The simulators were based on the same technology. Both of them contained digital maps of surfaces, for instance, and both were intended to train operators to do their best at highly sensitive and risky work.

The big difference was that in one case the customer was the Swedish Air Force and in the other it was the Montefiore Medical Center in New York City.

Lockheed Martin Naval Electronics and Surveillance Systems in Akron, Ohio, had shipped Sweden's Air Force two full mission simulators as well as five multimission simulators by the conclusion of 1999.

The full mission simulators were designed to replicate all controls of the JAS 39 Gripen aircraft and incorporate visual displays of a mission environment, including terrain, as well as ground and airborne threats. Multimission simulators feature a three-display visual environment in a simulated cockpit.

A change of the simulator's database for precision rather than speed and for tissue manipulation instead of aircraft tactics resulted in the development of Lockheed Martin's endoscopic sinus surgery simulator. The virtual terrain thus became smaller—the human sinus instead of Northern Europe.

Using an endoscopic sinus surgery simulator, doctors can practice a variety of complex nasal procedures and reduce the risk to patients.

The surgery simulator was originally a military device, too. The contract to develop it came from the U.S. Army Medical Research and Materiel Command, and the first one was delivered to an Army hospital. The sinus simulator went to its first civilian client, Montefiore Medical Center/Albert Einstein College of Medicine in the Bronx, N.Y., early last year.

Nasal surgery is performed for several reasons, many of them cosmetic. Others involve nasal obstructions, injuries, or breathing complications, where surgery is requested more out of necessity than vanity. Although nasal surgery is common and has become more sophisticated over the years, nasal procedures are not simple.

While rhinoplasty, typically known as "a nose job," is the most common nasal surgery, the most dramatic developments have been made in functional endoscopic sinus surgery. This procedure is performed to improve the patient's health by restoring free breathing, and because it is not plastic surgery, it is not commonly encouraged to improve the patient's self-esteem or social status.

Surgery to repair a deviated septum is also a common, noncosmetic procedure. Complementary effects of this operation include a possible reduction in allergy-related symptoms, a decrease in the occurrence of sinusitis, and sometimes a reduction in nasal-related headaches.

Using simulation technology originally designed for military applications, the simulator features a dummy named Martin and can simulate a broad range of situations, including the effects of medication on a patient.

The benefits of such surgery do not accrue without risks, however. According to Marvin Fried, the chief surgeon for otolaryngology at Montefiore Medical Center, endoscopic nasal sur-gery is particularly complex for several reasons. "The proximity to the brain is an important aspect of nasal surgery," he said.

Risks include potential perforation of the nasal septum if the cartilage and mucous membranes do not heal correctly, postoperative bleeding from the nose, infections, occasionally a decrease in the sense of smell, and in rare cases a change in external appearance.

Inevitable Risks

"The biggest risk," according to Fried, "is that there have been instances where during the course of the procedure, the optic nerve is cut and either seriously impairs the vision or blinds the patient."

This complexity makes sinus and nasal surgeries among the most litigated of medical procedures. Fried explained that the proximity to the brain and, subsequently, to the central nervous system, makes the risks inevitable.

"Because this is high-risk surgery, repetitive training may make a difference in surgical outcomes," said Fried. "Sinus anatomy is complex and rigid, so having a database model is practical."

Graphics displayed on the simulator's monitor are derived from actual cadaver scans that were converted into three-dimensional images

During sinus surgery, the surgeon inserts an endoscope, or camera-tipped probe, into the sinus passageway to view the procedure on a monitor during the operation. The surgeon uses other instruments, such as small forceps, needles, and scalpels, to manipulate, inject, and remove tissue.

Fried explained that surgeons must recognize anatomy landmarks to ensure that they don't probe too deeply up the passageway into the brain or cut crucial arteries. He said a medical simulator used to train surgeons could be helpful in making sure a doctor knows exactly what to do in various situations.

Surgery for Dummies

Using simulation technology that was borrowed from naval applications, Lockheed Martin designed a surgical simulation mannequin for use in training surgeons in this complex and risky procedure. The mannequin, appropriately named Martin, provides visual and haptic simulation of nasal sur-gery for training.

"It's the same technology used by the Navy to simulate terrain and combat conditions in military training," explained Andrew Gurcak, the medical simulation product manager at Lockheed Martin.

During sinus surgery, a doctor inserts an endoscope to monitor the procedure as it takes place. There are serious risks involved with nasal surgery because of the proximity of the brain and optic nerve to the nasal passage.

"Our experience in training simulators for military aircraft enabled us to solve technical problems associated with real-time simulation of surgical procedures. The primary difference with the nasal simulator is that instead of simulating terrain, and battle conditions, it simulates nasal anatomy for surgical precision," said Gurcak.

"In the realm of fighter aircraft simulation, our image database creates a real-world environment that is sometimes moving at the speed of sound," Gurcak explained. "With surgical simulation, it's not the speed of the action, but the exactness of simulated tissue deformation, reaction to drugs and trauma, and the tactile feel of surgical instruments that is necessary."

Simulator Training

The simulator is designed to train nasal surgeons and ear, nose, and throat residents to evaluate new techniques, handle instruments more efficiently, and familiarize themselves with anatomy.

Instructors or students can select from several surgical suites of anatomical variants, such as a deviated septum, for training in each of these disciplines using accurate models of human sinus conditions. In addition, the simulator allows users to hear the virtual patient's heart rate when drugs are injected, teaching doctors what to expect in the course of an actual surgery. The instruments also feature haptic feedback to simulate tissue resistance when incisions are performed.

The anatomical models are based on the imagery supplied by the Visible Human Project that was conducted by the National Library of Medicine in Bethesda, Md.

The Visible Human Project began in 1993 when researchers sliced thousands of razor-thin cross sections of tissue from one male cadaver and one female cadaver. Each view was digitally photographed to be converted into full-color, three-dimensional images, thus providing a virtual tour of the entire human body. One of the main intentions of the project was to allow a pursuit of surgical simulations.

Past and Promise

According to Gurcak, Lockheed Martin developed the first endoscopic sinus surgery simulator for Madigan Army Medical Center in Tacoma, Wash., in 1997. Medical students there began using it for hands-on training.

In 1998, voice recognition technology was added to the Madigan simulator. Since that time, an additional simulator was delivered to the U.S. Naval Medical Command in San Diego. The initial commercial delivery was made to Montefiore Medical Center in the Bronx early last year.

F-16 Mission Training Center units for the U.S. Air Force that use the same simulation technology as the nasal simulator are scheduled for delivery late this year and in early 2002.

Henry Grausz, who is himself a surgeon and the president of MedOps, a consortium of surgeons headquartered in Wilmington, Del., said, "Montefiore Medical Center and the Albert Einstein College of Medicine represents an opportune debut for the simulator, considering that there are approximately 120 nasal specialists in the New York City area along with the 24 ENT residents at Montefiore alone."

Grausz, whose group has exclusive licensing and distribution rights to the Lockheed Martin simulator, hopes that if use of the simulator can reduce the number of risks in nasal surgery, it may encourage health care insurance providers to require such training of surgeons in the future.

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