H. N. Whitfield

A comparison of bipolar and monopolar diathermy probes in experimental animals

The effects of monopolar and bipolar diathermy were studied in laboratory animals. The power required to coagulate transected vessels in air was established and the effect of immersion in saline and water during electrocoagulation was investigated. Tissue heat conduction from each type of probe was measured and compared. Tissue damage was assessed by light microscopy of histochemically stained sections. The bipolar system operated at a lower power output (13 W) with less heat conduction, and was unaffected by the surrounding medium.

The Treatment of 100 Consecutive Patients with Ureteral Calculi in a British Stone Center

Of all ureteral calculi 20 per cent will require removal. The use of extracorporeal shock wave lithotripsy has changed dramatically the treatment of ureteral stones requiring intervention. We reviewed 111 procedures for 108 stones in 100 consecutive patients. Primary techniques included extracorporeal shock wave lithotripsy after retrograde manipulation (63 cases), percutaneous nephrolithotomy alone (1) and after retrograde manipulation (3), ureteroscopic removal (29), cystoscopic removal (2) and open ureterolithotomy (2). These techniques and the results are discussed. Of the patients 11 required a secondary procedure, including extracorporeal shock wave lithotripsy in 3, ureterorenoscopy for failed extracorporeal shock wave lithotripsy in 2, an open operation for complications of ureterorenoscopy in 2 and correction of associated stricture in 2. All patients ultimately were free of stones. Our experience with in situ extracorporeal shock wave lithotripsy is described. An open operation was done only when less invasive forms of treatment failed or electively to correct an associated anatomical abnormality.

Clinical Experience Using the Wolf Piezolith Device at 2 British Stone Centers

Machines using the principle of piezoelectric extracorporeal shock wave lithotripsy have been developed. This has allowed the prospect of painless treatment for renal and ureteral calculi. The experience with use of 2 Wolf Piezolith machines for 1 year is presented. Different second generation lithotriptors have varying techniques of production of shock waves and different imaging methods. The Wolf Piezolith device uses ultrasound imaging and piezoelectric crystals for shock wave generation. Between June 1987 and May 1988, 545 patients 5 to 84 years old were treated with the Wolf Piezolith device. Of these patients 2-month followup data are available for 367 (398 renal units). Outpatient treatment was used routinely. For renal calculi complete fragmentation (into particles less than 2 mm. in size) was achieved in 94 per cent of the patients, with 53 per cent being completely free of stone at 2 months. For ureteral stones treated in situ the best results were obtained in the upper and lower ureter. Over-all, 62 per cent of the patients required more than 1 treatment, with the number of treatment sessions required increasing with the size of the stone treated. Morbidity was low. Ultrasound imaging has proved to be as effective as x-ray imaging. Compared to Dornier HM-3 lithotripsy, installation and running costs were low. The machine offers a favorable alternative to first generation lithotriptors.

Tissue effects of an ultrasonic scalpel for clinical surgical use

SummaryThe effects of a new ultrasonic scalpel were studied in laboratory animals. Tissue heat conduction from the tip of the ultrasonic blade was measured. Tissue damage was assessed by light microscopy of histochemically stained sections. The ultrasonic scalpel incised nonfibrous tissue effectively, with minimal heat conduction, and the incisions healed with no evidence of fibrosis nor of tissue destruction.

Post-irradiation bladder dysfunction: development of a rat model.

SummaryThe aim of this research was to establish a small animal model for the functional and morphological study of post-irradiation bladder dysfunction. Young adult female Wistar rats were X-irradiated with single doses of 10, 15, 20 or 25 Gy. Filling cystometry was performed to assess changes in reservoir function: the volume infused to produce a rise in intravesical pressure of 5 cmH2O was calculated as an index of compliance. A biphasic reduction in this index was noted in animals receiving 15–25 Gy; the first reduction developed at about 4 weeks, and the second started at 3–4 months and persisted at 6 months. Bladder tissue was taken at this time (6 months post-irradiation) for morphological study. Histological examination demonstrated an increased mast cell density in the irradiated bladders, but was otherwise non-specific; fibrosis was discernible in only half of the 18 animals studied. Electron microscopy showed focal degeneration of smooth muscle cells, and in some areas there was selective degeneration of unmyelinated axon profiles. The biphasic reduction in the compliance index is consistent with the timing of the symptoms of the acute and late irradiation reactions reported by radiotherapy patients. Changes in axon profiles and mast cell density may be of functional significance.

Post-irradiation bladder dysfunction: muscle strip findings

Strips of rat detrusor muscle were studied in an organ bath 6 months after X-irradiation at doses of 15 and 25 Gy; cystometric studies in these animals had shown a persistent and significant reduction in compliance. The organ bath study demonstrated an increase in the purinergie sensitivity of irradiated detrusor muscle as compared with control. This was significant: p<0.0145 for the 25 Gy dose group (n=8) and p<0.0456 for the 15 Gy group (n=8) at an α,β-methylene-ATP concentration of 10-4 M (Mann-Whitney U-Test). There was no difference in sensitivity to cholinergic or noradrenergic stimulation, or to electrical stimulation of the transmural nerves. The finding of purinergic hypersensitivity in irradiated muscle, coupled with ultrastructural evidence of a neural injury, raises the interesting possibility that a denervation super-sensitivity phenomenon may contribute to the pathophysiology of post-irradiation bladder dysfunction.

An Experimental Study of Calculogenesis and Biocompatibility of Plastics for Urological Use

Silicone, Polyvinylchloride, Nylon and a Polyethylene Copolymer were studied in the urinary tracts of experimental animals. Continuous administration of Ascorbic Acid Sulphadimidine was used to control urinary pH and infection. Scanning Electron Microscopy with a Back Scattered mode was used to examine the surface of the tubes and to define the inorganic element composition of the encrustations, by X-ray Energy Spectroscopy. To check the compound composition of the encrustations Infra-red Spectroscopy was performed. Light microscopy was used to compare the urothelial surfaces in contact with the implants.

Grey Scale Image Discrimination: an Accurate Method of Stone Targeting?

Accurate stone targeting is desirable during lithotripsy because of concern over renal injury. A method has been developed to control Shockwave release during real time imaging with ultrasound, so that firing occurs only when the stone is in the F2 focus.

Radionuclide Evaluation Pre- and Postextracorporeal Shock Wave Lithotripsy for Renal Calculi

Forty-two patients were evaluated pre- and postextracorporeal shock wave lithotripsy (ESWL) using [99mTc]DTPA renography. A quantitative evaluation showed that the relative renal function decreased 2-3 days post-ESWL on the treated side, and the parenchymal transit time index (PTTI) increased 2-3 days post-ESWL (p less than 0.001) on the treated side and returned to the pretreatment level by 3 wk post-ESWL. The untreated side showed an increase in PTTI 2-3 days post-ESWL (p less than 0.01), which returned to normal by 3 wk post-ESWL. A significantly greater increase in PTTI was seen in patients who received greater than 1,000 shocks as compared with those who received less than 1,000 shocks. Five patients developed obstructing uropathy post-ESWL, when stone fragments caused ureteric obstruction.