Modelling the flow of congestive heart failure patients through a hospital system

The number of hospital admissions in England due to heart failure is projected to increase by over 50% during the next 25 years. This will incur greater pressures on hospital managers to allocate resources in an effective manner. A reliable indicator for measuring the quantity of resources consumed by hospital patients is their length of stay (LOS) in care. This paper proposes modelling the length of time heart failure patients spend in hospital using a special type of Markov model, where the flow of patients through hospital can be thought of as consisting of three stages of care—short-, medium- and longer-term care. If it is assumed that new admissions into the ward are replacements for discharges, such a model may be used to investigate the case-mix of patients in hospital and the expected patient turnover during some specified period of time. An example is illustrated by considering hospital admissions to a Belfast hospital in Northern Ireland, between 2000 and 2004.

Characterisation and evaluation of novel surfactant bacterial anti-adherent coatings for endotracheal tubes designed for the prevention of ventilator-associated pneumonia.

It is accepted that ventilator-associated pneumonia is a frequent cause of morbidity and mortality in intensive care patients. This study describes the physicochemical properties of novel surfactant coatings of the endotracheal tube and the resistance to microbial adherence of surfactant coated endotracheal tube polyvinylchloride (PVC). Organic solutions of surfactants containing a range of ratios of cholesterol and lecithin (0:100, 25:75, 50:50, 75:25, dissolved in dichloromethane) were prepared and coated onto endotracheal tube PVC using a multiple dip-coating process. Using modulated temperature differential scanning calorimetry it was confirmed that the binary surfactant systems existed as physical mixtures. The surface properties of both surfactant-coated and uncoated PVC, following treatment with either pooled human saliva or phosphate-buffered saline (PBS), were characterised using dynamic contact angle analysis. Following treatment with saliva, the contact angles of PVC decreased; however, those of the coated biomaterials were unaffected, indicating different rates and extents of macromolecular adsorption from saliva onto the coated and uncoated PVC. The advancing and receding contact angles of the surfactant-coated PVC were unaffected by sonication, thereby providing evidence of the durability of the coatings. The cell surface hydrophobicity and zeta potentials of isolates of Staphylococcus aureus and Pseudomonas aeruginosa, following treatment with either saliva or PBS, and their adherence to uncoated and surfactant-coated PVC (that had been pre-treated with saliva) were examined. Adherence of S. aureus and Ps. aeruginosa to surfactant-coated PVC at each successive time period (0.5, 1, 2, 4, 8 h) was significantly lower than to uncoated PVC, the extent of the reduction frequently exceeding 90%. Interestingly, the microbial anti-adherent properties of the coatings were dependent on the lecithin content. Based on the impressive microbial anti-adherence properties and durability of the surfactant coating on PVC following dip coatings, it is proposed that these systems may usefully reduce the incidence of ventilator-associated pneumonia when employed as luminal coatings of the endotracheal tube.