Abstract
Humidity levels of respired gases in spontaneously breathing patients were measured with a quadrupole mass spectrometer (Medishield Model MS-2) and compared between various anaesthetic systems during clinical anaesthesia. In studies of high flow rebreathing non-absorption systems the mean inspired absolute humidity averaged approximately16 mg.l-1 (range 14.7 to 16.1 mg.l-1) compared to a semiclosed circle absorption system (BOC MK 111) in which values for absolute humidity varied from 6.8 ± 5.1 mg.l-1 for children through 9.5 ± 3.0 mg.l-1 for adults, and the closed circle absorption system in which values of 20.5 ± 2.3 mg.l-1 were only gradually reached. Addition of a functioning Revell circulator to the circle absorption system provided immediately markedly higher levels of inspired humidity during clinical use, either semiclosed (15.4 ± 5.1 mg.l-1 in children to 18.8 ± 2.4mg.l-1 in adults), or closed (23.3 ± 1.8mg.l-1 in adults). These markedly higher inspired levels of absolute humidity were attained during forced circulation of respired gas provided by the Revell circulator without the concomitant disadvantages of rebreathing or the potential hazards associated with some humidifying devices.
Résumé
A l’aide d’un spectromèlre de masse, on a mesuré l’humidité absolue des gaz respirés spontanément à travers différents montages d’anesthésie par des patients sous anesthésie.
Pour les systèmes à grand débit de gaz avec réinspiration sans absorption de CO2, l’humidité absolue moyenne était de 16 mg par litre (14.7 à 16.1 mg par litre). Pour le système demi fermé avec absorption (BOC MK 111), ces mêmes valeurs étaient de 6.8 ±5.1 mg par litre pour les enfants et 9.5 ± 3mg par litre pour les adultes. Pour le système fermé avec absorption, l’humidité absolue parvenait graduellement à 20.5 ± 2.3 mg par litre. L’inclusion, dans les circuits avec absorption, d’un circulateur de Revell, élevait rapidement les niveaux d’humidité à 15.4 ± 5.1 mg par litre chez les enfants et à 18.8 ±2.4 mg par litre chez les adultes pour le circuit demi fermé et à 23.3 ± 1.8 mg par litre pour le circuit fermé. Ces niveaux êlevés d’humidité absolue sont possibles grâce au circulateur de Revell qui permet d’éviter les désavantages des systèmes avec réinspiration et les complications toujours possibles de certains appareils d’humidification.
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Presented in part at the Anaesthetics Research Society Meeting July 4, 1981 in Cambridge, England.
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Flynn, P.J., Morris, L.E. & Askill, S. Inspired humidity in anaesthesia breathing circuits: comparison and examination of effect of Revell circulator. Can Anaesth Soc J 31, 659–663 (1984). https://doi.org/10.1007/BF03008764
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DOI: https://doi.org/10.1007/BF03008764