Rarely is time on the side of the operating room. In many cases, every minute costs dearly. And more and more often, pressure ulcers are being seen as a potentially expensive outcome of time spent in the OR, one that can create ripple effects throughout the entire healthcare system. That pressure sore that’s found on the nursing home resident may very well have started in the OR.

“Awareness of OR-acquired pressure sores has increased over the last few years,” said Dan Allen, a consultant for STERIS Corporation, Mentor, OH. “Longer surgeries are being performed on higher risk patients. The risks of developing a pressure ulcer as the result of an OR experience is increasing every year.”

“Time is one of the biggest issues in pressure ulcer development,” explained Allen, who specializes in surgical table accessories, patient posturing, pressure management and pressure sore prevention. The developer of the Allen Stirrup, he has spent the last 25 years devoted to developing posturing devices that protect patients from injuries that may occur as a result of lengthy surgical procedures.

The Association of periOperative Registered Nurses (AORN) 2006 Recommended Practices for Positioning the Patient in the Perioperative Setting, state that “procedures longer than two and one-half to three hours significantly increase the patient’s risk for pressure ulcer formation.”

While AORN guidelines recommend pressure relief surfaces for surgeries lasting longer than two hours, “pressure sores can start to form in as few as 20 minutes,” acknowledged Michael Bredal, vice president, sales for Action Products Inc., Hagerstown, MD. “It’s important to think about how quickly they can form.”

Complicating the matter, said Allen, “When a patient’s under anesthesia, they can’t tell you what hurts. The highest level of risk occurs when the patient is least able to provide feedback to deal with it.”

Therefore, “Vigilance and making sure they’re using products that are appropriate is key to pressure ulcer prevention”, said Bredal.

“Pressure sores develop from a combination of intrinsic and environmental causes,” said Allen. Patients are at greatest risk for pressure sore development as the result of pressures created at the bone-tissue interface. Bony prominences (heels, sacrum, shoulder blades, back of the head and elbows) are the most susceptible sites. Allen calls these sites “the landing gear” because they are the primary support structures interfacing with the table surface. “The goal of posturing a patient to achieve pressure relief is accomplished when pressure is redistributed away from the bone-tissue interface to areas where the bone is no longer pressing into tissue,” he said.

Vertical and horizontal shear also contribute to the formation of pressure sores. Capillaries allow only one blood cell to pass through at a time. If you stretch or elongate the capillary enough, it can become so thin as to be occlusive. If that occurs, blood cells can’t get through and tissue can die. According to early studies, it takes only 32 mm/Hg interface pressure to close a capillary, Allen noted. AORN guidelines state “studies suggest that positioning devices should maintain normal capillary interface pressure of 32 mm/Hg or less.” (1)

If you’ve ever shopped for pressure management devices, or even a new mattress for your home, you’ve probably seen a pressure map. With areas that are considered to be high pressure marked in red, and low pressure areas marked in shades of white and blue, pressure maps are often used in an attempt to compare interface pressures to represent the efficacy of patient surfaces, but manufacturers cautioned against using them as the sole measure of a product’s pressure-relieving performance. Looks can be deceiving, they agreed.

For one, the scales representing pressure can be set for favorable results. Allen explained, “A number of comparative pressure maps utilize a scale of 0 (white) to 125 (red) to represent the quality of their pressure management surface. It would be better science for manufacturers to supply pressure mapping using a much lower scale range. Since interface pressures greater than 32 mm/Hg close capillaries, the pressure maps should be set at 0-50 with any interface pressure greater than 50mm/Hg being depicted in red. Unless lower scales are applied to this mapping, it will continue to be difficult to evaluate patient surfaces.”

Action’s Bredal pointed out another nuance related to pressure maps that buyers should be aware of. “The way that pressure maps are conducted is that you do an average of all of the sensors that are activated. There are pressure points that would go beyond 32 mm/ Hg, but on average they are below. That is the industry standard for measuring pressure.”

Added Michael Brown, senior programs manager for therapeutic surfaces, Kinetic Concepts Inc. (KCI), San Antonio, TX, “An individual pressure map really only represents how a surface performed for the patient being measured, by the technology (equipment) used to measure, and dependent on how the equipment was set up and calibrated. Bottom line, pressure maps can be misleading.”