Examining a Study of “Predictors and Clinical Outcomes from Failed Laryngeal Mask Airway Unique”
In the study “Predictors and Clinical Outcomes from Failed Laryngeal Mask Airway Unique™: A Study of 15,795 Patients,” published in the June issue of Anesthesiology, Dr. Satya Krishna Ramachandran (Assistant Professor, Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan) and colleagues studied risk factors predicting laryngeal mask airway (LMA Unique™, uLMA™; LMA North America, Inc., San Diego, CA) failure. The primary outcome of the study was uLMA™ failure, which was defined as an airway event requiring uLMA™ removal and tracheal intubation. The secondary outcomes were the incidences of difficult mask ventilation and unplanned hospital admission.
Data were obtained by reviewing the prospective perioperative electronic clinical information available within authors’ anesthesiology department. Of the 15,795 cases in the study, 1.1% of patients experienced uLMA™ failure. Certain variables were included for analysis based on a literature review of factors associated with a difficult airway and airway obstruction, including Mallampati class 3–4, reduced thyromental distance estimated less than 6 cm, reduced mouth opening estimated less than 3 cm, etc. Within the aforementioned group, 60% suffered from hypoxia, hypercarbia, or airway obstruction, and 42% presented with inadequate ventilation related to leaks. There were four independent predictors for failed uLMA™: surgical table rotation, male gender, poor dentition, and elevated body mass index. Unplanned hospital admission occurred in 13.7% of ambulatory patients with uLMA™ failure. Difficult mask ventilation occurred in 5.6% of patients with uLMA™ failure, a 3-fold increase.
This study confirmed that the use of uLMA™ is an effective supraglottic device with a low failure rate of 1.1%. However, there is an increased risk of difficult mask ventilation and unplanned hospital admission in the patients whom experience uLMA™ failure.
In the accompanying editorial, “Complications with Supraglottic Airways: Something to Worry About or Much Ado About Nothing?,” published online first on 12 April 2012, Dr. Takashi Asai (Department of Anesthesiology, Kansai Medical University, Takii Hospital, Osaka, Japan) notes,
“…recent studies of a large number of patients (including the study of Ramachandran et al.) indicate that there is also no doubt that even now the incidence of complications associated with the use of a supraglottic airway is not low enough.”
Pulmonary aspiration, for example, is the same whether a patient’s trachea is intubated or if a supraglottic airway is used.
Furthermore, his conclusion as stated in the editorial is,
“We need to make further efforts not only to elucidate causative factors of complications and difficulties with the use of a supraglottic airway, but also to perform accurate preoperative assessment of patients’ conditions and provide adequate depth of anesthesia, to establish a safe use of a supraglottic airway.”
The American Society of Anesthesiologists offers CME credit based on this post and its accompanying article.