A comparison of the cuffed oropharyngeal airway (COPA) with the laryngeal mask airway (LMA) during manually controlled positive pressure ventilation

Study Objective: To examine the cuffed oropharyngeal airway (COPA) during p ositive pressure ventilation (PPV) and to compare its reliability and effic acy with the laryngeal mask airway (LMA). Design: Prospective, randomized, controlled trial. Setting: University Hospital. Patients: 60 adult ASA physical status I and II patients scheduled for urol ogic surgery. Interventions: Patients were randomly assigned to be ventilated with a COPA (n = 33) or a LMA (n = 27) during a standardized anesthetic procedure. Fol lowing preoxygenation and induction with alfentanil and propofol, the respe ctive airways were inserted. Patients were ventilated manually with the res ervoir bag of the anesthesia respirator. Inspiratory airway pressure was li mited to 20 cm H2O, and the target tidal volume was 7 ml/kg. Respiratory ra te was adjusted to achieve an end-tidal pressure of carbon dioxide of 35 mm Hg. Anesthesia was maintained with propofol, nitrous oxide in oxygen, and a lfentanil as appropriate. Measurements and Main Results: We evaluated ease of insertion (nominal scal e: easy, moderate, difficult, or impossible) and recorded the number of man euvers performed during insertion until an airtight seal of the airway was achieved. Reliability for "hands free" ventilation-defined as ventilation w ithout the need to further augment the position of the airway device manual ly-was determined (nominal scale: adequate ventilation, adequate ventilatio n with manual assistance, and inadequate ventilation leading to airway chan ge). Ventilation and oxygenation parameters were derived from the anesthesi a respirator and a capillary blood gas sample, respectively. The incidence of laryngopharyngeal discomfort and the amount of salivation were assessed by nominal scales. The COPA was easier to insert than the LMA (p < 0.001), but more positional maneuvers (P < 0.001) were necessary with this device. "Hands free" ventilation was achieved less often with the COPA (p < 0.02). Ventilation and oxygenation were comparable with both devices. The COPA was associated with less salivation (p < 0.01) and laryngopharyngeal discomfor t (p < 0.05) than the LMA. Conclusion: Although effective ventilation can be accomplished with both de vices, the LMA is more reliable for "hands free" ventilation than the COPA. The lower incidence of laryngopharyngeal discomfort and salivation with th e COPA may be beneficial for patients at risk for developing laryngospasm. (C) 1999 by Elsevier Science Inc.