2.2. Grouping
Prior to each full operating day, half of the patients were randomly assigned to receive fasting instructions from the hospital and the other half received fasting instructions from the anaesthetist.
Hospital Group(HG) had fasting guidelines as normally recommended by the hospital nursing staff. These patients were told to fast for 6 hours(solids) and 2 hours(water) prior to surgery.
Anaesthetic Group(AG) had fasting guidelines as recommended in preoperative anaesthetic telephone consultation. This involved similar fasting guidelines(fast for 6 hours prior to surgery for solids and 2 hours for clear liquids) with additional instruction to consume 2 mL/kg of clear apple juice 2 hours prior to their scheduled surgical time.
The sample size(180) was determined with power analysis with the t-test at a power of 80%(at 5% significance level) to detect a significant difference between a mean PPPM value of 10 in the Hospital Group and a mean PPPM value of 8 in Anaesthetic Group, assuming a standard deviation of 4. The above sample size estimation has incorporated a drop out rate of 15%.