[Comparison of different laryngeal mask airways in a resuscitation model]

Abstract

Objective: The standard laryngeal mask airway LMA-Classic is recommended in the ILCOR guidelines as alternative to facemask and tracheal tube during cardiopulmonary resuscitation. LMA-Unique, LMA-Fastrach and LMA-ProSeal are additional variants that are compared with the standard LMA in a resuscitation model.

Methods: Tidal volumes, chest compressions and signs of gastric inflation are measured in a standardized resuscitation model (Ambu Cardiac Care Trainer with notebook and thumper). Ten 3-minute resuscitation cycles were performed with facemask and all LMAs (Classic, Unique, Fastrach, ProSeal, all size 4) with a ventilation : compression ratio of 2:15. To allow comparison with tracheal tube and to judge safety margins, another ten resuscitation cycles were performed with tracheal tube and all laryngeal masks with continuous chest compressions after two initial ventilations. The bag-valve device used for ventilation was replaced by an automatic transport ventilator in a third series with continuous chest compressions. Cuff pressures were set at 80 cm H2O.

Results: During interrupted chest compressions, adequate ventilation was possible with all devices. Tidal volumes for facemask, LMA-Fastrach and LMA-ProSeal were significantly (p < 0.001) higher than with LMA- Classic and LMA-Unique. During continuous chest compressions, significant differences (p < 0.001) occurred when comparing tracheal tube, Fastrach and ProSeal with the other two laryngeal mask airways, which did not reach recommended tidal volumes. During ventilation with the automatic transport ventilator, values for all devices except LMA-ProSeal dropped significantly, adequate ventilation was possible with tracheal tube, Fastrach and ProSeal. Signs of gastric inflation were found during ventilation with facemask and - to a lesser extent - with LMA-Classic.

Conclusion: In the resuscitation model chosen, all laryngeal mask airways are possible alternatives for ventilation during cardiopulmonary resuscitation. The new LMA-ProSeal and also the LMA-Fastrach allow higher tidal volumes even during elevated intrathoracic pressures caused by continuous chest compressions, performing superior to the standard laryngeal mask airway. For inclusion of these devices in the ILCOR guidelines, further research in patients is warranted.