Heuristic evaluation and simulated use testing of infusion pumps to inform pump selection.

BACKGROUND: Poorly designed infusion pumps can lead to user errors and adverse incidents. Therefore, assessments of their usability and performance that can inform managerial decisions about the selection of appropriate medical devices are essential. OBJECTIVE: This study aimed to identify design deficiencies and evaluate the usability and performance of four infusion pump models and thus inform decisions about infusion pump selection. METHODS: Four evaluators evaluated the interface designs of the pumps according to a series of design principles in a heuristic evaluation in order to identify pump design deficiencies. Additionally, 60 registered nurses participated in simulated use testing to perform a series of tasks using the pumps in order to examine the pump performances. Outcome measures included task completion time, frequency of deviations, frequency of requests for assistance, and nurses' perceptions. RESULTS: Design issues identified included system status visibility, information access, and error prevention. The results of simulated use testing favored some pumps over others, depending on which outcome measures were considered. CONCLUSIONS: Heuristic evaluations and simulated use testing can provide information about the basic usability of medical devices and related operational issues. However, practitioners should select appropriate evaluation principles, testing tasks, and outcome measures based on the tested medical devices and contexts.

Viral clearance and inflammatory response patterns in adults hospitalized for pandemic 2009 influenza A(H1N1) virus pneumonia.

BACKGROUND: Little is known about the virological and inflammatory responses of severe pandemic 2009 influenza A(H1N1) virus pneumonia during antiviral treatment. METHODS: In a prospective observational study, we recruited consecutive adults hospitalized with confirmed pandemic 2009 H1N1 infection during a 16-week period. Nasopharyngeal aspirate and non-respiratory samples (blood, stool and urine) were collected at presentation, and serial nasopharyngeal flocked swabs (NPFS) and tracheal aspirates (TA) were collected after initiating oseltamivir treatment for quantitative viral RNA assay, using real-time reverse transcriptase-PCR. Serial plasma samples were collected for cytokine/chemokine assay using cytometric bead array. Patients with severe pneumonia (lung infiltrates and hypoxaemia) were compared to those with milder illnesses. RESULTS: A total of 66 patients were studied (mean age 43 ±20 years); 28 (42%) developed severe pneumonia, of whom 10 (15%) required intubation. Severe pneumonia was associated with older age, dyspnoea, delayed presentation >2 days from onset, extrapulmonary virus detection (13-28%) and higher viral concentration despite late-presentation (multiple linear regression, ß=0.94, 95% confidence interval 0.15-1.74; P=0.02). Patients with severe pneumonia exhibited slow viral clearance with oseltamivir treatment, particularly in the lower respiratory tract (median [interquartile range] durations of RNA positivity after antiviral initiation were NPFS 6.0 days [3.0-8.0], TA 11.0 days [7.8-14.3] versus milder illness group NPFS of 2.0 days [1.0-3.0] days; P<0.01). High viral load in lower respiratory tract despite upper-tract RNA negativity and viral rebound after stopping treatment were noted in some patients. H275Y mutation was absent. High plasma levels of interleukin (IL)-6, CXCL-8 (IL-8), CCL2 (monocyte chemoattractant protein-1) and soluble tumour necrosis factor receptor-1 were observed, which correlated with the extent and progression of pneumonia in hospital. CONCLUSIONS: In severe 2009 H1N1 pneumonia, viral clearance is slow with treatment, particularly in the lower respiratory tract. A more sustained antiviral regime appears warranted.