This is a closed-loop system which is embodied in a novel and intelligent algorithm that takes into account patients' vital signs. The system allows better and responsive titration of personalized pain relief together with non-invasive physiological monitoring that measures oxygenation, breathing and heart rate continuously.

A glaring safety gap in the administration of commonplace Patient Controlled Analgesia (PCA) opioids unfortunately exists. A significant proportion of patients may suffer from respiratory depression with the use of PCA opioids and it is imperative to discover solutions to improve the safety of PCA opioids, therein improving medication safety, enhancing quality of postoperative care and providing economic cost savings. Currently, no continuous monitoring system that integrates an intelligent decision making response exists.

The investigators primary aim is to develop and commercialise a Vital-signs-integrated (using oxygen saturation, respiratory rate, heart rate) Patient-assisted Intravenous opioid Analgesia (VPIA) that can be integrated into the hospital-wide monitoring systems is capable of making intelligent decision making responses to bridge the PCA safety gap within 12 months.

This VPIA delivery system will be a closed-loop system for safety and efficacy. It will be integrated with continuous vital signs monitoring, and provide appropriate response to breach of safety parameters. It will be part of a larger surveillance system that provides tiered medical and nursing alerts to safety parameters.

Inclusion Criteria:

• Age 21-70 years old, female
• Healthy participants who are American Society of Anesthesiologists physical status 1 and 2 (with well controlled medical problems)
• Undergoing elective surgery with the intent of using postoperative PCA with morphine for postoperative analgesia

Exclusion Criteria:

• Allergy to morphine
• With significant respiratory disease and obstructive sleep apnea
• Unwilling to place oxygen saturation monitoring devices during study period
• Unable to comprehend the use of patient controlled analgesia
• Pregnant

Only female patients undergoing elective surgery in this institution will be recruited. The study site is specialised in providing healthcare only to women and children in Singapore.