AVP and Hyponatremia: However, a systematic review and meta-analysis [21,24] of previous studies showed a significantly higher incidence of hyponatremia in patients that received a hypotonic treatment vs. an isotonic treatment, which included the ICU setting, surgical conditions, neonates, and varying types of fluids (0.18% NaCl, 0.3% NaCl, 0.45% NaCl) because non-osmotic stimuli to antidiuretic hormone secretion are triggered by pain, stress, nausea, and operations; moreover, surgical patients also had fluid leaking, which worsened their hyponatremia.