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Blood Pressure (Low)

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Blood Pressure (Low)
Summary
  • Low Blood Pressure, also known as Hypotension, occurs when blood pressure is weak and oxygen and nutrients carried by the blood cannot reach the body's tissues.
  • Symptoms of Low Blood Pressure include fainting, dizziness, "blackouts" or confusion.
  • Blood tests may be taken to check your general health and nutritional status.
Description

Low Blood Pressure, also known as Hypotension, occurs when blood pressure is weak and oxygen and nutrients carried by the blood cannot reach the body's tissues.

Blood Pressure is the pressure exerted by the blood on the surrounding arteries. The heart contracts regularly to pump blood throughout the body. A blood pressure reading consists of the systolic reading and the diastolic reading. The systolic reading measures the blood pressure when the heart contracts. The diastolic reading measures blood pressure when the heart relaxes between beats. The systolic number is higher and is always shown on top. For example; 120 (systolic) over 80 (diastolic) or 120/80.

Normal Blood Pressure is considered to be roughly 100-140 systolic and 60-80 diastolic. However, since Blood Pressure readings change in each person throughout the day, there is no one figure that is perfect. What is normal for one person may be too low for another. It is important to remember that people with Hypertension (high blood pressure) may still have periods of Low Blood Pressure, especially if medications have recently been changed. Generally, a Blood Pressure reading of less than 100/60 requires further investigation.


Cause

Symptoms of Low Blood Pressure include fainting, dizziness, "blackouts" or confusion. Low Blood Pressure is not a disease in itself, but is a symptom of an underlying problem. Always consult your Doctor, as many conditions may have similar symptoms. There are many causes of Low Blood Pressure.

  1. Orthostatic or Postural Hypotension. When a person who is lying or sitting down suddenly stands up, the change in gravity causes blood to flow away from the brain, and blood pressure drops. This problem is more common in the elderly and often occurs first thing in the morning. It may be caused by the body becoming deficient in sodium (salt) overnight.1
  2. Postprandial (after eating) Hypotension2. Low Blood Pressure after a meal is also common in the elderly. It is thought to be related to a sudden rush of glucose, as high carbohydrate meals are often to blame.3
  3. Hypovolaemia. Hypovolaemia means the volume of blood and body fluids in the circulation is too low. This may be the result of blood loss, dehydration, severe vomiting or diarrhoea, diuretic medications, kidney dialysis4 or diabetes.5 Any kind of heart disease can cause Hypovolaemia by affecting the heart's ability to pump.
  4. Post Exercise Hypotension. Moderately intensive exercise causes a temporary drop in blood pressure, because the veins dilate and become less resistant. These changes are more severe in people who suffer Hypertension (high blood pressure).6
  5. Other causes. These may include high blood pressure medications, 7Parkinson's disease,8 anaemia, alcohol,9 pregnancy or poor diet.


Prevention

The following tips can help reduce the symptoms of Low Blood Pressure.10 Always consult your Doctor to identify and treat the underlying cause.

  • When rising, move from a lying to a sitting position. Breathe deeply and wiggle the legs and feet to improve circulation. Wait a few moments before standing.
  • Drink at least 8 glasses of water or fluids per day.
  • Check your medications with your Pharmacist to make sure they are not the cause.
  • Increase your salt intake IF your Doctor has agreed to this.
  • Drink a caffeinated beverage (tea or coffee) with meals IF your Doctor agrees.
  • Reduce or eliminate alcohol altogether, especially if you take medications for high blood pressure.
  • Elevate the head of your bed a few inches or sleep on several pillows to reduce the effect of gravity.
  • To avoid postprandial (after eating) hypotension, eat smaller, more frequent meals and rest after eating. Reduce the amount of carbohydrates in the meal.
  • Use support stockings, which help return blood to the upper body.
  • Management

    As with all conditions your Doctor should be consulted to diagnose and treat this condition. Ask your Doctor about the latest advice on this ailment. Your Doctor will check your blood pressure using a blood pressure monitor, first while you are lying down, then while you are standing. Blood tests may be taken to check your general health and nutritional status. Medication may be required.


    Lifestyle

    Diet Hints
    1. Reducing carbohydrates may help prevent postprandial (after eating) Hypotension.11 Limit the intake of bread, potatoes, pasta and rice.
    2. Caffeine drinks (tea or coffee) with meals may help prevent postprandial (after eating) hypotension, by constricting the arteries and raising blood pressure.12 Consult your Doctor before increasing caffeine intake as this may be unhealthy for some people.
    3. Increasing sodium (salt) intake may help prevent postural Hypotension.13 Consult your Doctor before increasing salt intake, as this may be unhealthy for some people.
    4. Alcohol tends to increase the severity of low blood pressure, even at moderate levels.14 People with Low Blood Pressure should avoid alcohol.
    5. Drink at least 8 glasses of fluid per day (not counting caffeinated drinks). High fluid intake can increase blood volume and help prevent Low Blood Pressure.


    Vitamins/Minerals/Herbs

    Nutritional supplements may only be beneficial if the dietary vitamin intake is inadequate. Consult your Doctor before commencing supplements, as some may have interactions with other medications.

    • Vitamin B12 deficiency has been associated with Low Blood Pressure.15
    • Butcher's broom (Ruscus aculeatus) may help prevent Low Blood Pressure by constricting the veins and improving blood flow back to the heart.16
    • Liquorice herb may help prevent low blood pressure.17
    • Guar gum can slow down glucose absorption and reduce the incidence of postprandial (after eating) Hypotension.18
  • Pharmacist's Advice

    1. Follow the Diet Hints.
    2. Many medications can cause Low Blood Pressure. Check with your Pharmacist.
    3. Exercise can cause a drop in Blood Pressure. Always consult your Doctor before starting an exercise programme. Start slowly and gradually build up intensity over weeks.
    4. Raise the head of the bed a few inches or sleep on several pillows, to reduce the effect of gravity on blood pressure.
    5. Support stockings will help blood return to the heart, especially if you spend a lot of time standing. Your Pharmacist can recommend a brand.
    6. Alcohol should be avoided as it tends to increase the severity of low blood pressure, especially when combined with anti-hypertensive medications.
    7. Salt tablets may be beneficial for some people. Check with your Pharmacist.
  • Notes

    Organisations & Support Groups

    Heart Foundation of Australia - http://www.heartfoundation.com.au/


    References

    1. Pechere-Bertschi A et al. Circadian variations of renal sodium handling in patients with orthostatic hypotension. Kidney Int 1998 Oct;54(4):1276-82.
    2. Jones KL et al. Guar gum reduces postprandial hypotension in older people. J Am Geriatr Soc 2001 Feb;49(2):162-7.
    3. Macdonald IA. Carbohydrate as a nutrient in adults: range of acceptable intakes. Eur J Clin Nutr 1999 Apr;53 Suppl 1:S101-6.
    4. Daugirdas JT. Pathophysiology of dialysis hypotension: an update. Am J Kidney Dis 2001 Oct;38(4 Suppl 4):S11-7.
    5. Beers M et al (eds). The Merck manual of diagnosis and therapy (17th ed). New Jersey: Merck Research laboratories; 1999.
    6. Halliwill JR. Mechanisms and clinical implications of post-exercise hypotension in humans. Exerc Sport Sci Rev 2001 Apr;29(2):65-70.
    7. Meredith PA. Is postural hypotension a real problem with antihypertensive medication? Cardiology 2001 Sep;96 Suppl 1:19-24.
    8. Senard JM et al. Orthostatic hypotension in patients with Parkinson's disease: pathophysiology and management. Drugs Ageing 2001;18(7):495-505.
    9. Kawano Y et al. Effects of propranolol on cardiovascular and neurohumoral actions of alcohol in hypertensive patients. Blood Press 1999;8(1):37-42.
    10. Web MD Health. Hypotension. Accessed December 13, 2001. At URL http://my.webmd.com/content/article/3608.772
    11. Macdonald IA. Carbohydrate as a nutrient in adults: range of acceptable intakes. Eur J Clin Nutr 1999 Apr;53 Suppl 1:S101-6.
    12. Rakic V et al. Effect of coffee and tea drinking on postprandial hypotension in older men and women. Clin Exp Pharmacol Physiol 1996 Jun-Jul;23(6-7):559-63.
    13. Pechere-Bertschi A et al. Circadian variations of renal sodium handling in patients with orthostatic hypotension. Kidney Int 1998 Oct;54(4):1276-82.
    14. Narkiewicz K et al. Alcohol potentiates orthostatic hypotension : implications for alcohol-related syncope. Circulation 2000 Feb 1;101(4):398-402.
    15. Girard P et al. Orthostatic hypotension revealing vitamin B12 deficiency. [Article in French] Rev Neurol (Paris) 1998 May;154(4):342-4.
    16. Redman DA. Ruscus aculeatus (butcher's broom) as a potential treatment for orthostatic hypotension, with a case report. J Altern Complement Med. 2000 Dec;6(6):539-49.
    17. Basso A. Liquorice ameliorates postural hypotension caused by diabetic autonomic neuropathy. Diabetes Care. 1994 Nov;17(11):1356.
    18. Jones KL et al. Guar gum reduces postprandial hypotension in older people. J Am Geriatr Soc 2001 Feb;49(2):162-7.
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