Thursday, May 16th 2013
Vaccines work best when kept within a narrow temperature range, but many medical facilities fail to meet these standards, often erring on the side of keeping their refrigerators too cold. Since poor temperature management can damage vaccines and reduce their effectiveness, researchers are looking for ways to ensure temperature stability in vaccine storage areas. A recent project from engineering students at Rice University paired temperature sensor equipment with a controller that regulates power to make refrigeration more consistent.
The Rice University project was prompted by Dr. Patrick McColloster, an associate professor of family and community medicine at Baylor College of Medicine, whose research in vaccine storage has shown that many medical providers fail to implement proper temperature controls. In a 2011 study of Houston medical facilities, McColloster found that many were freezing their vaccines, which reduces their effectiveness.
His findings were supplemented by a U.S. Department of Health and Human Services study that found vaccine refrigeration problems around the country. In that study, vaccines at 76 percent of the providers audited were exposed to inappropriate temperatures for at least five cumulative hours during a two-week study period.
"The problem isn't that the vaccines are wasted or thrown away because of improper temperature management," said Amanda Walborn, a member of the SAFE Vaccine team, which developed the refrigeration control solution. "It's that the vaccine gets damaged and nobody knows it. And it gets administered anyway."
Solving the storage problem
The problem of inconsistent temperatures could be addressed by installing laboratory-grade refrigerators at medical providers' facilities, but doing so is cost prohibitive for most smaller practices, McColloster explained. Many of these providers use commercial refrigerators, which lack sophisticated temperature monitoring and control features.
The Centers for Disease Control and Prevention's vaccine handling guide mandates most vaccines be kept between 2 degrees C and 8 degrees C. Vaccines are often exposed to temperatures outside this range due to a lack of temperature regulation in the refrigerator unit. Since nurses and doctors are constantly opening refrigerators throughout the day, they often turn down the refrigerator's thermostat to compensate for the outside heat, McColloster found. This approach can cause the vaccines to freeze when the door is left closed for extended periods.
"They set it to the lowest setting to keep it cold enough," explained Andres Martin de Nicolas, another student on the SAFE Vaccine team. "But if they leave it there overnight and during weekends, the temperature will drop too much. It's very easy to overlook."
The SAFE Vaccine team's solution addresses this issue by connecting temperature sensors inside the refrigerator to a controller mounted on the outside. Based on the sensor input, the controller regulates the amount of power the refrigerator draws, thus impacting the amount of cooling.
Some of the students plan to keep working on the project over the summer to create a functional prototype that incorporates features such as a power backup system, essential for avoiding temperature swings in a blackout or brownout. While McColloster's original project plan called for the construction of a new refrigerator, the students determined it would be easier, more precise and more cost effective to develop an external temperature monitoring system.
Medical facilities can implement similar technology to keep their vaccines at a stable temperature by deploying temperature sensors like the ones from ITWatchDogs. Temperature sensor data can be used to create regulating systems such as the SAFE Vaccine team's device or to enable remote monitoring that allows facility owners to respond quickly in the event of unusual temperature conditions. By leveraging sensor data, medical providers can improve vaccine storage and reduce the prevalence of vaccines being rendered ineffective due to poor temperature conditions.
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