Description of Event or Problem · 1
THE PT, A 38-YEAR-OLD FEMALE NOTICED ERYTHEMA IN A PATCH ON HER BACK FOLLOWING THE X-RAY PROCEDURE ON 10/10/94. THE REDDENING PROGRESSED TO BLISTERING AND FINALLY TURNED BLACK. WHEN SHE WAS SEEN BY DR, THE REGION WAS PINK AND APPEARED TO BE HEALING INWARD FROM THE EDGES. SHE DID NOT INITIALLY ASSOCIATE THE PROBLEM WITH THE X-RAY PROCEDURE BUT SAW A SUCCESSION OF PHYSICIANS INCLUDING A A DERMATOLOGIST. THE PROCEDURE DONE ON THIS PT WAS AN RF CATHETER ABLATION PROCEDURE DONE IN CARDIOVASCULAR ROOM #1. THE EXISTENCE OF A SKIN BURN SUGGESTS THAT EITHER THE FLUORO TIME OR THE DOSE RATE WAS EXCESSIVE. ACCORDING TO PT RECORDS, AND THE ROOM LOG, TOTAL FLUOROSCOPIC TIME WAS 65 MINUTES. TYPICAL FLUORO TIMES FOR THIS PROCEDURE ARE ON THE ORDER OF 45 MINUTES BUT RANGE AS HIGH AS 100 MINUTES. SIMILAR FLUOROSCOPIC MEAN TIMES HAVE BEEN REPORTED IN THE LITERATURE. DOSE RATE IS A FUNCTION OF PT SIZE AND OPERATIONAL MODE. BIGGER PTS REQUIRE A HIGHER DOSE THAN SMALLER ONES DUE TO GREATER X-RAY ABSORPTION IN THE FORMER. DOSE IS HIGHER IF ELECTRONIC MAGNIFICATION MODES ARE USED AND IS ALSO HIGHER IN CINE THAN IN FLUORO. ACCORDING TO RECORDS, ONLY FLUOROSCOPY WAS DONE (NO CINE) AND ACCORDING TO THE ROOM TECHNOLOGIST THESE PROCEDURES ARE USUALLY DONE WITHOUT MAGINIFICATION. THE PT IN THIS CASE WAS NOT A LARGE PT. BECAUSE THE RF ABLATION CATHETER IS AN INVESTIGATIONAL DEVICE, THE TUBE KVP AND MA WERE RECORDED AS PART OF THE PROTOCOL, MEASURED EARLY IN THE PROCEDURE. THE KVP AND MA VALUES OF 67 KVP AND 2.8 MA ARE REASONABLE AND CONSISTENT WITH A NORMAL DOSE RATE FOR AN AVERAGE PT. BECAUSE LOWER DOSE MODES WERE APPARENTLY USED AND THE FLUOROSCOPIC TIME WAS NOT EXCEPTIONALLY LONG, THE EXISTENCE OF A SEVERE BURN IN A SMALL PT SUGGESTS EQUIPMENT MALFUNCTION. AT 2:23 PM ON 10/10/94, THE MANAGER REPORTED THAT THE AP FLUOROSCOPE IN ROOM 1 HAD FAILED AND THAT A LOUD NOISE WAS HEARD FROM THE TUBE LOCATION INSIDE THE TABLE BASE. CO SERVICE PERSONNEL CAME AND REPLACED THE X-RAY TUBE AS WELL AS OTHER REPAIR. THE SERVICE EXTENDED INTO THE NEXT DAY. THE ENGINEERS PERFORMING THE REPAIR ALSO NOTED THAT A FUSE HAD BLOWN IN THE BRIGHTNESS CONTROL CIRCUIT WHICH CONTROLS THE DOSE-RATE. THE PROBLEM APPARENTLY PERMITTED THE X-RAY TUBE CURRENT (AND THE PT DOSE) TO GO TO AN EXCESSIVE LEVEL, WHICH PRECIPITATED THE TUBE FAILURE.