By shrinking an entire chemistry lab to the size of a pinhead, technology now enables physicians to watch a patient’s condition almost as if they’d shriveled themselves up and traveled inside his body.
Doctors can quickly spot even subtle changes in the carbon dioxide and oxygen levels in a patient’s blood, as well as shifts in acidity or temperature, allowing them to take corrective action immediately.
Beyond patient care, the new technology shows great potential for helping certain researchers discover effective new therapies far more quickly and at far less expense.
But the immediate attraction of the technology is how it improves patient care. Saving even a few minutes can be a tremendous advantage, said Dr. Samuel Appavu, chairman of surgical critical care at Cook County Hospital, and the information helps doctors adjust therapies to optimal levels more quickly.
“Patients who might take three or four hours to stabilize before can be stable within an hour now,” said Appavu.
The new technology relies upon tiny sensors inserted directly into a patient’s artery to analyze blood as it passes by. Chemical interactions between the blood and small membranes in the sensor cause a beam sent down an optical fiber to change color. A mirror reflects the light back up the fiber and a computer converts the light signal to numerical information.
All this happens continuously, in contrast to traditional blood gas analysis that requires a technician to draw blood from a patient and take it to a lab for processing.
“In most hospitals, it takes 30 to 60 minutes from the time you draw blood until you get readings,” said Appavu. “Here we have the lab right down the hall from the patient, so we can get information in 10 minutes, but that is still a lot of time. You’re always working with information about what the patient’s condition was 15 or 20 minutes ago instead of what it’s like now.”
Indwelling arterial monitors enable physicians to see at once the effect of increasing a patient’s oxygen intake by a small amount, so stabilization is much more precise, he said.
Patients whose deteriorating condition is spotted by the monitor can be attended to even before outward signs of distress attract a nurse’s attention, as must happen before traditional blood gas tests will be ordered.
The new technology, called Paratrend 7, is made by Diametrics Medical Inc., of Roseville, Minn., a St. Paul suburb. The company sees it as part of the trend to bring tests out of the lab to the bedside and to minimize cutting and probing of the patient.
Paratrend 7 is the first technology of its kind approved by the federal Food and Drug Administration, but even with its apparent advantages, the product may face an uphill battle for acceptance.
This is because of the conservative nature of physicians, who are slow to abandon something they know works for new technology, as well as because of the economics peculiar to hospitals.
Dr. Appavu has been using the technology for nearly a year and during much of that time he has continued to take blood gas measurements the traditional way to assure that the readings from Paratrend 7 match those of large-scale lab equipment.
The values have matched closely, Appavu said.
Even though the new technology is cheaper to use and offers improvements to patient care, the economics can be tricky, he said.
Clinicians who order traditional blood gas tests for patients typically don’t pay lab fees from their budgets, but they would pay the $350 cost for each Paratrend 7 sensor they used as well as the $20,000 for the monitoring equipment to interpret and display the data.
A traditional blood gas test probably costs a hospital $30 to $40 to perform and they may bill the patient $100 for it, Appavu said, doing 6 to 10 in a day.
One Paratrend 7 sensor may be used for several days or weeks without generating new costs or charges, he said.
“Overall, the hospital will save money (with Paratrend), but it saves money from one department’s budget while adding costs to another’s budget, so you have to make a good case for an administrator to follow,” he said.
David Giddings, chief executive of Diametrics, said that more than half of his firm’s sales are abroad and that Paratrend 7 is especially popular in Japan. Analysts project Diametric’s total sales for this year at $12 million to $13 million.
The company is testing new applications for the technology, including monitoring babies born prematurely and keeping tabs on brain function, said Giddings.
A physician at the University of Illinois at Chicago, Dr. Fady Charbel, is pioneering use of the Paratrend 7 in the brain, having used the technology in more than 140 patients.
Charbel said that getting precise information about changing blood gases may help physicians anticipate when a neurosurgery patient is in danger of having a stroke so that they can apply treatments to avert it.
“There’s a window of opportunity of about 60 to 90 minutes when you can treat a patient, but if you miss that window, it’s too late,” said Charbel.
Besides helping doctors determine when patient treatment is warranted, the miniaturized sensors may also alert physicians to the best experimental drugs to do the job.
Charbel said that one new drug thought to help prevent strokes was known to have both good and bad effects on patients. It increased the amount of oxygen in the blood, which was good, but decreased blood flow, which was bad.
By getting a real-time look at how these things changed when the drug was administered, Charbel said, doctors decided the bad effects outweighed the good. They soon gravitated toward another drug found to improve both the flow of blood and its oxygen content.
The researchers were able to make these distinctions while using the drugs in only a dozen patients who were monitored with sensors.
“Usually it takes years of treatment and thousands of patients to determine these subtle effects,” said Charbel. “By giving us a window on brain function, this technology provides a tool that provides answers quickly and without breaking the bank.
“I think drug companies are going to jump on this in a big way.”
