Novel instrumentation to determine peel force in vivo and preliminary studies with adhesive skin barriers.

BACKGROUND/PURPOSE: Adhesive barriers secure medical devices to skin. Laboratory adhesion models are not predictive of in vivo performance. The objectives of these studies were to validate a novel peel force device, and to investigate relationships between barrier formulations, barrier width, subjective discomfort during barrier removal, and substrates. METHODS: Three hydrocolloid barrier formulations in three widths were adhered to ethylene/methyl acrylate film (EMA), VITRO-SKIN(®) and human abdominal skin. Peel force was measured using a MTS Insight™ and a cyberDERM Inc. Mini Peel Tester (CMPT). Subjects reported their discomfort. RESULTS: Peel forces were highly correlated between devices and highly dependent on substrate. Data suggested a weak direct association between peel force in vivo and discomfort. The 0.5″-wide barriers had the most precise peel forces measurements in vivo. A weak negative relationship between normalized peel force and barrier width on human skin was found. There was a strong positive relationship between peel force in vivo and on EMA, whereas no correlation was observed with VITRO-SKIN(®). CONCLUSION: The CMPT correlates with a standard instrument and can advantageously investigate adhesion in vivo. Barrier width and substrate impact the reliability and predictability of peel force measurements.

Fecal containment in bedridden patients: economic impact of 2 commercial bowel catheter systems.

BACKGROUND: Fecal contamination is a major challenge in patients in acute/critical care settings that is associated with increased cost of care and supplies and with development of pressure ulcers, incontinence dermatitis, skin and soft tissue infections, and urinary tract infections. OBJECTIVES: To assess the economic impact of fecal containment in bedridden patients using 2 different indwelling bowel catheters and to compare infection rates between groups. METHODS: A multicenter, observational study was done at 12 US sites (7 that use catheter A, 5 that use catheter B). Patients were followed from insertion of an indwelling bowel catheter system until the patient left the acute/critical care unit or until 29 days after enrollment, whichever came first. Demographic data, frequency of bedding/dressing changes, incidence of infection, and Braden scores (risk of pressure ulcers) were recorded. RESULTS: The study included 146 bedridden patients (76 with catheter A, 70 with catheter B) who had similar Braden scores at enrollment. The rate of bedding/dressing changes per day differed significantly between groups (1.20 for catheter A vs 1.71 for catheter B; P = .004). According to a formula that accounted for personnel resources and laundry cycle costs, catheter A cost $13.94 less per patient per day to use than did catheter B. Catheter A was less likely than was catheter B to be removed during the observational period (P = .03). Observed infection rates were low. CONCLUSION: Catheter A may be more cost-effective than catheter B because it requires fewer unscheduled linen changes per patient day.

Statistical modeling of dental unit water bacterial test kit performance.

OBJECTIVE: While it is important to monitor dental water quality, it is unclear whether in-office test kits provide bacterial counts comparable to the gold standard method (R2A). Studies were conducted on specimens with known bacterial concentrations, and from dental units, to evaluate test kit accuracy across a range of bacterial types and loads. METHODOLOGY: Colony forming units (CFU) were counted for samples from each source, using R2A and two types of test kits, and conformity to Poisson distribution expectations was evaluated. Poisson regression was used to test for effects of source and device, and to estimate rate ratios for kits relative to R2A. RESULTS: For all devices, distributions were Poisson for low CFU/mL when only beige-pigmented bacteria were considered. For higher counts, R2A remained Poisson, but kits exhibited over-dispersion. Both kits undercounted relative to R2A, but the degree of undercounting was reasonably stable. Kits did not grow pink-pigmented bacteria from dental-unit water identified as Methylobacterium rhodesianum. CONCLUSION: Only one of the test kits provided results with adequate reliability at higher bacterial concentrations. Undercount bias could be estimated for this device and used to adjust test kit results. Insensitivity to methylobacteria spp. is problematic.

The impact of incomplete vaccination schedules on the magnitude and duration of protective antigen-specific IgG responses in recipients of the US licensed anthrax vaccine.

Using a cross-sectional analysis design, we measured serum anti-protective antigen (PA) concentrations in individuals receiving six or fewer US licensed anthrax vaccinations. Samples were collected from 363 individuals with a mean of 29.6+/-8.42 months after their last vaccination (range 3-57 months). An enzyme-linked immunosorbent assay (ELISA) developed and validated by the Centers for Disease Control and Prevention (CDC) was used to evaluate the range and status of anthrax vaccine-induced serum antibody concentrations. A significant correlation (r=0.73, P< or =0.001) was found to exist between the number of vaccinations received and specific anti-PA immunoglobulin G (IgG) concentrations. We observed two discrete groups comprised of one to three doses (5.9-11.7 microg/ml) and four to six doses (26.2-30.2 microg/ml). These data indicate that anti-PA IgG is present at low but detectable levels after as few as two vaccinations (5.9+/-6.43 microg/ml). These findings may have significance for anthrax vaccine recipients who are unable to complete the primary or full regimen with this licensed product.

Diagnosis of militarily relevant diseases using oral fluid and saliva antibodies: fluorescence polarization immunoassay.

This laboratory is developing fluorescence polarization (FP) methods as diagnostic tools to assay antibodies in saliva and other oral fluids. FP provides quantitation of molecular interaction, such as antigen-antibody binding, of a single, small-volume sample in real time and without prior separation of components such as blood cells. There is potential for wide-spread use of these homogeneous assays as noninvasive tests, especially as more compact, simplified fluorescence polarimeters become available. FP tests can be designed that are applicable to a wide spectrum of microorganisms and may be used in a clinic or far-forward deployed setting to aid in diagnosis of disease or verification of vaccination. Rapid salivary diagnostics, including FP, have been identified by the Office of Naval Research as requirements for future naval capabilities in basic and applied medical research for warfighter protection in casualty prevention. The applications of FP salivary diagnostics for determination of tuberculosis exposure and of anthrax immunization status are discussed as examples.