HEMODYNAMIC-CHANGES WITH THE LARYNGEAL MASK AIRWAY - OFF-THE-CUFF

The cross-sectional area of the common carotid artery bulb was measure d using a 5 MHz pulse wave Doppler probe in a patient undergoing gener al anaesthesia using a laryngeal mask airway (LMA). A simultaneous mea surement of blood velocity was performed to allow determination of the blood flow. Following inflation of the cuff on the IMA, the cross-sec tional area of the right carotid artery bulb decreased from 1.09 to 0. 89 cm(2), flow velocity increased 120 to 176 cm s(-1) and the blood fl ow increased from 130.8 to 156.6 cm(3) s(-1). On the left the cross-se ctional area decreased from 1.16 to 1.13 cm(2), the velocity increased 136 to 151 cm s(-1) and the blood flow increased from 157.8 to 170.6 cm(3)s(-1). While a reduction in cross-sectional area was observed in the carotid bulb in this patient, this was accompanied by an increase in the velocity and a consequent increase in blood flow. In patients w ith atheromatous disease involving the carotid arteries this decrease in cross-sectional area may prove clinically significant. The use of t he LMA may not be suitable for this population.