What Works

Smart choices lead to substantial savings in pulse oximetry

by Barbara Jacobs, GWUH

Pulse oximetry is often referred to as the fifth vital sign. The value of continuous oxygenation monitoring in the critical care setting is nearly unquestioned, and the presence of it is ubiquitous. Recent advances in pulse oximetry technology have made the practice more reliable, safer, less prone to false alarms, and far stronger under duress than ever. But the use of all those sensors makes the cost of pulse oximetry a major factor in a hospital’s budget.Lowering this cost depends almost totally on the technology and durability of the pulse oximetry a hospital chooses.

The science of pulse oximetry depends upon the ability of the sensor to pick up the signal of two beams of light that have passed through the patient’s tissue and returned to the oximeter for processing. If processed correctly, the oximeter will determine the oxygen content in the patient’s blood flow. The sensitivity and precision required to read such a fine text, particularly under mitigating conditions like low perfusion and motion, must be keen. The math is in the algorithm, but often the magic is in the sensor itself. Unfortunately, when the sensor can’t return a signal, clinicians reach for another sensor, and then another sensor, in their attempt to find a suitable application site. Their frustrations increase, and so do their hospital’s costs. 

The promise of reusable sensors, obviously, is extended sensor life, and resultant lower costs. The problem all manufacturers face is that reusable sensors are necessarily bigger and may compromise the integrity of the blood flow in such a tender area as a digit. Most importantly, because they do not establish and maintain the same level of contact with the application site as the adhesive sensor, they often do not resolve the clinical issue of picking up weak patient signals.Adhesive sensors, then, which are as light as thin band-aids, continue to obtain better results than the reusables, but at a higher operational cost. So in order to accomplish the best of both worlds, the race among manufacturers is to somehow extend the life of adhesive sensors.

Three medical centers in the last several months have found enormous savings with oximeters belonging to the “next generation” technological era.

The new GWUH
In 2001, George Washington University Hospital began preparations to build a huge new hospital directly across the street from their old one. The project was completed last August 23 with a massive overnight move. The $96 million facility features architectural beauty that holds $45 million in new medical equipment and technology.

One of the great benefits of the move was that all departments underwent a technology review. Barbara Jacobs, director of Critical Care / Respiratory Therapy, oversaw the technology review in the NICU and PICU. The flagship mandate of the new move was “Improving Patient Safety.” Under that spirit, the staff at George Washington University Medical Center began reviewing the literature and testing various technologies, including pulse oximetry. Eventually, the pulse oximetry options were pared to two: the hospital’s existing technology from another pulse oximetry manufacturer or Masimo SET Pulse Oximetry from Masimo Corp., Irvine, CA. The recommendation from the nurses was that, in the spirit of “Improving Patient Safety,” Masimo SET was the favored option. The time came for Jacobs and staff to analyze the cost of the change.

Dollars and sensors
Using their existing manufacturer’s technology, the adult critical care units of George Washington University Hospital were spending $75,000 per year on the needed pulse oximetry sensors. Reviewing the Masimo SET technology, clinicians discovered two major benefits to the product: improved design for sensor rejuvenation, which they felt would outlast their current product by several times, and an innovative approach to reading signals through motion and low perfusion, which would at the same time require fewer sensors to be placed on a patient in the first place. Barbara Jacobs commented, “Sometimes I would walk onto the floor and find five sensors hanging from different parts of the same patient. The nurse was desperately trying to get a reading, but was spending a fortune on sensors in the process.” These two findings led staff to predict total annual cost with Masimo SET technology at $45,000, a savings of 40 percent over the previous technology. The conversion was made.

About six months through the conversion, the nurses were as enthusiastic about the new technology as they’d hoped. But the GWUH staff decided to run yet another cost analysis to check on their original math. When the analysis was completed, the estimated annual expenditure on pulse oximetry was no longer $45,000, but had actually been cut to $20,000. This constituted a further savings of 74 percent, a savings so extreme that it raised some questions. As Jacobs investigated, she found the figure to be accurate.

Jacobs gave the nursing staff a choice when it came to pulse oximetry sensor use: they could use the remaining store of disposable sensors, they could use the new Masimo disposable sensors, or they could use a combination of the new Masimo reusables and remaining inventory disposables. To her surprise, she found that in the majority of cases, nurses were happy with the Masimo reusables. They were not prone to false alarm, they were not prone to falling off the patient, and they were successful in reading through low perfusion and motion.

Even on patients in extreme situations, nurses still preferred the Masimo products, although they were more likely to use a adhesives in these situations. Disposable sensors, as previously implied, have a greater flexibility and a less cumbersome fit. Primary candidates for disposable sensor use are patients who generate much motion, for example, neonates (in which motion is a healthy and desired outcome), or adults with shivers or uncontrolled tremors. Disposables have also had a better record with some of the more advanced cases of low perfusion or low saturation. The disposables also had a far longer life than the hospital’s previous disposables, which was longer than even the hospital’s predictions. Jacobs reported that the Masimo adhesive, which is cleaned with just a dab of alcohol, would rejuvenate many times. Jacobs indicated she had heard reports from one hospital that a single sensor was rejuvenated over 60 times in a NICU under a policy of changing the placement of sensors each day. Even without the heavy use of the reusable sensors, the savings in disposable sensor use was profound.

The same savings east of GWUH
At around the same time as Barbara Jacobs at GWUH experienced a real decrease in pulse oximetry cost, researchers in Germany scientifically tested disposable sensors from the same two companies.1 Researchers, led by Thomas Erler, MD, studied a total of 121 infants at two medical centers. The Masimo SET LNOP Neo sensors lasted an average of 9.1 days, compared with the other pulse oximeter, which lasted 3.9 days. The Masimo sensors lasted over twice as long. Erler et al explained: “Sensor construction differs between manufacturers, with identified shortcoming being life of electrical components, loss of adhesive preventing appropriate emitter and detector alignment, and susceptibility to moisture with resultant bad odor. Particularly in a humidified incubator, PO [pulse oximetry] sensors ate easily soiled and develop an unpleasant odor. The humidity also leads to less adhesion. Therefore the consumption of PO sensors increases in this setting and so do costs. If the useful life of sensors is increased, as shown in our results for Masimo technology, a remarkable savings in costs in the NICU can occur. Our results show a more than two-fold longevity of the Masimo sensors.”

Spend money elsewhere
As pulse oximetry speeds toward higher fidelity, sensitivity and specificity, it also speeds away from misleading alarms and higher costs. The next generation of pulse oximetry has been marked by vastly increases fidelity, reliability, sensitivity, and specificity. Now, some of the new pulse oximetry technology is bringing the medical community positive advancement in the critical area of cost, as well. 

HPN

1 Erler, Thomas, MD, Avenarius, Stefan, MD, Wischniewski, Esther, MD, Schmidt, Katerina, MD, Klaber, Hans-George, MD. “Longevity of Masimo and Nellcor Pulse Oximeter Sensors in the Care of Infants.” Journal of Perinatology 2003; 23:133-135.

July 2003