Laryngeal mask airway failure rare but problematic
MedWire News: Failure of laryngeal mask airway is rare but associated with serious complications, shows a large study.
Satya Krishna Ramachandran (University of Michigan, Ann Arbor, USA) and colleagues found a failure rate of just 1.1% among 15,795 cases of ventilation with the Laryngeal Mask Airway Unique (uLMA; LMA North America, Inc., San Diego, California).
"Our data shed light on a largely unstudied clinical issue commonly encountered by anesthesia providers," they write in Anesthesiology.
"Through identifying risk factors for intraoperative uLMA failure in a large patient sample, this study allows for a clinician's decision to use or refrain from using an uLMA to be drawn in part from evidence, rather than solely clinical intuition."
The team identified four independent predictors for uLMA failure: intraoperative surgical table rotation, male gender, poor dentition, and increased body mass index (BMI). Surgical table rotation raised the risk for uLMA failure fivefold, BMI raised it by 6% per unit increase, and poor dentition and male gender raised the risk around 1.5-fold.
Adverse respiratory events were common in patients with uLMA failure, with desaturation, hypercapnia, or increased peak inspiratory pressures occurring in 62.3%. Severe desaturation (oxygen saturation ≤85% for >1 min) occurred in 22.4% of patients, 13.7% were admitted to hospital because of the complications, and two patients were admitted to the intensive care unit for persistent hypoxemia.
Notably, mask ventilation was prone to fail in patients with failed uLMA ventilation, occurring in 5.6% of 84 patients with uLMA failure versus 1.9% of 1005 without. Ramachandran et al say this finding is "of concern," although the numbers were too small for them to confirm the association on multivariate analysis.
"This finding could suggest a common tendency to airway closure in these patients or simply be a reflection of the high incidence of laryngospasm associated with uLMA failure," they comment.
In an accompanying editorial, Takashi Asai (Takii Hospital, Osaka, Japan) says that, although low, the complication rate reported here is not yet acceptable, especially since there would have been other complications with the uLMA not resulting in tracheal intubation.
"There would have been patients in whom serious complications, such as laryngospasm, occurred during the use of the device, and have been treated by deepening anesthesia and giving a neuromuscular blocking agent, without tracheal intubation," he says.
He notes that such complications reportedly occur in about one in 20 patients, in which case, "we cannot regard that our clinical practice using a supraglottic airway is optimal."
By Eleanor McDermid