Supine Tops Seated for Orthostatic Hypotension Assessment

New research shows that supine orthostatic hypotension (OH) is more common and better predicts falls and orthostatic symptoms than seated OH, supporting a supine OH protocol in clinical practice, the researchers say.

“Older adults at risk for falls undergoing assessment for OH should lie supine rather than sitting prior to standing to get the most informative OH assessment,” study author Stephen Juraschek, MD, PhD, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, told theheart.org | Medscape Cardiology.

“The findings call for a change in current practice,” Juraschek said.

He presented the study September 29 at the American Heart Association (AHA) Hypertension Scientific Sessions 2021.

The seated position for detecting OH is “commonly used for convenience. Since many clinics already perform a seated blood pressure, it saves time for people to stand shortly afterward,” he explained.

“It has also been thought that the two are interchangeable (i.e. the change in blood pressure from seated to standing was just a lower magnitude than the change from supine to standing). However, we showed that the physiology is on average quite different, questioning prior perspectives on the interchangeability of the two protocols,” he added.

The researchers studied 522 adults (mean age, 76 years; 42% women) at high risk for falls and with vitamin D levels in the insufficient/deficient range participating in the Study to Understand Fall Reduction and Vitamin D (STURDY).

The study showed that vitamin D supplementation was not associated with OH or the main study outcome of falls.

The study used two different OH assessment protocols — seated-to-standing and supine-to-standing — and Juraschek’s team used the data to gauge the impact of supine and seated positions on OH prevalence and its relation with fall risk and orthostatic symptoms.

OH was defined as a drop in systolic BP of at least 20 mm Hg or diastolic BP of at least 10 mm Hg

At baseline, mean BP was 129/68 mm Hg. Mean BP increased 3.4/2.6 mm Hg after sitting, but decreased 3.7/0.7 mm Hg after lying supine.

Of the 953 OH assessments (supine and seated), OH was detected in 14.8% of the supine measurements but in only 2.2% of the seated measures.

Supine OH better predicted falls (hazard ratio [HR], 1.60; 95% CI, 0.98 – 2.61; P = .06) than seated OH (HR, 0.70; 95% CI, 0.30 – 1.60; P = .39).

Although both were nonsignificant, “potentially due to power,” the association with falls was stronger for supine OH than for seated OH, Juraschek said.

In addition, seated OH was not associated with orthostatic symptoms, whereas supine OH was significantly associated with a greater risk of fainting, blacking out, seeing spots, room spinning, and headache in the previous month (P  = .048 to .002).

Useful Study Confirms Anecdotal Evidence

This is a “useful study” from a “reputable” group, “and the results reveal what I would have expected,” Robert Carey, MD, University of Virginia, Charlottesville, who wasn’t involved in the study, told theheart.org | Medscape Cardiology.

The findings, Carey said, show that measuring supine, compared with standing, “actually correlates much better with the untoward effects of orthostatic hypotension which are falls and symptoms such as dizziness and spots before your eyes.”

“Seated BP is mostly used for convenience and a little bit shorter protocol. Most clinical trials do seated orthostatic hypotension measurements. I’ve always taught my medical students and others to use the supine to standing because I’ve just anecdotally felt that this was a much better way of detecting true orthostatic hypotension and that’s how we do it at the University of Virginia Hospital,” Carey said.

The study had no funding. Juraschek and Carey have no relevant conflicts of interest.

Hypertension Scientific Sessions 2021: Oral abstract 49. Presented September 29, 2021.

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