Investigation on Differences in Skin Sodium Content Between Normal Subjects and ICU-patients

According to the current paradigm ICU-acquired hypernatremia is mainly an iatrogenic problem, caused by sodium overload or water deficit. In spite of several interventions to reduce sodium intake and optimize fluid balance, critically ill patients still develop hypernatremia. These patients also seem to have an inability to excrete sodium, hence develop a positive sodium balance. In animals sodium storage in the third compartment was found. Our hypothesis is that sodium storage in the third compartment is different in critically ill patients and this difference could play a role in the development of ICU-acquired hypernatremia.

Inclusion criteria

• 50-80 years (septic patients), 45-85 years (CABG and hip replacement-patients)
• Patients undergoing hip replacement: no relevant medical history (i.e. chronic and/or systemic diseases with a suspected influence on sodium / sodium handling)
• Septic patients: fulfilling the criteria for the systemic inflammatory response syndrome in the presence of a(n expected) new infection

Exclusion criteria

• Absence of both upper legs
• Skin disease that makes skin biopsies in healthy skin impossible
• Subjects with in their history formation of exaggerated scar tissue
• Subjects suffering from psoriasis or lichen ruber
• Use of skin corticosteroids on all skin of both upper legs < 2 weeks before inclusion
• Tattoos covering the whole surface of both upper legs
• Use of diuretics in the past month
• Current renal replacement therapy
• Septic patients: not being sedated
• Patients undergoing hip replacement: hip replacement because of an inflammatory disease