ABSTRACT
The conventional perioperative fluid management of patients who have undergone elective or emergency surgical procedures is aimed at maintaining vital signs within the normal range and at assuring a urine output of at least 0.5mL/kg/hr. This approach to fluid therapy is based on the tacit assumption that the maintenance of hemodynamic stability in conjunction with a satisfactory urinary output is universally predictive of a satisfactory postoperative outcome from the standpoint of perioperative morbidity and mortality. However, this approach does not take into consideration the impact of the severity of the injury (how complicated was the procedure, whether the patient suffered a period of hypoperfusion with a consequent period of ischemia-reperfusion, the extent of a preoperative or intraoperative septic insult, the duration and depth of the anesthesia, as well as the duration of the procedure itself), and other factors commonly encountered during surgical procedures. Furthermore, it disregards the concomitant effect of the anesthetic management on the relationship between oxygen delivery (DO2) and oxygen consumption (VO2) during the procedure itself, and in the immediate postoperative period (1,2). Additionally, this approach to perioperative fluid therapy is not tailored to the patient’s risk for perioperative complications based on American Society of Anesthesiologists score, preoperative risk evaluation by validated predictive models such as the physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM) model (3), or the amount of oxygen debt incurred during the procedure by the individual patient (2,4).
