Abstract
Purpose
The introduction of the laryngeal mask airway (LMA) has had a major impact on anaesthetic practice in the last ten years. Previous authors have demonstrated pressures equivalent to mean arterial blood pressure within the cuff of the LMA. This study examined the effects of cuff inflation on the cross sectional area, flow and velocity of blood flow at the level of the carotid sinus.
Methods
Seventeen patients scheduled to have LMAs inserted as part of routine anaesthetic management were recruited into the study. Measurements of the common carotid artery bulb area, peak velocity and blood flow were performed upon LMA cuff inflation and deflation using a 5 MHz pulse wave Doppler probe.
Results
Deflation of the cuff resulted in an increase in the cross sectional area (from 0.58 ± 0.05 to 0.64 ± 0.04 cm2;P < 0.005), an increase in blood flow (from 65.6 ± 5.6 to 73.9 ± 5.6 cm3· sec−1; P < 0.05) and a slight but non significant increase in velocity of blood flow.
Conclusion
This study demonstrates that inflation of the cuff on the LMA results in a decrease in carotid bulb cross sectional area which results in a decrease in blood flow.
Résumé
Objectif
Au cours des dix dernières années, l’introduction du masque laryngé (ML) a eu un impact considérable sur la pratique de l’anesthésie. Certains auteurs ont déjà démontré des valeurs de pression interne de la manchette du ML équivalentes à la pression artérielle moyenne. Cette étude examine les effets de l’insufflation de la manchette sur la surface transversale du sinus carotidien et sur le débit et la vélocité du sang à ce niveau.
Méthodes
Dix-sept patients programmés pour l’insertion d’un ML au cours d’une anesthésie normale ont participé à l’étude. Des mesures avec une sonde Doppler utilisant une onde puisée de 5 MHz de la surface du bulbe carotidien, de la vélocité de pointe et du débit sanguin ont été effectuées au moment du gonflement et du dégonflement de la manchette.
Résultats
Le dégonflement de la manchette a provoqué une augmentation de la surface sagittale (de 0,58 ± 0,05 à 0,64 ± 0,04 cm2;P < 0,005), une augmentation du débit sanguin (de 65,6 ± 5,6 à 73,9 ± 0,56 cm3· s−1 ; P < 0,05) et une légère augmentation non significative de la vélocité du flot sanguin.
Conclusion
Cette étude montre que le gonflement de la manchette du ML produit une baisse de la surface transversale du bulbe carotidien et une baisse du débit sanguin.
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Colbert, SA., Ohanlon, D.M., Flanagan, F. et al. The laryngeal mask airway reduces blood flow in the common carotid artery bulb. Can J Anaesth 45, 23–27 (1998). https://doi.org/10.1007/BF03011987
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DOI: https://doi.org/10.1007/BF03011987