Can Alternating Mattress Systems induce Ischemic/Reperfusion Injury?


Abstract- Alternating pressure and low-air loss mattress systems play an important role in critical care by simulating normal active hyperemia in the approximately 10% of the in-patient population that are insensate, non-ambulatory, unconscious or paralyzed. Conversely, about 90% of the in-patient population are semi-ambulatory, capable of functional normal active hyperemia and do not benefit from powered bed systems which can induce discomfort and insomnia due to their heat, noise and movement. The overutilization of powered mattress systems is a major unnecessary cost in healthcare today. Powered systems can also be misadjusted and patients must be carefully matched to powered low-air loss and alternating mattress systems. A US Patented real-time mattress interface pres- sure / deep tissue oxygen tension evaluation and design technology demonstrates that powered mattress systems are not indicated for most patients and that they are capable of inducing a repetitive is- chemic/reperfusion injury. Flat architecture non-powered and powered mattress systems can induce significant and repetitive focal pressures on heals. All mattress systems must be used in strict accor- dance with manufacturer’s guidelines and the use of pressure/shear protective boots should always be considered.


Evaluating clinical mattress systems- Beginning 2014, this Patented Mattress Evaluation and Development System has tested sixteen (16) of the most common commercial clinical mattresses. This included non-powered, powered low-air loss and alternating mattress system designs. Testing was conducted with multiple subjects and outcomes were averaged. The system has been utilized to develop mattress and bed systems with superior clinical characteristics.

In this graphic comparison, a newly developed Mattress and Bed Frame (top) is compared to a leading intergraded bed / frame system. This unique system allows for the real-time and simultaneous measurement of patient / mattress interfacial pressures and deep tissue oxygen tensions. The system is able to detect subject silhouette pressure changes during breathing and sense changes in oxygen tensions when the subject hyperventilates.


Some Alternating Mattress designs can induce Ischemic / Reper- fusion Injury- During in-hospital and laboratory research, it was not- ed that when some alternating mattresses are not adjusted correctly for patient weight or other electronic feedback systems are not operating as intended, the alternating cells can become too hard, then too soft. This can induce focal pressures and Repetitive Reactive Hyperemia when 20% + Delta pressure changes are experienced in the occipital, scapula, sacrum, trochanter, ischium and heels.

In the above graph- alternating mattress “A” is an example of an alternating mattress inducing reactive hyperemia in the sacral tissue where tissue oxygen tensions (red-line) alternate with the cyclic cell pressure changes between 95-70% (95% = instrument 100% full-scale) and a 25% pressure (delta) change. When the alternating mattress air cell is decompressed and the sacrum is off-loaded, the sacral tissue oxygen tension rebounds to full- scale and remains in sustained, uncontrolled vasodilation (reactive Hyperemia). When the mattress air cell is compressed, the increased focal pres- sure reduces blood flow and the sacral tissue oxygen tension goes down.

Clinicians should be aware that alternating mattress systems should be adjusted to simulate normal patient-induced off-loading movements (active hyperemia). Normal active Hyperemia would be defined as 15% or less Delta oxygen tension change. Extreme alternating changes in oxygen tensions can induce a repetitive I/R injury syndrome leading to an ischemic reperfusion injury and eventual pressure ulcer development.

In the above graph- Alternating Mattress system “B” is an example of an alternating mattress, simulating a patient induced normal  active  hyperemia. The sacral tissue oxygen tensions (red line) alternate between an average of 86-73% (13% Delta) when the alternating mattress air cell is decompressed and tissues are off-loaded and when the mattress air cell is com- pressed and sacral tissue oxygen tension goes down.

A comparison of the two graphs demonstrates the differences in sacral oxygen tension fluctuations between an alternating  mattress  “B”  properly adjusted to simulate normal patient off-loading active hyperemia and the alternating mattress “A” that is misadjusted. Any Oxygen Tension Delta change exceeding 20% is considered problematic. The “A” Sacral oxygen tensions routinely exceed the recommended Delta and their long duration  at full scale implies fully uncontrolled vasodilation reactive hyperemia and pending repetitive reperfusion injury where neutrophil (white cell) adherence to the capillary vessel endothelium that causes vessel damage, cell rolling and a decrease in blood flow and tissue oxygen tensions with each repetitive reperfusion injury cycle.

The above graph represents a theoretical progression of I/R over 2-hour patient turning cycles. The three peaks on the right side of the graph are extrapolated from actual testing depicted in the two graph peaks at the left   side of the graph. These two events are actual tests conducted 90-minutes apart with a 13-minute and then a 17-minute uncontrolled reactive hyperemia of the subject’s sacrum. Based on our test results to date, we believe that this extrapolated 2-hour data to the right is representative of the actual progression of repetitive ischemia and hypoxia leading to significant I/R in- jury and a progressive blood flow reduction/occlusion injury and then ulcer. The authors continue to research this bio-mechanical process. Actual turning intervals required to prevent I/R injury are unique in each patient.


  1. For over 60 years, healthcare mattress systems have been de- signed solely on patient/mattress interface pressure mapping and subjective Our research and clinical trials support the pre- dominant literature that pressure mapping alone is not a reliable real-time indicator of mattress design superiority.
  2. In 2008, CMS declined to pay for care related to Hospital Acquired Pressure Ulcers (HAPU). The limited technology at the time supported assumptions that placing all patients on elaborate powered mattress systems would mitigate pressure ulcers. This has demonstrated to be largely incorrect. The over-utilization of powered mattress systems has resulted in multiple millions of dollars in unnecessary healthcare costs for powered mattress equipment and the induced insomnia can have a negative effect on Length of Stay.
  3. It is estimated that 90%+ of all hospital and long-term care facility patients are capable of clinically functional normal active hyperemia and should be placed on non-powered weight redistribution mattress systems to improve restorative sleep and lower cost of Only Patients incapable of semi-ambulatory movement and unable to induce normal active hyperemia should be placed on powered mattresses systems.
  4. Tissue interface pressure and blood perfusion are not inversely proportional. Simultaneous pressure/oxygen saturation testing indicates that there is no positive correlation between increased patient/mattress interface pressures and decreased blood perfusion in tissue as measured by blood oxygen saturation oximetry.
  5. The pathophysiology of pressure injury and ulcer development is just beginning to be The true dynamics of repetitive is- chemia/reperfusion injury as they relate to deep-tissue oxygen/nutrient supply and cell metabolite management are critical to pres- sure injury prevention, ulcer development, and wound care.
  6. The time and tissue interface pressures required to induce an ischemic/reperfusion injury event vary significantly from patient to patient with age, co-morbidities, and functional circulatory auto-regulation as major factors.
  7. Flat architecture mattress systems suspend the weight of the leg between the gluteal muscles/ischium and the heel. This places high focal pressures on the heels and can induce near immediate ischemia and leading to a pressure injury as demonstrated during actual pressure / oxygen testing.
  8. Sleep Disturbances can also be experienced when the knee joint is locked and induces a proprioceptive autonomic feedback known to inhibit deep restorative (REM) It is recommended that any flat architecture mattress system not be used without using a pillow under the leg calf to elevate the heels. Protective heel boots should always be considered with an appreciation that improperly adjusted boots that fail to suspend the ankle can actually increase focal heel pressures.


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  5. OXY-MAT ™ CMS / Medicare Homecare #EO373 Advance Pres- sure Reducing Mattress;
    USA & Foreign Patents Awarded #9,295,599 & Patent Pending
    #7,761,945 – US20130281804-A1, Meets Canadian Bed Entrapment Standards
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