Fluid resuscitation: what works best

The NEJM produced a review recently covering fluids for resuscitation. There are pretty pictures in the original paper.

The theory:
The compartment model is useful in predicting where different types of fluid go. Interstitial oedema is the primary concern with fluid loading. Cardiac overload and neuro-humoural effects can also be problematic.
The glycocalyx is an endothelial structure on the luminal side which affects oncotic pressure. Glycocalyx disruption occurs in inflammatory states (i.e. sepsis, surgery) and leads to protein leak into the interstitium.
Interstitial protein increase oncotic pressure, shifting fluid from other spaces, causing interstitial oedema. organ specific consequences of interstitial oedema include respiratory failure and intra-cranial hypertension.

One study of febrile, dehydrated children showed increased mortality with either normal saline or albumin, bringing doubt on whether fluids are beneficial in other conditions.

What to use:

There is some evidence for what fluids are best to use, but nobody knows what volumes are ideal.
Resuscitation to endpoints, like arterial or venous blood pressure, has limitations.
Albumin and normal saline are largely equivalent, except that albumin achieves similar physiological endpoints with lower volumes (ratio ~ 1 : 1.5).
Albumin can increase mortality in neuro-trauma, probably from intra-cranial hypertension.
Normal saline promotes hyper-chloraemic metabolic acidosis;
'Balanced' solutions like Haartmanns have specific side effects depending on what is used to replaced sodium chloride (lactate, acetate and calcium).  Lactate - hypotonicity; acetate - cardiotoxicity; calcium - microthrombi with citrate stabilised blood products.
Compared to balanced solutions, Normal saline was associated with more renal impairment and infections in the operative setting.
Hydroxyethyl starch (HES) is of little benefit over any other, but with greater risks.

Summary:
Fluids can be bad for patients. balanced solutions are usually > saline.


Resuscitation Fluids
John A. Myburgh, M.B., B.Ch., Ph.D., and Michael G. Mythen, M.D., M.B., B.S.
N Engl J Med 2013; 369:1243-1251September 26, 2013DOI: 10.1056/NEJMra1208627