Portal de Periódicos da CAPES

Use of Future Diagnostic STAT Intraoperative Parathyroid Hormone Instrument

2009; Lippincott Williams & Wilkins; Volume: 8; Issue: 2 Linguagem: Inglês

10.1097/poc.0b013e3181a4fad7

1533-0303

Vida Montgomery,

Pituitary Gland Disorders and Treatments

University of Southern California University Hospital is a private, 269-bed research, teaching hospital staffed by the faculty of University of Southern California's Keck School of Medicine. For the past 4 years, the mean number of parathyroidectomies per year was 30 to 35. Of these, a mean of 23 cases per year have been assisted by intraoperative (IO) parathyroid hormone (PTH) testing. Before the inception of IO PTH testing in January 2004, all our PTH testings were performed at a reference laboratory, with turnaround times of 4 to 5 days! Although our surgeons were guided by pathological findings using frozen section of the excised tissue, we noticed some cases of unexplained persistent hypercalcemia after parathyroidectomies. These cases were usually attributed to unrecognized ectopic or multiple adenomas, unrecognized supernumerary glands, insufficient excision of hyperplastic tissue, and occasional difficulty in histologically differentiating between adenomatous and hyperplastic glands on frozen sections. We implemented Nichols Advantage Quick-Intraoperative Bio-Intact PTH assay (Nichols Institute/Quest Diagnostics, San Juan Capistrano, Calif) as of January 2004. Some of the factors that went into consideration were the availability of a reagent lease, good correlation with our routine PTHs that were also tested on a Nichols instrument at the reference laboratory, portability to the operating room (OR), and ease of use. In October 2005, the Food and Drug Administration removed the Nichols PTH kits off the market. We implemented the Future Diagnostics STAT (Wijchen, The Netherlands) Intraoperative Intact PTH (IO-I-PTH) at our hospital in July 2006. Our administration was delighted by a reagent lease structure that was quantity driven, ensuring higher savings with increased volume. One of the attractive features of the STAT IO-I-PTH was the ease of calibration with the STAT-Pipet. The calibration setup takes only approximately 0.5 hour, resulting in increased staff satisfaction, efficiency, comfort, and lower stress levels. The surgeons are thrilled with an 8-minute vein-to-brain turnaround time. We find that the cleanup and shutdown only take approximately 5 minutes and is best done while still in the OR. For periodic maintenance, the washer probes are cleaned once a month, taking approximately 5 minutes. A licensed medical technologist spends 2 to 3 hours per case and is available in the surgical suite throughout the case. We decided to house the instrument in the laboratory so that we have easy access to perform our periodic maintenance and check for reagent expiration more readily. To validate the instrument, we performed a correlation with the Nichols instrument that also utilized an immunochemiluminescent assay. I had frozen 20 plasma samples in duplicate from former patients and ran those samples on the STAT IO-I PTH instrument. We observed a Deming slope of 1.081, with a correlation coefficient (r) of 0.9989. This instrument has a published sensitivity of 6 pg/mL and lack of a high dose hook effect in PTH concentrations of up to 500,000 pg/mL.1 As an added measure of quality assurance, we have an ongoing patient reproducibility study each day there is a case. In addition to normal calibration and quality control, duplicate plasma samples of patients from previous cases are tested as an internal quality assurance indicator. We have performed close to 50 cases with this system since installation. In cases showing lack of localization with presurgical scans, the system has been invaluable. In one such case, the left and right internal jugular baseline PTH concentrations were 1626 and 184 pg/mL, respectively. The surgeon located and removed a hidden left inferior parathyroid adenoma minutes after the results were reported. The procedure took 55 minutes from start to finish, limiting postsurgical complications, increasing OR staff and surgeon satisfaction, and improving OR suite turnover. Summary: Intraoperative I-PTH provides immediate confirmation of the surgical outcome. Even more importantly, in nonlocalized cases, comparison of baseline PTH concentrations in right versus left internal jugular vein samples directs the surgical exploration and lessens surgical time spent on the case. In re-exploration cases, PTH levels from the jugular veins can show if there is parathyroid function on the side of the neck with a previously operated gland. From the point of view of a medical technologist, one of the most rewarding advantages of doing IO PTH is the close interaction with the surgical team. It raises job satisfaction and empowers technologists to be actively involved during an operation and delivers results that can immediately and visibly enhance patient outcome.