Operation theatre light is a medical device intended to assist medical personnel during a surgical procedure by illuminating a local area or cavity of the patient. A combination of several surgical lights is often referred to as a "surgical light system".
Surgical lights, also known as surgical lighting or operating lights, are mainly used in hospital operating rooms and ambulatory surgery centers, but can also be used in various locations throughout the facility to provide high quality lighting for procedures. Examples include emergency rooms, labor and delivery, examination rooms, and anywhere where procedures are completed. They are used by clinicians, surgeons and proceduralists. A surgical light illuminates the operative site on a patient for optimal visualization during a procedure.1 Surgical lights can provide hours of bright light without excessively heating the patient or staff. A variety of lights are available to meet the needs of providing optimal visualization during surgery and procedures. An examination light is used during medical exams, while operating room lights are used during surgical procedures.
TYPES OF SURGICAL LIGHTS
There are various types of surgical lights, and each type plays specific roles in illumination before, during, and after a medical procedure. They can be categorized by lamp type or mounting configuration. Two lamp types are conventional (incandescent) and LED (light emitting diode).
Surgical lighting configurations may include ceiling-mounted, wall-mounted, or on floor stand. Depending on the model, a surgical light may also be used in all three configurations.1 A ceiling-mounted light can be mounted on a fixed point on the ceiling of a procedure room. Similarly, wall-mounted lights are mounted on a wall of the OR. The wall-mounted configuration is more often used with examination lights versus surgical lights. For greater mobility, floor standing surgical lights are standalone and typically on wheels enabling them to move room to room. Mobile floor standing lights are often used in examinations. All three types play an important role in illuminating a surgical site during a procedure.
LED Lighting
In the early 2000s, LED became a standard offering in many industries, including ORs and other procedural areas,13 and surpassed conventional halogen light sources as the preferred light source used during surgical procedures.14 They are solid-state semiconductor devices that emit light as currents flow through it. They have a more refined energy usage and require significantly less energy than a halogen to produce equal to higher, quality illumination. The plastic encapsulant and the lead frame compose most of the bulb’s structure and the light-generating chip is comparatively small in comparison. Light is generated inside the chip, a solid crystal material when current flows across the junctions of different materials. The spectral emission of the LED light depends on the materials used to form the semiconductor, the most common combinations being aluminum indium gallium phosphide and indium gallium nitride.6 The composition of the materials determines the wavelength and color of the light (ie, red, yellow, green, blue or white). Initially LED surgical lighting used a combination of red, green, blue and white LEDs to achieve a bright white illuminance. This strategy was the primary means to achieve high light output superior to what using all white LEDs could produce. Unfortunately, the light would change color when one or more of the colors were blocked by a hand placed in the sterile field.
LEDs can be extremely small, durable, reliable and have a much higher bulb-life rate than conventional lighting. The light output of LEDs is determined by the current through the semiconductor and its temperature and when using the maximum current recommended by the manufacturer, LEDs can have a long life of up to 60,000 hours.6 However, most are generally rated for 25,000 to 40,000 hours of full light and rather than failing abruptly like halogen bulbs, they gradually fade in brightness. In terms of luminous efficacy, LED lights used during procedures typically do not require a filtering media, as is needed with halogen lamps and contributes to their relatively low luminous efficacy. LEDs offer higher efficacy allowing for reductions in connected load of 50% or more, virtually eliminating the problem of infrared radiation caused by excessive heat, with potential for additional energy savings through constant-color dimming and reduced cooling load in the OR.8 The latest LED products are high-flux and have luminous efficacies up to 100 lumens per watt (lm/W) and higher.6 Because past OR practices involved turning lights up to full intensity, original perioperative staff would do the same with LED lights. Unfortunately, this created distortion. To avoid distortion, standard practice is to begin at a 50% intensity level. Many offer enhanced properties for mitigation of shadows cast by the surgeon and perioperative team and some products also allow for color adjustment.8 Their availability in a wide range of spectral power distributions (SPDs) permits the development of spectrally tunable surgical luminaires, where an array of LEDs with distinct SPDs can be mixed to produce a variety of spectra from a single luminaire.15
Surgeons need the correct light source that maximizes visibility and efficiencies in the OR. 5
Lighting for Open Surgery
Traditional open surgery can utilize overhead lighting when the operative site is not deep within the patient. LED lighting is the most conventional light source used for open surgery. Emphasizing the reduction of shadows is crucial for open surgery. It is common to have obstructions between the light source and the surgical site, i.e., head, shoulders, hands, instruments, etc.
Lighting for Minimally Invasive Surgery
IN-CAVITY SURGICAL LIGHTING
In-cavity surgical lighting emits very little lighting and is best used during minimally invasive applications. The light source is outside the sterile field, often fixed on a surgical instrument. Allowing to supplement overhead and headlamp lighting in non-invasive surgical procedures. Heat management is the most critical factor of consideration when using in-cavity lighting fixtures.3
SURGICAL MICROSCOPE
Surgical microscopes, also known as an operating microscope, is an optical microscope designed specifically to be used for microsurgery. The surgical microscope provides an adjustable magnification, bright illumination, and clear visualization of the surgical field and has been used more progressively in operating rooms. State-of-the-art surgical microscopes are integrated with various imaging modalities, such as optical coherence tomography (OCT), fluorescence imaging, and augmented reality (AR) for image-guided surgery. The surgical microscope is a powerful tool that can offer optional magnifications, bright illuminations, and clear visualization.17
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