Early Cognitive Function and Recovery in Elderly Patients After Laser Laryngeal Surgery: Desflurane-based vs Propofol-based Anesthesia

The allocation sequence is generated by computer random number generation, and the allocation is placed in sequentially numbered opaque sealed envelopes by a non-investigator. Enrolment and data collection are performed by trained research staff who are not involved in the care of the patients. The treating clinicians are not blinded to the assignment group, but all other staff involved in both the collection and collation of data, and administration of neurocognitive testing, are blinded to group allocation

The primary measurement is the MMS scores. The secondary measurements are intraoperative desaturation score (multiplying Spo2 < 90% by time (seconds)), extubation time, orientation time, and time to discharge from the post-anaesthesia care unit (PACU).

A sample size of 35 was determined by using a power analysis based on the assumptions that the incidence of postoperative cognitive impairment in adult after otorhinolaryngological surgery would be as high as 50 %, b) a 70% reduction (from 50% to 15%) would be of clinical significance, and c) α= 0.05, β= 0.2.

The continuous variables were expressed as means ± standard deviation (SD) whereas categorical variables were expressed as frequency and percentage for data description.

The outcome of interest is cognitive decline. A Generalized estimating equation (GEE) model with compound symmetry covariance structure was constructed to compare differences between two treatments with different time points as the repeated factors. As the effect of treatments may vary across different time points, an interaction between treatments and time was included in the model. Bonferroni-corrected post hoc test was conducted to adjust the observed significant level for multiple comparisons if the null hypothesis was rejected.