Trending Toward Point-of-Care Glucose Testing

By Dana Hinesly

Since its introduction in the 1970s, point-of-care (POC) glucose testing has gained steady acceptance in the medical community. The ability to monitor a patient’s blood-sugar level within minutes revolutionized the care physicians were able to give hyperglycemic patients in the hospital.

“The move toward increasing the volume of point-of-care testing has happened because the immediate turnaround means you can make quick clinical decisions,” says Neil Grey, MD, FACP, FACE, medical director, Diabetes LifeCare, Hartford Hospital (Hartford, Conn). “It has virtually replaced other laboratory glucose determinations.”

Providing information immediately made these tests popular, but the relatively recent introduction of short- and rapid-acting insulins—which can begin working in as little as 5 minutes—has made them lifesavers.

“These newer insulins make this rapid turnaround of information all the more important,” says Grey. “If you know the blood sugar is high, you can treat the patient immediately and know the blood sugar will react to the therapy right away.”

This is a dramatic improvement over the glycemic control measures in place 20 years ago. Not only did insulin take upward of 30 minutes to take effect, but it was often administered only after blood was drawn and processed in the lab, which resulted in as much as a 2-hour delay.

Proving the Case
One factor driving the increase in glucose testing at the bedside is the work done at Providence St Vincent Medical Center (Portland, Ore) by Anthony Furnary, MD, FACS, FACC, senior surgeon, and a member of the Starr-Wood Cardiac Group.

The study, called the Portland Diabetic Project, was able to show hyperglycemia has an adverse effect on cardiac surgical outcomes. This study focused specifically on illustrating the connection between hyperglycemia and negative outcomes of cardiac surgical procedures in diabetic patients, as well as the role intravenous insulin therapy plays in reducing both the morbidity and mortality in these individuals.

Over the course of 17 years, more than 5,000 open-heart patients at Providence St Vincent were studied. During the perioperative period, each patient’s blood-glucose level was tested routinely at 30-minute to 2-hour intervals. The study found that increasing blood-glucose levels were directly associated with increasing rates of death. Results also indicated that the reverse was true: Continuous intravenous insulin (CII) therapy independently reduced the risk of death by 57%.

CII is a nurse-run protocol that determines the patient’s appropriate glucose level and implements POC testing to maintain it. Using this approach lowered the mortality rate for diabetic coronary artery bypass grafting patients to equal the rate of nondiabetic individuals.

According to the published report, “Target blood glucose levels of less than 150 mg/dL and a 3-day postoperative duration of CII therapy are both important variables that determine the effect of the CII therapy on improved outcomes.”

Fewer Infections, Faster Discharge
The Portland Project also demonstrated that achieving correct blood-sugar levels impacted other areas of patient health, including deep sternal wound infections (DSWI) and the length of a patient’s hospital stay. The application of CII therapy reduced the risks of DSWI by 66%.

The staff at Hartford Hospital also incorporated POC testing of glucose levels into the facility’s quality-improvement program, which is working to decrease surgical-site infections. In addition to closely monitoring the patient’s body temperature, one tenet of the program is tight glycemic control.

“Hyperglycemia is a risk factor for surgical-site infections,” explains Grey, noting that the program requires every patient who comes in for surgery to receive POC blood-sugar testing via a finger-stick test. “Patients with either a history of diabetes or a blood sugar greater than 125 mg/dL are evaluated by us for the need for insulin, to ensure they are euglycemia throughout the perioperative period.”

According to Grey, the literature also suggests a tie between increased blood sugar and stenosis of coronary stents in patients undergoing stent placement. “We’re now measuring blood sugars in patients in the cardiac cath lab,” says Grey. “There’s some evidence that patients who come to the cath lab with normal blood sugar do better than patients who have hyperglycemia at the time of care.”

Making It Happen
Furnary’s team believes their findings demonstrate the necessity of implementing CII therapy as the “standard care for glycometabolic control in all patients undergoing open-heart surgical procedures.”

Commonly referred to as simply the Portland Protocol, the provisions dictate that all patients should receive regular testing and insulin treatments through the morning of the third postoperative day, as most infection was found in those who were hyperglycemic on the day of surgery and the following 2 days.

“Our data have spawned a paradigm shift in medicine,” says Furnary. “Frequent glucose POC testing and intensive glycemic control of hospitalized patients is the new standard of care for diabetics.”

Grey believes the next generation of monitoring tools will further increase participation in the Portland Protocol.

“Many institutions are utilizing intravenous insulin infusions in critically ill patients, for example in the ICU, after open-heart surgery, in those with acute myocardial infarction,” he says. “But not all of them are doing it, and I think that one of the perceived obstacles is the need for more frequent finger-sticks.”

A system that constantly monitors a patient’s blood sugar would provide the necessary information without any bother to the patient, removing one more hurdle. Grey is looking forward to the day when a patient’s glucose level is available with the flip of a switch, much like today’s telemetry systems.

Changing Roles in the Clinical Lab
The ever-increasing use of POC glucose testing inevitably changes the dynamic between physicians and the clinical lab.

“Most of the values we rely on for clinical decision-making come from point-of-care testing,” says Grey. He adds that blood-sugar values in lab results are often obtained after technicians download them from the testing system done at the bedside.

While POC glucose testing doesn’t take clinical lab professionals completely out of the picture, it will alter their role. The responsibility for quality control falls to the team in the lab, for example.

“Our clinical lab technicians are the people who really have the responsibility for point-of-care testing, and they need to be involved for a number of reasons,” says Grey. “If you simply turned the meters loose on the floors with no quality control, then you might make mistakes in clinical judgment based on erroneous lab values.”

At Hartford Hospital, POC testing is seen as part of the responsibility of a dedicated team from the clinical lab, providing the hospital staff with an immediate resource to answer questions or perform troubleshooting on faulty meters. The facility also has safeguards in place to ensure that the meters are reading accurately throughout the day.

“If a glucose exceeds 400mg/dL, it calls for an automatic lab draw to confirm, as does a glucose level of less than 60,” says Grey. “As we perform more and more point-of-care testing, the more important it is to have quality control built into the process.”

It is also imperative that lab professionals work with clinicians to ensure that POC systems are calibrated as often as necessary to help guarantee accurate results. Hartford Hospital’s lab professionals calibrate their meters at least once each day and sometimes on each shift, roughly every 8 hours.

“Clinical lab techs do not do the point-of-care testing at the bedside,” says Furnary. “However, they will be required to know the ins and outs of all systems and to help the clinical caregivers choose the best system for their hospitals.”

Grey concurs that the responsibility of screening and approving new systems for purchase also falls to the lab staff.

“They review competitive bids and compare different systems and meters for accuracy,” he says. “They make decisions not only based on science , but also on what feels comfortable and how it works on the floor.”

Dana Hinesly is a contributing writer for Clinical Lab Products.