Frisbie & Steele 1997; USA
Downs & Black=13
Observational
N=231

Population: SCI; Ephedrine (medically treated for OH) group: mean age=57±15 years, duration of paralysis 26±15 years; No ephedrine group: mean age=51±15.2 years, 22±13.5 years post-injury
Treatment: Retrospective chart review of use of ephedrine (n=30), salt supplementation (n=6), fludrocortisone (n=3) or physical therapy.
Outcome Measures:OH symptoms, serum sodium and urine osmolality.

1. 3/4 patients on ephedrine who started salt supplementation with meals became independent of ephedrine use.
2. Symptoms of OH were reduced consciousness (100% of subjects), strength (75%), vision (56%) and breath (53%). Precipitating factors were hot weather (77%) bowel care (33%) and meals (30%).
3. Low blood sodium found in 54% of the ephedrine (OH) patients and 16% of those without, P < 0.001.

Muneta et al. 1992; Japan
Downs & Black=11
Case Report
N=1

Population: 72-year old woman with non-traumatic SCI and paroxysmal hypotension.
Treatment: Several weeks of salt supplement (7 then 15 g/day) was followed by L-threo-3,4-dihydroxyphenylserine (100 mg up to 600 mg/day)
Outcome Measures: Blood pressure, catecholamines (epinephrine & non-epinephrine), plasma renin activity.

1. After salt supplement, a marked ↑BP and norepinephrine were observed in response to sitting, along with a decrease in basal plasma renin activity.
2. Addition of L-threo-3,4-dihydroxyphenylserine for 2 weeks, showed elevation in catecholamines about 5 and 10 times without an apparent increase in resting BP level.

3. Significant improvement in the symptoms of the paroxysmal hypotension and patient able to participate in rehabilitation program.

Frisbie 2004; USA
Downs & Black=8
Observational
N=4

Population: Chronic cervical complete tetraplegia; AIS A
Treatment: Evaluation of urinary salt and water output in relation to prescribed dosage of ephedrine (doses range from 0 to 100 mg daily)
Outcome Measures: Severity of OH, urinary output.

1. With decreasing ephedrine dose (and OH severity), there was a ↑mean daily output of urine sodium (from 50 to 181 mEq), ↑water (from 1.5 to 5.3 L),↑ rate of creatinine secretion, ↑rates of water excretion, ↓urine osmolality, and ↑sodium concentrations.