title: Postoperative fluid retention after heart surgery is accompanied by a strongly positive sodium balance and a negative potassium balance.
abstract: The conventional model on the distribution of electrolyte infusions states that water will distribute proportionally over both the intracellular (ICV) and extracellular (ECV) volumes, while potassium homes to the ICV and sodium to the ECV Therefore, total body potassium is the most accurate measure of ICV and thus potassium balances can be used to quantify changes in ICV In cardiothoracic patients admitted to the ICU we performed complementary balance studies to measure changes in ICV and ECV In 39 patients, fluid, sodium, potassium, and electrolyte-free water (EFW) balances were determined to detect changes in ICV and ECV Cumulatively over 4 days, these patients received a mean ± SE infusion of 14.0 ± 0.6 L containing 1465 ± 79 mmol sodium, 196 ± 11 mmol potassium and 2.1 ± 0.1 L EFW This resulted in strongly positive fluid (4.0 ± 0.6 L) and sodium (814 ± 75 mmol) balances but in negative potassium (-101 ± 14 mmol) and EFW (-1.1 ± 0.2 L) balances. We subsequently compared potassium balances (528 patients) and fluid balances (117 patients) between patients who were assigned to either a 4.0 or 4.5 mmol/L blood potassium target. Although fluid balances were similar in both groups, the additionally administered potassium (76 ± 23 mmol) in the higher target group was fully excreted by the kidneys (70 ± 23 mmol). These findings indicate that even in the context of rapid and profound volume expansion neither water nor potassium moves into the ICV.
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands lara.hessels@gmail.com.
authors.forename: Lara
authors.initials: L
authors.lastname: Hessels
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Oude Lansink
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Maurits H
authors.initials: MH
authors.lastname: Renes
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Iwan C C
authors.initials: IC
authors.lastname: van der Horst
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands Department of Anesthesiology, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Miriam
authors.initials: M
authors.lastname: Hoekstra
authors.affiliation: Department of Clinical Pharmacy and Pharmacology, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Daan J
authors.initials: DJ
authors.lastname: Touw
authors.affiliation: Department of Critical Care, University of Groningen University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Maarten W
authors.initials: MW
authors.lastname: Nijsten
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001826:Body Fluids / Q000378:metabolism; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D004487:Edema / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood* / Q000175:diagnosis; D011188:Potassium / Q000097:blood*; D012189:Retrospective Studies; D012964:Sodium / Q000097:blood*; D014882:Water-Electrolyte Balance / Q000502:physiology; D014883:Water-Electrolyte Imbalance / Q000097:blood* / Q000175:diagnosis / Q000209:etiology
chemical_list: D012964:Sodium; D011188:Potassium
keywords: Extracellular volume; intracellular volume; osmolytes; potassium; sodium