Continuous Non-Invasive SpHb and PVI Monitoring on Intra-Operative and Post-Surgical Clinical Outcomes

Inclusion Criteria: * Adult patients undergoing major surgeries associated with possibility of significant blood loss (e.g. such that blood is cross-matched and available before the start of the case as per hospital routine practice) under general anesthesia. * At least one finger available and accessible for performing non-invasive hemoglobin monitoring. Exclusion Criteria: * Patient has skin abnormalities affecting the digits such as psoriasis, eczema, angioma, scar tissue, burn, fungal infection, substantial skin breakdown, nail polish or acrylic nails that would prevent the proper fit and application of the sensors * Procedures performed using robotics surgery * Any patients with a known hemoglobinopathy * Any patients undergoing Cardio-Pulmonary Bypass (CPB) * Any patients who cannot be transfused or has refused consent for a blood transfusion * Patients being treated by any artificial oxygen carriers within 30 days of hospital stay * Patients being managed outside of an operating room in the participating centers, or in operating room with conditions not conducive to perform and complete the study procedures (including use of the hemoglobin monitoring device) * Patients younger than 18 years old * Patients who are pregnant * Patients with cardiac arrhythmia * Patients with tidal volume setting \< 6ml/kg * Patients with PEEP \>= 10cm H2O * Patients undergoing cardiac and/or any open chest procedures * Emergency patients due to the foreseeable difficulty in consenting * Patients deemed not suitable for study at the discretion of the Principal Investigator