Validity of the Waterlow screening tool and risks for pressure injury in acute care

Objectives: To assess the validity of the Waterlow screening tool in a cohort of internal medicine patients and to identify factors contributing to pressure injury. Design: Longitudinal cohort study Setting: A tertiary hospital in Brisbane, Australia Participants: 274 patients admitted through the Emergency Department or outpatient clinics and expected to remain in hospital for at least three days were included in the study. The mean age was 65.3 years. Interventions: Patients were screened on admission using the Waterlow screening tool. Every second day, their pressure ulcer status was monitored and recorded. Main outcome measures: Pressure ulcer incidence Results: Fifteen participants (5.5%) had an existing pressure ulcer and a further 12 (4.4%) developed a pressure ulcer during their hospital stay. Sensitivity of the Waterlow scale was 0.67, (95% CI: 0.35 to 0.88); specificity 0.79, (95% CI: 0.73 to 0.85); PPV 0.13, (95% CI: 0.07 to 0.24); NPV 0.98, (95% CI: 0.94 to 0.99). Conclusion: This study provides further evidence of the poor predictive validity of the Waterlow scale. A suitably powered randomised controlled trial is urgently needed to provide definitive evidence about the usefulness of the Waterlow scale compared with other screening tools and with clinical judgement.

Combustion products of bulk aluminum rods burning in high pressure oxygen

Characterization of the combustion products released during the burning of commonly used engineering metallic materials may aid in material selection and risk assessment for the design of oxygen systems. The characterization of combustion products in regards to size distribution and morphology gives useful information for systems addressing fire detection. Aluminum rods (3.2-mm diameter cylinders) were vertically mounted inside a combustion chamber and ignited in pressurized oxygen by resistively heating an aluminum/palladium igniter wire attached to the bottom of the test sample. This paper describes the experimental work conducted to establish the particle size distribution and morphology of the resultant combustion products collected after the burning was completed and subsequently analyzed. In general, the combustion products consisted of a re-solidified oxidized slag and many small hollow spheres of size ranging from about 500 nm to 1000 µm in diameter, surfaced with quenched dendritic and grain-like structures. The combustion products were characterized using optical and scanning electron microscopy.