Measurement of the Colloid Osmotic Pressure in Patients

Abstract

A study is made of the conditions that must be fulfilled when determinations of colloid osmotic pressure are made in clinical medicine. The colloid osmotic pressure is best determined if the blood can be obtained from an artery or central vein. If the blood sample is obtained from a peripheral vein, it should be taken during brief stasis. The plasma should be separated from the crythrocytes immediately, but the plasma can be stored at 4°C for up to a week before determination. Haemolysis must not occur. It is of great importance that the patient should be confined to bed when the sample is taken, but of little importance whether the patient is fasting or not. The daily fluctuations in the patient confined to bed are ± 10.5 per cent at the 5 per cent level. The Tybjærg Hansen osmometer is used for the measurements.

Key Words:

• Plasma
• osmosis