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A524
October 15, 2006
9:00 AM - 11:00 AM
Room Hall E, Area E
Preliminary Experience with a New Reusable Laryngeal Mask: The Ambu Aura40
Harald V. Genzwuerker, M.D., Luc Aniset, M.D., Oliver Jandewerth, M.D., Jochen Hinkelbein, M.D.
Clinic of Anaesthesiology and Intensive Care Medicine, University Hospital Mannheim, Mannheim, Germany
Objective: After introduction of a single-use laryngeal mask in 2004, Ambu (Ambu A/S, Denmark) has launched a reusable version made from silicone called “Aura40” in March 2006. Immediately after availability, the device underwent investigation at our institution to judge feasibility for routine surgical interventions. As in the PVC model, now named “AuraOnce”, the curved shape of the airway tube is supposed to allow easy insertion and the soft cuff aims at achieving a reliable airway seal. Ease of insertion and quality of airway seal as judged by airway leak pressure are tested in patients undergoing elective surgical procedures.

Methods: After approval of the local institutional review board and obtaining written informed consent, 30 ASA I and II patients without history of cervical spine problems or known pathology of the respiratory tract undergoing elective surgical procedures were included in the trial. Standard monitoring (ECG, blood pressure, pulse oximetry) was attached. Anesthesia was induced with Fentanyl 0.25 mg and Propofol 200 mg after preoxygenation with a facemask for three minutes. No muscle relaxants were used. The Aura 40 was inserted according to manufacturer´s instructions. Time was measured from removal of the facemask until first tidal volume. Ventilation was considered sufficient when bilateral equal chest movements, a tidal volume of at least 4 ml per kg and a square endtidal CO2 wave without oral or gastric leak were achieved. Airway leak pressure was tested with a cuff pressure of 60 cm H2O by closing the valve of the circle system until air leakage was noticed over the mouth or stomach. Patients were questioned for sore throat, dysphonia and dysphagia 1 hour after removal of the laryngeal mask.

Results: Demographic data of patients are listed in table 1. 16 patients underwent orthopaedic surgery, 14 patients were anaesthetized for small abdominal interventions. Insertion was possible in the first attempt in 28 patients (93.9 %), a second attempt was required in 2 patients (no failure after 2 attempts). A size 4 Aura40 was used in 15 patients (all female), size 5 in the other 15 patients (2 female, 13 male). Insertion time was 14.9 ± 3.7 seconds. Peak pressure was 14.5 ± 2.3 cm H2O. Airway leak pressure was 28.7 ± 4.9 cm H2O, with oral leak in all patients and no signs of gastric inflation. For the size 4 (n=15), the airway leak pressure was 27.8 ± 4.9 cm H2O, and 29.5 ± 4.9 cm H2O for the size 5. Ventilation with a tidal volume of 6.7 ± 1.7 ml per kg was performed for 37 ± 25 minutes without any adverse events. No sore throat, dysphonia or dysphagia were stated by any patients in the postoperative interview in the recovery area.

Conclusion: In a first clinical trial, the reusable Ambu Aura40 allows rapid airway maintenance with a high insertion success rate and an airway leak pressure exceeding 25 cm H2O.[table1][figure1]

Anesthesiology 2006; 105: A524
Demographic data
Gender13 male, 17 female
Age44.0 ± 11.7 years
Height1.72 ± 0.09 m
Weight76.8 ± 13.9 kg
Body mass index26.0 ± 3.0 kg per m²
Data are mean ± standard deviation
Figure 1