Various approaches have been used to identify possible routes for improvement of patient flow within an emergency unit (EU). One such approach is to use simulation to create a 'real world' model of an EU and carry out various tests to gauge ways of improvement. This paper proposes a novel approach in which simulation is used to create a 'perfect world model'. The EU at a major UK hospital is modelled not as it is, but as it could be. The 'efficiency gap' between the 'perfect world' and the 'real world' demonstrates how operational research can be used effectively to identify the location of bottlenecks in the current 'whole hospital' patient pathway and can be used in the planning and managing of hospital resources to ensure the most effective use of those resources.

A 21-year-old woman was admitted to the authors' hospital with symptoms of breathlessness, pleuritic chest pain and haemoptysis having been unwell for 1 week with a flu-like illness. Clinical examination revealed a rapid respiratory rate (36/min), tachycardia (134 beats per minute), pyrexia (39°C), bibasal coarse crepitations and bronchial breathing. Investigations showed hypoxia (PO2 12.4 on 100% oxygen), raised inflammatory markers (C-reactive protein 324 mg/litre), thrombocytopenia (platelets 144 × 109/litre), leucopenia (2 × 109/litre) and neutropenia (0.88 × 109/litre). Chest X-ray revealed bilateral air space shadowing (Figure 1). The patient was admitted to the high dependency unit and started on intravenous co-amoxiclav (1.2 g three times per day) and clarithromycin (500 mg twice daily). Blood cultures at 24 hours grew Staphylococcus aureus resistant to penicillin and fusidic acid. The patient was switched to intravenous flucloxacillin. Admission was complicated by the development of a small pleural effusion. The patient was managed with high flow oxygen therapy, did not require ventilatory support at any stage and was discharged home after 17 days. The patient received flucloxacillin for a total of 4 weeks. The S. aureus isolate carried enterotoxins G and I and the Panton-Valentine leucocidin gene. Throat swab was positive for influenza B by a molecular method.

Acute tubular necrosis (ATN) is a common condition following cadaveric renal transplantation with an incidence in many series of nearly SO %. The aetiology is uncertain; however, it would appear to be related to damage to the transplant kidney either prior to retrieval, during cold preservation or during re-warming of the kidney at the time of anastamotic construction. There is no specific therapy for ATN and treatment is comprised of an expectant policy with supportive dialysis and fluid restriction. Renal function improves in the majority of cases, though there may be delayed function for several weeks. We report a case of dialysis-dependent ATN that had persisted for S months following transplantation. Following conversion to tacrolimus there was immediate improvement in renal function, and after a month of tacrolimus therapy the patient was dialysis-independent.Key words Acute tubular necrosis, tacrolimus, cyclosporin . Tacrolimus, ATN, cyclosporin . Cyclosporin, ATN, tacrolimus . Conversion, cyclosporin, tacrolimus In trod udionTacrolimus (Prograf) has been shown in clinical trials to be effective both as primary immunosuppression therapy and in the treatment of refractory rejection [5,9]. We have recently had success with tacrolimus in the treatment of a patient with primary non-function secondary to acute tubular necrosis (ATN) that had persisted for S months following transplantation. Case reportA 41-year-old gentleman underwent cadaveric renal transplantation in October 1995 for hypertensive nephropathy. The donor was a young male who had died from a cerebral haemorrhage. The human leucocyte antigen (HLA) mismatch was 1:2:0. Whilst on the intensive care unit the donor experienced a single hypotensive episode lasting 30 min; however, he maintained a good urine output throughout. The kidney was preserved in University of Wisconsin preservation solution and the cold ischaemia time was 16 h and 55 min.A small lower pole artery that had been damaged at the time of retrieval was anastamosed end-to-side to the main renal artery, and the anastamosis time for the renal-iliac anastamosis was 40 min. At the time of the recipient operation, the lower pole of the kidney was noted to be poorly perfused.The patient was commenced on triple therapy immunosuppression consisting of cyclosporin 8 mg/kg per day, azathioprine 1.5 mg/ kg per day and prednisolone 0.3 mg/kg per day. Dosing of cyclosporin (Neoral) was based on 12-h trough levels that aimed to maintain blood concentrations of 80-200 ng/ml (Emit assay). The dose of azathioprine and steroids remained constant. The patient also received the standard supplementary therapy that included nifedipine 10 mg twice daily, ranitidine 150 mg once daily, co-trimoxazole 480 mg twice daily and amphotericin lozenges 4 per day.The transplant kidney exhibited primary non-function and the patient remained anuric. A duplex ultrasound scan demonstrated thrombosis of the lower pole renal artery with approximately 10

Bed capacity management is an important factor in the effective provision of hospital services. Despite the prevalence of analytical tools suitable for this task, a barrier remains between the techniques available to operational researchers and strategic decision makers. In this paper we introduce a bespoke discrete event simulation package for the analysis of bed usage, which has been developed with a focus on usability and extendibility. A case study is presented for the transfer of Neurosurgery services between two sites, demonstrating the advantages of discrete event simulation over deterministic approaches which do not account for variation in the hospital system.