5 Operating Room Setup and Handling
of Surgical Microscopes
K. Wiechert
5.1
Introduction
With use of the surgical microscope, some basic con- siderations have to be taken into account in order to provide precise and comfortable working conditions.
Standardization of the setup and of the operating room conditions is therefore highly recommended. The en- tire nursing team dealing with the microscope should also be carefully trained in order to ensure trouble-free use of the microscope. Many of the mentioned topics may seem basic to some, but they are essential to make microsurgical spine surgery easier, safer, and more comfortable for the surgeon and the entire team [1, 2].
5.2
Room and Microscope Setup
Since the surgical microscope and the video equip- ment, as well as the frequently used C-arm, are often bulky, the chosen operating room should be large enough to enable comfortable working conditions without increasing the risk of contaminating sterile ar- eas and equipment. The setup of the entire equipment within the operating room should be standardized to facilitate maximum performance by the surgeon and the entire team (Fig. 5.1). The patient and the operating table are usually placed in the center of the room to cre- ate enough space for all the equipment and so the air- flow mechanisms can take full effect. The surgical mi-
Fig. 5.1. Example of a standard setup in the operating room
croscope, the instrument table, and the video equip- ment are the key elements to be taken into account. All the equipment has to be placed in such a position that the surgeon has maximum flexibility and is as comfort- able during the procedure as possible. The video equip- ment must be placed in such a way that the scrub nurse has full view of the screen to follow the procedure.
Since the surgical microscope plays the key role in performing spinal microsurgery its position in the room depends on the lever-arm construction of the mi- croscope and the joints of the optical unit. If the arms are long enough, positioning the microscope behind the surgeon enables easy handling. Also, if X-ray con- trol becomes necessary during the procedure, the lever arm of the microscope can be tilted upward toward the ceiling or be turned sideways in total to create space for the C-arm without moving the entire stand. If the mi- croscope is ceiling mounted, it should be movable side- ways in that particular situation. The joints of the cen- tral oculars and handlebars need not be readjusted.
If the arms of the microscope are not long enough to provide comfortable conditions for the surgeon, the en- tire microscope should be placed on the assistant’s side.
Since most available microscopes have an asymmetri- cally constructed optical unit, attention has to be paid to choosing the surgeon’s and the assistant’s side cor- rectly before draping starts. The surgeon’s side is al- ways the one with the closer eye–ocular distance.
The joints of the lever arms should be bent in such a way that the optical unit is midline squared toward the patient, and the surgeon and the assistant have a com- fortable working position, especially regarding their head and neck posture.
The height of the table has to be adapted in such a way that the surgeon has his arms at a comfortable 90°
flexion position at elbow level.
Immediately before starting the procedure, orienta- tion for the surgeon is facilitated if the final position of the optical unit in regard to the surgical field and the position of the respective motion segment is checked.
Any tilt in either plane should be avoided at the begin- ning, because it may lead to unnecessary dissections in wrong planes and directions, not only but frequently with inexperienced surgeons [2].
Chapter 5
5.2.1
Audio-visual Equipment
Standard audio-visual equipment consists of a high- resolution TV monitor and a digital videotape recorder or a DVD recorder. A digital 3-chip camera is mounted onto one of the tubes of the microscope and is connect- ed to the recorder. Documentation of the important surgical steps is facilitated and highly recommended, not only for medicolegal aspects but also to enable the scrub nurse, the anesthesiologist, and the entire surgi- cal team to follow the procedure efficiently and thereby enhance performance. The lighting in the operating room should be dimmed to increase vision in the surgi- cal field by omitting non-focal lighting and reducing diffuse lighting around the oculars, distracting from the surgical field. Dimming also increases contrast of the video monitor [2].
5.3
Microscope Handling
5.3.1 Draping
Usually the draping of the microscope is done by the scrub nurse and the operating room technician. There are several key points which are important during drap- ing for comfortable use of the microscope. Most surgical microscopes have two handlebars on either side of the optical unit. Several buttons allow focusing, zoom, lighting alterations, and movement control in all de- grees of freedom. These handlebars should be covered tightly with the drape, allowing proper handling with- out slipping of the drape or unwanted accidental activa- tion of the controls. The draping starts with the optical lens, which has a tight-fitting ring around it leaving the lens open for maximum optical quality. While the opti- cal unit around the lens remains sterile, the lens itself is uncovered and thereby unsterile. If surgical instru- ments touch the lens accidentally, they must be immedi- ately removed from the field and sorted out of the sterile environment. The drape, which is usually custom-made for a specific microscope model and available through the microscope manufacturer, is tightened around the joints, allowing full movement of all joints. Attention should be paid to loose folds of the drape over the lever arms that might come in contact with the non-sterile headcover of the surgeon or the assistant. Special atten- tion should also be paid to the oculars. Tight fit of the drape is mandatory in this area. The ends and folds of the drape must not overlap the oculars so the eye con- tact to the oculars themselves is not obstructed. Mini- mal microscope drapes that cover only the handlebars and leave the rest unsterile do not fulfill the aseptic re- quirements of microsurgical spine surgery.
5.3.2
Surgeon’s Settings
Since the entire optical unit does not have the lens sys- tem in the center of the microscope, it has a surgeon’s side and an assistant’s side. The surgeon should stand on the side with the shorter eye–lens distance to have a more comfortable working position. The tilt of the ocu- lars and the interocular distance can be adapted as well as the ocular length extensions. Surgeons wearing glas- ses should choose the shortest ocular length, others should increase it. The tilt of the oculars is frequently readjusted by the surgeon as well as the assistant. Em- ploying an over-the-top technique for microsurgical decompressions with an oblique view and an oblique tilt of the operating table is a classic situation for fre- quent readjustments of the ocular tilt (Fig. 5.2a, b).
Some microscopes have the option for settings of fo- cus and zoom speed, light intensity, and magnification range. The author proposes a medium zoom speed, quick focus speed, maximum light intensity, and full magnification range. The xenon or halogen light source
a
b
Fig. 5.2. a Short length of the oculars. b Long length of the ocu- lars
24 General
can provide sufficient lighting within the surgical field only when the alignment of the microscope toward the surgical field is precise and potentially light- and view- obstructing soft tissue is retracted or removed. The lighting blind should be opened to its maximum at the beginning of the procedure and limited to the retractor size as soon as they are placed. The lighting intensity is thereby increased and illumination, especially in deep anatomical structures, is improved.
The handlebars allow for monomanual adjustment of all important settings, especially zoom and focus and the movable degrees of freedom. However, this can only be reached if the entire microscope is balanced correctly. After release of the lock, the microscope must not drop in any direction if it is balanced properly. On microscopes that provide lateral movement of the han- dlebars, the handle for the surgeon’s dominant hand should be tilted upward about 45°. More space for han- dling of the instruments is obtained.
5.3.3 Magnification
The extent of magnification in a specific situation de- pends, of course, on personal preference. Generally, the more meticulous the anatomical structures dissected, the higher should be the magnification.
5.3.4
Assistant’s Settings
On most models, the surgeon’s settings regarding mag- nification, lighting, and zoom are displayed through the assistant’s side as well. However, on some models
the assistant has the option of obtaining his own set- tings of these parameters. A certain degree of magnifi- cation below that of the surgeon has proved useful to keep the overview. The individual settings for the ocu- lars and their tilt have to fit individual considerations.
5.4
Transporting the Microscope
Before moving the microscope to another room, all the lever arms have to be bent inward to ensure that the space taken up by the device is minimal. The joints and the footbrakes must be locked as soon as the micro- scope is in its final position. Often the manufacturer provides an extra cover for the optical unit to prevent dust accumulating, and this should always be used when the microscope is not in the operating room.
The cables connecting to the monitor and the re- corder as well as the electrical power cables should be sorted out and kept attached to the microscope to speed up the setup process next time it is used.
The entire microscope should be cleaned daily, and the maintenance of the optical unit and the lenses should be carried out according to manufacturer’s guidelines.
References
1. Mayer HM (ed) (2000) Minimally invasive spine surgery, 1st edn. Springer, Berlin Heidelberg New York
2. McCulloch JA, Young PH (eds) (1998) Essentials of spinal microsurgery. Lippincott-Raven, Philadelphia
5 Operating Room Setup and Handling of Surgical Microscopes 25
