# POTS, orthostatic hypotension, and vasoplegic shock

An evidence-comparison aid for discussions about methylene blue. This is not a diagnostic worksheet or treatment protocol.

| Feature | POTS | Classical orthostatic hypotension | Vasoplegic shock |
|---|---|---|---|
| Defining pattern | Chronic upright symptoms and excessive heart-rate rise without sustained diagnostic orthostatic BP fall | Sustained BP fall within three minutes upright | Acute loss of vascular tone with circulatory failure |
| Relevant measurements | Heart rate, BP, upright symptoms and daily function | Upright and supine BP, symptoms, falls and function | Perfusion, vasopressor support, organ function and survival |
| Evidence question | Does methylene blue improve symptoms and sustained function in confirmed POTS? | Does it improve chronic orthostatic symptoms without unacceptable supine pressure effects? | Does it improve outcomes during monitored critical care? |
| Evidence located for the article | No controlled POTS efficacy trial located | No controlled evidence establishing routine chronic OH treatment located | Septic-shock trials, including a 2023 placebo-controlled study with 91 analyzed patients |
| Main inference limit | Vascular mechanisms and anecdotes do not establish clinical benefit | ICU pressor effects cannot establish chronic outpatient benefit or safety | Shorter vasopressor duration does not establish a treatment for POTS |

## Questions to bring to a clinical discussion

1. Which condition and measurements does the claim actually concern?
2. Does the cited study enroll patients with my diagnosis?
3. Does it measure meaningful symptoms and function, or only a vascular response?
4. How do route, duration and accompanying medicines differ from the proposal?
5. What safety information and alternatives apply to my situation?

## Source basis

1. [NIH expert consensus account of POTS](https://pmc.ncbi.nlm.nih.gov/articles/8455420/): diagnostic context.
2. [Autonomic societies' definitions](https://www.sciencedirect.com/science/article/pii/S156607021100035X): classical orthostatic hypotension.
3. [Ibarra-Estrada et al., 2023](https://link.springer.com/article/10.1186/s13054-023-04397-7): septic-shock randomized trial; median vasopressor discontinuation at 69 versus 94 hours; mortality similar.

Prepared for the article “Methylene blue and POTS: why vascular mechanisms do not establish treatment”, September 12, 2026.