Comparison of the VBM laryngeal tube and laryngeal mask airway for ventilation during manual in-line neck stabilisation.

INTRODUCTION

The purpose of this study is to assess whether the newly-developed VBM (Medizintechnik GmbH, Sulz, Germany) laryngeal tube (LT) is able to provide adequate ventilation and oxygenation to patients with an unstable neck and require airway management. The haemodynamic responses to insertion between the two devices were also studied. We compared the LT to the laryngeal mask airway (LMA) as an alternative airway management tool in adult patients with unstable neck and who underwent intubation with manual in-line neck stabilisation.

METHODS

A randomised single-blinded prospective study was conducted involving a total of 40 American Society of Anesthesiology I and II pre-medicated patients who were divided into two groups, LT or LMA, for airway management during elective surgery. There were 20 patients for each group. After pre-oxygenation, anaesthesia was induced using intravenous (i.v.) fentanyl and i.v. propofol. The neuromuscular blockade was produced with either i.v. vecuronium or i.v. atracurium. The LT or LMA was inserted after neuromuscular blockade was confirmed using a peripheral nerve stimulator (train-of-four 1). A size 3, 4 or 5 LT or a size 3 or 4 LMA was inserted while the patient's head and neck were being stabilised by an assistant who held the sides of the neck and the mastoid processes (manual in-line stabilisation). If it was not possible to ventilate the lungs, or if end-tidal carbon dioxide and/or chest movement did not indicate a patent airway, the LT or LMA was removed. After three failed attempts, the study was terminated and the airway was secured in the most suitable manner determined by the anaesthetist. After successful placement of LT or LMA, anaesthesia was maintained with 66 percent nitrous oxide in oxygen and 2 minimum alveolar concentration sevoflurane. All patients received standard anaesthesia monitoring. The ease of insertion, the number of attempts needed to successfully secure the airway, episodes of desaturation (less than 95 percent) and end-tidal carbon dioxide at various time intervals were studied. The haemodynamic parameters such as systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate at different time intervals were also studied.

RESULTS

The study showed a statistically significant difference in time required for successful insertion between the groups; time required for LT was 24.8 +/- 7.7 seconds and LMA was 36.1 +/- 17.3 seconds (p-value equals 0.01). Both groups had no statistical differences (p-value is greater than 0.05) in number of attempts needed to achieve a patent airway, and the successful insertion rate was 100 percent for both groups. There were also no statistical differences in the haemodynamic response to insertion and the end-tidal carbon dioxide in this study.

CONCLUSION

We conclude that, under anaesthesia, the LT was a valuable and better alternative to LMA for ventilation and airway management when the patient's head and neck are stabilised by the manual in-line method.