Impact of the laryngeal tube as supraglottic airway device on blood flow of the internal carotid artery in patients undergoing general anaesthesia.

INTRODUCTION: Laryngeal tubes (LT) are supraglottic airway devices routinely used in emergency airway management. During cardiac arrest in a swine model, the carotid artery blood flow is reduced after insertion of a LT. A compression of the internal carotid (ICA) artery by the inflated cuff was shown. Up to now there is no information if the LT has similar effects in humans with possible negative implications for use of the LT in case of cardiac arrest.

OBJECTIVE: We hypothesized that the use of a LT in humans significantly reduces the blood flow in the ICA compared facemask ventilation. A significant reduction was defined as a 25% reduction from baseline values.

MATERIAL AND METHODS: After induction of general anaesthesia and reaching a haemodynamic steady state (stable heart rate >50/min and mean arterial pressure >60 mmHg), blood flow within the ICA was measured via doppler sonography during pressure-controlled ventilation with facemask-, laryngeal tube- and laryngeal mask.

RESULTS: We found no differences in the carotid blood flow. Neither between the facemask ventilation (right side 419 ± 159 ml min-1 , left side 355 ± 120 ml min-1 ) and the laryngeal tube ventilation (right side 400 ± 131 ml min-1 , left side 384 ± 124 ml min-1 . p = 0.86 and p = 0.12), nor the facemask-ventilation and the laryngeal mask ventilation (right ICA 415 ± 150 ml min-1 , left ICA 485 ± 274 ml min-1 , p = 0.49 and 0.26).

CONCLUSIONS: In humans the LT does not impair blood flow of the internal carotid artery during ventilation in general anaesthesia. Further studies are needed to confirm our findings under the conditions of cardiac arrest.