A clinical warning system that uses wireless sensors to track the vital signs of at-risk patients is undergoing a feasibility study at Barnes-Jewish Hospital in St. Louis.
When the full system is operational, sensors will take blood oxygenation and heart-rate readings from at-risk patients once or twice a minute. The data will be transmitted to a base station and combined with other data, such as lab test results, in the patient’s electronic medical record.
The incoming vital signs and data in the medical record will be continually scrutinized by a machine-learning algorithm looking for signs of clinical deterioration. If any such signs are found, the system will call a nurse on a cell phone, alerting the nurse to check on the patient.
The idea is to create a virtual ICU where the patients are not wired to beeping machines and instead are free to move about as they please, said Chenyang Lu, PhD, a computer scientist and professor at Washington University in St. Louis, who was the principal investigator for the prototype-network trial.
The performance of the prototype network, which was installed at Barnes-Jewish Hospital from June 4, 2009, until Jan. 31, 2010, was described at the SenSys ’10 conference in Zurich, Switzerland. The feasibility study of the clinical warning system now under way at the hospital will be presented at the American Medical Informatics Association Annual Symposium this October.
The clinical warning system is part of a burgeoning new field called body sensor networks or wireless health that, Lu said, will change the future of medicine.
Once they worked out the kinks, the computer scientists installed a prototype network in a cardiac step-down unit at Barnes-Jewish Hospital. Lu said he was pleased to find physicians and hospital administrators at the hospital who were technology savvy and willing to let him install the prototype network.
Clinical deterioration is a major concern in every hospital unit, said Thomas C. Bailey, MD, professor of medicine (infectious diseases) in the Washington University School of Medicine, who is collaborating with Lu on the system. Of hospitalized patients, between 4% and 17% suffer an adverse event such as myocardial infarction or respiratory arrest.
Most patients exhibit changes in their vital signs hours before an adverse event, sometimes as much as six hours before. In ICUs, vital signs continuously are monitored by wired devices, but in the step-down units, they often are measured intermittently by the unit’s clinical staff. A wireless sensor network could monitor vital signs tens or hundreds of times more frequently.
According to Lu, it will not be long before any patient with a serious medical condition, such as diabetes or asthma, will wear a wireless medical device that will allow him or her to monitor his or her own vital signs on a smartphone that also will call relatives or doctors if serious problems arise.
The device for an asthma sufferer, for example, might keep track of respiration rate, air quality and pollen counts, among other features. A frail patient might wear a wireless sensor with built-in accelerometers or gyroscopes that would monitor for falls.
The possibilities are endless, Liu said, and they all promise better, more consistent care at lower cost — the primary objective of healthcare.