Can a colloid intravascular volume expander be used in chronic orthostatic hypotension?

Question

For conditions such as POTS (Postural orthostatic tachycardia syndrome) which are unable to regulate appropriate blood pressure / HR on postural changes, they are treated with volume expansion - like an effective chronic hypovolemia - even though technically they are euvolemic.

Various treatments for these conditions include salt tablets and water intake, or regular home IV saline infusions. These have to be done regularly, however, or healthy kidneys will eliminate the excess fluid.

Wouldn't a colloidal volume expander like Gelofusine or Albumin last longer, by maintaining the oncotic pressure?

I recognize that unfortunately, it seems to be hard to get, as wikipedia explains in the article on albumin:

For patients with low blood volume, there is no evidence that albumin reduces mortality when compared with cheaper alternatives such as normal saline, or that albumin reduces mortality in patients with burns and low albumin levels. Therefore, the Cochrane Collaboration recommends that it not be used, except in clinical trials.

However, this research all seems to be about treating acute hypovolemia, such as in cases of blood loss or severe dehydration. In those cases, saline works just as well while being less expensive.

But for EDS patients, the problem isn't low blood volume, but inability to regulate that volume. Saline boosts the quantity of fluid while decreasing oncotic pressure, which is ultimately self-defeating. Maintaining oncotic pressure would, in theory, be ideal. Perhaps we could find a colloid that the kidneys will not eliminate rapidly.

Can blood volume be chronically increased effectively with colloid volume expanders?

Answer 1

Albumin is expensive and potentially dangerous, colloids have never been shown to be better than crystalloids, and there is no good evidence for their effective use in orthostatic hypotension.

Albumin, due to its cost and the traceability requirements inherent to all blood-derived products, is rarely prescribed as first-line treatment ¹

Synthetic colloids provide a plasma expansion property of close to 100% (80%–120% depending on the product; Table 2) but with a risk of anaphylaxis, renal failure and clotting disorders. ¹

The plasma expansion property of a solution theoretically has direct metabolic effects. A product with a high expansion property corrects blood volume more effectively, limiting the risks of tissue hypoperfusion responsible for lactic acidosis. The expected benefit of a colloid should therefore be logically greater than that of a crystalloid, but this superiority has never been demonstrated. ¹

Neurogenic orthostatic hypotension, postprandial hypotension and exercise-induced hypotension are common features of cardiovascular autonomic failure. Despite the serious impact on patient’s quality of life, evidence-based guidelines for non-pharmacological and pharmacological management are lacking at present. Here, we provide a systematic review of the literature on therapeutic options for neurogenic orthostatic hypotension and related symptoms with evidence-based recommendations according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Patient’s education and non-pharmacological measures remain essential, with strong recommendation for use of abdominal binders. Based on quality of evidence and safety issues, midodrine and droxidopa reach a strong recommendation level for pharmacological treatment of neurogenic orthostatic hypotension. In selected cases, a range of alternative agents can be considered (fludrocortisone, pyridostigmine, yohimbine, atomoxetine, fluoxetine, ergot alkaloids, ephedrine, phenylpropanolamine, octreotide, indomethacin, ibuprofen, caffeine, methylphenidate and desmopressin), though recommendation strength is weak and quality of evidence is low (atomoxetine, octreotide) or very low (fludrocortisone, pyridostigmine, yohimbine, fluoxetine, ergot alkaloids, ephedrine, phenylpropanolamine, indomethacin, ibuprofen, caffeine, methylphenidate and desmopressin). ²

1. https://www.medscape.com/viewarticle/730821_2
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5686257/