Heart rate (electrocardiogram), noninvasive blood pressure (NIBP), pulse oximetry, end-tidal carbon dioxide (EtCO₂), and temperature (choice of nasal/rectal/axillary) are monitored at all times. Once the surgery has begun, the anesthesiologist no longer has easy direct access to the airway. Therefore, the use of pulse oximetry and end-tidal CO₂ monitors is indispensable. A warming blanket should be used to avoid hypothermia. Blood loss determination should be made by a calibrated catchment trap in the suction line and by weighing sponges. Blood loss rarely exceeds 10% of circulating blood volume; however, properly crossmatched and screened blood should be available but used only if necessary.