In the past, some guidelines advised no oral intake for at least 8 hours before any surgery, However, research has shown risks associated with excessive fasting, such as postoperative insulin resistance, and advantages in shorter fasting protocols, such as reduced postoperative nausea and vomiting.

The perioperative fasting guidelines of the European Society of Anaesthesiology focus on preoperative carbohydrates. They hold that it is safe for patients to drink carbohydrate-rich fluids up to 2 hours before elective surgery and that drinking carbohydrate-rich fluids improves subjective well-being, reduces thirst and hunger, and reduces postoperative insulin resistance at an evidence level of 1++. Nevertheless, data on drinking carbohydrate fluids before surgery in elderly patients are limited.

Some factors have been known to influence the gastric emptying rate, as for example, old age, pain, and the use of opioid analgesics.

In the previous study, evidence of increased pain was reported in patients undergoing staged bilateral total knee arthroplasty, in whom the second operated knee had greater sensitivity (tertiary hyperalgesia) due to the surgical injury to the first operated knee.

In the present study, the investigators will evaluate the effect of old age, surgical stress, pain, and the use of analgesics on the residual gastric volume in elderly patients undergoing staged-bilateral total knee arthroplasty.

Inclusion Criteria:

• Patients scheduled for staged bilateral total knee arthroplasty aged 65 to 85 years
• American Society of Anesthesiologists physical status classification 1, 2, and 3
• Body mass index < 35 kg/cm2
• Patients administered carbohydrate-containing fluid 2 hours prior to surgery

Exclusion Criteria:

• Previous surgery of the upper gastrointestinal tract
• Achalasia
• Diabetes

Study participants will be patients whom are scheduled to undergo staged bilateral total knee arthroplasty requiring administration of carbohydrate-containing fluid 2 hours prior to surgery.