Prescribing IV fluids Flashcards
Total body water is approx what % of total body weight in males? What about in females?
60%
55%
Explain the 2/3 rule.
Flesh 24kg, water 46L
30L of that water is intracellular and the other 16L is extracellular.
11L if the extracellular water is interstitial and the other 5L is vascular.
Remember that fluid moves between compartments.
What 3 things can you prescribe to replace volume?
Crystalloids (water with varying degrees of salts)
Colloids (protein-rich and some salts in them as well)
Blood products
Crystalloids.
0.9% Saline 5% Dextrose 4%/0.18% dextrose/saline Ringer’s Lactate Solution Hartmann’s Solution (Propriotary infusion solutions) 0.45% Saline
Which crystalloids can you not add/change K+?
Why?
Ringer’s Lactate Solution
Hartmann’s Solution
(Propriotary infusion solutions)
As they contain K+ already.
Why are colloids preferable to crystalloids?
Colloids stay in vascular compartment better than crystalloids due to containing protein.
What does 0.9% and 0.45% Saline contain?
Na+, Cl-
What does 5% Dextrose contain?
Glucose
What does 4%/0.18% dextrose/saline contain?
Na+, Cl-, Glucose
What do Ringer’s Lactate Solution and Hartmann’s Solution contain?
Na+, K+, Ca2+, Cl-, lactate
Normal plasma range of Na+
137-144
Normal plasma range of K+
3.5-4.9
Normal plasma range of Ca2+
2.2-2.6
Normal plasma range of Cl-
95-107
Normal plasma range of lactate
0.3-1.3
Which crystalloids change both ECF and ICF?
All apart from 0.9% saline
Which crystalloids change only ECF?
0.9% saline
Which crystalloids change mainly ECF (about 90%)?
Ringer’s lactate and Hartmann’s
How can normal saline cause hyperchloraemic acidosis?
NaCl + H20 ↔ HCl + NaOH The HCl and NaOH should cancel Due to difference in composition of 0.9% saline and plasma, [Cl-] rises significantly (relative to [Na+]) and this tips the acid-base balance toward HCl, thus metabolic acidosis.
What is K+ available as?
Available as 20mmol/L or 40mmol/L, in:
• 0.9% Saline
• 0.18% Saline + 4% dextrose
• 5% dextrose
What is the fastest rate of K+?
Not to be given more than 20mmol/hr
Give three examples of colloids.
Gelofusine, Volplex, Haemaccel
What are colloids?
Contain high molecular weight proteins and electrolytes
Why are colloids not commonly used anymore?
• Some trial in sepsis suggests inferior
• ?Used in volume resuscitation
• NICE guidance moves it down the choices
• Small risk of allergic / anaphylactoid reactions /
anaphylaxis