Upper tract pressure flow studies in four clinically unobstructed ureters with double J stents in situ indicated that urinary flow occurred mainly around the stent and that there was significant vesicorenal pressure transmission. This study examined the dynamics of ureteric urinary flow and morphological effects consequent upon stenting a ureter in vivo. In a porcine model, ureteric intubation caused a rise in intrapelvic pressures, hydroureter, vesicorenal reflux and generalised thickening of the ureteric wall with characteristic histological changes in the urothelium. These findings suggest that double J stents may compromise urinary drainage when ureteric obstruction is not present, urging caution in their use in the damaged, unobstructed upper urinary tract.

We investigated the relationship between the pain experienced by 50 patients with osteoarthritis of the hip and the resting intra-articular pressure of the synovial fluid. We found a significant linear correlation between these factors, greater pain being experienced by patients with higher pressures. In 20 cases we showed that the pressure rises in extension and medial rotation and is least in flexion and mid-abduction. These results help to explain the benefits of rotation osteotomy of the hip and of psoas release. They also help explain the natural resting position of the hip in patients with an acute effusion and the fixed deformities associated with late osteoarthritis of the hip.

The urethral response to bladder filling has been studied by synchronous measurement of four points in the proximal urethra and bladder using microtip transducers. Twelve male patients with urodynamically proven bladder instability had falls in urethral closure pressure of 30 cm of water 3 s before the unstable detrusor contraction. There was a lack of awareness of the urethral relaxation, the sensation of urgency occurring only when the detrusor contracted. The suggestion is made that the sequence of events occurring in these patients with bladder instability is fundamentally no different from a normal voiding sequence and that it may be more appropriate to re-educate the muscles of the proximal urethra than to treat the detrusor instability.

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.

Direct measurement of upper urinary tract dynamics during perfusive stress is an accepted method of investigating the dilated upper urinary tract when a clear diagnosis of obstruction cannot be refuted by indirect radiological or renographic means. Transparenchymal renal puncture for intrapelvic pressure transduction has become an accepted technique over the last 15 years, well-defined "standard" fluid stresses being determined to uncover covert obstructions with strict criteria for the determination of such a state. These antegrade perfusionipressure tests do not, howcver, take into account the role of upper tract peristalsis, an important factor for the promotion of renal drainage in multicalyceal animals.Fifteen patients with equivocal upper urinary tract obstruction had their upper urinary tract dynamics determined prospectively by a modification of the standard Whitaker test, results of these studies being compared with measurements of pelvic peristalsis and baseline intrarenal pressure made by using an intrapelvic microtransducer-tipped catheter interfaced to a computerised recording system. This system enabled the measurement of pelvic dynamics in various postures without the necessity for transducer rezeroing. Six patients showed abnormalities of pclvic peristaltic activity indicative of the obstructed upper tract, only three of whom had unequivocally obstructed Whitaker tests. All obstructed patients had accentuation of their peristaltic abnormalities in the sitting position, underlining the importance of performing direct dynamic measurements in a physiological position. We have found that measurement of pelvic peristaltic activity as well as baseline intrapelvic pressure during perfusion is important for the delineation of the equivocally obstructed kidney, suggesting that the antegrade perfusionipressure test should be modified to allow more physiological study of renal outflow dynamics.