Comparison of the LMA-Classic with the new disposable Soft Seal laryngeal mask in spontaneously breathing adult patients

Background: The laryngeal mask airway LMA-Classic has been used widely in clinical practice. A new disposable supraglottic airway device, the Soft Seal LM, has been introduced recently. In a randomized study, the authors compared the LMA-Classic and the disposable Soft Seal LM in terms of their clinical performance, cuff pressures during nitrous oxide anesthesia, position of the laryngeal mask in situ by fiberoptic evaluation, and morbidity in a wide range of routine general surgery procedures. Methods: A total of 200 adult patients were randomly assigned to a size 4 laryngeal mask in two equal-sized groups for airway management during surgery: (1) LMA-Classic (Intavent Orthofix Ltd., Maidenhead, Berkshire, United Kingdom); or (2) Soft Seal LM (Portex Ltd., Hythe, Kent, United Kingdom). Anesthesia was administered with fentanyl, propofol, nitrous oxide, oxygen, and sevoflurane. The variables studied were ease of insertion, fiberoptic view, time in situ, incidence of blood on the laryngeal mask at the time of removal, and the incidence of postoperative sore throat at 2 and 24 h. The laryngeal mask cuff pressures were measured continuously. Intracuff pressure limitation was not attempted. Results: The LMA-Classic and the Soft Seal LM showed similar clinical performances, as shown by their insertion time (successful insertion at first attempt was achieved within 20 s in 97% with LMA-Classic vs. 95% with Soft Seal LM), fiberoptic evaluation of the anatomic position of the laryngeal mask, and satisfactory anesthesia conditions. Laryngeal mask cuff pressures increased from 45 to 100.3 mmHg in the LMA-Classic and from 45 to 46.8 mmHg in the Soft Seal LM (P < 0.001). Macroscopic blood was seen on only four occasions in the LMA-Ckissic group. The incidence of sore throat was significantly increased at 2 h postoperatively when using the LMA-Classic, although there was no difference at 24 h after surgery. Conclusions: In spontaneously breathing adult patients requiring a size 4 laryngeal mask airway, the new disposable Soft Seal LM device is an acceptable alternative to the reusable LMA-Classic, resulting in a good larngeal seal and offering similar clinical performance. Cuff pressures increase substantially when the LMA-classic is used but not when using the Soft Seal LM. There was less trauma to patients using the Soft Seal LM, as assessed by the incidence of sore throat in the early postoperative period.