What Entities are Included within Orthostatic Intolerance?

Uncategorized

Patient Presentation
A 15-year-old male came to clinic after passing out while at work the day before. He had a summer job as a dishwasher and toward the end of shift said he felt like he was going to pass out, became lightheaded and then he remembers waking up on the dish station floor. The other dishwasher told him that he stopped talking, looked pale and then basically fell to the ground. He came to right away and was oriented to time/place and situation. He did not have any abnormal movements and was awake within a few seconds. He was oriented to time, place and situation. He said he felt better after sitting for a few minutes and having something to drink. He was wet from the wet flooring but denied any loss of bowel or bladder, nor any head or other trauma due to the fall. He said that it was very hot and because of the shift being very busy he had not eaten and had not really been drinking much either. He denied palpitations before or after the event. His mother was worried because her grandmother had recently died because of a heart attack. He denied any other syncopal or near-syncopal episodes. The review of systems was otherwise negative.

The pertinent physical exam showed a healthy male with heart rate of 76 beats/minute, blood pressure of 108/72, and respirations of 18/minute. Repeated blood pressure and heart rate did not change substantially with standing. His heart examination was normal as was the rest of his examination.

The diagnosis of a provoked vasovagal syncopal episode was made. The pediatrician recommended that he make sure that he drank quite a bit and also ate food that included some additional salt. “I realize that it is a small space but make sure that you move your legs a lot and don’t just stand in one spot. Switch spaces with your other partner and take a moment to even do some deep knee bends so that you keep the blood flowing. You are no help to yourself or the restaurant if you end up on the floor, so take that extra few seconds to keep your legs moving and drinking,” the pediatrician counseled.

Discussion
People are upright beings with most of their blood volume residing below their heart (~70%) and with the normal cardiovascular and autonomic nervous system compensatory mechanisms maintaining blood pressure and cerebral perfusion above the heart. Otherwise, hypotension and syncope/loss of consciousness would occur.

Normal blood pressure is generally considered between 90/60 and 130/80 mmHg for most situations for patients > 10 years. For pediatric patients, hypertension is generally considered BP > 95% for age and gender.
Hypotension is based on age and generally the following is used:

Age Blood Pressure
Neonates < 60 mmHg or weak pulses
Infants < 70 mmHg or weak pulses
1-10 years < 70 mmHg + (age in years x2)
> 10 years < 90 mmHg

Syncope is very common with at least 40% or more individuals having at least 1 syncopal episode in their life. With transient loss of consciousness (LOC), the patient appears unconscious and must have loss of motor control, loss of response to speech/touch, and amnesia for the LOC period. Syncope is a transient LOC due to global cerebral hypoperfusion. Syncope overlaps with orthostatic intolerance discussed below.

Transient hypotension and/or syncope often are benign but can be serious. Shock, sepsis/infection, hypovolemia, cardiac arrhythmia, seizures, stroke/transient ischemic attacks, anaphylaxis, metabolic abnormalities, and medications are just some of important causes of hypotension and/or syncope that need more evaluation and intervention usually acutely.

Orthostatic intolerance (OI) is “…defined as having difficulty tolerating the upright posture because of symptoms that abate when returned to supine. Typical symptoms include a sense of impending loss of consciousness, cognitive deficits (memory loss and decreased reasoning and concentration), visual difficulties, lightheadedness, headache, fatigue, weakness, nausea, abdominal discomfort, tremulousness, exercise intolerance, and reported signs such as pallor, diaphoresis, tachycardia, bradycardia, or hypotension.” It is a broad term with several different entities within this definition. Normally BP decreases to its lowest amount within 10-15 seconds after standing. BP usually is restored within 30 seconds. However increases in heart rate (HR) and cerebral blood flow can take longer. Lightheadedness can occur if these compensatory mechanisms and timing are not matched.

Sometimes history and physical examination are all that are needed to determine a likely cause such as a provoked vasovagal syncope such as the example above or when a teenage girl who is nervous about her choir concert is standing in robes under hot lights on a stage. Many people have witnessed or experienced these situations. Other times more persistent OI symptoms or timing may require tilt table testing which generally is considered the standard for diagnosis of and between the different entities. Postural tachycardia syndrome (POTS) often requires a tilt table test to make the diagnosis.

OI associated co-morbidities include: anxiety/depression, cognitive dysfunction, chronic fatigue syndrome, headache, joint hypermobility, sleep disorder, functional gastrointestinal disorders

Countermeasures/treatment includes awareness and lying down as needed, increasing fluid and salt intake, exercise training, and possibly cognitive behavioral therapy. Drugs to support BP support or have other cardiovascular effects can be used.

Learning Point
OI entities include:

  • Initial Orthostatic Hypotension – most common type of OI
    • Cause/Definition: occurs when rising and is considered clinically significant with a systolic BP decrease of > 40 mmHg or diastolic BP of > 20 mmHg
    • Time: should resolve within 1 minute
    • Syncope: generally no, but can have lightheadedness
  • Orthostatic Hypotension (OH)
    • Cause/Definition: sustained systolic BP decrease of > 20 mmHg or diastolic BP of > 10 mmHg, can have tachycardia
    • Time: occurs within 3 minutes of rising
    • Syncope: can have lightheadedness or syncope
  • Vasovagal Syncope (VVS)
    • Cause/Definition: transient loss of consciousness and postural tone due to rapid onset cerebral hypoperfusion.
      BP and HR both are initially decreased and then recover.

    • Time: within 2 minutes of rising
    • Syncope: Yes
    • Other: very common in teenage females. It can be provoked by emotional stress or noxious stimuli.
      There are situational variants too including defecation, voiding, and cough.
  • Postural Tachycardia Syndrome (POTS)
    • Cause/Definition: chronic problem where there is excessive tachycardia without hypotension. Tachycardia in adults should be > 40 beats/minute increase or > 120 beats/minutes.
    • Time: within 10 minutes of rising
    • Syncope: yes, but not as commonly
    • Other: very common in teenage females
  • Prolonged Bedrest (>23 hours)
    • Cause/Definition: gravitational deconditioning and with various physiologic changes
    • Other: can symptomatically appear like OH, VVS or POTS.
  • Hypocaloric weight loss
    • Cause/Definition: even as little as 1% weight loss can cause various physiologic changes
    • Other: worse if also associated with concomitant bedrest. Can symptomatically appear like OH, or POTS.

Questions for Further Discussion
1. What are secondary causes of hypertension? A review can be found here
2. What are symptoms of autonomic dysreflexia? A review can be found here
3. How is acute hypotension treated?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Autonomic Nervous System Disorders and Low Blood Pressure.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Stewart JM, Boris JR, Chelimsky G, et al. Pediatric Disorders of Orthostatic Intolerance. Pediatrics. 2018;141(1):e20171673. doi:10.1542/peds.2017-1673

Flynn JT. What Level of Blood Pressure Is Concerning in Childhood? Circ Res. 2022;130(5):800-808. doi:10.1161/CIRCRESAHA.121.319819

Stewart JM, van Dijk JG, Balaji S, Sutton R. A framework to simplify paediatric syncope diagnosis. Eur J Pediatr. 2023;182(11):4771-4780. doi:10.1007/s00431-023-05114-w

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa

Published