TY - CHAP M1 - Book, Section TI - Management of Patients with Fluid & Electrolyte Disturbances A1 - Butterworth IV, John F. A1 - Mackey, David C. A1 - Wasnick, John D. PY - 2022 T2 - Morgan & Mikhail’s Clinical Anesthesiology, 7e AB - KEY CONCEPTS Osmotic pressure is generally dependent only on the number of nondiffusible solute particles. This is because the average kinetic energy of particles in solution is similar regardless of their mass. Potassium is the most important determinant of intracellular osmotic pressure, whereas sodium is the most important determinant of extracellular osmotic pressure. Fluid exchange between the intracellular and interstitial spaces is governed by the osmotic forces created by differences in nondiffusible solute concentrations. Serious manifestations of hyponatremia are generally associated with plasma sodium concentrations less than 120 mEq/L. Excessively rapid correction of hyponatremia has been associated with demyelinating lesions in the pons (central pontine myelinolysis) and more generally in both pontine and extrapontine central nervous system structures (osmotic demyelination syndrome), resulting in both temporary and permanent neurological sequelae. A major hazard of increased extracellular volume is impaired gas exchange caused by pulmonary interstitial edema, alveolar edema, or large collections of pleural or ascitic fluid. Intravenous replacement of potassium chloride is usually reserved for patients with, or at risk for, significant cardiac manifestations or severe muscle weakness. The goal of intravenous therapy is to remove the patient from immediate danger, not to correct the entire potassium deficit. Because of its lethal potential, hyperkalemia exceeding 6 mEq/L should always be corrected. Symptomatic hypercalcemia requires rapid treatment. The most effective initial treatment is rehydration followed by brisk diuresis (urinary output 200–300 mL/h) using an intravenous saline infusion and a loop diuretic to accelerate calcium excretion. Symptomatic hypocalcemia is a medical emergency and should be treated immediately with intravenous calcium chloride (3–5 mL of a 10% solution) or calcium gluconate (10–20 mL of a 10% solution). Some patients with severe hypophosphatemia may require mechanical ventilation postoperatively because of muscle weakness. Severe hypermagnesemia can lead to respiratory and cardiac arrest. Isolated hypomagnesemia should be corrected before elective procedures because of its potential for causing cardiac arrhythmias. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1190610804 ER -