Don’t try this at home.

Just checking which well-informed Authors have been citing RSE&GM paradigm and I came across this one from Flinders, Adelaide published last year, full text is free;

Bolus intravenous 0.9% saline, but not 4% albumin or 5% glucose, causes interstitial pulmonary edema in healthy subjects http://jap.physiology.org/content/119/7/783.abstract

Just to make sure you get the message, the running title at the top of each page is “Pulmonary Edema after Bolus 0.9% Saline in Healthy Subjects • Bihari S et al.”

Six euvolaemic volunteers were given around 2 litres of each solution at 100 ml/ min (close to maximal Jv capacity) in order to see what harm this causes! And exactly as RSE&GM predicts, both solutions caused hypervolaemia with pulmonary congestion and the no-COP 0.9% saline caused more Jv (as seen in Lung B-lines on ultrasound). I hope that regular readers of fluidphysiology.org will see the design flaw in this experiment.

restricted figure 3.001

That’s right, it is an abuse of kinetics and context sensitivity. In this experiment, the euvolaemic volunteers were at or close to their healthy J point. The rapid fluid infusion took them immediately to the right and so up the steep part of their J curve. The 0.9% saline rapidly diluted πp (red line) while isoncotic albumin maintained πp (blue line); Jv was therefore increased by both solutions, but more so by 0.9% saline. In clinical practice we would only give resus fluids to patients whose Pcap is thought to be low (suspected hypovolaemia). Then, as the J curve tells us, either fluid can be used to increase Pcap and move the patient to the right along the curve towards his J point and euvolaemia. Used in the context of low Pcap/ hypovolaemia neither fluid will have more than a minimal effect on Jv and won’t cause oedema.

As neither they nor their Editors were familiar with the J curve the Flinders team erroneously conclude “The different effects of these two resuscitation fluids may be due to differences in active signaling in the pulmonary vasculature or a protective effect of albumin.” It is gratifying to have been cited, it would have been better to have been read and understood.

 

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