2014A13 Compare and contrast the pharmacology of normal saline and 4% albumin.

0.9% Normal saline

4% albumin

Type

Crystalloid = small, charged, dissolved particles

(leaks into ISF quickly)

Colloid = large, dispersed particles

(stays in plasma longer)

Production

Distilled water + pure NaCl

Blood donation

Pasteurisation (heat 60°C 10 hours)

Cost

Very low

High

Storage

PVC

Glass vial (breakable)

Contents

154mmol/L Na⁺

154mmol/L Cl^-

(9 grams NaCl)

Albumin 40g/L

Na⁺ 140 mmol/L

Cl^- 128 mmol/L

Octanoate 6.4mmol/L

Osmolality

308 predicted

290 measured

(not ideal solution)

260

Tonicity

Iso

Hypo

Oncotic pressure

0

20-30mmHg

->iso-oncotic

pH

5.5

7

Feature

Normal saline

4% albumin

Absorption

Distribution

-Where

ECF: plasma ¼, ISF ¾

(more in plasma if hypovolaemic)

Plasma 70-100% >> ISF

(prefer if deplete)

-Duration of blood volume expansion

30 minutes

12-24 hours

Metabolism

Nil

Hepatic proteolysis

Excretion

Urine Na⁺, Cl^-, H₂O

Urine Na⁺, Cl^-, H₂O

Protein recycled

Normal saline

4% albumin

Specific indications

Resuscitation for hypovolaemia

Neurosurgery

Liver failure

Hypoalbuminaemia

Haemorrhage

Metabolic disturbance

Hyperchloraemic acidosis (high [Cl^-] -> ↓SID -> ↑dissociation of H₂O -> acidosis

(for preservation of electrical neutrality)

Anaphylaxis

No

1 in 10,000

Infection

No

Unlikely - pasteurized

APO

More likely

Less likely