Predictive value of neurological examination for early cortical responses to somatosensory evoked potentials in patients with postanoxic coma

Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how neurological signs are associated with SEP results. The aim of this study was to investigate whether specific clinical neurological signs are associated with either an absent or a present median nerve SEP in patients after CPR. Data from the previously published multicenter prospective cohort study PROPAC (prognosis in postanoxic coma, 2000–2003) were used. Neurological examination, consisting of Glasgow Coma Score (GCS) and brain stem reflexes, and SEP were performed 24, 48, and 72 h after CPR. Positive predictive values for predicting absent and present SEP, as well as diagnostic accuracy were calculated. Data of 407 patients were included. Of the 781 SEPs performed, N20 s were present in 401, bilaterally absent in 299, and 81 SEPs were technically undeterminable. The highest positive predictive values (0.63–0.91) for an absent SEP were found for absent pupillary light responses. The highest positive predictive values (0.71–0.83) for a present SEP were found for motor scores of withdrawal to painful stimuli or better. Multivariate analyses showed a fair diagnostic accuracy (0.78) for neurological examination in predicting an absent or present SEP at 48 or 72 h after CPR. This study shows that neurological examination cannot reliably predict absent or present cortical N20 responses in median nerve SEPs in patients after CPR

Energy-Saving UHMW Polymeric Flow Aids: Catalyst and Polymerization Process Development

Crude oil and refinery products are transported worldwide to meet human energy needs. During transportation via pipeline, huge pumping power is required to overcome the frictional pressure drop and the associated drag along the pipeline. The reduction of both is of great interest to industry and academia. Highly expensive ultrahigh molecular weight (UHMW, MW a million Dalton) drag reducing polymers (DRPs) are currently used to address this problem. The present paper, therefore, emphasizes particularly the development of a high-performance catalyst system that synthesizes DRPs (using higher alpha-olefins)—a highly promising cost reduction alternative. This homogeneous catalyst system features a new concept that uses a cost-effective titanium-based Ziegler–Natta precatalyst and a cocatalystLewis base complex having both steric hindrance (around N heteroatom) and electronic effect. This novel work, which involves precatalyst–cocatalyst molecular separation and cocatalystmonophenyl amine association-dissociation phenomena, already generated several US patents. The subject catalyst prepares UHMW DRPs at room temperature, avoiding the use of zero and sub-zero temperatures. The resulting product almost tripled the rate of transportation of a selected grade of refinery product and saved about 50% pumping energy at ppm level pipeline concentration. It is also very easily soluble. Hence, massive modification of existing pipeline will be unnecessary. This will save additional infrastructure cost. This paper also summarizes challenges facing the development of improved heterogeneous catalysts, dispersed polymerization process, molecular simulation-based DRP product formulation, and model/theory of turbulent mixing and dispersion in the transportation pipeline setting.</jats:p