Ramgolam GL, Hall G, Zhang M et al.
British Journal of Anaesthesia 2018; 20 (3): 571-580
Background
– Adeno-/tonsillectomies are a common ENT procedure in the paediatric population
– Unfortunately peri-operative respiratory adverse events are also relatively common
– A significant proportion of these procedures are performed using an LMA
– Controversy remains regarding the timing of removal of LMA (Deep vs Awake)
– In healthy patients, timing of LMA removal appears independent to risk of respiratory adverse events
– Unknown whether same applies to children with risk factors for respiratory adverse events
Study Design
– Single tertiary centre (Princess Margaret Hospital for Children, Perth, Australia)
– Open-label parallel arm randomised controlled trial
– Children aged 0-16 undergoing Adeno-/tonsillectomy +/- myringotomy with at least one risk factor for adverse respiratory event
Primary Outcome
“…difference in the rate of occurrence of peri-operative respiratory adverse events between an awake removal and a deep removal of the laryngeal mask airway in children with at least one risk factor for these events having (adeno) tonsillectomy (with or without myringotomy) procedures”
Secondary Outcomes
Exploratory post-hoc assessment of difference in rates of peri-operative adverse events depending on:
– LMA removal in theatre (emergence) vs recovery
– Number of risk factors present
– Respiratory vs other risk factors
– Presence/severity of OSA
Statistical analysis
– Two-group chi-squared analysis (used to determine significant relationship between two variables [non-continuous data])
– Binary logistic regression (predicts probability of observation falling into category based on other variables)
– Power = 80% (primary outcome) to detect a difference in rate (effect size) of at least 15%
– Intention to treat
Results
Data was collected between July 2009 – Jan 2014. Over 437 children assessed for suitability and 290 children recruited with 145 children randomised to each group. 7 data sets were excluded due to use of ETT rather than LMA.
Primary Outcome
Adverse respiratory events were more likely in the awake than the deep group (45% vs 35%, p = 0.09) although this did not reach significance. There was no difference between the amount of time spent in recovery in either group.
Secondary Outcomes
Some of the secondary outcomes showed significant differences between the groups. Adverse events were more likely in awake group if:
– LMA removed awake in recovery
– Children had five or more risk factors
– One or more respiratory risk factor
– Sleep apnoea
However the study was not weighted to test for these…
Discussion
Pros: The audience commended the large participant number particularly in the paediatric population and were encouraged by the frequent use of LMAs for this type of surgery in a tertiary centre.
Cons: The audience felt some of the classified “adverse events” such as coughing to be protective reflexes which we would encourage and that the study should have been weighted appropriately to adequately assess the secondary outcomes.
Summary by Dr S Bacciarelli. Journal Club Meeting 12 April 2018.
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