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Summary Introduction This study evaluates COVID-19 related patient risk, when undergoing management within one of the largest specialist centres in Europe, which rapidly implemented national COVID-19 safety guidelines. Method A prospective cohort study was undertaken in all patients who underwent surgical (n = 1429) or non-operative (n = 191) management during the UK COVID-19 pandemic peak (April–May 2020); all were evaluated for 30-day COVID-19 related death. A representative sample of elective/trauma/burns patients (surgery group, n = 729) were selected and also sub-analysed within a controlled cohort study design. Comparison was made to a random selection of non-operatively managed (non-operative group, n = 100) or waiting list (control group, n = 250) patients. These groups were prospectively followed-up and telephoned from the end of June (control group) or at 30 days post-first assessment (non-operative group)/post-operatively (surgery group). Results Complex general (9.2%, 136/1483) or regional (5.0%, 74/1483) anaesthesia cases represented 14.2% (210/1483) of operations undertaken. There were no 30-day post-operative (0/1429)/first assessment (0/191) COVID-19 related deaths. Neither the three sub-speciality plastic surgery, or non-operative groups, displayed increases in post-operative/first assessment symptoms in comparison to each other, or to control. The proportion of COVID-19 positive tests were: 7.1% (1/14) (non-operative), 5.9% (2/34) (burns) and 3.0% (3/99) (trauma); there were however no significant differences between these groups, the elective (0%, 0/54) and control (0%, 0/24) groups (p = 0.236). Conclusion We demonstrate that even heterogeneous sub-speciality patient groups, who required operative/non-operative management, did not incur an increased COVID-19 risk compared to each other or to control. These highly encouraging results were achieved with described, rapidly implemented service changes that were tailored to protect each patient group and staff.

Sixteen patients with paralysis of the anterior interosseous nerve (AIN) in 19 limbs who were treated in a single unit were reviewed at a mean of 6.4 years (range 2–14 years) following onset of the paralysis. There was a high incidence of incomplete lesions (seven limbs) and of associated neurological lesions (six limbs) in the same or opposite upper extremity. Patients treated conservatively and with surgical exploration showed no difference in the time of onset of recovery, the time taken to achieve complete recovery or the extent of recovery. Those with incomplete lesions recovered well irrespective of the type of treatment. A distinct cause of compression of the AIN or visible changes in the AIN were seen in just three of the eight limbs that were explored. Surgery is indicated in complete lesions with no evidence of recovery for at least 6 months; incomplete lesions and other neurological signs are indications for conservative management in the first instance.

Combined execution of realistic models of large highly integrated process flowsheets using conventinal simulation strategies is prohibitive in terms of computation time and computer storage requirements. Hierarchical solution strategies based on concept first proposed by Rosen discussed. The process flowsheet is viewed as consisting of a collection of process sections each involving multiple equipments items. Process section models are assumed to be assembled using conventional modular simulators. Linear material balance models of various levels of aggregation are proposed for use at the overall process level. The balance models are solved using a novel non-iterative solution method. Trials results indicate that a two level strategy employing sequential single pass execution of the section simulations coupled with solution of a partially aggregated process material blance model which incorporates recycles between sections as well as recycles internal to sections requires least time. Implementation of the mehtod and the required file structure are discussed.

A methodology for machine layout of process streams involving multiple directional changes given the equipment layout and stream connection information is formulated. Also considered are the drawing of these streams and of various process equipment symbols as well as the layout and drawing of peripheral flowsheet symbols and messages. The key concepts involved are the use of a coded grid representation of the drawing space, a structural classification of stream configurations, efficient constructions for generating stream paths, and the formulation of a ranking of stream paths. A program package implementing the methodology which includes a simple yet flexible data structure for generating and storing equipment symbols is discussed and example flowsheet are given.

In this reporting period work has been completed on the simulation model of the hydrotreating process section. This model successfully tested the integrated operation of the Simulation System including the physical properties subsystems and involving pseudo-components and solids stream flows. The hydrotreating reactor model was modified to include improved temperature profile predictions. The plant capital cost estimation subsystem has been redesigned to allow use as a stand alone package. The revised package will include a redesigned cost data bank, equipment costing programs, factored plant and auxiliary equipment programs as well as a profitability analysis routine. Implementation of the revised economics package is expected to be completed during the third quarter of 1978. The physical properties package has been updated by the addition of routines for the accurate estimation of the thermodynamic properties of steam. A steady state model of the methanation section has been assembled. Scrubber, multi-phase separator, and turbine models have been developed for the vapor recovery and heat recovery process sections. Work is in progress on a detailed model of the char lift leg and the steam reformer. progress has been delayed but work is continuing on the hierarchical process calculation system outlined in Fe--2275-7.

Work was completed on the coding and testing of the plant cost estimation package PCOST. Significant effort was expended in adapting the ORNL PRP evaluation program to make it compatible with PCOST. Continuing efforts include completion of the user's manual and rechecking of the cost data base entries. Continued miscellaneous revisions and additions arising from user suggestions were made to the S4 and PPROPS packages. The two phase flash routine was modified to more efficiently accommodate single components. The three phase flash routine was revised to include generation of sharper initial estimates and phase stability tests. A versatile process utilities section model was implemented and tested. This program will perform the balance calculations, will select turbine design conditions, and will determine required auxiliary boiler loads for a plant steam system containing multiple steam pressure levels. Integrated simulations of the hydrogen and vapor recovery sections have been assembled and design case studies are in progress. The integrated simulation of the hydrotreating, acid gas removal, and hydrogen plant sections is being prepared for combined execution using the hierchiacal strategy tested in the previous quarter. Alternate numerical methods are being tested for accommodating the severe stiffness which has been encountered in the differentialmore » equations of the lift tube model.« less

The plant capital cost estimation package has been largely implemented. Testing and documentation is projected to be completed by the end of the next quarter. Additions consisting of the physical properties package of entropy estimation capabilities and of automatic selection of the steam table routines when appropriate were made. Significant progress has been made in developing equipment modules for the pyrolysis vapor recovery, heat recovery, bulk methanation, and H/sub 2/ plant sections. These modules include an ejector model, an electrostatic precipitator model, an alternate three phase column routine, a multiphase heat exchanger design routine, as well as a steam reformer furnace design program. Case studies have been carried out on the heat recovery section. Integrated simulations of the methanation, vapor recovery, and H/sub 2/ plant sections are in various stages of assembly. The hierarchical calculation strategy which is to allow execution of over-all flowsheet simulations in terms of a linked sequence of process section simulations has been demonstrated successfully. An available ethylene oxide/glycol process simulation model was used as a test case. Execution time reductions to 1/3 of the direct simulation time could be shown. Work is in progress in generalizing the interfacing and applying the strategy to portions ofmore » the modified COED flowsheet. Successful linkage of the combined pryolysis, gasifier, lift-tube, and combustor models was achieved. These models include detailed kinetics, heat transfer calculations as well as particle balance calculations which allow both particle shrinkage at constant density and reduction of particle density at constant size. Several case studies were run and more are projected.« less

Manuals have been completed for the physical properties (PPROPS), process costing (PCOST), and detailed simulation (DSP-I) packages. Further modest revisions to these packages are being completed. A final manual has been issued for the steady state pyrolysis system (SS/PP) model. A major activity has been an extensive overhaul of the process simulation package (S4). The new simulation package was used to execute simulations of the bulk methanation and water quench pyrolysis vapor recovery process sections. Sample results from these simulations are given. The DSP-I system has also been used to execute design calculations for the process steam and power generation section. This application illustrates an interesting feature of the PROCES Subroutine Concept used in DSP-I, namely, the ability to accomodate conditional logic in the sequence of module calls required to execute the flowsheet calculations. Additional testing has been completed to further clarify the efficacy of alternate computational tactics used in the hierarchical strategy for executing large scale simulations. The executive system LSP has been implemented and testing on a major portion of the modified COED process is in progress. Finally, work has been completed on the lift-tube model. The mixed algebraic and ordinary differential equation model is quite stiff andmore » requires the use of Gear's implicit method for successful integration. Parameter studies have been run to investigate trends in the temperature and composition profiles. These case studies indicate that, for purposes of converging the gasifier-combustion section recycle flows, a simplified form of the lift-tube model will suffice. However, for design of the device, the detailed model is required.« less

A computer aided methodology is presented for determining the positions of equipment symbols in a flowsheet given only the equipment connection information. A two pass logic is used. In the first pass the location of process sections is determined by reducing the process section level flowsheet and generating a mesh structure using a modification of Rubin's algorithm. The approximate dimensions of each section are determined using a depth first search, and, the locations of the process section centroids are selected heuristically. In the second pass, the equipment symbols are positioned within the sections taking into account external equipment connections to other process sections as well as the flow patterns within the section. An experimental program has been developed and some test examples are presented.

An unusual congenital anomaly of a bilateral complete cleft of the primary palate, a complete cleft of the left secondary palate with abnormal nostrils without external openings and right choanal atresia is presented. The child also has a lachrymal fistula below the right lower eyelid and a coloboma of the same eyelid medially. Neither lachrymal system drained into the nose.