SEPTEMBER 1992, VOL 56, NO 3
AORN JOURNAL
Video Technology BASICS FOR PERIOPERATIVE NURSES William D. O’Connell, RN
T
he use of video technology has become common in health care today. It also has become complex with the addition of more components than the simple camera and monitor used for arthroscopy 10 to 15 years ago. There is not a single surgical specialty that has not been touched by this technology, and the prospects for growth seem unlimited.
Cords, Connectors
C
ords and connectors are frequent sources of problems. Systems that use locking connectors are best (Figs 1 , 2, 3, and 4). Gold-plated connectors are recommended by many retailers of video accessories with the theory that the higher conductivity of the gold provides a higher quality image than William D. O’Connell, RN, MA, is the clinical manager, operating rooms, St Joseph Hospital, Lancaster, Pa. At the time this article was written, he was a clinical nurse specialist, operating room, and a clinical instructor, Thomas JefSerson University Hospital, Philadelphia. He earned his bachelor of science degrees in secondary education, biology, and nursing from Pennsylvania State University, University Park, and his muster of arts degree in healthfacilities managementfrom Webster University, St Louis.
The author would like to thank Panasonic, Inc, Secaucus, NJ, for contributing to the preparation of this article. 442
other connectors. A technician commissioned at the author’s request, however, was unable to detect any difference in conductivity or resistance of gold-plated connectors compared to regular, commercial-grade connectors of the same type. Because the cord connecting the camera to the controller is subject to failure,’ a camera with a removable cord is a wise choice. The cord can be replaced without sending the unit out for repair. Spare cords for all equipment should be placed in the cabinet where the equipment is stored.
Storage Cabinets
T
he equipment cabinet should have front and rear access to facilitate equipment setup, maintenance, and troubleshooting. The cabinet should be lockable to prevent tampering and theft, large enough to contain the system and accessories, and small enough to be easily transportable. A pull-out and/or pivoting mount for the monitor also is helpful.
How Video Technology Works
K
nowledge of how the components work is necessary to properly choose, set up, and aintain a video system. A good starting point is an examination of how the television (TV) set works. It begins with a radio frequency (RF) signal from a TV station that is sent through the air or via cable. The tuner on the TV allows the user to select the channel, and it feeds the RF
SEPTEMBER 1992, VOL 56, NO 3
~. .___.
AORN JOURNAL
Fig I . Locking connectors frequently used for video systems.
Fig 2 . F-plugs may be “push fit” or threaded for locking connection. These are uniformly used for radio frequency signal connections.
Fig 3. Nonlocking plugs, also known as phono plugs, that are widely used for audio connections. They sometimes are used for video connections.
Fig 4. Multiple conductor plugs. These or other types of multiple conductor plugs are used for super very high speed and red, green, and blue digital systems. signal to an RF converter, which converts the vgnal to electncal impulses that can be made into &I picture. This electrical signal has three part\ chrominance, luminance, and synchronization. The chrominance portion of the signal a l w 1’1 known as the red, green, and blue portion (RGB). It is adjusted with the color and hue controls on the TV. The luminance signal i 4 ‘I black-and-white picture that is “washed” by the chrominance signal to complete the total image. much as when an artist uses water color5 to complete a black-and-white drawing and make a color picture. The luminance is adjusted with
the brightness and contrast controls. The synchronizing signal contains instructions necessary for decoding the other signals (ie. it synchronires the scanning of the image). These signals are converted to a picture by single or triple guns at the rear of the picture tube. which are adjusted by the focus or sharpness control of the T V . These guns fire a xtreani of electrons (ie, scan) that cause the phosphorous coating of the picture tube to glow. which creates the picture. The TV picture is composed of 525 horizontal lines. The guns scan the even-numbered lines first to form the 443
SEPTEMBER 1992, VOL 56, NO 3
.
____
AORN JOURNAL
In addition to increasing the resolution, image quality can be improved by changing the way a video signal is coded and processed. first field. The odd-numbered lines are scanned next to make the second field. This entire scanning process takes approximately 1/30 of one second. When combined, the two fields become one frame. As in a movie, the illusion o t motion comes from changes in the image from one frame to the next. A TV set is called a receiver because it hax ii tuner and an RF converter. A monitor does not have either of these devices and must usc ;in electrical signal rather than an RF signal (ie. it must get its signal directly from a camera o r from a device with an RF converter, such as ii videocassette recorder [VCR]) (Fig 5). There are some receiver/monitors now on the market that have terminals to permit the user to bypass the tuner and RF converter.
Signal Clarity
E
very time a signal is converted from onc form to another, it becomes distorted and loses clarity. Surgeons need the best picture possible; therefore, running a pure electrical signal from a camera directly to a monitor, rather than converting an RF signal, is the best choice. In addition to a direct electrical signal, thc quality of an image depends on the amount o f resolution available in the receiver or monitor. which is determined from a test pattern. Lines of resolution are the number of black-and-white lines per inch that can be seen as distinct lines. High-resolution TV begins at 450 lines per inch but is not available to consumers yet. Some cameras are capable of as many as 800 lines per inch, and some monitors are capable of as many as 600 lines per inch. Television sets and VCRs are limited to 250 to 300 lines per inch of resolution. Therefore, a camera capable of 800 lines per inch of resolution is wasted if the image is viewed on a monitor with only 300 lines per inch of resolution.
Twenty-inch monitors, as measured diagonally across the screen, are the most popular for surgical applications. Larger monitors are not as bright as smaller ones because the signal is spread over a larger area. Twelve-inch monitors have very bright images, but they must be placed near the operative field because of their size.
Signal Processing
I
n addition to increasing the resolution, changing the way the video signal is coded and processed is another means of improving the quality of the image. Originally, three systems for coding TV signals developed in different parts of the world. In the United States. the National Television Standards Committee (NTSC) established the NTSC coding system. The Sequential Couleur a Memoire (SECAM) system was established in France, and the Phase Alteration Line (PAL) system was established in England. All of these signals are composite signals; however, the systems are all different, and equipment constructed to decode one system will not decode another. These systems were designed for broadcast, where the priority is transmitting the signal over long distances. There are other more
Fig 5 Back panel of consumer-grade VCR: Ifi-om /eft] RF input (antenna), RF output, video input and output, audio input and output. 445
SEmEMBER 1992, VOL 56, NO 3
AORN JOURNAL
recently developed means of formatting signals that result in superior images. These nonbroadcast formats are super very high speed (SVHS), also h o w n as Y/C, and RGB. Super VHS separates the chrominance (ie, color) portion of the signal from the luminance (ie, black-and-white) portion and sends the synchronization portion on one of the color bands. Two signals are produced and transported on two separate lines from the camera to the monitor. The RGB system separates the color signals into discrete lines and passes the luminance and synchronization signals on a fourth line. Both of these systems result in superior images,2 and both of these systems are compatible with monitors using NTSC or PAL coding. Recently, RGB systems that code part of the signal digitally have been developed, creating digital and analog RGB (Fig 6).
Fig 6. Back panel of state-of-the-art monitor with connections for video (NTSC), SVHS, RGB analog, and RGB digital.
Fig 7. Back panel of professional-grade SVHS VCR: (fromleB) video input and output, S-VHS input and output, auxiliary input and output, audio input and output. Note the lack of RF input and output. because the tuner and RF converter they contain make them subject to abuse and theft. There are some professional-grade S-VHS VCRs now made that do not contain tuners and RF converters (Fig 7). They are capable of 350 to 400 lines per inch of resolution when coupled to a camera that outputs S-VHS. This is the best type of VCR for hospital use. Threequarter inch U-matic cassette recorders offer the best resolution of all, but they are very expensive and are less user-friendly than the 1/2-inch VHS recorders. The video printer is a combination of computer and instant camera3 (Fig 8). It stores a still image taken from the video camera, monitor, or VCR similar to how a computer stores
Recording Images
A
s of the writing of this article, there are three methods for recording video images for future use, including VCR, video printer (ie, Mavigraph), and video disc. The VCR is the only one of these that records a moving image; however, VCRs are used for recording only a few surgical procedures because their image quality is limited to 250 to 300 lines per inch of resolution and Fig 8. Mavigraph or video printer. 446
AORN JOURNAL
data in its memory. It prints the image on special paper, much like an instant camera. These printouts can then be placed in the patient’s chart. More sophisticated units can make splitscreen prints and record data such as dates and times; however, the memory of the unit must be cleared before another subject can be printed, so there is no long-term electronic storage. Image quality is equal to the resolution of the signal input into the unit. The video disc recorder stores images on floppy disc and has the advantages of spaceefficient electronic storage and rapid access to images (Fig 9). A disadvantage is that the images are limited to video and cannot be printed without a video printer.
Fig 9. Video disc recorder. (Photograph courtesy of Panasonic, Inc, Secaucus, NJ)
Surgical Video Equipment
T
he miniature camera and controller used for surgical applications has two component parts: the endocoupler and the charged coupled devices (CCDs). The endocoupler contains the optical lenses, the focusing adjustment, and the coupling for gripping a telescope or other endoscope and may be detachable from the other portion of the camera (Fig 10). The coupler may be a “beam splitter,” which allows the surgeon a direct view and video imaging, or a “direct coupler,” which has video imaging only. Beam splitters divide the avail448
SEPTEMBER 1992, VOL 56, NO 3
Fig 10. Camera and endocoupler disassembled. able light in half, which may result in a dimmer picture on video. Typically, beam splitters also cause a loss in the field of view resulting in a smaller image on the monitor. The CCDs are chips that are light sensitive and produce the unprocessed video signal. There are one-, two-, and three-CCD cameras. Having fewer CCDs makes the camera smaller, but having more CCDs results in better color and image q ~ a l i t y . ~ Three-chip ca eras usually are necessary /% for use with microscopes, because the high magnification requires extra resolution. Most other applications are satisfied with single-chip cameras, which typically cost about one-third the price of three-chip cameras. Some of the more advanced systems presently available have no endocoupler because the camera is fully integrated with the telescope or endoscope. This integration of components is good because it prevents problems with fogging and avoids the optical inefficiencies of endocouplers. On the other hand, this integration also reduces the flexibility of a system, because many types of telescopes can be attached to a direct coupler. One system currently exists with the camera, controller, and light source as an integrated unit with a small fiberoptic catheter that is introduced into the body. This system is intended for diagnostic use because the imaging is not yet sufficient for operative use.
SEPTEMBER 1992, VOL 56, NO 3
Light Sources
L
AORN JOURNAL
camera to avoid overexposing small cavities. Exposure control from a dedicated light source is a necessity for abdominal work, because panoramic views require more light than closeup views. Some cameras have adjustable sensitivity (ie, F-stop), which also increases the adaptability to different light levels.
ight sources are characterized by color and temperature. The color of light is based on a comparison to the color of light produced by heated metal, which is expressed using the Kelvin temperature scale. As metal is heated, it produces a luminescence that progresses from red to yellow to Contraindications white to blue-white as the temperature increases. The temperature needed to produce a given any cameras are not compatible with color is an objective means of describing that laser use, especially with neodymium yttrium aluminum garnet and CO, color (eg, candle light = 1800 K = yelloulaser systems. The intense infrared radiation orange; incandescent light bulb = 2800 K = yelfrom these lasers can damage the CCDs in low; xenon light source = 5400 K = blue ~hite).~ unprotected cameras or cause systems with automatic exposure to shut down to protect the Light sources also are described by temperaCCDs. ture. This is somewhat contradictory to the u q color is described; the temperature description 01‘ Purchasing color is the reverse of its tone.6 The blue-whitc xenon light source is considered “cold” light ‘ideo technology is inescapably technibecause of its cool color tone. Yellow light i \ cal. and systems tend to become out“warm,” and red light is “hot.” dated in 3 to 5 years.7 When purchasing Camera controllers contain a “white balance“ a s j \tern, the best technology available and mechanism that adjusts the color produced h> price must be balanced. No single system can the camera to the “color” of the light sourcc be everything to all surgical specialties. If a Units that produce levels of light sufficient for. system must serve a wide spectrum of needs, surgical procedures can cause draping materials the most advanced and specialized system will to scorch or smolder from the intensity of the not be a good choice. If the system is to be used light. for a specific purpose, however, a system Better camera systems require a dedicated designed for that purpose is a wise choice. light source (ie, one matched to the camera) Because there is a wide variety of flexible comcoupled to the camera controller (Fig 1 I ) to provide automatic light level and exposure control. The level of light required for a given procedure is related to the size of the cavity into which the scope is placed. A knee joint requires less light for a good image than does the abdomen. The diameter of the scope also is important. The smaller the scope, the fewer fiberoptic fibers it can contain to illuminate the cavity. A system that is going to be used for multiple specialties should have a powerful light source (eg, 250 watts or more) F i g / 1 . Back panel of camera controller showing conand automatic exposure control in the nection to dedicated light source and output to monitor.
M
V
d+ 449
Setting Up The person in charge of the video equipment should segregate the power cords of the components from the signal cords. Under some circumstances,power cords parallel and in proximity to signal cords interfere with the video image. The best way to avoid this is to run the power cords down one side of the cabinet or cart to a power strip. Run the signal cords down the opposite side of the cabinet. If power and signal cords must be in close proximity, the person setting up the equipment should cross them at right angles and secure this position with tape, twist ties, or rubber bands (Fig l).’ Each power cord should be labeled with tape as to which device it belongs and which end is connected to which unit (Fig 2). This facilitates troubleshootingand maintenance. Also, cords should be coded and secured to prevent prob lems with excess cording (eg, kinks). The person setting up the equipment puts the monitor next to the camera for the best picture possible. If the system has a receiver instead of a monitor, there must be a VCR between the receiver and the camera to convert the electrical signal into RF so that the receiver can make an image; how-
Fig l. Twist tie maintains 90-degree angle between power and signal cords.
452
Fig 2. Signal cord labeled with point of connection in system. ever, this extra component tends to decompose the image because of the signal conversion. A slave monitor is useful for many reasons, and it is best placed at the end of the component sequence (Fig 3). In this position, the surgeon can replay an image from the VCR on the slave while the real-time image remains on the master monitor. If the surgeon is using a video printer or video disc recorder, the slave can be used for printing or recording, which also leaves the realtime image on the master. The slave also may save neck and muscle strain for the surgical team,especially when the fist assistant and camera operator must stand opposite the surgeon. Both can have a straight view of the procedure without turning or twisting from the field. If a VCR is being used without a slave monitor, playback from the VCR is not possible without running a line from the VCR to the monitor. Although playback is not a normal requirement during surgery, it may, at times, be desirable. Two solutions to this problem include 1) using a slave monitor for playback or 2) running a line from the VCR output to “line B” input on the monitor (Fig 4). The input from the camera can go into the “line A” input of the monitor.
SEPTEMBER 1992, VOL 56. NO 3
AORN JOURNAL
-
a System
Fig 3. The monitor is placed first in the system after the camera and controller. The documentation device follows the monitor. and the slave is last.
Switching the monitor from line A to line B will provide playback capability. Documentation devices should be placed next to the monitor. Personnel setting up the equipment should couple the output of the monitor to the input of the recording device. If a VCR is used in conjunction with a video printer or video disc recorder, which component to put first is a difficult choice. Putting the VCR first reduces resolution of the other device; however, putting the video printer first deletes the image from the VCR while a print is being made. The order of the components does not affect the image if S-VHS equipment is used. A switching unit will permit shifting from one component to the other with a minimum of difficulty, but a better approach is to use only one fonn of documentation.
Fig 4 . Connection of VCR back to monitor for playback.
Note 1 M E David, ed, The Intelligenf Idcor’s Guide to Honie Video Equipment (Philadelphia: Running Press. 1982) 52.
ponents, hospital purchasing agents should insist that sales representatives demonstrate several systems and components before deciding which system to purchase. After the video system is purchased, one person in the department should be responsible for it. This person should read all instruction manuals carefully, assemble the system, and make a checklist for others who will use the system. (See “Setting Up a System.”) The checklist and a diagram of the components should be attached to the video equipment cabinet or storage cart for easy reference.
Conclusion
A
lthough video technology is complex and changes rapidly, a basic understanding of how these systems work can help nurses influence purchasing decisions, perform preventive maintenance, and troubleshoot problems. Knowing which systems work well in which clinical settings and which problems occur most frequently helps nurses anticipate problems and fix some video problems without losing valuable time by sending the system to the 0 manufacturer for repair unnecessarily. Notes 1. R T Marousky, “Camera literacy: Understanding OR video systems,” Today’s OR Nurse 13 (March 1991) 16-21. 2. Circon Co, A Straightforward Guide to Purchasing a Medical Video Camera (Santa Barbara, calif: Ckcon, Co, 1990). 3. S Pinkwas, “Technically speaking: How still printers turn tapes into snaps,” Video 14 (March 1992) 14-15. 4. M E David, ed, The Intelligent Idiot’s Guide to Getting the Most out of Your Home Video Equipment (Philadelphia: Running Press, 1982) 135. 5 . J Thayer, D Jackson, “Videoarthroscopy: What an orthopaedist should know about video equipment,” Contemporary Orthopaedics 6 (February 1983) 51-58. 6. Ibid. 7 . Marousky, “Camera literacy: Understanding OR video systems,” 16-21.
454
Ethical Guides for Nursing Faculty The act of cheating can jeopardize students’ learning, self-esteem, and future as nursing professionals, even when those who know about the dishonest behavior remain silent. One penalty of cheating is losing the respect of others. When a student is caught cheating, faculty members must take the appropriate actions to instill in students the ethical principles. According to an article in the March/April 1992 issue of Nursing Outlook, student dishonesty has become common and is viewed as a perennial problem in academic circles. The article states that approximately 50% to 60% of students in higher education programs are affected by cheating. One explanation for this problem is that intense pressure is placed on students to earn high grades and honors while they are still developing their moral character. Those with a strong motivation to succeed, according to the article, may not be able to resist the temptation to cheat. Another explanation is that cheating may be a result of social learning. Students sometimes believe that cheating is acceptable because others do it and are not punished. Students often see and hear accounts of well-known citizens who are involved in illegal or unethical practices but students rarely are exposed to accounts of exemplary behavior. When student actions do not meet the ethical standards set by an institution, faculty members must deal with the situation appropriately. Faculty members should use the situation to stimulate the student’s moral development. Policies to guide faculty members exist in each institution, and faculty members are responsible for knowing the procedure for handling incidences of academic dishonesty.
AORN JOURNAL
Video Technology BASICS FOR PERIOPERATIVE NURSES William D. O’Connell, RN
T
he use of video technology has become common in health care today. It also has become complex with the addition of more components than the simple camera and monitor used for arthroscopy 10 to 15 years ago. There is not a single surgical specialty that has not been touched by this technology, and the prospects for growth seem unlimited.
Cords, Connectors
C
ords and connectors are frequent sources of problems. Systems that use locking connectors are best (Figs 1 , 2, 3, and 4). Gold-plated connectors are recommended by many retailers of video accessories with the theory that the higher conductivity of the gold provides a higher quality image than William D. O’Connell, RN, MA, is the clinical manager, operating rooms, St Joseph Hospital, Lancaster, Pa. At the time this article was written, he was a clinical nurse specialist, operating room, and a clinical instructor, Thomas JefSerson University Hospital, Philadelphia. He earned his bachelor of science degrees in secondary education, biology, and nursing from Pennsylvania State University, University Park, and his muster of arts degree in healthfacilities managementfrom Webster University, St Louis.
The author would like to thank Panasonic, Inc, Secaucus, NJ, for contributing to the preparation of this article. 442
other connectors. A technician commissioned at the author’s request, however, was unable to detect any difference in conductivity or resistance of gold-plated connectors compared to regular, commercial-grade connectors of the same type. Because the cord connecting the camera to the controller is subject to failure,’ a camera with a removable cord is a wise choice. The cord can be replaced without sending the unit out for repair. Spare cords for all equipment should be placed in the cabinet where the equipment is stored.
Storage Cabinets
T
he equipment cabinet should have front and rear access to facilitate equipment setup, maintenance, and troubleshooting. The cabinet should be lockable to prevent tampering and theft, large enough to contain the system and accessories, and small enough to be easily transportable. A pull-out and/or pivoting mount for the monitor also is helpful.
How Video Technology Works
K
nowledge of how the components work is necessary to properly choose, set up, and aintain a video system. A good starting point is an examination of how the television (TV) set works. It begins with a radio frequency (RF) signal from a TV station that is sent through the air or via cable. The tuner on the TV allows the user to select the channel, and it feeds the RF
SEPTEMBER 1992, VOL 56, NO 3
~. .___.
AORN JOURNAL
Fig I . Locking connectors frequently used for video systems.
Fig 2 . F-plugs may be “push fit” or threaded for locking connection. These are uniformly used for radio frequency signal connections.
Fig 3. Nonlocking plugs, also known as phono plugs, that are widely used for audio connections. They sometimes are used for video connections.
Fig 4. Multiple conductor plugs. These or other types of multiple conductor plugs are used for super very high speed and red, green, and blue digital systems. signal to an RF converter, which converts the vgnal to electncal impulses that can be made into &I picture. This electrical signal has three part\ chrominance, luminance, and synchronization. The chrominance portion of the signal a l w 1’1 known as the red, green, and blue portion (RGB). It is adjusted with the color and hue controls on the TV. The luminance signal i 4 ‘I black-and-white picture that is “washed” by the chrominance signal to complete the total image. much as when an artist uses water color5 to complete a black-and-white drawing and make a color picture. The luminance is adjusted with
the brightness and contrast controls. The synchronizing signal contains instructions necessary for decoding the other signals (ie. it synchronires the scanning of the image). These signals are converted to a picture by single or triple guns at the rear of the picture tube. which are adjusted by the focus or sharpness control of the T V . These guns fire a xtreani of electrons (ie, scan) that cause the phosphorous coating of the picture tube to glow. which creates the picture. The TV picture is composed of 525 horizontal lines. The guns scan the even-numbered lines first to form the 443
SEPTEMBER 1992, VOL 56, NO 3
.
____
AORN JOURNAL
In addition to increasing the resolution, image quality can be improved by changing the way a video signal is coded and processed. first field. The odd-numbered lines are scanned next to make the second field. This entire scanning process takes approximately 1/30 of one second. When combined, the two fields become one frame. As in a movie, the illusion o t motion comes from changes in the image from one frame to the next. A TV set is called a receiver because it hax ii tuner and an RF converter. A monitor does not have either of these devices and must usc ;in electrical signal rather than an RF signal (ie. it must get its signal directly from a camera o r from a device with an RF converter, such as ii videocassette recorder [VCR]) (Fig 5). There are some receiver/monitors now on the market that have terminals to permit the user to bypass the tuner and RF converter.
Signal Clarity
E
very time a signal is converted from onc form to another, it becomes distorted and loses clarity. Surgeons need the best picture possible; therefore, running a pure electrical signal from a camera directly to a monitor, rather than converting an RF signal, is the best choice. In addition to a direct electrical signal, thc quality of an image depends on the amount o f resolution available in the receiver or monitor. which is determined from a test pattern. Lines of resolution are the number of black-and-white lines per inch that can be seen as distinct lines. High-resolution TV begins at 450 lines per inch but is not available to consumers yet. Some cameras are capable of as many as 800 lines per inch, and some monitors are capable of as many as 600 lines per inch. Television sets and VCRs are limited to 250 to 300 lines per inch of resolution. Therefore, a camera capable of 800 lines per inch of resolution is wasted if the image is viewed on a monitor with only 300 lines per inch of resolution.
Twenty-inch monitors, as measured diagonally across the screen, are the most popular for surgical applications. Larger monitors are not as bright as smaller ones because the signal is spread over a larger area. Twelve-inch monitors have very bright images, but they must be placed near the operative field because of their size.
Signal Processing
I
n addition to increasing the resolution, changing the way the video signal is coded and processed is another means of improving the quality of the image. Originally, three systems for coding TV signals developed in different parts of the world. In the United States. the National Television Standards Committee (NTSC) established the NTSC coding system. The Sequential Couleur a Memoire (SECAM) system was established in France, and the Phase Alteration Line (PAL) system was established in England. All of these signals are composite signals; however, the systems are all different, and equipment constructed to decode one system will not decode another. These systems were designed for broadcast, where the priority is transmitting the signal over long distances. There are other more
Fig 5 Back panel of consumer-grade VCR: Ifi-om /eft] RF input (antenna), RF output, video input and output, audio input and output. 445
SEmEMBER 1992, VOL 56, NO 3
AORN JOURNAL
recently developed means of formatting signals that result in superior images. These nonbroadcast formats are super very high speed (SVHS), also h o w n as Y/C, and RGB. Super VHS separates the chrominance (ie, color) portion of the signal from the luminance (ie, black-and-white) portion and sends the synchronization portion on one of the color bands. Two signals are produced and transported on two separate lines from the camera to the monitor. The RGB system separates the color signals into discrete lines and passes the luminance and synchronization signals on a fourth line. Both of these systems result in superior images,2 and both of these systems are compatible with monitors using NTSC or PAL coding. Recently, RGB systems that code part of the signal digitally have been developed, creating digital and analog RGB (Fig 6).
Fig 6. Back panel of state-of-the-art monitor with connections for video (NTSC), SVHS, RGB analog, and RGB digital.
Fig 7. Back panel of professional-grade SVHS VCR: (fromleB) video input and output, S-VHS input and output, auxiliary input and output, audio input and output. Note the lack of RF input and output. because the tuner and RF converter they contain make them subject to abuse and theft. There are some professional-grade S-VHS VCRs now made that do not contain tuners and RF converters (Fig 7). They are capable of 350 to 400 lines per inch of resolution when coupled to a camera that outputs S-VHS. This is the best type of VCR for hospital use. Threequarter inch U-matic cassette recorders offer the best resolution of all, but they are very expensive and are less user-friendly than the 1/2-inch VHS recorders. The video printer is a combination of computer and instant camera3 (Fig 8). It stores a still image taken from the video camera, monitor, or VCR similar to how a computer stores
Recording Images
A
s of the writing of this article, there are three methods for recording video images for future use, including VCR, video printer (ie, Mavigraph), and video disc. The VCR is the only one of these that records a moving image; however, VCRs are used for recording only a few surgical procedures because their image quality is limited to 250 to 300 lines per inch of resolution and Fig 8. Mavigraph or video printer. 446
AORN JOURNAL
data in its memory. It prints the image on special paper, much like an instant camera. These printouts can then be placed in the patient’s chart. More sophisticated units can make splitscreen prints and record data such as dates and times; however, the memory of the unit must be cleared before another subject can be printed, so there is no long-term electronic storage. Image quality is equal to the resolution of the signal input into the unit. The video disc recorder stores images on floppy disc and has the advantages of spaceefficient electronic storage and rapid access to images (Fig 9). A disadvantage is that the images are limited to video and cannot be printed without a video printer.
Fig 9. Video disc recorder. (Photograph courtesy of Panasonic, Inc, Secaucus, NJ)
Surgical Video Equipment
T
he miniature camera and controller used for surgical applications has two component parts: the endocoupler and the charged coupled devices (CCDs). The endocoupler contains the optical lenses, the focusing adjustment, and the coupling for gripping a telescope or other endoscope and may be detachable from the other portion of the camera (Fig 10). The coupler may be a “beam splitter,” which allows the surgeon a direct view and video imaging, or a “direct coupler,” which has video imaging only. Beam splitters divide the avail448
SEPTEMBER 1992, VOL 56, NO 3
Fig 10. Camera and endocoupler disassembled. able light in half, which may result in a dimmer picture on video. Typically, beam splitters also cause a loss in the field of view resulting in a smaller image on the monitor. The CCDs are chips that are light sensitive and produce the unprocessed video signal. There are one-, two-, and three-CCD cameras. Having fewer CCDs makes the camera smaller, but having more CCDs results in better color and image q ~ a l i t y . ~ Three-chip ca eras usually are necessary /% for use with microscopes, because the high magnification requires extra resolution. Most other applications are satisfied with single-chip cameras, which typically cost about one-third the price of three-chip cameras. Some of the more advanced systems presently available have no endocoupler because the camera is fully integrated with the telescope or endoscope. This integration of components is good because it prevents problems with fogging and avoids the optical inefficiencies of endocouplers. On the other hand, this integration also reduces the flexibility of a system, because many types of telescopes can be attached to a direct coupler. One system currently exists with the camera, controller, and light source as an integrated unit with a small fiberoptic catheter that is introduced into the body. This system is intended for diagnostic use because the imaging is not yet sufficient for operative use.
SEPTEMBER 1992, VOL 56, NO 3
Light Sources
L
AORN JOURNAL
camera to avoid overexposing small cavities. Exposure control from a dedicated light source is a necessity for abdominal work, because panoramic views require more light than closeup views. Some cameras have adjustable sensitivity (ie, F-stop), which also increases the adaptability to different light levels.
ight sources are characterized by color and temperature. The color of light is based on a comparison to the color of light produced by heated metal, which is expressed using the Kelvin temperature scale. As metal is heated, it produces a luminescence that progresses from red to yellow to Contraindications white to blue-white as the temperature increases. The temperature needed to produce a given any cameras are not compatible with color is an objective means of describing that laser use, especially with neodymium yttrium aluminum garnet and CO, color (eg, candle light = 1800 K = yelloulaser systems. The intense infrared radiation orange; incandescent light bulb = 2800 K = yelfrom these lasers can damage the CCDs in low; xenon light source = 5400 K = blue ~hite).~ unprotected cameras or cause systems with automatic exposure to shut down to protect the Light sources also are described by temperaCCDs. ture. This is somewhat contradictory to the u q color is described; the temperature description 01‘ Purchasing color is the reverse of its tone.6 The blue-whitc xenon light source is considered “cold” light ‘ideo technology is inescapably technibecause of its cool color tone. Yellow light i \ cal. and systems tend to become out“warm,” and red light is “hot.” dated in 3 to 5 years.7 When purchasing Camera controllers contain a “white balance“ a s j \tern, the best technology available and mechanism that adjusts the color produced h> price must be balanced. No single system can the camera to the “color” of the light sourcc be everything to all surgical specialties. If a Units that produce levels of light sufficient for. system must serve a wide spectrum of needs, surgical procedures can cause draping materials the most advanced and specialized system will to scorch or smolder from the intensity of the not be a good choice. If the system is to be used light. for a specific purpose, however, a system Better camera systems require a dedicated designed for that purpose is a wise choice. light source (ie, one matched to the camera) Because there is a wide variety of flexible comcoupled to the camera controller (Fig 1 I ) to provide automatic light level and exposure control. The level of light required for a given procedure is related to the size of the cavity into which the scope is placed. A knee joint requires less light for a good image than does the abdomen. The diameter of the scope also is important. The smaller the scope, the fewer fiberoptic fibers it can contain to illuminate the cavity. A system that is going to be used for multiple specialties should have a powerful light source (eg, 250 watts or more) F i g / 1 . Back panel of camera controller showing conand automatic exposure control in the nection to dedicated light source and output to monitor.
M
V
d+ 449
Setting Up The person in charge of the video equipment should segregate the power cords of the components from the signal cords. Under some circumstances,power cords parallel and in proximity to signal cords interfere with the video image. The best way to avoid this is to run the power cords down one side of the cabinet or cart to a power strip. Run the signal cords down the opposite side of the cabinet. If power and signal cords must be in close proximity, the person setting up the equipment should cross them at right angles and secure this position with tape, twist ties, or rubber bands (Fig l).’ Each power cord should be labeled with tape as to which device it belongs and which end is connected to which unit (Fig 2). This facilitates troubleshootingand maintenance. Also, cords should be coded and secured to prevent prob lems with excess cording (eg, kinks). The person setting up the equipment puts the monitor next to the camera for the best picture possible. If the system has a receiver instead of a monitor, there must be a VCR between the receiver and the camera to convert the electrical signal into RF so that the receiver can make an image; how-
Fig l. Twist tie maintains 90-degree angle between power and signal cords.
452
Fig 2. Signal cord labeled with point of connection in system. ever, this extra component tends to decompose the image because of the signal conversion. A slave monitor is useful for many reasons, and it is best placed at the end of the component sequence (Fig 3). In this position, the surgeon can replay an image from the VCR on the slave while the real-time image remains on the master monitor. If the surgeon is using a video printer or video disc recorder, the slave can be used for printing or recording, which also leaves the realtime image on the master. The slave also may save neck and muscle strain for the surgical team,especially when the fist assistant and camera operator must stand opposite the surgeon. Both can have a straight view of the procedure without turning or twisting from the field. If a VCR is being used without a slave monitor, playback from the VCR is not possible without running a line from the VCR to the monitor. Although playback is not a normal requirement during surgery, it may, at times, be desirable. Two solutions to this problem include 1) using a slave monitor for playback or 2) running a line from the VCR output to “line B” input on the monitor (Fig 4). The input from the camera can go into the “line A” input of the monitor.
SEPTEMBER 1992, VOL 56. NO 3
AORN JOURNAL
-
a System
Fig 3. The monitor is placed first in the system after the camera and controller. The documentation device follows the monitor. and the slave is last.
Switching the monitor from line A to line B will provide playback capability. Documentation devices should be placed next to the monitor. Personnel setting up the equipment should couple the output of the monitor to the input of the recording device. If a VCR is used in conjunction with a video printer or video disc recorder, which component to put first is a difficult choice. Putting the VCR first reduces resolution of the other device; however, putting the video printer first deletes the image from the VCR while a print is being made. The order of the components does not affect the image if S-VHS equipment is used. A switching unit will permit shifting from one component to the other with a minimum of difficulty, but a better approach is to use only one fonn of documentation.
Fig 4 . Connection of VCR back to monitor for playback.
Note 1 M E David, ed, The Intelligenf Idcor’s Guide to Honie Video Equipment (Philadelphia: Running Press. 1982) 52.
ponents, hospital purchasing agents should insist that sales representatives demonstrate several systems and components before deciding which system to purchase. After the video system is purchased, one person in the department should be responsible for it. This person should read all instruction manuals carefully, assemble the system, and make a checklist for others who will use the system. (See “Setting Up a System.”) The checklist and a diagram of the components should be attached to the video equipment cabinet or storage cart for easy reference.
Conclusion
A
lthough video technology is complex and changes rapidly, a basic understanding of how these systems work can help nurses influence purchasing decisions, perform preventive maintenance, and troubleshoot problems. Knowing which systems work well in which clinical settings and which problems occur most frequently helps nurses anticipate problems and fix some video problems without losing valuable time by sending the system to the 0 manufacturer for repair unnecessarily. Notes 1. R T Marousky, “Camera literacy: Understanding OR video systems,” Today’s OR Nurse 13 (March 1991) 16-21. 2. Circon Co, A Straightforward Guide to Purchasing a Medical Video Camera (Santa Barbara, calif: Ckcon, Co, 1990). 3. S Pinkwas, “Technically speaking: How still printers turn tapes into snaps,” Video 14 (March 1992) 14-15. 4. M E David, ed, The Intelligent Idiot’s Guide to Getting the Most out of Your Home Video Equipment (Philadelphia: Running Press, 1982) 135. 5 . J Thayer, D Jackson, “Videoarthroscopy: What an orthopaedist should know about video equipment,” Contemporary Orthopaedics 6 (February 1983) 51-58. 6. Ibid. 7 . Marousky, “Camera literacy: Understanding OR video systems,” 16-21.
454
Ethical Guides for Nursing Faculty The act of cheating can jeopardize students’ learning, self-esteem, and future as nursing professionals, even when those who know about the dishonest behavior remain silent. One penalty of cheating is losing the respect of others. When a student is caught cheating, faculty members must take the appropriate actions to instill in students the ethical principles. According to an article in the March/April 1992 issue of Nursing Outlook, student dishonesty has become common and is viewed as a perennial problem in academic circles. The article states that approximately 50% to 60% of students in higher education programs are affected by cheating. One explanation for this problem is that intense pressure is placed on students to earn high grades and honors while they are still developing their moral character. Those with a strong motivation to succeed, according to the article, may not be able to resist the temptation to cheat. Another explanation is that cheating may be a result of social learning. Students sometimes believe that cheating is acceptable because others do it and are not punished. Students often see and hear accounts of well-known citizens who are involved in illegal or unethical practices but students rarely are exposed to accounts of exemplary behavior. When student actions do not meet the ethical standards set by an institution, faculty members must deal with the situation appropriately. Faculty members should use the situation to stimulate the student’s moral development. Policies to guide faculty members exist in each institution, and faculty members are responsible for knowing the procedure for handling incidences of academic dishonesty.
