Is traditional stone clinic the optimal use of NHS resources?

There is no clear guidance on the efficacy of stone follow-up. NICE have been unable to make recommendations with current published evidence. The aim of this study was to understand the patient journey resulting in surgical intervention, and whether traditional stone follow-up is effective. A retrospective review of patients undergoing ureteroscopy (URS) or percutaneous nephrolithotomy (PCNL) over a 3 year period identified 471 patients who underwent these procedures to treat stone disease. Records were interrogated for the following: symptoms, mechanism of booking, reason for intervention, stone size, stone location, risk factors and previous follow-up. Of 471 patients who underwent intervention, 168 were booked from stone clinic follow-up (36%). Of these, 96% were symptomatic and 4% were asymptomatic. When risk factors were removed, this figure was reduced to 1%. Sepsis rate for emergency admissions differs between those followed up (13%) versus new presentations (19)%. There was no statistically significant difference in the outpatient imaging frequency between patients booked from an emergency admission (80% having imaging every 6 months) and those from the clinic (82%). Our Hospital provides on average 650 stone clinic appointments a year with a cost of £93,000. Given the low rate of intervention in patients with asymptomatic renal stones, a symptomatic, direct-access emergency stone clinic could be a better model of care and use of NHS resources. Urgent research is required in this area to further assess if this is the case.

Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry.

The unusually high heats of vaporization of room-temperature ionic liquids (RTILs) complicate the utilization of thermal evaporation to study ionic liquid reactivity. Although effusion of RTILs into a reaction flow-tube or mass spectrometer is possible, competition between vaporization and thermal decomposition of the RTIL can greatly increase the complexity of the observed reaction products. In order to investigate the reaction kinetics of a hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) was aerosolized and reacted with gaseous nitric acid, and the products were monitored via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Reaction product formation at m/z 42, 43, 44, 67, 85, 126, and higher masses was observed as a function of HNO3 exposure. The identities of the product species were assigned to the masses on the basis of their ionization energies. The observed exposure profile of the m/z 67 signal suggests that the excess gaseous HNO3 initiates rapid reactions near the surface of the RTIL aerosol. Nonreactive molecular dynamics simulations support this observation, suggesting that diffusion within the particle may be a limiting step. The mechanism is consistent with previous reports that nitric acid forms protonated dicyanamide species in the first step of the reaction.

Fourier transform infrared studies in hypergolic ignition of ionic liquids.

A class of room-temperature ionic liquids (RTILs) that exhibit hypergolic activity toward fuming nitric acid is reported. Fast ignition of dicyanamide ionic liquids when mixed with nitric acid is contrasted with the reactivity of the ionic liquid azides, which show high reactivity with nitric acid, but do not ignite. The reactivity of other potential salt fuels is assessed here. Rapid-scan, Fourier transform infrared (FTIR) spectroscopy of the preignition phase indicates the evolution of N 2O from both the dicyanamide and azide RTILs. Evidence for the evolution of CO 2 and isocyanic acid (HNCO) with similar temporal behavior to N 2O from reaction of the dicyanamide ionic liquids with nitric acid is presented. Evolution of HN 3 is detected from the azides. No evolution of HCN from the dicyanamide reactions was detected. From the FTIR observations, biuret reaction tests, and initial ab initio calculations, a mechanism is proposed for the formation of N 2O, CO 2, and HNCO from the dicyanamide reactions during preignition.