Let the computer do the math

Clinicians and information technology experts worked together to create a heparin dosing calculator for their electronic health record.

Where: The Cleveland Clinic, a 9-hospital system based in Cleveland, Ohio.

The issue: Improving heparin dosing and administration.


Since residency, Aaron Hamilton, MD, FACP, had recognized heparin dosing as a challenging aspect of hospital care. “I'd get called in the middle of the night. I'd have to wake up, look at a chart, and do some complicated math to figure out how to adjust the dose that our patient was getting,” said Dr. Hamilton, now a hospitalist and medical director for patient safety at the Cleveland Clinic.

Even after the advent of electronic health records (EHRs) at the Cleveland Clinic, clinicians were still doing the calculations on paper or a pocket calculator. “At our hospital, we often had event reports that were related to problems or errors in the titration of heparin dosing, or in the initial dose,” said Dr. Hamilton. “That prompted us to think about, with the electronic health record, how can we leverage some of the capabilities that exist there and build upon them, to make the process of titrating heparin more reliable?”

The hospital's EHR (made by Epic) didn't come with a heparin calculator, so clinicians and information technology experts joined together to build their own.

How it works

To start with, the team built a calculator, put it on the Internet, and embedded a link to the calculator in the medication administration record. “You would manually put in the [patient's] weight, the most recent PTT [partial thromboplastin time] value, and you'd click ‘calculate’ and it would tell what your dose adjustment would be,” said Dr. Hamilton.

The calculator worked, but errors were still occurring. “People sometimes would pull the wrong weight or the wrong lab value—maybe the lab value from yesterday instead of today,” he said.

The team refined the calculator so it would automatically pull the necessary information for its calculations. “They no longer had to remember what the lab value was or toggle back and forth between windows. It was all right there in front of them,” said Dr. Hamilton. To allow clinicians to confirm the accuracy of the information collected by the calculator, it also shows the date and time that the weight and PTT value it uses were obtained.


After the team trained clinicians on its use, the calculator caught on. It now gets more than a thousand hits a day, according to an abstract presented by Dr. Hamilton and William H. Morris, MD, FACP, at Hospital Medicine 2014, held in Las Vegas in March.

The calculator's adoption notably improved the accuracy of heparin use, evidenced by a reduction in adverse events. The researchers also looked for improvements in patients' time in the therapeutic range of heparin dosing, and they found them: a 10% increase in attaining therapeutic PTT within 24 hours (P<0.001) and a 5% increase in time spent in the therapeutic range (P<0.001).

“That was really important in convincing other health care providers and caregivers that...not only was it efficient, but it was also a safe way to deliver care for our patients,” said Dr. Hamilton.

The calculator was part of a larger bundle of initiatives to improve heparin use, so other changes could also have contributed to the observed improvements. The bundle included a new order set for prescribing heparin, with more built-in information, and an effort by the phlebotomy team to get labs drawn more quickly. “We also worked with our nurses,” said Dr. Hamilton. “We instituted a dual signoff process for nurses whenever they adjust heparin, so 2 nurses have to confirm that the right change is being made.”

Challenges and next steps

After the team had hospital clinicians eagerly using their calculator (thanks to multiple educational initiatives involving both nurses and physicians), one challenge was how heparin would be dosed if the EHR system went down.

Their solution was to leave links on the hospital's Intranet to the old online calculator, for use if the EHR goes down but the Internet is still accessible. If the computers are all down, clinicians have to revert back to paper calculations. “When this has happened, it highlighted the real value of the tool we have developed,” Dr. Hamilton said.

The Cleveland team is now considering whether a similar solution would work for other medications. “We are exploring options for other calculators for titratable meds. One of the ones that immediately comes to mind is insulin,” said Dr. Hamilton. “We're thinking about other high-risk medications like opioids.”