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Some people have dizzy spells which may significantly interfere with their day to day living


In some cases, patients may even pass out. These symptoms are referred to as Orthostatic Intolerance.

There are many possible causes. But, the 2 common ones which I tend to look for are whether or not the blood pressure drops or the heart rate rises more than it should

Normally, when a person stands up, approximately 1 litre of their blood volume will shift into their legs. The result is that their blood pressure drops by up to 10mmHg and so their body reacts by making heart rate speed up by up to 25bpm, which in turn helps maintain blood flow to the brain and other organs. This is an important autonomic reflex.

But, for some people, this doesnt happen like it should:

The mechanisms are not fully understood, but basically, there are 3 groups of people with orthostatic intolerance.

Orthostatic Hypotension

Blood pressure drops within 5 minutes of standing

These people drop their blood pressure more than it should [systolic >20mmHg  or diastolic > 10mmHg and their heart rate may not speed up. The general reasons for this is either because they are either 'volume depleted' [making their blood pressure fall a lot] or/and there is something wrong with their autonomic reflex [neurally mediated orthostatic hypotension]

But, in some patients, the symptoms may occur early on after standing, and the blood pressure drop may not occur right away. In cases, like this a 'tilt table test' may be required to establish the diagnosis

Vasovagal/ Reflex

Blood pressure drops and heart rate may actually drop as well

This may occur after as little as 30 seconds of standing or in unique situations such as

  • emotional stress or

  • physical pain

  • swallowing large chunks of food, urinating strongly

  • Coughing fits

  • After a meal

Paroxysmal Orthostatic Tachycardia Syndrome [POTS]

Heart rate speeds up much more than it should within 10 minutes of standing

These people find that their heart rate speeds up by more than 30bpm with very little pressure drop

The explanation  is beyond the scope of this article

Why does this happen in these patients?

Normally, when a person stands up, a few things will happen

  • up to a litre of blood volume may 'drop down' and temporarily collect in your legs [venous pooling]. The entire body has approximately 5 litres, and this poling can result in less circulating blood for important things [like your brain]

  • Fortunately, your body's autonomic nervous system quickly reacts in order to minimize the impact of this by having

    • the heart rate speed up and

    • the heart contracts more strongly

    • the body's arteries narrow [vasoconstriction] and

    • these things allow your body to maintain proper perfusion to your central organs including your brain and avoid you feeling dizzy and/ or passing out.

  • As a result, a normal person may notice a minimal drop in their blood pressure accompanied by a small rise in their heart rate

But, in patients with Orthostatic Intolerance, they may experience an abnormal blood pressure or/and heart rate response,

  • some appear to have impaired vasoconstriction and/or excessive venous pooling

  • some appear to have a smaller blood volume, and

  • these patients may experience an impaired sympathetic response when they stand up 

  • All  of this taken together can result in a significant blood pressure drop and/or a significant rise in the heart rate... and this leads to symptoms which may include lightheadedness, fatigue, racing heart beat, etc

Clinical concerns

So, what does this mean?

Both groups of people tend to have a lot of difficulty getting up or staying on their feet for prolonged periods of time as a result of the lightheadedness which may accompany the above changes. Some, will be chronically fatigued, or feel racing heart beats. Other patients may even be prone to passing out.


There are some common approaches which may help in each group of patients.

But, each component of this treatment strategy has advantages and disadvantages and we always need to account for the unique features of each patient before deciding how to best manage you.

Treatment of most forms of situational syncope is based upon avoiding or ameliorating the triggering activity.

When the activity cannot be avoided, general treatment measures include maintenance of intravascular volume, protected posture (eg, sitting rather than standing) and slow postural changes, and these guidelines may need to be tailored depending on the individual needs of the patient.

Maintaining adequate hydration

Increased intake of salt and fluids may help to augment your vascular volume which in turn may make you less prone to a low blood pressure episode. In general, I recommend at least 4000mg of sodium per day along with at least 2-3 litre of fluids as tolerated. In some patients, I may recommend up to 8000-10,000 mg of sodium per day. We may use urine testing to help us ensure that you aren't getting too much sodium. We need to be especially careful not to trigger 'high blood pressure' when you are supine/sleeping.


Physical maneuvers

Counter-pressure maneuvers, such as tensing the arms with clenched fists, leg pumping, and leg-crossing, may prevent passing out or at least delay it long enough so that you can lay down. In many cases, this works by squeezing the blood which has pooled in the legs to be redirected to the upper part of the body and maintain blood flow to the brain.

In some patients, we recommend compression stockings, since this helps to minimize the amount of blood volume which pools in your legs when you stand up.

Some clinicians advocate that exercise training should have a central role in treatment of POTS

Reassurance and Patient Education

For most patients, this is not a life threatening condition; although, for many, it can be a life disabling condition.

Diet and Meals

  • Maintain hydration [at least 2-3 Litres a day]

    • Some patients may respond well to rapidly drinking 1/2 Litre of water within a 5 minute period of time. These patients may raise their blood pressure for about an hour​. This trick can be used to as needed depending on the patient's circumstances

  • Maintain sodium intake [olives, pickles, soups, etc]​​

  • Maintain good nutrition

    • B12 deficiency may aggravate postural stability​

    • Anemia may aggravate symptoms

  • Modify your meals , especially when symptoms appear to occur in association with eating. Normally, when we eat a meal, our body redirects part of our blood volume to the 'gut area' in order to help with digestion.The more than you eat, the more blood volume will be directed and for a longer time.

  • For those patients whose symptoms are aggravated after a meal, try to eat smaller and more frequent meals, and avoid over-eating, especially meals high in carbohydrates since this may cause blood to pool in the abdominal vasculature

  • Minimize alcohol intake [which may cause skin flushing as well as increased urinary output both of which can reduce your central circulating blood volume

  • Avoid activities or sudden standing immediately after eating

  • Caffeine in the morning is probably helpful to many patients

Posture and Body Awareness

  • Be aware and cautious when you are standing for prolonged periods of time.

  • Avoid periods of prolonged inactivity

  • Arise slowly , in stages , from supine to seated to standing. Especially important i the morning when symptoms may be maximum

  • Consider using compression stockings [waist high, 30-40mmHg pressure] especially if you have varicose veins, since this may help to reduce pooling of blood in your legs

  • Consider using abdominal compression/binders which may help to reduce splanchnic pooling; Most venous pooling is thought to occur in the area of the abdomen.

  • Consider raising the head of your bed 10-15 degrees

    • raise the head of the bed to be 6-9 inches higher than your feet.

    • raising the head of the bed may help to keep your morning blood pressure up, because  when you lay down, you can get:

      • Volume depleted overnight, because the supine hypertension may trigger more urine output

      • Volume depleted overnight, because you dont reabsorb as much sodium [ your aldosterone levels decrease]

    • this can also help to minimize the impact of potential supine hypertension [high BP while laying down] which can be a complication of some of the measures that we implement as we try to control your  daytime/upright symptoms, and which can lead to other problems.

  • Postural counter-measures may help [any muscular contraction in the legs to help with distribute blood volume away from the legs]

  • Exercise needs to be done regularly,

    • Start low, go slow, 

    • Avoid over-exertion which may raise your body temperature, cause vasodilation, and make you more prone to venous pooling

    • Consider recumbent type exercise which may be more tolerable than upright exercise. Recumbent type exercise is the type of exercise that can be done  while on your back or in a reclined  or prone position.  This allows you to avoid the postural trigger that may come on when you normally stand up, and gives you a chance to improve your physical conditioning, which is believed to be an important part of managing these patients.

      • use a rowing machine or do Mat based exercises that focus on your legs and your core muscles. ​

      • swimming pool exercise may be tolerable because during the moments when you are upright, the external pressure of the water compressing your legs may reduce your venous pooling.

      • The important thing appears to be the avoidance of 'upright exercises'

    • Lower body/leg exercises may be particularly helpful in minimizing your propensity to venous pooling.

    • Ensure adequate hydration prior to exercising.

  • Inactivity can be bad for you and this is because it contributes to a reduction of your blood volume


  • Learn to avoid potential triggers

  • Avoid warm environments which can create a shift of your blood volume peripherally. So, stay away from hot saunas, showers, baths, etc

    • Use a shower chair if necessary​

  • Avoid straining, coughing, and walking in hot weather; these activities can reduce venous return and worsen orthostatic hypotension

  • Avoid taking medications that might lower your blood pressure.


In patients who have persistent symptoms, we may consider the use of a medication. There are a number of drugs that we can try with you. There is no consensus on which drug works best. Many centres will attempt to tailor the drug choices based on the unique features of each patient


There are also a number of medications which you should not be taking, because they may actually be contributing to your dizziness. Your doctor would need to evaluate the risks and benefits of these drugs in the event that you have been needing them in the management of other medical conditions. In some cases, you may need to decide whether or not you are overall better on the drug or off of it.

It is helpful for your doctor, if you can create a diary of blood pressure and heart rate readings to show him/her at your visits. Do this in the morning [when readings are likely to be the lowest]. Take readings while laying down for 5minutes and again after standing up for 5 minutes and as tolerated. If symptoms are bad after meals, then check your measurements before and after your meals.


Your doctor may also periodically wish to check your urine sodium level provided that you arent taking a diuretic, as well as monitor you for possible side effects from the different drugs that may be tried.


Rarely, a pacemaker may be necessary for those patients who experience a significant heart rate drop as a cause of recurrent 'passing out episodes'.



2015 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Treatment of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia, and Vasovagal Syncope. Sheldon, Robert S. et al.. Heart Rhythm , Volume 12 , Issue 6 , e41 - e63

2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.

Acute volume loading and exercise capacity in postural tachycardia syndrome, Journal of Applied Physiology Published 15 September 2014 Vol. 117 no. 6, 663-668 DOI: 10.1152/ japplphysiol.00367.2014.

Short-term exercise training improves the cardiovascular response to exercise in the postural orthostatic tachycardia syndrome. Shibata, S., Fu, Q., Bivens, T. B., Hastings, J. L., Wang, W. and Levine, B. D. (2012), The Journal of Physiology, 590: 3495–3505. doi:10.1113/jphysiol.2012.233858

Exercise Training Versus Propranolol in the Treatment of the Postural Orthostatic Tachycardia Syndrome

Exercise in the Postural Orthostatic Tachycardia Syndrome. Qi Fu and Benjamin D. LevineAuton Neurosci. 2015 Mar; 188: 86–89.

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