The laryngeal tube (VBM Medical, Sulz a.N., Germany) (Fig. 1) is a new airway device for general anaesthesia that can also be used as an alternative to endotracheal intubation for emergency airway management. The device provides a patent airway in a majority of patients at the first attempt of insertion and allows adequate ventilation of the lungs [2,3]. This single-lumen tube is inserted blindly, and the pharyngeal and oesophageal cuffs are then inflated through a single inflation line. Because of its shape, the tip of the laryngeal tube should always be positioned in the proximal oesophagus with the ventral opening facing the glottis. Galli and colleagues evaluated the laryngeal tube in 140 patients : insertion was considered easy in 68.3%, difficult in 29.4% and impossible in 2.1%; ventilation and oxygenation were considered adequate. They also verified the position of the laryngeal tube fibreoptically in 20 patients; although ventilation was adequate in all patients, the glottis was visible in only 16. However, when other devices such as the laryngeal mask and the intubating laryngeal mask airways are also considered, it is possible that there is no relation between the position of the ventilation outlet and the adequacy of lung ventilation .
We obtained approval from the local Ethics Committee and written informed consent from our patients. We inserted the laryngeal tube in 10 patients who were about to undergo elective surgery with general anaesthesia. In all participants the laryngeal tube was easily placed at the first attempt (average time 18.8 s, SD ± 3.4 s) and adequate lung ventilation and oxygenation were achieved (mean tidal volume 0.486 L, SD ± 0.051 L; SpO2 99-100%; mean end-tidal PCO2 3.51 kPa, SD ± 0.4 kPa). The view of the glottic aperture through the laryngeal tube was judged by one anaesthetist - using a flexible fibreoptic bronchoscope - in all patients using a four-point scale: 'excellent' (complete view of the glottic aperture); 'good' (partial view of the glottic aperture, complete after manipulation on the tube); 'sufficient' (glottic aperture initially not visible, complete or partial view after manipulation on the tube); and 'poor' (no view of the glottic aperture even with manipulation of the tube). After removal of the laryngeal tube, an endotracheal tube (size 7.5 mm) was inserted and its correct position verified fibreoptically. Tidal volume and peak airway pressures were registered during ventilation of the lungs using a bag with both airway devices. Auscultation over the epigastrium during lung ventilation with the laryngeal tube showed no sign of gastric insufflation.
The fibreoptic view through the ventilation outlet of the laryngeal tube was graded excellent in four patients, good in three patients, sufficient in two patients and poor in one patient. The tip of the laryngeal tube was positioned in the proximal oesophagus in all patients. The tidal volumes (0.486 L, SD ± 0.05 L) during lung ventilation with the laryngeal tube were comparable with those reached with the endotracheal tube (0.500 L, SD ± 0.06 L, Wilcoxon signed rank sum test, P = 0.39), and there were no significant differences in peak airway pressure (laryngeal tube 26.8 cm H2O, SD ± 3.9 cmH2O, endotracheal tube 24.9 cmH2O, SD ± 3.6 cmH2O, P = 0.27).
Other investigators have found lung ventilation and oxygenation to be adequate in up to 97.9% of individuals [4,6]; however, an excellent or good view of the glottis through the laryngeal tube could not be achieved in all our patients. The presence of two inflated cuffs seemed to create a space that allows sufficient lung ventilation independent of the position of the ventral opening in respect to the glottic opening. Gas leakage is a common problem during positive-pressure ventilation of the lungs when the laryngeal mask airway is used ; this might be reduced with the laryngeal tube because of the good airway seal achieved even under increased airway pressure . The distal cuff closes the proximal oesophagus, possibly resulting in better protection against regurgitation . Further investigations of the laryngeal tube are necessary.
Department of Internal Medicine Fuerst-Stirum-Hospital Bruchsal, Bruchsal, Germany
H. V. Genzwuerker
Department of Anaesthesiology and Intensive Care Medicine University Hospital, Mannheim, Germany
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