Lay summary
Over 300,000 New Zealanders receive oxygen during and after surgery each year, but the optimal level of oxygen to administer is unknown. The aim of the Hospital Operating Theatre Randomised Oxygen (HOT-ROX) randomised clinical trial is to find the optimal oxygen level to administer to reduce wound infection and other important complications of surgery, and determine the effect of different oxygen levels on overall recovery, quality of life and mortality. Pulse oximeters are used to continuously measure the oxygen level in the bloodstream during surgery and in numerous illnesses where oxygen therapy may be needed. Overseas studies have reported that pulse oximeters can be unreliable in people with very dark skin. The pulse oximetry bias (SpO2-bias) study will be embedded within HOT-ROX and will test if pulse oximeters are reliable in the range of darker skin tones seen in the Aotearoa New Zealand population.