Abstract
Purpose
Warming and humidification of inspired gases is standard care for intubated patients whose lungs are ventilated mechanically for prolonged periods. We examined whether active humidification of inspired gases might reduce laryngopharyngeal discomfort in patients undergoing brief laryngeal mask airway (LMA) anesthesia.
Methods
In a prospective trial, 200 adult patients undergoing elective surgery under general anesthesia were randomly assigned to receive ventilation without airway warming and exogenous humidification (Group C - control), or active warming and humidification of inspired gases (Group HUM - humidified), using a humidifier with a heated wire circuit. Inhalational anesthesia was maintained via a circle system. The temperatures and relative humidities of inspired gases were monitored continuously throughout surgery. Postoperative sore throat, dysphonia, and dysphagia were assessed one and 24 hr after anesthesia. Whenever symptoms were present, their severities were graded using a 101-point numerical rating scale.
Results
The mean temperature and relative humidity of the inspired gases in Group HUM were greater compared to Group C (36.1 ± 0.4°C and 99.5 ± 0.5%vs 26.9 ± 0.8°C and 76.4 ±10.9%, respectively). Postoperatively, the overall frequencies of laryngeal and pharyngeal discomfort were similar in the two groups (53.8% and 54.9% in Group Cvs 51.6% and 41.9% in Group HUM at one and 24 hr respectively,P > 0.05). The groups were also similar with respect to the severity scores of laryngo-pharyngeal discomfort.
Conclusion
Active warming and humidification of inspired gases has no clinically appreciable effect in reducing the incidence and severity of laryngo-pharyngeal complaints after brief (< two hours) LMA anesthesia.
Résumé
Objectif
Le réchauffement et l’humidification des gaz inspirés sont la norme pour les patients intubés dont les poumons sont ventilés mécaniquement pour de longues périodes. Nous avons évalué si l’humidification des gaz inspirés réduisait l’inconfort laryngo-pharyngé des patients anesthésiés à l’aide d’un masque laryngé (ML).
Méthodes
Lors d’une étude prospective, 200 patients adultes devant subir une chirurgie élective sous anesthésie générale ont été répartis en deux groupes de façon aléatoire: dans le premier groupe, les patients étaient ventilés sans réchauffement ni humidification exogène des voies aériennes (groupe T - témoin); alors que dans le second groupe, les patients étaient ventilés avec réchauffement et humidification actifs des gaz inspirés (groupe HUM - humidifié) en utilisant un humidificateur à circuit métallique chauffé. L’anesthésie par inhalation était maintenue en circuit fermé. Les températures et humidités relatives des gaz inspirés étaient constamment surveillées durant toute la chirurgie. Les maux de gorge postopératoires, la dysphonie, ainsi que la dysphagie ont été évalués une et 24 h après l’anesthésie. Si des symptômes étaient présents, leur gravité était mesurée à l’aide d’une échelle numérique de 101 points.
Résultats
La température moyenne et les humidités relatives des gaz inspirés du groupe HUM étaient plus élevées que celles du groupe C (36,1 ± 0,4°C et 99,5 ± 0,5 % vs 26,9 ± 0,8°C et 76,4 ± 10,9 %, respectivement). Après l’opération, la fréquence moyenne d’inconfort laryngé et pharyngé était semblable dans les deux groupes (53,8 % et 54,9 % dans le groupe T vs 51,6 % et 41,9 % dans le groupe HUM, une et 24 h après l’opération respectivement, P > 0,05). Les niveaux d’inconfort laryngo-pharyngé sur l’échelle numérique étaient également semblables dans les deux groupes.
Conclusion
Le réchauffement et l’humidification actifs des gaz inspirés n’ont pas d’effet clinique appréciable dans la réduction de l’incidence et de la gravité des douleurs laryngo-pharyngées après une brève (< deux heures) anesthésie avec masque laryngé.
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Competing interests: This study was funded by departmental sources only. The authors have no financial interests in the companies which manufacture the studied devices.
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Duk-Kyung, K., Ka-Young, R., Won-Kyoung, K. et al. A heated humidifier does not reduce laryngopharyngeal complaints after brief laryngeal mask anesthesia. Can J Anesth 54, 134–140 (2007). https://doi.org/10.1007/BF03022010
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DOI: https://doi.org/10.1007/BF03022010