The importance of aggregation in calcium oxalate urolithiasis, although not fully understood, has long been postulated. Previous investigators of calcium oxalate crystal aggregation have applied static crystallization rather than continuous flow techniques to their studies. We describe the use of a Couette agglomerator in series with our previously reported continuous flow mixed suspension-mixed product removal crystallization system. We compared synthetic urine controls with 5 per cent volume-in-volume human urine additions from normal persons or patients with calcium oxalate stones. There was no significant difference in nucleation, linear crystal growth rate or total crystal mass between normal persons and those with stones. Control nucleation rate was significantly higher than in either human urine addition group. Comparison of aggregator particle size distributions revealed significant differences in aggregation among the control, normal and stone groups. We concluded that urine inhibitors to aggregation are somewhat deficient in patients with stones, resulting in the generation of larger particle masses or eventually stones.

Background:Selection of the ideal airway device in patients with difficult airways (DA) or potentially difficult airways remains controversial, especially, for a novice anesthesia physician (NP) who must deviate from conventional direct laryngoscopy with a rigid laryngoscope following a failed intubation and employ one of the several alternative devices. The author determines and compares tracheal intubation success rates, times to success and complications of a novice physician using four alternative airway devices in 20 obese (BMI more than 27.5) patients who may be more difficult to intubate than normal weight patients.Materials and Methods:In this prospective randomized experimental study the author investigates a novice physician's use of the Bullard™, Fiberoptic™, Fastrach™ and Trachlight™ comparing reliability, rapidity and safety of orotracheal intubations. Following induction of anesthesia the NP was allowed up to a maximum of two attempts per device at oral intubation. Mean intubation times plus/minus SD, per cent success rates and postoperative complications were evaluated for each device.Results:The Fastrach™ was successful 100% of the time on the first attempt requiring a mean time of 55 seconds plus/minus 6.6. All intubations were unsuccessful following two attempts with the Fiberoptic™. A success rate of 20% (one of five) was achieved with the Trachlight™ on first attempt after 95 seconds. The Bullard™ was successful in 40 % (two of five) of the patients after a mean time 60 seconds plus/minus five, but was the only device to result in mild oral discomfort one day post operatively.Conclusions:In the hands of a novice physician managing a difficult or potentially difficult airway, often encountered in obese patients, the Fastrach™ demonstrated the highest success rate.

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