Glucose saline

Short description, the difference between isotonic, hypotonic & hypertonic fluids. Contraindications.

1. By: Alaa Fadhel Hassan
Drug information center, Pharmacovigilance member
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Osmolality Vs Tonicity
 Osmolality is the measurement of the concentration of body fluids (ratio of solute to the
solvent), its unit is milliosmole/kilogram of water (mOsmol/kg), while Tonicity is the
measurement of the molecules that affect movement of water (e.g. sodium, glucose, etc)
[1].
 Osmolality reflects the ability of a solution to create osmotic pressure and hence affect
the movement of water. Hence, an increase in the osmolality of the ECF will cause water
to move from the ICF to the ECF, while decreased osmolality will have the reverse effect
[1].
 The osmolality of each fluid compartment is maintained by:
Extracellular fluid---sodium
Intracellular fluid---potassium
Intravascular fluid---plasma proteins [1].
 Serum osmolality range 275–295 mOsmol/kg [2][3] while other ref. stated that normal
osmolarity ranged from 280 to 310 mOsmol/L [4].
Hypotonic, Isotonic & Hypertonic solution [5].
Isotonic solutions have a concentration of
dissolved particles similar to plasma, and osmolality of 250 to 375 mOsmol/L. These fluids
remain within the extracellular compartment and are distributed between intravascular (blood
vessels) and interstitial (tissue) spaces, increasing intravascular volume. Hypertonic solutions
have a concentration of dissolved particles higher than plasma and an osmolality > 375
mOsmol/L. So causes the osmotic pressure gradient to draw water out of cells, increasing
extracellular volume [6].

2. Hypotonic solutions have a
concentration of dissolved
particles lower compared to
plasma and an osmolality < 250
mOsm/L. Hypotonic fluids lower
serum osmolality within the
vascular space by causing fluid
to shift out of the blood into the
cells and tissue spaces [6].
What about Intravenous Fluid, Normal Saline & Glucose water?
 The osmolarity of a dextrose solution is different from with other types of IV solutions
because once the dextrose is metabolized the osmotic effect changes. Then, these
dextrose solutions have a different physiological osmolarity than they do in the IV bottle.
As the dextrose is metabolized, free water remains for hydration [7].
 The Glucose solutions classified according to their concentrations; 2.5% (hypotonic), 5%
(isotonic), 20% and 50% (hypertonic). While Saline solution classified as: 5% & 3%
NaCl (hypertonic), 0.9% NaCl (isotonic), 0.45% & 0.2% NaCl (hypotonic)[1][7].
 Other reference stated that “0.9 % saline is often thought of as a relatively hypertonic
solution because the sum of its osmotically active components gives a theoretical in vitro
osmolality of 308 mOsmol/kg H2O (154mmol/l sodium plus 154mmol/l chloride).
However, it is more accurately referred to as an isotonic solution as its constituents –
sodium and chloride – are only partially active, with an osmotic coefficient of 0.926 & its
calculated in vivo osmolality (tonicity) of is 285 mOsmol/kg H2O” [3].
Glucose saline, concentrations
Conc. 4%
dextrose
/ 0.18%
NaCl
5%
dextrose
/ 0.2%
NaCl
5%
dextrose
/ 0.33%
NaCl
4%
dextrose
/ 0.45%
NaCl
2.5%
dextrose/
0.45%
NaCl
5%
dextrose/
0.45%
NaCl
5%
dextrose/
0.9%
NaCl
10%
dextrose/
0.9%
NaCl
0.9%
NaCl
Na
(mmol/l)
30 [1][11]
31[8]
34 [4] 56 [4] 77 [8] 77 [4][9] 75 [11]
77 [4]
150 [11]
154 [4][5]
154 [4] 150 [11]
154 [3]
Cl
(mmol/l)
30 [1][11]
31[8]
34 [4] 56 [4] 77 [8] 77 [4][9] 75 [11]
77 [4]
150 [11]
154 [4][5]
154 [4] 150 [11]
154 [3]
glucose
(g)
40
[1][8][11]
50 [4] 50 [4] 40 [8] 25 [4][9] 50 [4][11] 50 [4][11] 100 [4] -
PH 4.5 [8] 4 [4] 4 [4] 3.2-6.5
[12]
4.5 [4] 4.5 [4] 4 [4] 4 [4] 4.5-7
[3]
Osmo-
larity
mOsmol/
L
282-284
[8][10]
321 [4] 365 [4] 280.15
[12]
280 [4]
294 [10]
406 [4]
432 [10]
560 [4][6]
586 [10]
813 [4] 286 ~
308 [3]
Class. Isotonic
[1][10]
Hypoto
nic [11]
hypotoni
c [6]
isotonic
[10]
isotonic
[6]
hypertoni
c [10]
hypertoni
c [6][10]
hypertoni
c [4]
isotoni
c
[1][7][11]

3. Glucose saline, contraindications [10]:
• Know hypersensitivity to the active substances/ allergy to corn or corn products, because
cornstarch is used as raw material for glucose production.
• Cardiac failure including congestive heart failure – hyperkalaemia & severe impairment of
renal function.
• Lacto-acidosis - uncontrolled diabetes & clinically significant hyperglycaemia.
•bloating-ascitic syndrome in cirrhosis.
• Acute ischaemic stroke & patients who have had a head trauma within 24 hr.
• Pt. presenting with a clinical state in which there exists oedema with sodium retention, or with
renal, hepatic or cardiac impairment with oedema, hypervolaemia, & hypernatraemia.
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References
1. Lisa Dougherty & Julie Lamb. Intravenous Therapy in Nursing Practice, 2
nd
edition.
Blackwell Publishing, 2008.
2. Sherilyn Alvaran Tuazon, Ricardo Cardona. Jennifer Alvaran Tuazon et al. Serum
Osmolality, Laboratory medicine. Medscape website, 2015.
3. Sumeet Reddy, Laurence Weinberg, and Paul Young. Crystalloid fluid therapy. Critical
care, 2016.
4. Dextrose 5% in 0.9% sodium chloride (dextrose and sodium chloride inj) drug. RxList
professional website, 2019.
5. Laura Willis. Fluid and electrolyte made incredibly easy. 6
th
Edition, Wolters Kluwer
Health, 2015.
6. Lippincott Nursing Center, Nursing Pocket Card. IV Fluids. Network website, 2019.
7. UNMH Clinical Education Department. Intravenous Therapy Skills Course, Clinical
Education - Intravenous Therapy Skills. Network website, 2019.
8. NICE clinical guideline 174. Composition of commonly used crystalloids, ‘Intravenous
fluid therapy in adults in hospital’, 2016.
9. Marie K. Holowaychuk. Practical Approach to Fluid Therapy. Network website.
10. Baxter International Inc. GLUCOSE AND SODIUM CHLORIDE Data Sheet (Based on
Australian PI most recent amendment 10 February 2015; and CCSI43720140821 &
CCSI43820140821). Baxter Healthcare Ltd, 2018.
11. IV fluid guidelines, Intravenous fluids chart. Network website
www.rch.org.au/clinicalguide/cpg.cfm?doc_id=5203
12. Serum products company. Glucose saline 2.5% & 0.45% drug label.