• decreased sympathetic response to position changes and the loss of reflex vasoconstriction;
• decreased vascular tone;
• excessive venous pooling in the lower limbs; and
• decreased venous return resulting in decreased cardiac output.

Signs and Symptoms

• light headedness
• fainting
• dizziness
• pallor
• blurring or changing in vision
• fatigue
• nausea
• excessive sweating above the level of injury
• muscle weakness
• syncope (side-effect that can result from cerebral flow reduction)

Treatment Considerations

• Patient Education (Goal is to mitigate signs and symptoms rather than normalize blood pressures)
• Non pharmacological
  • Postural changes
  • Gradual postural changes from supine to sitting, then standing
  • Compression stocking or custom hose with abdominal binder when up out of bed
  • Adequate Hydration
  • Increased salt intake
  • Wheelchair with elevated leg rests, reclining or tilt in space
• Pharmacological
  • Midodrine: Alpha adrenergic agonist leading to vasoconstriction. Usual doses are 2.5 mg twice daily or three times a day. Max dose is 30 mg/day. Avoid giving after 5:00 pm to avoid supine hypertension.
    • Side Effects: Hypertension, Headaches, Tachycardia, Parasthesias, Pruritis
  • Fludrocortisone (Florinef): Mineralocorticoid. Starting dose is 0.1 mg daily. Max dose is 0.4 mg/day. Dose adjustments recommended weekly or biweekly. Should be discontinued when appropriate.
    • Side Effects: Hypertension, edema, Hypokalemia, Hypernatremia, Hypomagnesemia, Avoid in congestive heart failure.
  • Pseudoephedrine: non selective alpha and beta receptor agonist. Dose: 12.5 to 25 mg three times a day.
    • Side Effects: Tachycardia, arrhythmias, supine hypertension, tremor, Insomnia, Diaphoresis, Urinary retention