NOISE-POLLUTION IN INTENSIVE-CARE UNITS - NOISE-REDUCTION BY MODIFICATION OF GAS HUMIDIFICATION

Today, noise pollution is an evident and ubiquitous problem even in in tensive care units. Noise can disturb the physiological and psychologi cal balance in patients and staff. Especially intubated patients and t hose breathing spontaneously through a T-piece are exposed to the nois e emitted by the nebuliser used to humidity the respiratory gas. This may make patients feel uncomfortable. To reduce noise pollution in the ICU a modified T-piece has been developed and investigated. In order to heat and humidity the respiratory gas a Conchaterm III unit (Kendal l company) and a thermo flow cylinder (DeVilbiss company) is necessary . While respiratory gas is flowing, water is sucked out of the heated thermoflow cylinder and nebulised according to the Venturi-Bernoulli p rinciple. To adjust the oxygen concentration of the respiratory gas a plastic ring must be turned to either close (98% oxygen) or open a val ve allowing room air to mix (40% oxygen). Noise pollution of the unit varies with admixture of room air. With a new device - a special oxyge n - air mixing chamber - the oxygen concentration of the respiratory g as can be adjusted outside the thermoflow cylinder, hardly producing a ny noise pollution. Therefore the principle of nebulisation could be c hanged to humidification. A thermoflow cylinder without the nebulisati on unit allows the respiratory gas to flow through the thermoflow cyli nder over heated and evaporating water, hardly causing any noise pollu tion. In both types of T-pieces the temperature of the respiratory gas is controlled and corrected by the Conchaterm unit. As the result of these modifications, noise pollution has been reduced from 70 dB(A) to 55 dB(A). In the modified T-piece,the quality of humidification has b een evaluated with a fresh gas flow of 22 l/min and at a gas temperatu re of 37 degrees C, not only collecting condensed water but also lost water. The modified T-piece allows a physiological humidification of t he respiratory gas. The modified T-piece is a simple and efficacious s ubstitute. Patients and staff are protected from adverse noise effects and patient well-being might be improved.