What do systematic reviews say?

Incidence of serious adverse events (we used the NIH definition of adverse events. A serious event includes death, a life‐threatening event that requires hospitalization or prolonged hospitalization, disability or congenital anomaly) · participants undergoing surgery with peripheral nerve block

Mortality (in‐hospital death and 30‐day mortality) · adults receiving intravenous fluids whilst undergoing any form of surgery

Incidence of serious adverse events (we used the NIH definition of adverse events. A serious event includes death, a life‐threatening event that requires hospitalization or prolonged hospitalization, disability or congenital anomaly) · peripheral nerve block

Death (at one month) · participants ventilated by one‐lung

Risk of suffering a serious adverse event, reported dichotomously as the occurrence of any of: admission to high‐dependency unit, postoperative cardiac or respiratory complication, or death · participants aged 6 months or older undergoing surgical procedures under general anaesthesia