Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 4 2 2018 04 30 468 476 EN Zahid Hussain Khan Professor of Anesthesiology and Critical Care, Deputy for Research, Department of Anesthesiology and Critical Care, Imam Khomeini Medical Complex, Tehran University of Medical Sciences, Tehran, Iran. Kasra Karvandian Department of Anesthesiology and Critical Care, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. Jayran Zebardast Department of Anesthesiology and Critical Care, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. Hussein Ali Hussein Department of Anesthesiology and Critical Care, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. 2017 07 28 2018 03 10 Intraoperative fluid equilibrium is a decisive matter in perioperative anesthesia management, because most of evaluation studies consider intraoperative fluid administration as a major participating agent in improving or worsening patient outcomes after surgery and it revolves within the responsibility of an anesthesiologist. The understanding of fluid physiology in the human body, clinical features of available intravenous fluid, and nature of surgery indeed will contribute to the success plan of management. Maintaining of patients’ physiological milieu by preserving normal extracellular volume, adequate tissue perfusion, and a balanced acid base condition are the main goals of intraoperative fluid infusion. This review was conducted to overview fundamental basics of fluid therapy during the intraoperative period. Due to the dearth of supporting data for appropriate volume and the available definitions of restrictive and liberal are diffident, the polemic about which particular method of volume expansion still exists. Colloid versus crystalloid controversy in surgical patients is still going on and this would again be encouraged to be a topic for many clinical trials in the future. The current findings’ trend prefers guided and restricted intraoperative fluid therapy with isotonic balanced crystalloids because such fluids are cost effective and have fewer side effects than other fluids. https://aacc.tums.ac.ir/index.php/aacc/article/view/140 https://aacc.tums.ac.ir/index.php/aacc/article/download/140/326