camoußages better with skin, but it is more expensive than white tape; therefore, the brown tape is usually used at the completion of Mohs surgery. Micropore tape is also hypoallergenic and, for that reason, can also be used to substitute adhesive bandages.

Lastly, Mohs surgery generates large amounts of waste. Regulated waste has to be disposed of in containers that are closeable and constructed to contain all contents and prevent leakage of ßuids during handling, storage, transport, or shipping. If outside contamination of the waste container occurs, then it needs to be placed in a second container. There are three types of waste containers necessary in the OR: a large wide-mouthed container for noncontaminated, non-sharps waste (table paper, paper towels, etc.), a sharps container, and a contaminated waste container. The sharps container has to be leak proof and puncture resistant and replaced regularly so that it does not overÞll. Only dispose of appropriate materials in the sharps and contaminated waste disposal because it is expensive to manage them.

Additional miscellaneous operating room equipment useful to the Mohs surgeon is listed below [1]:

1.Magnifying glasses: Provide magniÞcation with good working distances, allowing the Mohs surgeon better visibility of the surgical Þeld.

2.Tool chest on wheels: For emergency resuscitation equipment and medication.

3.Surgical instrument sharpener: Used to maintain sharp equipment, including curettes, punches, and scissors. It is easy to use and highly functional. There are also services that can be purchased to sharpen instruments.

4. Gentian violet pens and pen holders: These are ethylene oxide re-sterilizable. The pen holder allows the pens to be stored point down, preventing premature loss of function.

5.Liquid gentian violet for marking deep tissue: Gentian violet can be painted on tissue with a sterile cotton tip applicator as a grid to help orient tissues that may distort or shrink after they are removed from the patient. Alternatively, an entire deep tissue plane can be painted with gentian violet. If the tissue was not completely removed, the gentian violet remains visible after the removal of the specimen. In this manner, the Mohs surgeon can be alerted to the fact that an incomplete layer was taken.

6.Alligator hair clips: Useful in keeping the patientÕs hair out of the surgical Þeld and can be ethylene oxide sterilized.

Summary: Surgical Waiting Room

¥The patient has to wait for the tissue specimen to be prepared and read, which usually takes about half an hour or longer.

¥It is optimal to have a surgical waiting area separate from other patients.

¥The surgical waiting room should be large enough to accommodate at least Þve patients, each with their accompanying family member or friend.

¥Patient satisfaction and comfort can be enhanced with quiet music, a variety of current magazines, or even with a television.

¥Bathrooms should be easily accessible, and emergency alarms should be placed in the bathrooms within easy reach.

11.3Surgical Waiting Room

After a layer of skin is removed, the patient has to wait for the tissue specimen to be prepared and read, which usually takes about half an hour or longer. Patients can be sent back to general patient reception area, but this is not ideal. Patients may feel awkward with large dressings and other patients may feel apprehensive about sitting near surgical patients with these dressings. Therefore, it is optimal to have a discrete surgical waiting area for the Mohs patients.

The surgical waiting room should be large enough to accommodate at least Þve patients, each with their accompanying family member or friend. All seats should be in full view of a staff receptionist trained in CPR. The seats need to be wide enough for obese patients and have arms to support and assist older patients in standing up and sitting down. They should be arranged so that the patients can sit somewhat apart from one another but next to an accompanying family member or friend [1].

In addition to comfortable seating, patient satisfaction and comfort can be enhanced with quiet music, a variety of current magazines, or with a television. According to a systematic review in 2008, music intervention had positive effects on reducing pain and anxiety in the perioperative setting in approximately half of the reviewed studies. Music has also been shown to reduce heart rate, blood pressure, respiratory rate, and cortisol levels.

Recommendations include slow and ßowing music approximately 60Ð80 beats per minute, nonlyrical, and maximum volume at 60 dB [2]. A television can be set to show a movie with appropriate language, content, and minimal violence or can be used to educate patients on Mohs surgery and other services the dermatology ofÞce provides. The volume level should not be distracting.

Moreover, bathrooms should be nearby. It is required that they be accessible to individuals with disabilities. Emergency alarms should be placed in the bathrooms within easy reach. Snacks and drinks should be provided as needed. The staff needs to remain alert for potential problems, for example, a patient may be bleeding through the bandage or may feel dizzy. In the occasional instant that a patient needs to lie down, take the patient to a room and notify the surgeon, who may place the patient in Trendelenburg position. Surgical patients should be supervised at all times. Overall, the surgical waiting room should be private, clean and comfortable, and regularly monitored by the staff.

Summary: The Histopathology Laboratory

¥The lab should be located out of sight and hearing of patients and have a microscope slide reading area.

¥The modern Mohs laboratory conÞguration consists of an air-conditioned room with a recirculating fume hood housing an automated slide stainer.

¥The fume hoodÕs ßow rate should be approximately 380 L/s and an average face velocity of 0.5 m/s.

¥The total ßow rate should be 480 L/s; with 40 L/s of fresh air brought into the lab from the external environment. This system should provide at least 4.3 complete air changes per hour, taking into account the dimensions of the room.

¥The lab needs to have running water, good overhead lighting, shelf space for supplies, and room for slide staining equipment.

¥It is important to look up and abide by local and state regulations regarding OSHA and laboratory setup requirements, which may be variable in regards to ventilation over the staining equipment.

11.4The Histopathology Laboratory

Each Mohs surgeon should strive to build and equip the best Mohs lab within space and budgetary limitations. Investing in a well-trained histotechnician and equipment to create the ideal laboratory is worthwhile, as this is the foundation of the surgery. A well-trained Mohs histotechnician that has access to a well-equipped lab will result in an efÞcient production of high-quality frozen section slides.

The lab should be located out of sight and hearing of patients and have a microscope slide reading area. It requires a cool, dry environment. It is best that the lab air-conditioning is separated from the general ofÞce air-conditioning because cryostats generate heat in the process of producing and maintaining an internally cold microtome temperature [1]. Heat inlet ducts should be fully closeable.

The Mohs laboratory has evolved signiÞcantly over the years. Older laboratories had an early-model automated slide stainer in which the technicians were required to replenish ßuid levels throughout the processing. An extractor fan adjacent to the slide stainer, with a ßow rate of approximately 50 L/s, allowed for ventilation. The new Mohs laboratory conÞguration consists of an air-conditioned room with a recirculating fume hood housing a modern automated slide stainer. Hazardous chemicals should always be handled within the fume hood. The fume hoodÕs ßow rate should be approximately 380 L/s and have an average face velocity of 0.5 m/s. Air is Þltered through particulate and activated carbon Þlters and is then returned to the room. The lab should have its own air-conditioning system separate from the general ofÞce. The total ßow rate should be 480 L/s, with 40 L/s of fresh air brought into the lab from the external environment. This system should provide at least 4.3 complete air changes per hour, taking into account the dimensions of the room [3].

The lab needs to have running water, good overhead lighting, shelf space for supplies, and room for slide staining equipment. Floor space is required for one cryostat (preferably two), and for an area where specimens can be processed (grossed, inked, and labeled) and paperwork can be completed.

Safety equipment for laboratory technicians includes safety glasses, an emergency eyewash station, nitrile gloves, and gowns. A stool should be provided even though most technicians prefer to stand while cutting tissue. The ßoor covering should be relatively stain resistant

[1]. It is important to look up and abide by local and state regulations regarding OSHA and laboratory setup requirements, which may be variable in regard to ventilation over the staining equipment.

Summary: Grossing and Inking

¥The grossing and inking area should have a separate light task.

¥A cutting board is necessary to divide specimens and to make relaxing incisions.

11.5Grossing and Inking

The grossing and inking area should have a separate light task. A cutting board is necessary to divide specimens and to make relaxing incisions, which are also useful to line up the leading edge of the epidermis for better sectioning. Metal salt dyes can be used and are grossly colorful, but with transillumination appear indistinguishably black. The dye can be applied with pipe cleaners, cotton swabs, and wooden applicators, all which are inexpensive when bought in bulk. For a Þner point, however, a paint brush is more ideal, such as an artistÕs No. 2 or 3 round synthetic brush with a metal ferrule [4]. Indelible marking pens for histology are used to label the glass slides because the ink they contain will not wash off during processing. Space is required for the Mohs map to be close at hand to verify the congruence between specimen inking and mapping [1].

A telephone intercom system between the lab and the OR is useful because it allows the surgeon to call the histopathology technician from the OR when a new specimen is ready to be picked up for processing. It can also be used to call the technician when there are quality assurance problems with the slide being read or if recuts are necessary [1].

Summary: Embedding and Mounting Tissue

and the Cryostat

¥The most important and expensive piece of equipment in the lab is the cryostat.

¥Cryostats vary in cost, features, and size and dimension of the cryochamber working space.

¥The microtome is the heart of the cryostat. It is a tool that can cut fresh, frozen material into very thin slices.

¥Properly mounting the tissue onto the chuck is important because failing to do so may result in an uneven Mohs cut leading to skip areas on the slides.

¥Flattening the tissue specimen is an important method in order to examine 100% of the surgical margin.

¥All cryostats can be adjusted to produce frozen sections of varying thickness.

¥Cryochamber temperature settings can also be varied although most technicians cut tissue at −20¡C to −30¡C.

¥A backup cryostat is essential in case of unit failure.

¥Preventivemaintenanceofcryostatsisextremely important.

11.6Embedding and Mounting Tissue and the Cryostat

The most important and expensive piece of equipment in the lab is the cryostat. The cost to purchase one varies from $2,000 to $65,000, depending on whether it is purchased used or as a top-of-the-line new cryostat. Not only is cost a factor in deciding which cryostat to purchase, but so is the desired range of features. Some of these features include the following: an ultraviolet option to disinfect the cryochamber from bacteria, spores, and viruses; memory function; self-cleaning systems; double compressors that markedly increase reliability; and programmable digital controls. In fact, portable cryostats are also now available for purchase and can also be used as a backup.

Cryostats vary in cost, features, and size and dimension of the cryochamber working space. The height of some cryostats can be widely adjusted, while others are set at a permanent height. The advantage in the ability to adjust the height is that it can allow the technician to cut tissue sitting in a standard chair [1].

The microtome is the most important part of the cryostat. It is an instrument that can cut fresh, frozen material into very thin slices. This instrument moves over a Þxed knife blade and has a gear that advances

the object holder a set distance with each turn of the rotating handle. The distance that the object holder advances can be adjusted and determines the thickness of the tissue sections being cut [1]. As previously mentioned, there are now cryostats available in which a memory function allows for predeÞned advancement of the tissue specimen to the knife blade. Another feature to consider when selecting a cryostat is the ease of removal of the microtome for cleaning. If this is difÞcult, there can be delay in processing tissue.

The microtome holds the chuck holder (object holder). There are two general types of chuck holders. The rectangular holder is Þxed in an either upright or turned 180¡ in position. This Þxed position is an advantage when using cryomolds to prepare tissue specimens for cutting. A cryomold is a plastic mold that holds the specimen while freezing and aids in making the surgical margin of the specimen completely even [1].

The yoke system object holder can permit 360¡ rotation of the tissue block and can adjust most of the cutting angle in reference to the cryostat blade [1]. There are round cryomolds that can be used with the yoke system, but they must frequently be adjusted to give a perfectly ßat cutting plane.

Properly mounting the tissue onto the chuck is important because failing to do so may result in an uneven Mohs cut, leading to skip areas on the slides. An important step in tissue preparation is sufÞciently ßattening the specimen and placing it centrally on the chuck in a proper amount of medium [5].

Flattening the tissue specimen is critical in order to examine 100% of the surgical margin. Flattening devices may be useful when using a yoke system chuck holder. There are several devices and methods that can be used to ßatten the tissue. One such way is the conventional method. A frozen tissue embedding medium, called OCT (optimal cutting temperature), is placed onto a cold chuck. A heat sink is then applied to freeze and ßatten the OCT base, and afterward, the tissue specimen is placed on the center of the OCT. Fresh OCT is placed on top of that specimen, followed by placing the heat sink on the tissue again. The frozen tissue is now embedded in OCT and transferred to the cryostat [6].

The Miami Special device is also used to prepare and ßatten tissue specimens (Figure 11.1). In a busy practice, frozen section preparation is the limiting step. A study has demonstrated that the CryoHistª

Fig. 11.1 Preparing the microtome stage for placement of the Mohs specimen

embedding machine allows tissue to be processed faster than Cryocupª and the Miami Special [7]. Liquid nitrogen is required for the use of the Miami Special instrument. For fatty specimens that do not freeze well, liquid nitrogen and cooled isopentane minimize ice crystals [4].

All cryostats can be adjusted to produce frozen sections of varying thickness. Most Mohs surgeons prefer sections 5Ð7 mm in thickness with a range of 4Ð10 mm. All cryostats are adjustable well beyond the range of thickness needed for Mohs surgery.

Cryochamber temperature settings can also be varied within a wide range; however, most technicians cut tissue at −20¡C to −30¡C. Warmer temperatures may be required to cut cartilage and colder temperatures to cut adipose tissue [1].

Cryostat knife holders can hold disposable or reusable blades. Disposable blades are available in thin and thicker, more durable varieties. Disposable blades may require an adapter for use with certain blade holders. Reusable blades are available in lengths ranging from 10 to 25 cm. An advantage of a longer blade is that if one portion dulls while cutting, another portion of the blade can be situated into position to continue cutting. A disadvantage is that a longer blade can allow for a greater chance of injury to the technician. The most common injury to a Mohs technician is cuts from the blade. For safety, a blade guard can be placed on the exposed end of a blade [1].

Blades that can be resharpened are available and are honed with an automatic blade sharpener after each use. Cryostat blades should be sharpened after each use. If the ofÞce has two cryostats, three or four