Colloids vs Crystalloids for resuscitation
There have been long standing debates on the use of colloids vs crystalloids for resuscitation. Crystalloids (eg. Saline 0.9%) are cheap and easy to use, and are associated with fewer side effects. However, you will need to give more bags of crystalloids to achieve the same haemodynamic response as a bag of colloid as colloids expand plasma to a greater extent, and remain longer in the intravascular space. Furthermore, crystalloid resuscitation can cause more interstitial oedema than colloid treated patients as crystalloid solutions move rapidly into the interstitial compartment.
However, studies have shown that fluid resuscitation with saline or with 4% albumin, achieve similar outcomes in critically ill patients¹. A recent Cochrane review showed no evidence from randomised controlled trials that resuscitation with colloids reduces the risk of death, compared to resuscitation with crystalloids, in patients with trauma, burns or following surgery⁷. There is very little evidence regarding resusication of the medically ill patient (eg. septic shock).
In practice, colloids such as Gelofusin, can be useful during the acute phase of resuscitation, especially when volume losses are continuing and you need to increase the intravascular volume quickly and with greater response. Albumin can be used for treatment of hypoproteinaemia, but is not generally recommended for routine volume replacement.
Teacher's Comment
It is important to distinguish between fluid and electrolytes for normal existence (daily maintenance) and for resuscitation or replacement of abnormal losses.
Rules of fluid replacement
Following are examples of causes of hypovolemia, and types of fluid which might be appropriate for replacement :-
1)Replace blood with blood
Causes: Trauma, GI bleed, Internal bleeding
2)Replace plasma with colloid
Causes: Burns, Peritonitis
3)Resuscitate with colloid and/or crystalloid
4)Replace ECF depletion with saline (Loss of water and salt)
Causes: Vomiting, diarrhoea, renal losses.
5)Rehydrate with dextrose (Loss of water alone)
Causes: Reduced intake, sepsis