Perioperative Fluid Management

Abstract

Fluid therapy is an important aspect of perioperative care to attain optimal outcomes. Fluid therapy should be viewed like a medication and prescribed with the same vigilance as drugs. Too little fluid can lead to organ hypoperfusion whilst too much can lead to downstream problems such as ileus, pulmonary issues, and edema. This fluid therapy is key to avoid complications and increased length of hospital stay. Fluid therapy is a key component in many surgical and perioperative guidelines and recommendations. Adoption of Enhanced Recovery after Surgery pathways have simplified fluid therapy by ensuring the patient is not dehydrated prior to surgery and standardizing early oral intake after surgery resulting in a reduction of the duration and quantity of intravenous fluids needed to be given to patients. The increasing use of minimally invasive surgery (laparoscopic and robotic assisted) and the recognition of the importance of reducing perioperative blood loss has also had an impact in simplifying the approach to perioperative fluid therapy by reducing fluid shifts. Another important aspect of modern fluid therapy is the reduction of excess infusion of sodium-containing fluids above admission weight. Maintenance of intravascular volume is essential and overall fluid balance needs to be slightly positive to achieve this as a result of some sequestration in tissue perioperatively. However, positive fluid balance over 30–40 mL/kg (2–3 L positive in a 70 kg man) is associated with harm. Avoidance of fluid overload is key for return of normal bowel function and to reduce the risk of all cause complications. Perioperative fluid variance is one of the key factors still contributing to variable surgical outcomes. Goal-directed therapy is a term used to target parameters such as stroke volume using fluid and sometimes inotropes to optimize blood flow and oxygen delivery and has been shown to benefit high-risk patients, but benefits are diminished in patients who are on an ERAS Pathway. //paperpile.com/c/a1qCNe/I6oQ+HYW4Recent large cohort publications have demonstrated the importance of maintaining a mean arterial pressure (MAP) of greater than 60 to 65 mmHg to reduce the risk of AKI (acute kidney injury). Further studies optimizing stroke volume first and then MAP with low-dose vasopressors have shown reductions in not only AKI but pulmonary complications (because of avoidance of fluid overload) and gut dysfunction and sepsis (because of improved blood flow to the gut). This approach has led to the new term of Goal Directed Hemodynamic Therapy ensuring fluid, cardiac output, and oxygen delivery is optimized and then low-dose vasopressors are used to maintain perfusion pressure within near-normal physiological values. Patients presenting for emergency surgery have complex physiology with a mixture of hypovolemia, fluid shifts, and vasoplegia. The rapid restoration of intravascular volume and MAP using fluids and vasopressors is a key component prior to surgery to reduce morbidity and mortality.