Combined International Multi-Center Phase I and II Study on Safety and Performance of theAMBU A/S Laryngeal Mask
Presentation Time: Monday, 9:15 a.m. - 10:45 a.m.
AUTHORS: C. A. Hagberg1, F. S. Jensen2, H. Genzwurker3, R. Krivosic-Horber4, B. U. Schmitz1, H. Menu4;
AFFILIATION:1University of Texas Medical School at Houston, Houston, TX, 2Amtssygehuset i Gentofte, Hellerup,Denmark, 3University Horpital of Mannheim, Mannheim, Germany, 4Hopital Roger Salengro, Lille Cedex, France.
Presentation Number: S-211
Introduction: Since the introduction of the LMA, supraglottic airway devices have become an established tool in
airway management.1,2 The Ambu laryngeal mask airway is a new disposable supraglottic airway device similar indesign to the LMA-Classic. This multi-center trial was designed to evaluate the performance and safety of the Ambu
laryngeal mask in elective surgical patients during positive pressure ventilation.
Methods: Following approval by the local Ethics Committees and written informed consent, 118 (29-30 at each center)patients presenting for elective surgery under total intravenous anesthesia were included. Patients were ASA I/II,
Mallampati I/II, aged 18-65 years with a BMI <30 kg/m2. Propofol was used for induction (2.5mg/kg) and maintenance(12mg/kg/hr propofol) of anesthesia along with a choice of narcotic agent. Patients were ventilated with intermittent
positive pressure ventilation, a respiratory rate of 12/min, an inspiratory/expiratory ratio of 1:2, a fresh gas flow of
3L/min in order to maintain CO2 <45mmHg and SpO2 ≥95%. Data was collected on size of device, number of insertion
attempts, cuff inflation, and oropharyngeal leak pressures. The position of the Ambu laryngeal mask was confirmedwith fiberoptic endoscopy and the view recorded. Perioperative and postoperative complications were noted. Patientswere examined for sore throat, dysphonia, and dysphagia 1hr and 24hrs postoperatively.
Results: Demographically, patients were 42.8±13.97yrs of age (60.2% female, 39.8% male), 171.2±8.30cm in height,
with a BMI of 24.5±3.11kg/m2 and Mallampati grade I/II (62.9%/37.1%) Patients received a size 3 (0.8%), 4 (51.7%),
or 5 (47.5%) Ambu laryngeal mask, according to manufacturer’s recommendations. A cuff pressure of 60cm H2O wasaccomplished with a volume of 24.3±5.41mL of air. Duration of surgery was 67.0mins (25-250mins). All patients weresuccessfully intubated on the first or second attempt (92.4% and 7.6%, respectively) with an insertion time of
44.9±37.91sec. Oropharyngeal leak pressures were 24.1±5.44cm H2O. The vocal cords could be visualized by fiberoptic
endoscopy in 91.5 % patients and adequate ventilation was achieved in all patients. Complications included blood onthe device (8.5%), bucking during removal (0.8%), and minor trauma to the tongue (0.8%), or lips (0.8%).
Postoperative complaints 1hr after surgery were sore throat (mild-5.1%, moderate-1.7%), dysphonia (mild-0.8%),
dysphagia (mild-2.5%, moderate-1.7%). For complaints 24 hrs after surgery only mild sore throat (2.2%) and mild
dysphonia (1.1%) remained.
Discussion: In anesthetized, non-paralyzed patients, the Ambu laryngeal mask is easy and quick to insert. It forms asafe and efficient seal during positive pressure ventilation. Further studies are warranted.
References:
1. Anesth Analg 1996;82:129-33.
2. Anesthesiology 1996;84:686-99.

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28-02-2005