Balancing scarce hospital resources during the COVID-19 pandemic using discrete-event simulation.

COVID-19 has disrupted healthcare operations and resulted in large-scale cancellations of elective surgery. Hospitals throughout the world made life-altering resource allocation decisions and prioritised the care of COVID-19 patients. Without effective models to evaluate resource allocation strategies encompassing COVID-19 and non-COVID-19 care, hospitals face the risk of making sub-optimal local resource allocation decisions. A discrete-event-simulation model is proposed in this paper to describe COVID-19, elective surgery, and emergency surgery patient flows. COVID-19-specific patient flows and a surgical patient flow network were constructed based on data of 475 COVID-19 patients and 28,831 non-COVID-19 patients in Addenbrooke's hospital in the UK. The model enabled the evaluation of three resource allocation strategies, for two COVID-19 wave scenarios: proactive cancellation of elective surgery, reactive cancellation of elective surgery, and ring-fencing operating theatre capacity. The results suggest that a ring-fencing strategy outperforms the other strategies, regardless of the COVID-19 scenario, in terms of total direct deaths and the number of surgeries performed. However, this does come at the cost of 50% more critical care rejections. In terms of aggregate hospital performance, a reactive cancellation strategy prioritising COVID-19 is no longer favourable if more than 7.3% of elective surgeries can be considered life-saving. Additionally, the model demonstrates the impact of timely hospital preparation and staff availability, on the ability to treat patients during a pandemic. The model can aid hospitals worldwide during pandemics and disasters, to evaluate their resource allocation strategies and identify the effect of redefining the prioritisation of patients.

Disruption of gypsy moth mating with microencapsulated disparlure.

Broadcast applications of microencapsulated disparlure at rates of 2.5 to 15.0 grams per hectare are capable of reducing successful mating of wild gypsy moths under field conditions. In test plots, population densities were as high as 32 pairs of pupae in an area of about 700 square meters.

Long-term study of re-infection following successful eradication of Helicobacter pylori infection.

BACKGROUND: 'Re-infection' with Helicobacter pylori after eradication has been estimated to occur in 0-14% of patients, although most so-called 're-infections' occur within the first year following 'eradication' and many may actually be due to recrudescence of a temporarily suppressed infection. AIM: To study the true re-infection rate, we have studied re-infection rates after eradication therapy by excluding the first year's data, minimizing the possible confounding effect of recrudescence. METHODS: All patients tested for H. pylori infection following eradication therapy between 1987 and 2004 were evaluated. Testing was carried out by urea breath test and gastric biopsy. Patients were included if they were found to be negative for H. pylori infection by testing at least 1 year following eradication and underwent at least one further test for H. pylori. RESULTS: 1162 patients met the inclusion criteria with median post-eradication follow-up of 3 years (1.5-14) including 4668 tests; 3319 years of follow-up were analysed. Thirteen cases of re-infection occurred (re-infection rate 0.4% per year). CONCLUSIONS: This large study of H. pylori re-infection avoided cases of recrudescence by excluding the first post-eradication year. True re-infection is probably less common than previously thought.

Coeliac disease presenting with intraperitoneal haemorrhage.

A 42-year-old man, who was previously fit and well, presented in haemorrhagic shock due to a spontaneous left mesocolonic haematoma and intraperitoneal bleed. His INR was noted to be raised on admission. Later investigations showed him to have villous atrophy on biopsy of the second part of his duodenum and a positive anti-reticulin antibody. His duodenal biopsy and INR normalized on a gluten-free diet. Coeliac disease may present with a single vitamin deficiency with potentially catastrophic results.

Does sodium play an adverse role in hypertension?

It is clear that salt is known to be a health hazard from the ancient times. Sodium intake, which was minimal during evolution, increased significantly with the civilization. The rise in prevalence of hypertension in populations with increased consumption of salt suggested a casual relationship. However, several of these studies showed conflicting results. Many investigators agree that salt-sensitive persons often have a family history of hypertension. Such individuals possess a sodium transport inhibitor in the arterial smooth muscle cells, which affects their sodium handling (as compared to other persons). However, many of the putative defects related to sodium can be dissociated from blood pressure and sodium consumption status. It is possible that calcium defects of deficiency of potassium and magnesium follow hypertension and sodium status. For example, the pressure response to sodium chloride may be dissociated from sodium, which may be secondary to adverse effects of chloride on calcium homeostasis. Clinical studies also indicate that the role of sodium is controversial in hypertension. Sodium restriction can benefit salt-sensitive persons and might not otherwise. However, most authorities believe that moderation of salt intake to a relevant extent is justifiable. Large scale, long-term intervention studies and shortterm clinical studies in different communities, in the light of recently investigated dietary factors, are necessary to establish the role of sodium in essential hypertension.

Magnesium in atherosclerotic cardiovascular disease and sudden death.

Magnesium ions are important for maintaining the functional and structural integrity of the myocardium. Epidemiologic studies suggest that myocardial hypomagnecytia can predispose to sudden cardiac death and that hard water protective factor preventing heart attack could be magnesium. Recent studies show that infarcted portion of the myocardium has lowered magnesium content as compared to noninfarcted segment. Magnesium deficiency sensitises the myocardium to the toxic effect of various drugs, hypoxia etc. and magnesium administration is protective. The metabolic, biochemical and electrophysiologic effects of magnesium appear to be significant in treatment of myocardial ischaemia. Magnesium is a metal-coenzyme and activates adenosine-triphosphatase which may be inhibited by nonglucose fuels like lactate and free fatty acids. Magnesium deficiency may be responsible for the chronic electrical instability of the myocardium predisposing to sudden cardiac death. The acute precipitating stress dependent trigger which lie in the brain may also be related to magnesium. In addition to fast Na and Ca channels there could be a Mg-carrying transport system maintaining the electrical activity of the myocardium. There is sufficient evidence to suggest the use of magnesium salts against ischaemic heart disease and sudden cardiac death. Magnesium is cardioprotective and influences action potential duration, membrane potential and perhaps maintains the fast response. The therapeutic and prophylactic value of magnesium needs further assessment.

Magnesium metabolism in essential hypertension.

Hypertension is a complex, heterogeneous disorder of which the exact etiology is unknown. The difficulty in ascribing an independent role to a single dietary constituent in blood pressure regulation may be due to interactions among nutrients which influence blood pressure. The effect of any one nutrient, particularly magnesium, on hypertension should be considered within the context of overall nutrition in each patient. Clinical, experimental and epidemiologic studies support the role of magnesium in hypertension, whereas a few studies negate this role. Magnesium ions are important in arterial smooth muscle contraction. Since magnesium is found mainly at the inner surface of the cell membranes, it could play a role in cell membrane permeability for sodium and calcium which is important in the etiopathogenesis of hypertension. Magnesium deficiency can predispose to increased contractility of the arteries and its excess can modulate smooth muscle contractility caused by bradykinin, angiotensin II, serotonin, prostaglandins and catecholamines. Magnesium therapy can prevent the development of resistant hypertension and arrhythmias in hypertensives with diuretic-induced hypomagnesemia. It might also reduce blood pressure at least up to 10/5 mm Hg provided adequate magnesium salts are given for an adequate period of time. In view of the still ill defined role of magnesium in hypertension, magnesium supplementation is advised only to those hypertensives who are receiving diuretics and develop resistant hypertension or who have frank magnesium deficiency. A diet rich in magnesium may be used for prevention of hypertension in predisposed communities because of the other advantages of such a diet in prevention.

Endoscopy and implantable electronic devices.

The increasing use of implantable electronic devices such as cardiac pacemakers and neurostimulators means that they are being increasingly encountered in endoscopy departments. The electromagnetic fields generated during electrosurgery and with magnetic imaging systems have the potential to interfere with such devices. The authors present a case that highlights some of the steps necessary for minimising risk, review the evidence and summarise the currently available guidance.

Colorectal cancer detection: time to abandon barium enema?

OBJECTIVES: To assess the sensitivity of double contrast barium enema (DCBE) for diagnosing colorectal cancer (CRC). DESIGN: Retrospective evaluation of DCBE performed in the 2 years prior to diagnosis of CRC. SETTING: Teaching hospital in Cambridge, UK. PATIENTS: 1310 consecutive cases of CRC identified from cancer registry data. INTERVENTIONS: DCBE and colonoscopy. MAIN OUTCOME MEASURES: Sensitivity of DCBE for diagnosing CRC. RESULTS: 215 patients had undergone a DCBE within the 2 years prior to diagnosis with CRC. After excluding those reported as inadequate, 37 of these were reported as normal, giving a sensitivity of 83% (81-85%). CONCLUSIONS: The performance of DCBE is inadequate for the exclusion of CRC. Expansion of colonoscopy and CT colonography capacity is urgently required nationally so that DCBE can finally be abandoned as a firstline test in patients at risk of CRC.