How to Choose Surgical Lights

Properly illuminating a surgical site is not nearly so simple as it may first appear. To see clearly and correctly, the light must be intense and uniform. It also needs to be as close to white as possible, so that the structures it illuminates show up in their true color. It should be adjustable to prevent glare. It should in effect be able to travel around obstacles like instruments and hands, so that shadows don't interfere with the procedure. And it needs to do all this without generating much heat, since this can dessicate tissue and make the surgical team uncomfortable.

If you are in the market for new OR lights, you need to evaluate all these factors when making your decision. In this article, we will explain how and also discuss some of the new products you may wish to consider.

High Illumination
Since tissues and organs absorb a great deal of light and also possess poor reflective qualities, lights need to output enough illumination to facilitate accurate perception. The physical unit of illuminance is known as the lux or footcandle (there are 10.8 lux in one footcandle). The Illuminating Engineering Society of North America specifies that major OR surgical lights must produce a minimum lux of 100,000 (approximately 10,000 footcandles) at a distance of one meter from the light source.

Shadow Reduction
Even the brightest light is insufficient if it cannot remove unwanted shadows from the surgical field. Shadows fall into two types: contour and contrast. Contour shadows are beneficial; they help the surgeon differentiate between fine tissue striations and vasculature. Contrast shadows, on the other hand, are a hindrance. These shadows result from obstructions cast by hands or instruments. Accordingly, you should look for a light that reduces contrast shadows while retaining enough contour shadows to provide surgeons with optimal perception.

Color Temperature
If a light's color temperature is too low (below 3,500?? ? K), objects will take on a pink or a red hue. Likewise, if the color temperature is too high (in excess of 5,500?? ? K), objects tend to have a blue tint. In order to perceive true color, your light needs to fall somewhere in between.

Incidentally, there is another measurement scale designed to quantify color change. The color rendering index takes into account color temperature as it relates to other variables, including light intensity and the particular properties of the object viewed under a light, to gauge changes in color composition. The closer the numerical value on the color rendering index is to 100, the better.

Heat Generation
Lights that put out a lot of heat can cause tissue desiccation during prolonged procedures and make the patient and surgical team uncomfortable. The less heat, the better.

Focus and Intensity Control
If a light produces too large a field, the surgeon may get glare from the area around the surgical site. Too small a field may not be advantageous either, particularly if you need diffuse light so you can see the trays and other items. For these reasons, it's best to buy lights that allow you to adjust the light field size. The ideal light allows you to control field size while maintaining a constant intensity.

With these factors in mind, here's what's new in surgical lights:

Fewer Shadows
Shadows could be a thing of the past with the Angenieux surgical lights series from ALM Surgical Equipment. These lights deliver 80,000 to 130,000 lux depending on the specific model. Flat dichroic mirrors, which are able to absorb some light waves but reflect others, reflect the light through hundreds of microlenses that split the light into numerous beams and then diverge them towards the surgical site in a uniform field of light. The cruciform-shaped lighthead and its internal mobile mirrors, both of which are adjustable, combine to eliminate almost all contrast shadows, the company says. The company says the mirrors also do not reflect infrared rays, reducing the heat that gets to the surgical site. The heat produced at the surgical field is only 15 degrees centigrade. The color temperature is 3,800?? ? K and the color rendering index is 93. Call (800) 842-2555 or visit www.almsurgical.com.

Less Heat
If you're in the market for a more efficient surgical light, you may want to take a look at the surgical lights in the D-Series PLUS, available in July from Berchtold. The manufacturer claims that its single 150-watt bulb lights can produce 130,000 lux at a color temperature of 4,500?? ? K, well within the acceptable range. The trick is its new "T" reflector, which enables 97 percent of the bulb's original illumination to reach the surgical site.

Since the light uses only one low-wattage bulb, it generates very little heat, reducing tissue drying and discomfort for the patient and surgical team, the company says. Bulb replacement costs are low since there is only one. The main reflector and the "T" reflector produce more than 600 segments of light, reducing shadows and creating a homogenous light field, the company says.

If the primary bulb fails, a computer automatically activates a reserve within .3 seconds. Each bulb is rated at 1,000 hours of use (approximately three months of OR time). Call (800) 243-5135 or visit www.berchtoldusa.com.

A Brighter Light If your surgeons like intense illumination, consider the Genesis/Genie Plus surgery light and satellite unit from Burton. Combined, the two multi-bulb light heads produce approximately 227,000 lux at a color temperature of 4000?? ? K. That is more than double the minimum requirement for major surgical lights.

The lamps' intensity is maintained up to a field depth of 17 inches (43 cm) from the light source, therefore requiring no corrective refocusing. However, you have the option of focusing the lights to produce a broad field of 10 inches (25 cm) or a very tight, high-intensity spot of six inches (15 cm). There is also a dimming mechanism that allows the surgeon to increase or decrease the light's intensity in a continuous linear adjustment (as opposed to discrete steps).

Each halogen lamp has a rated life of 1500 hours. But since the light's six 50-watt halogen bulbs are wired in parallel, one bulb failure won't interrupt a case.

The company is offering a $500 rebate on the light until October 31. Call (800) 444-9909 or visit www.burtonmedical.com.

Lighter Headlamps
Traditional surgical headlamps use fiber bundles, often split into two portions that wrap around the surgeon's head, in order to channel light to the instrument. According to Cogent Light, this arrangement is less than ideal. The weight of the fiber bundles can contribute to surgeon fatigue. Also, unnecessarily lengthening the fibers reduces light available at the business end, since the fibers themselves absorb light. Cogent feels its SolarTec light source may be a better choice.

The SolarTec uses a single quartz fiber that is only 1 percent of the size of a traditional fiber bundle. Unlike other materials, quartz absorbs almost no light, so nearly all the energy makes it to the headlamp. There is also no spotting due to broken fibers; SolarTec's single plastic fiber is encased in a metal shell to prevent it from breaking.

The quality of light delivered by SolarTec's single fiber is greater than the light transmitted by fiber bundles, the company says, because all visible wavelengths are evenly transmitted. Since distance does not adversely effect the quality of the light, it is possible to house the light source outside of the operating room.

SolarTec is compatible with pre-existing glass bundles as well as single-fiber optics. The device also works with endoscopes and other surgical instruments. Call (800) 294-2989 or visit www.cogentlight.com.

Cooler Lights
Getinge/Castle's new FiberLux surgical illumination system generates light in a device that's located away from the surgical field, then sends it to the overhead surgical light, headlamp or instrument via fiber optics, the company says. Since nearly all the heat generation takes place away from the surgical field, there is virtually none at the site itself, the company says.

Each light head can produce as much as 130,000 lux (roughly 12,000 footcandles); the surgeon is able to adjust the light's output at his or her discretion. The "light engine" monitors the raw light and automatically color-corrects it prior to sending it to the site. The color temperature remains at 4,200?? ? K with a color rendering index of 95.

The company says it's easy to install the FiberLux in most existing operating rooms with minimal time and expense. For more information, call (800) 475-9040, ext. 5542, or visit www.getinge.com.

A Major Light for Minor Surgery
If you are primarily interested in a surgical light suitable for mid-range surgery, consider the Illuminator IV from Medical Illumination. Delivering approximately 54,000 lux (5,000 foot candles) at 36 inches distance from the light source, this surgical light surpasses the minimum requirement for minor surgical lights by more than 16,000 lux.

The single 2000 hour rated-life Quartz Halogen bulb and the 17-inch reflector provide superb shadow-free output, and a light field depth of over two feet, says the manufacturer. The color temperature is 4000+?? ? K. Heat-filtering elements keep the light cool and comfortable, the maker says. Contact Medical Illumination at (800) 831-1222 or visit www.medillum.com.

Minimal Shadows, Maximum Field Depth
Shadows should not be much of a problem with Skytron's new Millennium Gold surgical light. The light's Vertical Segmented Reflector Design optical system produces over 144 overlapping light segments which fuse to create a 54-inch column of light that the company says is uniform in intensity. Since each light segment is backed up by another, blocking one set of rays does not result in a shadow. The fact that the light remains intense for four and one half feet means you do not have to reposition the surgical light when you change table height.

Skytron says the light produces 120,000 lux (11,000 footcandles) per lighthead at a color rendering index of 95, and a color temperature of 4,000?? ? K. An automatic reserve bulb provides immediate bulb switching should bulb failure occur. Call (800) SKYTRON or visit www.medicom.com/skytron.

Best of Both Worlds
If small lightheads appeal to you because of their flexibility and positioning ease, and large-diameter lightheads are of interest because of their superior optical performance, consider the SQ240 surgical lighting system from Steris Corporation. Each 24-inch lighthead can rotate 360 degrees, enabling you to use them for any procedure, says the manufacturer. Additionally, lighthead heights are adjustable; they can be lowered to 29 1/2-inches above the floor in order to provide low lateral illumination.

The lamphead produces 129,174 lux, keeping contrast shadows to a minimum by projecting the light both vertically and horizontally, Steris says. The overall field depth is 26 inches; in 18 of those, the pattern definition is constant, eliminating the need for focusing, the maker says. The color temperature is approximately 4,400?? ? K and the color rendering index is 92.

An automatic lamp changeover system helps guarantee uninterrupted illumination; in the event that the primary lamp fails, the secondary lamp will automatically assume the other's position. Call (800) 548-4873 or visit www.steris.com.