Thinking twice before using the LMA for obese and older patients - A prospective observational study

Abstract

Introduction: Laryngeal Mask Airways (LMAs) have traditionally been used for short surgery under general anesthesia with good results. Many studies have reported favourable outcomes in safety profile, complication risk, ease of insertion, recovery of patients and cost analyses. However, there is an under reporting of complications arising during ventilation with this device and the risk factors associated with such complications in adult patients. These include laryngospasm, difficulty with insertion, suboptimal ventilation, bronchospasm, aspiration, desaturation, hypotension and conversion to intubation with ETT. These can be significantly serious and life threatening. Often times it is wrong patient selection for the wrong surgery that results in an undesirable outcome. Methods: By means of this prospective observational study we aimed to audit all general anesthesia cases performed with an LMA at our hospital over six months from February till August 2012. Included in the parameters observed were induction techniques, ventilation strategies and intraoperative problems during LMA ventilation. By means of a data collection form, the Anaesthetist in charge indicated the intraoperative events and outcomes. Results: 1,095 patients were included in the audit. The mean age of the patients was 40 years and mean weight was 66.4kg. The patients were given GA for a variety of procedures. LMA Proseal™ was used in 78.4% of patients while the LMA Supreme™ was favored when the surgeries required a lateral position. 7.1% of patients encountered problems with insertion whilst 7.8% had intraoperative problems related to difficulty with ventilation. This was more prevalent with the LMA Supreme™ (p=0.031). Age and BMI of the patient increased the incidence of complications (p=0.002 and 0.0008). A BMI >30 and an age >46 years are associated with a significant 2-fold increase in the probability of all ventilatory problems intraoperatively. Conclusion: LMA use in our Operating Theatre is generally safe as long as potential problems are recognised and managed accordingly. The risk of problems increases 2-folds with patients with a BMI>30 and age>46 years. LMA Supreme was more problematic compared with Proseal. © 2013 Cheon G, et al.