Properties of electromagnetic field focusing probe

Bacteriophage phi X-174 as an aerobiological marker for surgical plume generated by the electromagnetic field focusing system

The aerosol of surgical plume could be measured effectively with the use of bacteriophage phi X-174 as a biological marker, in contrast to previous methodologies reported by others. Recovery of virus plaque-forming units was highest from hydrophobic polytetrafluoro-ethylene membranes compared to hydrophobic polycarbonate screen filters or polyvinylidene difluoride depth filters, indicating that the method of virus recovery strongly affects the utility of a virus as an aerobiological marker. With this new method, surgical plume was indeed found in significant amounts when cutting tissue phantoms made with agar containing virus. The Electromagnetic Field Focusing System was used, which is a new thermal surgical device. The nominal power setting did not appear to be a factor in the amount of virus recovered. However, when pulse modulating the power by adjusting the crest factor from 1.4 to 4.3, a measure of the duty cycle for power delivery which adjusted the device from its cutting to haemostatic mode, a nearly five-fold increase in surgical plume, as evidence by the recovery of phi X-174 plaque forming units, was seen. The data indicate that bacteriophage phi X-174 can be used effectively as an aerobiological marker for aerosols generated during clinical procedures, and reinforce the need to use a safety vacuum during aerosol generating procedures. The availability of a safe and economical biological marker for aerosols from clinical procedures, which may lead to acquired infections in hospital personnel, makes evaluation of procedures and containment systems markedly easier. The data also indicates that surgical plume biohazard may be present in other techniques that employ pulse modulation including surgical lasers and electrocauteries.

Endoluminal thermal occlusion of the ureter with the electromagnetic field-focusing device

The authors attempted ureteral occlusion by means of heat application in nine ureters (24 sites) of New Zealand White rabbits with the electromagnetic field-focusing (EFF) device. The EFF device generates heat at the tip of a grounded probe by focusing eddy currents that have been induced within the tissues by an external radio-frequency field. The power settings were varied from 30 to 150 W. Heat was applied at multiple sites in each ureter. Immediate functional occlusion was seen in all nine ureters. Long-term complete occlusion was seen in six ureters at power settings ranging from 40 to 150 W, while long-term partial occlusion was seen in two ureters at 30-50 W. All sites at 30 W resulted in partial occlusions. Perforation of the ureter resulted in urinoma formation in one ureter at a site that was treated with 150 W. The EFF device can be used to endoluminally occlude the ureter by causing a fibrotic reaction to thermal injury. The effective power range for this application appears to be 40-100 W.

Intervascular occlusion of canine renal, splenic, and vertebral arteries using electromagnetic field focusing (EFF) probe

Electromagnetic field-focusing (EFF) probe is a precision surgical and interventional tool. Use of the device produces maximum temperature in excess of 1800 degrees C by convergence of radio-frequency (RF) induced eddy currents in biological tissues. Applications of the EFF probe in angioplasty, aneurysm thrombosis, and neurosurgery have been previously reported. In the present work, the EFF probe was guided under fluoroscopic control and used to occlude renal, splenic, and vertebral arteries in dogs. The occlusion was typically accomplished with about one minute of RF power application. Histology of the treated vessel three to six weeks posttreatment showed total occlusion consisting of intimal and subintimal changes and organized thrombus in the lumen. This suggests that the EFF probe in comparison with other procedures is an inexpensive, relatively safe precision interventional tool for performing an occlusion for experimental and therapeutic purposes.