Asunto(s)
Ingeniería Biomédica/educación , Ingeniería Biomédica/normas , Capacitación en Servicio/organización & administración , Servicio de Mantenimiento e Ingeniería en Hospital , Gestión de la Calidad Total/organización & administración , Análisis Costo-Beneficio , Predicción , Hospitales Universitarios , Capacitación en Servicio/economía , Equipos de Administración Institucional , Servicio de Mantenimiento e Ingeniería en Hospital/normas , Michigan , Evaluación de Programas y Proyectos de Salud , Recursos HumanosRESUMEN
We evaluated the water-vapor output from four brands of unheated, prefilled bubble humidifiers-the Aerwey 300, the Aquapak 301, the McGaw 250, and the Travenol 500-at oxygen flowrates of 2, 4, 6, and 81/min. We recorded relative humidity (RH) and temperature in a test chamber at intervals over a minimum period of 24 h, and we calculated water-vapor content (WVC) and corresponding RH at 37 degrees C. Ambient RH was 53.4% +/- 5.25% (mean +/- 1 SD) at a test-chamber temperature of 26.2 degrees C +/- 0.79 degrees C. Mean 24-h WVC at 2 1/min (n = 20) ranged from 20.4 +/- 0.63 mg/l (McGaw) to 17.2 +/- 0.76 mg/l (Aerwey). This corresponded to a range of RH at 37 degrees C of 46.6% +/- 1.43% (McGaw) to 39.1 +/- 1.72% (Aerwey). A statically significant difference in mean WVC existed between brands of humidifiers (P less than 0.001). The McGaw and Travenol humidifiers consistently delivered hydrated gas with a greater WVC than did either the Aerwey or Aquapak humidifiers (P less than 0.001). A statistically significant decrease in mean WVC and RH at 37 degrees C occurred as the oxygen flowrate increased (P less than 0.001). None of the humidifiers was able to hydrate the source gas to a mean equivalent of 50% RH at 37 degrees C, at any flowrate. The design of the humidifier bubble diffuser and the source-gas flowrate appear to be the prime determinants of the humidification efficiency of unheated, prefilled bubble humidifiers.
Asunto(s)
Diseño de Equipo , Equipos y Suministros de Hospitales , Humedad , Análisis de Varianza , Estudios de Evaluación como AsuntoRESUMEN
A simple model of a steady-flow HF chemical laser has been formulated in which the excited-state formation rate is limited by the H(2)-F mixing rate. Lasing is allowed to take place between several vibrational levels of the HF molecule simultaneously. With reasonable approximations, the power output and efficiency can be determined analytically. The dependence of these variables on the independent parameters is in qualitative accord with experimental observations on mixing lasers but differs markedly from the predictions for lasers in which the reactants are premixed.
