The Physiology, Pathophysiology, and Clinical Implications of Fluid Resuscitation in Critically Ill Patients

One of the most common interventions in the ED and ICU to restore physiologic homeostasis is fluid administration. It is essential for the intensivists and ED physicians to be aware of the physiological characteristics of different fluids and the potential harm associated with their use. In this article, we explore the physiology and pathophysiology of fluid administration in humans, emphasizing how fluid administration can alter acid-base balance, perfusion, osmotic and oncotic pressures, immunologic and inflammatory responses, and hemodynamics. We also discuss fluid resuscitation strategies across common clinical scenarios, such as septic shock, diabetic ketoacidosis, rhabdomyolysis, acute pancreatitis, and acute brain injury. The most recent guidelines, clinical trials, and observational studies on fluid resuscitation were discussed and critically analyzed. We also discussed fluid management in high-risk populations, such as patients with end-stage renal disease or congestive heart failure, who are particularly susceptible to hypervolemia.