Walls and Ceilings July 2011
Prescribing a New Hospital
Advances in medical technologies and practices have spurred new thinking about the construction of medical suites.
By Jon Mooney
A relatively inexpensive hobby of mine is the collecting of
old technology books. My collection includes books on rebuilding
player pianos, blacksmithing and a mail order course on how
to set up a vacuum tube radio repair shop (I will be set if
my time machine leaves me stranded in the 1850s or 1950s). One
of my favorite books was written in 1870 and describes the technology
of the day and includes a prediction of the U.S. and technology
in 1970. Although the future world it describes is interesting
(including mass transportation through giant wooden pneumatic
tubes) the 100-year prediction was too far a stretch to extrapolate
the technology of this period. Today's rate of technological
advancement makes even a 10-year prediction questionable. Therefore,
with that warning, I present the state of current hospital operating
room technology and venture a prediction of the surgical suite
in the year 2020.
Paging Dr. Difficult
If you have ever helped construct a surgical suite, you will
agree it is one of the more complicated and most inspected
project types. Most inspected because surgical suites must
comply with Department of Health regulations and Facilities
Guideline Institute design practices before they are approved
for use. More complicated since simple building component
designs cannot generally meet one performance requirement
without compromising another.
Present surgical suite design is heavily influenced by the FGI which publishes "Guidelines for Design and Construction of Healthcare Facilities" once every four years. The FGI is a collaboration between the American Institute of Architects and the United States Department of Health & Human Services.
To reduce the opportunity for organism growth within the surgical suite, the FGI guideline requires surgical suite ceilings to be "monolithic" (a surface free of fissures, cracks and crevices). Today, this usually means hard, smooth surfaces of epoxy finished gypsum. Walls are typically ceramic tile or epoxy finished wallboard and floors are seamless sheet vinyl, linoleum or rubber. But, because completely hard room finishes result in a reverberant room, they add to the cacophony of mechanical and medical equipment noise and reduce the speech intelligibility within the room. To address this issue, surgical suites in Europe have begun using stretched plastic ceilings with fiberglass sound absorber panels placed above them. Noise passes easily through the stretched plastic ceiling where it is absorbed by the fiberglass panels. According to Pascal Gicquel, president of Newmat USA Ltd., "While Newmat (stretched PVC ceiling) would be perfect for this particular application because of its monolithic aspect, the fact that it can be sealed, the fact that it is washable and the fact that we have a specific membrane with a "bio-pruf" treatment (anti-bacterial), we have been unable to be specified and/or used for this type of application in the United States. I am not clear on the reasons for this failure, since we have done similar applications throughout Europe."
Presently, washable and demountable sound absorption is allowed on the walls of a U.S. surgical suite. Robert Marshall, Technical Services Engineer for CertainTeed recommends Hygiene Advance Wall or Hygiene Foodtec Wall. "Essentially removable acoustic panels (for cleaning the panel and cleaning behind the panel) … provide excellent absorption."
Turn Your Head and…
Ventilation is another important regulated requirement of
surgical suites. The ventilation system is arranged so that
air drops down from the ceiling directly above the operating
table and travels outward. In the ideal case, every air molecule
travels along an airstream directly from inlet to return,
passing the operating table only once and spending only about
two or three minutes in the room. But, since most surgical
suites are not aerodynamic but rather rectangular rooms filled
with obstructions, airstreams tend to break up into less than
ideal patterns. Also, replacing all of the air in the room
every two or three minutes results in noise created by air
rushing in and out of ventilation grilles through ductwork
and control dampers and by the fans that supply the air. At
this high rate of ventilation, even air rushing out the bottom
and sides of doors can cause noise issues. Present FGI guidelines
recommend quiet operating rooms but also point out, "…
current ventilation system technologies and devices required
for sanitary purposes often result in sound levels higher
than these."
Also a function of ventilation is the control of room temperature. Preferred room temperature and temperature of air surrounding the patient depends on the type of operation and the needs of the surgeon. Surgeons and their staffs want to be cool because of gowning requirements and the amount of time they are in the OR but the type of surgery will dictate conditions in the room. Cardio procedures typically cool the patient while pediatric procedures may require a warm-up cycle.
Better or Worse?
Lighting requirements are much more complicated than one might
first suspect. Of course, the amount of light on the patient
must be at least the required minimum. The amount of infrared
light is kept at a minimum to prevent drying of tissue and
localized heating of the room. The amount of light on room
surfaces should not be less than one third of that on the
patient. This is to prevent the surgeon's eyes from becoming
fatigued as they periodically look up to monitor equipment.
Surgeons may prefer certain colors of light for specific operations.
A recent development is the replacement of incandescent surgical
lights with focused LED lights.
When I asked KJWW Engineering's Senior Clinical Engineer, Tom Todro, what equipment should be included in our future surgical suite he replied, "You would want to include surgical robots and surgical navigation systems as well as video integration. Though not yet an industry standard term, the 'wall of knowledge' is gaining more interest. There are all kinds of data sources, alarms, patient data, etc., that are all discrete systems. The wall of knowledge seeks to integrate these systems displaying only the information that the surgeon needs and alarm information should conditions change from the normal operating range. The prevalence of surgical navigation and surgical robots is growing at a phenomenal rate. These systems allow the surgeon to view not only the actual patient but also a composite image from a CT (Cat Scan). The surgical robot is operated by the surgeon and both systems allow for truly minimal invasive surgery (smaller incision) which leads to faster recovery, reduced stress on the patient and reduced post-surgical complications from infection."
Steady as She Goes
Micro-vibrations in the floor and ceiling of the surgical
suite, caused by mechanical equipment in a distant part of
the building, can cause blurry images in high resolution medical
equipment such as the surgical microscopes used in brain surgery.
The classic solution is to mount the equipment on a massive
concrete pad which sits on springs. However, as medical equipment
becomes more sensitive, the pads must be designed heavier
and the springs must be made longer. Presently, equipment
sensitivities require spring lengths and pad weights which
are becoming unwieldy in construction. A relatively new type
of isolator which doesn't require excessive weight or spring
lengths is the negative stiffness mechanism developed by Minus-K
Technology. According to Jim McMahon, President of Zebra Communications
and technical spokesman for Minus K, "I do understand,
with the increased use of sensitive optical instrumentation
in the OR, it is inevitable that non-intrusive vibration isolation
would be required. For quite some time, Negative-Stiffness
Mechanism vibration isolation has been used in laboratory
environments, including sensitive medical research applications,
not only because of its superior capability of canceling out
vibrations that can negatively influence operation of sensitive
optical instrumentation, but also because of its non-dependency
on electricity or pneumatic requirements, making NSM an ideal
system for critical environments such as Class 100 operating
rooms."
Utterly New and Not so Different
Starting with today's state of the art, we have developed
a concept of the surgical suite of 2020. Gypsum board manufacturers
and contractors will be happy to know the surgical suite of
2020 still has rectangular gypsum walls and ceilings. In most
cases, it just is not feasible to fit non-rectangular rooms
within a building envelope. To isolate the surgical suite
from building vibrations and noise from adjacent spaces, the
entire room floats on several NSMs. Beneath the gypsum ceiling
is a stretched plastic ceiling, supported by tubular framing
and given the shape of an isentropic expansion nozzle to encourage
ventilation air to remain laminar. Sound absorption, as well
as indirect room lighting, is hidden between the stretched
plastic ceiling and the hard gypsum lid. Borrowing from James
Dyson's bladeless fan look, we have anticipated a major advance
in ventilation design using concentric airfoil rings with
separate injected flows and allowing detailed airflow and
temperature adjustments with minimal noise.
Surgical lights have been taken off the ceiling and placed at the incision site. To make sure the room stays well sealed, entry doors are Tanaka-type automatic slat doors, each pair of slats opening only about 2 inches wider than the person or object passing through. To allow the room to be thoroughly disinfected without damaging medical electronics, the wall of knowledge is now a 3-D, holographic display with all of the electronics housed safely in a separate room. And although no-one else mentioned the need, I have seen enough operating rooms to know that a great sound system, preloaded with the surgeon's music library will definitely be part of the surgical suite of 2020. Take a tour and listen to the 2020 surgical suite on my Web site www.jwmooney.com. (available August 2011).