Management Of Osmolality Disorders in ICU
Mohammed Ibrahiem Mahmoud Al-Tantawy;
Abstract
Total body water in adult male 7o-kg averages 42 liter, classified into ICF (25-litters) and ECF ( 17-Lters), ECF is classified into interstitial fluid ( 13,5 liters) and intravascular volume (3,5-liters). Osmolality is the number of osmoles /kg of solvent, the major osmotic solutes of CF are potassium, magnesium, phosphorus and proteins, while the major osmotic sOlutes of £CF are Na+ and its accompanying anions. Cell membranes are relatively impermeable to most solutes, but freely permeable to water, so that JCF and ECF osmolality equalize despite different
composition by the movement of water. So increase of the ECF tonicity results in
cellular dehydration.
Normal plasma osmolality ranges between 280-295 ml.osm kg body water, as Na+ is the most abundant osmotically active solute in the ECF, control of ECF osmolality is synonymous with control of Na+ concentration. Baroreceptors and afferent renal arterioles act as sensors of intravascular volume. Changes in blood pressure at the carotid sinus modulates sympathetic activity and non-osmotic A VP secretion, while changes at the afferent arterioles modulates the activity of renine-angiotensive
aldosterone system, also stretch recepto"r in both atria sense changes in the intravascular volume OVV ), Atrial distension modulate release of A VP and ANP. Also adrenal glands sense changes in JVV and release Ouabian and Ouabian like factors which cause natriuresis and diuresis in hypervolemia, lastly decrease in effective JVV diminishes urinary Na+ excretion, while if it increase, it results in augmentation of urinary Na+ excretion.
Hyperosmolar states ( Posm > 295-mosmol/kg water) develops when total body solutes content increase to total body water, it is classified into hyperosmolatity without hypertonicity, it is due to increased permeant solu:es concentration (e.g. urea, ethanol), and hyperosmolality with hypertonicity, it is associated with hyponatrmia when the added solute is non Na+ salts (glucose in HHNC,it is treated by fluid
composition by the movement of water. So increase of the ECF tonicity results in
cellular dehydration.
Normal plasma osmolality ranges between 280-295 ml.osm kg body water, as Na+ is the most abundant osmotically active solute in the ECF, control of ECF osmolality is synonymous with control of Na+ concentration. Baroreceptors and afferent renal arterioles act as sensors of intravascular volume. Changes in blood pressure at the carotid sinus modulates sympathetic activity and non-osmotic A VP secretion, while changes at the afferent arterioles modulates the activity of renine-angiotensive
aldosterone system, also stretch recepto"r in both atria sense changes in the intravascular volume OVV ), Atrial distension modulate release of A VP and ANP. Also adrenal glands sense changes in JVV and release Ouabian and Ouabian like factors which cause natriuresis and diuresis in hypervolemia, lastly decrease in effective JVV diminishes urinary Na+ excretion, while if it increase, it results in augmentation of urinary Na+ excretion.
Hyperosmolar states ( Posm > 295-mosmol/kg water) develops when total body solutes content increase to total body water, it is classified into hyperosmolatity without hypertonicity, it is due to increased permeant solu:es concentration (e.g. urea, ethanol), and hyperosmolality with hypertonicity, it is associated with hyponatrmia when the added solute is non Na+ salts (glucose in HHNC,it is treated by fluid
Other data
| Title | Management Of Osmolality Disorders in ICU | Other Titles | معالجة الاضرابات السموزية في العانية المركزة | Authors | Mohammed Ibrahiem Mahmoud Al-Tantawy | Issue Date | 2001 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| Mohammed Ibrahiem Mahmoud Al-Tantawy.pdf | 1.4 MB | Adobe PDF | View/Open |
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