Prevention of Opioid-Induced Hypoxemia

The investigators will evaluate the feasibility of a fully randomized validation trial for the Oxalert EPO. All patients will wear the Oxalert for 24 hours preoperatively in the monitoring only mode (no alerts), throughout hospitalization up to six days, and for 24 post-discharge hours. Randomization will be to Oxalert in monitor-only mode or to its normal mode which provides progressive audible and tactile alerts for hypoxemia.

Inclusion criteria

• Adults having major laparoscopic and open abdominal or pelvic surgeries;
• Body Mass Index ≥25 kg/m2
• American Society of Anesthesiologists physical status 1-3;
• Age 18-85 years old;
• Able to understand and consent to the trial and fully participate;
• Anticipated primary opioid analgesia after surgery;
• Expected duration of hospitalization at least 24 hours after surgery;
• Consenting at least 24 hours before anticipated surgery.

Exclusion criteria

• Epidural analgesia (field and fascial plane blocks permitted);
• Pre-operative SpO2 <95%;
• No wrist available for the study;
• Severe hearing loss;
• Lack of English language fluency.
• Serious hearing deficit (unable to understand normal speech in a quite environment)
• Serious peripheral neuropathy (unable to feel pin prick at wrist).