During major surgical procedures, intravascular volume is maintained with the administration of isotonic fluids such as Lactated Ringers (LR), Normal Saline (NS) or Normosol-R. All three of these fluids are in common clinical use for this purpose. As large volumes of NS may result in a dilutional acidosis and an increasing base deficit, it may cloud clinical decision making when resuscitative efforts are guided by acid-base status on routine arterial blood gas analysis. This is a prospective, randomized study to evaluate changes in acid-base and electrolyte (sodium, potassium, calcium) status with the use of various isotonic fluids for intraoperative resuscitation.