Pen-line Diagnosis

The visiting doctor at the A.M.A. meeting had just had a little blood drawn from his arm. He watched while a technician dropped the specimen into the machine. Within a minute, he saw pastel-colored samples of his diluted serum being pumped through a dozen spaghetti-thin plastic tubes. Lights began to flash on and off, and a mechanical pen started to trace a red line on a chart. The doctor noted with equanimity that the thin red line passing through the columns of the chart was reporting normal amounts of calcium, albumin and cholesterol in his blood. Then the pen came to the last column, cryptically marked S.G.O.T. (serum glutamic oxaloacetic transaminase--an index of liver function). As the red line jumped to the top of the chart, above the 250 mark, the doctor exclaimed, "My God!" It was his first intimation that he was a victim of hepatitis.

By the tens of thousands, such diagnostic tests are now being run routinely in 80 U.S. hospitals, which have installed the machine called SMA-12 (sequential multiple analyzer, with twelve channels), produced by Technicon Instruments Corp. The saving in time and money to hospitals and patients is growing steadily.

Cheaper by the Dozen. Standard tests for single blood factors generally cost a patient from $2 to $5; half a dozen tests may cost a package price of $15 or so. The old-fashioned process is also costly in technicians' time, while doctor and patient wait hours or days for the results. Dr. Albert L. Chasson told a Technicon symposium last week in Manhattan that the SMA-12, which he operates at Rex Hospital in Raleigh, N.C., is testing 10,000 blood samples a year at a price to the patient of $9 for the dozen chemical determinations. Only one technician is needed during a day when the machine makes an average of 40 analyses--it is capable of 30 an hour.

Product of inventive research physicians and Technicon technologists, the autoanalyzer performs many delicate and highly sophisticated chemical and physical tasks in less time than it takes to describe them. First, the 3-milliliter blood sample (less than a teaspoonful) is centrifuged to get rid of the cells; the analyzer works with the serum that remains. The machine divides the serum into twelve portions and sends them racing through the plastic tubes by power from roller pumps.

Along the way, every sample is appropriately diluted and mixed with a specific reagent for each of the twelve tests. The resulting rivulets are variously colored, according to the reagent used and the interaction between reagent and serum.

Near the output end, each sample drops into a tube on the rim of a colorimeter that looks like a twelve-spoke wheel. A powerful light flashes a beam through the tubes, and photo-electric cells measure the intensity of the transmitted light. A computer converts these readings into values for the pen to draw on the chart paper (see diagram).

Diabetes Disclosed. The autoanalyzer has two main functions: it can be used as a general diagnostic screening device, and it can be used in hospitals for patients whose primary ailments are already known, but who may benefit from a careful check on their blood chemistry.

When the SMA takes on all comers, as at an A.M.A. convention, it turns up a surprising number of previously undiagnosed abnormalities. Dr. Vernon E.

Martens, director of the Washington Hospital Center's laboratories, now in charge of the A.M.A. screenings, reports that 23% of the physicians tested had higher-than-normal cholesterol levels, 15% had high uric acid, and 6% revealed some kidney trouble. In the last screening, six cases of unsuspected diabetes were disclosed. Similar findings could be expected in any group of professional men in the same age range.

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