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PubMed1982

Automatic dew-point temperature sensor.

A device is described for measuring dew-point temperature and water vapor pressure in small confined areas. The method is based on the deposition of water on a cooled surface when at dew-point temperature. A small Peltier module lowers the temperature of two electrically conductive plates. At dew point the insulating gap separating the plates becomes conductive as water vapor condenses. Sensors based on this principle can be made small and rugged and can be used for measuring directly the local water vapor pressure. They may be installed within a conventional ventilated sweat capsule used for measuring water vapor loss from the skin surface. A novel application is the measurement of the water vapor pressure gradients across layers of clothing worn by an exercising subject.

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Evaporative water losses through a temporary wound dressing under simulated wound conditions.

Patients with burns lose large amounts of water through evaporation from open wounds. Because the wound covering is the first line of defense for maintenance of body fluid balance in these patients, quantification of the evaporative water loss through wound coverings at the bedside would improve the accuracy of estimations of body water loss. The present experiment evaluates the use of a small ventilated capsule system automated with miniature resistance-type dew-point sensors for measurement of evaporative water loss through biologic dressings under simulated wound conditions. Evaporative water loss from wounds was simulated by pilocarpine-induced profuse sweating on the forearm. Evaporative water loss through uncovered skin was compared with that of skin covered with commercially available temporary wound dressings. Compared with an adjacent unstimulated area, forearm dew-point temperature in the capsule (Tcdp) and sweat rate increased immediately after pilocarpine exposure and remained significantly elevated and relatively constant for an additional 60 minutes. Evaporative water loss of the forearm was 29 +/- 4.8 gm/m2/hr (mean +/- SE) at baseline and rose significantly to 275 +/- 18.2 gm/m2/hr after pilocarpine exposure. The pilocarpine-stimulated sweat rate and Tcdp at neutral conditions were similar to those obtained from walking on a treadmill for 60 minutes in a 30 degrees C room. Compared with pilocarpine-induced evaporative water loss of the uncovered skin, temporary wound dressings significantly reduced evaporative water loss by 40% to 60%. No significant differences were observed between varieties of temporary wound dressings differing in thickness and/or porosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗