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.

10.Curtis HJ, Nesbitt ID, Cressey DM et al. Comparing the immediate complication rates of percutaneous dilatational tracheostomy on a tertiary referral intensive care unit: Ciaglia Blue Rhino ™ vs Tracoe expert ®. Produced as a poster for Intensive Care Society meeting, December 2008.

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