   LED 
                 
               
               
                 I 
                 LED 
               
             
           
         
       
     
         [0000]    where V B  is the voltage of the battery, and V LED  and I LED  are the recommended voltage and current respectively. Additional circuit alterations can be added to provide safeguards for in vivo use. 
         [0035]    This example uses a static, slide-on clip as the attachment mechanism. The clip had a base with two projections—the parts that actually clamp on to the retractor—on either side (shown in  FIG. 6 ).  FIG. 6A  shows a top view of the example of the lighting device, with the three LEDs visible through the surface of the casing, attached to or clipped onto a retractor with a clip attached to the bottom of the device.  FIG. 6B  shows a side view of the example lighting device and attached clip attached to or clipped onto a retractor. The inside face of the clip was lined with a rubber, micro-suction sheet in order to increase resistance between the clip to retractor interface, allowing for the device to stay on. This design was chosen because of simplicity; the clips allow for the light to easily be moved between instruments, as dictated by the particular surgical needs. 
         [0036]    A CEN-TECH® digital multimeter was used to measure the power consumption of this circuit. Across each LED was 2.65 volts. The current through one of the LEDs when the three LEDs were placed in parallel was 6.45 mA. Thus, the power consumption for one LED is simply: 
         [0000]      2.65×0.00645=0.017 Watts
 
         [0037]    The entire device, with three LEDs, is 3*0.017=0.051 Watts. This is an extremely low value; comparing this to a standard 100 W incandescent bulb which emits 98 W of power as heat. The battery has a capacity of 220 mAh. The following equation will determine how long the LEDs will stay lit: 
         [0000]    
       
         
           
             
               0.220 
                
               
                   
               
                
               Ah 
             
             = 
             
               
                 
                   
                     0.220 
                      
                     
                         
                     
                      
                     hr 
                     * 
                     
                       C 
                       . 
                     
                   
                   s 
                 
                  
                 
                   
                     3600 
                      
                     
                         
                     
                      
                     s 
                   
                   
                     1 
                      
                     
                         
                     
                      
                     hr 
                   
                 
               
               = 
               
                 
                   792 
                    
                   
                       
                   
                    
                   
                     C 
                     . 
                     
                       
 
                     
                      
                     792 
                   
                    
                   
                       
                   
                    
                   
                     C 
                     . 
                   
                   × 
                   
                     s 
                     
                       3 
                        
                       
                         ( 
                         0.00645 
                         ) 
                       
                     
                   
                 
                 = 
                 
                   
                     40 
                     , 
                     930 
                      
                     
                         
                     
                      
                     seconds 
                   
                   = 
                   
                     11.37 
                      
                     
                         
                     
                      
                     hrs 
                   
                 
               
             
           
         
       
     
         [0000]    Typically, 11.37 hrs is much longer than is needed for standard deep cavity procedures. 
         [0038]    In order to reach the thermally benign feasibility criteria, an experiment was conducted to see if the heat generated from the LEDs would result in an increase in tissue temperature. The maximum threshold temperature for tissue is 43° C., or 109.5° F. 0.46 lb of chicken breast was used as a representative of tissue. A digital thermometer probe was inserted into the chicken breast, placing the tip of the probe as close to the surface of the breast as possible. The ambient temperature was set at a constant 74° F. The lighting prototype was placed 60 mm away from the chicken breast for three hours, then again at a 30 mm distance for another three hours. In the first 1.5 hours of the experiment, the temperature was recorded at one minute increments because it was assumed that a greatest change in temperature would be seen in the first part of the experiment. The results from this part are shown in  FIG. 7A . Once it was seen that there was an existing trend, the temperature measurements were recorded at 10 minute increments. At the 60 mm distance, there was a total decrease in temperature of 2.5° F. over three hours. At the 30 mm distance, temperature declined slightly over three hours, with the temperature ranging only in a 0.5° F. difference, shown in  FIG. 7B . 
         [0039]    The results of these two trials show that external variables such as the temperature of the countertops had much greater influence on the chicken breast than the heat generated from the LEDs. After the experiment, the heat was subjectively tested by directly touching the LEDs after being on for six hours; a significant temperature change was not noted. Thus, the heat generated from the LEDs is negligible, and this prototype is thermally benign.