In the past two and a half years custom-made closed-tip catheters have been used to allow extensive temperature monitoring with multi-junction thermocouple probes during local hyperthermia. Data from animal experiments indicate that the use of thermometry probes within such a catheter provides reliable temperature measurements.In order to reduce stress to the patient the catheters were fixed so that they could stay in place during the total treatment series. The catheters, outer diameter 1' 22 mm, were introduced through hollow needles under sterile conditions before the first hyperthermia session, and fixed using Histo-acryl (tissue adhesive) and Tegaderm (transparent adhesive).Recently, the data concerning the first 180 catheters placed in 74 treatment areas were evaluated. In one patient, an abscess developed 10 days after removal of the (3) catheters, which required surgical intervention, but it was not clear whether these problems had developed as a result of catheter placement. There were no problems with 139 of the remaining 177 catheters (79 per cent) and in 50 treatment fields (68 per cent), respectively, for a duration of 9-55 (mean 23) days. Ten catheters (6 per cent) were lost during the treatment series after 1-22 (mean 10) days. With 28 catheters (16 per cent) infection was observed, 14-27 (mean 19) days after insertion, which necessitated catheter removal before the last treatment session in 11 cases (6 per cent). The complication rate decreased with increasing experience; from 29 per cent (25/85) in the early period to 14 per cent (13/92) in the later period.We conclude that the use of closed-tip catheters under proper control generally causes few, if any, problems. This results in the acquisition of a substantial amount of reliable temperature data at reproducible sites, and it is well tolerated by the patient. 337 Int J Hyperthermia Downloaded from informahealthcare.com by Queen's University on 01/05/15 For personal use only. Int J Hyperthermia Downloaded from informahealthcare.com by Queen's University on 01/05/15 For personal use only.