Osmolarity in the blood (physiology and ions involved)

Extracellular Fluids ECFs are similar except for the high protein content of plasma Sodium (Na+) is the major cation Chloride (Cl-)is the major anion

Intracellular Fluids Have low sodium and chloride Potassium (K+) is the chief cation Phosphate (PO4-) is the chief anion

Sodium in Fluid and Electrolyte Balance Sodium holds a central position in fluid and electrolyte balance Sodium is the single most abundant cation in the ECF

o Accounts for 90-95% of all solutes in the ECFo Contribute 280 mOsm of the total 300 mOsm ECF solute concentration

The role of sodium in controlling ECF volume and water distribution in the body is a result of:o Sodium being the only cation to exert significant osmotic pressureo Sodium ions leaking into cells and being pumped out against their electrochemical

gradient Sodium concentration in the ECF normally remains stable

o Rate of sodium uptake across digestive tract directly proportional to dietary intakeo Sodium losses occur through urine and perspiration

Changes in plasma sodium levels affect:o Plasma volume, blood pressureo ICF and interstitial fluid volume

http://www.highlands.edu/academics/divisions/scipe/biology/faculty/harnden/2122/notes/fluelect.htm

Effects of acute and chronic increase in osmolarity Decrease in plasma volume and increase in plasma osmolarity causes:

Dry mouth results from a decrease in water filtered from the bloodstream (therefore increased osmolarity) and therefore salivary gland receives less water, in turn producing less saliva

Hypothalamic stimulation occurs when water moves (due to hypertonic ECF) out of thirst center osmoreceptors by osmosis, causing osmoreceptors to become irritable and depolarize (therefore sensation of thirst)

http://www.nature.com/nrneph/journal/v10/n7/fig_tab/nrneph.2014.76_F2.html

Preventing Osmotic Complications of IV contrastFactors that have been associated with high risk of adverse reactions to contrast media include prior adverse reaction to contrast agents:

age >65 years CHF (NYHA IV) impaired renal function acute coronary syndromes (unstable angina or acute MI) and severe valvular disease

1. Contrast: Low osmolarity & non-ionic in high risk patients. Contrast agents with lower osmolarity are less dense and, therefore, less likely to interfere with blood flow to the kidneys.

2. Volume expansion with IV isotonic crystalloid (1.0–1.5 mL/kg/h) for 3– 12 h before the procedure and continued for 6–24 h afterwards.

3. Pharmacologic agents: Ascorbic acid N-acetylcysteine - 1,200 mg orally twice a day on the day before and after the

procedure +/- NaHCO3

Statins – CVD patients on statin therapy with a common low-density lipoprotein cholesterol target of <70 mg/dL have lower rates of AKI following procedure (preservation of endothelial function at the level of the glomerulus and reductions in systemic inflammatory factors)

Withhold metformin & NSAIDs - lactic acidosis can develop leading to systemic complications and death. NSAIDs decrease blood flow to the kidneys.

4. Haemofiltration 6hrs before & 12-18hrs after procedure.

http://cdn.intechopen.com/pdfs-wm/23203.pdf

http://besancon-cardio.org/recommandations/coro_acc.pdf

http://www.sciencedaily.com/releases/2006/12/061211124125.htm