Cause: high Na or H2O intake or inadequate Na or H2O elimination. Can cause strain on left ventricle causing left-sided heart failure over time. ClinMan: peripheral edema, periorbital edema, cerebral edema (leads to headache, confusion, irritability, anxiety, nausea, vomiting). Diag: CBC. Treatment: give diuretics that work w/ kidneys to get rid of excess fluid or give hypertonic solutions to shift excess fluid into intravascular space, change patient's position, monitor intake/output, fluid restrictive diet.