BLOOD PRESSURE & BIOFEEDBACK

  • BP is officially defined as: “the force exerted on blood vessels as a result of the heart working.”
  • Think of your blood vessels as tubing. Blood needs to move around this tubing to get to its destination. When it does so, it exerts some pressure on the tubes.
  • Naturally, your blood pressure (and thus, blood flow) works best without any blockage in the blood vessels or damage to the arterial walls
  • It is a dynamic process: blood pressure changes throughout the day. That is, with certain exercises and stressful situations, the blood pressure can increase temporarily in even the average non-hypertensive person.
  • BP is normally higher in the day (~20%) then it is in the night, known as “night time dipping”.
  • There are 2 measurements involved in BP: systole and diastole
    • Systole is a measure of the pressure in the cardiovascular system (tubing) when the heart contracts.
    • Diastole is a measure of the pressure in the cardiovascular system when the heart relaxes.
  • BP is a written as systole/diastole, e.g., 115/70.
  • The average BP is what we really care about, the mean arterial pressure (MAP). If your MAP is too high on average, that would be a problem. We don’t work directly with calculations of MAP on a daily basis in clinical practice, but it is an important concept to keep in mind.
  • It is the Cardiac Output [CO] x Total Peripheral Resistance [TPR]
  • TPR measures how much resistance your blood sees when it courses through your vascular system (i.e., the pressure the blood exerts on the walls of the tubing). It is influenced by your sympathetic nervous system, the presence of certain molecules in the body, and factors that have to do with the way your blood vessels are.
  • CO = the amount of blood your heart pumps out in a minute. in other words, it is the (heart rate [HR]) x {the volume blood pumped out by each heart contraction, aka the stroke volume [SV].
  • HR and SV are also influenced by the autonomic nervous system.
  • MAP = HR x SV x TPR
  • BP is regulated by the neurological (neural), endocrine (hormonal) and renal (kidney) systems. It is a complex interplay between these symptoms that determines one’s blood pressure. (Guyton and Hall, 2006)
  • The autonomic nervous system regulates the second-to-second MAP via a mechanism known as the baroreceptor system. (Ganong, 2005)
  • The kidneys and endocrine systems will regulate long-term regulation.
  • You may remember the inflatable cuff! Blood pressure is measured by a sphygmomanometer, the term used to describe an inflatable cuff.
  • These can be automatic or manual.
  • Certain procedures have to be followed to ensure that we are getting an accurate representation of your BP at that moment of time.
  • Sometimes your BP at that moment in time is not a true reflection of your MAP over the course of a day.
  • When a doctor suspects that your BP is ONLY high in the office but may be normal outside the office, that is, she suspects “white coat hypertension”, she may ask for you to:
  • Keep a BP journal and measure it on your own at home using an BP cuff approved by the Canadian Hypertensive Society
  • Come frequently to the office to have your BP checked to see if the pattern persists
  • Request a 24 hour blood pressure monitor, that is, a device you wear for 24 hours while you go about your day as usual.  It inflates and deflates on it’s own every 15 minutes and logs your BP readings.
  • There are 2 broad categories: Primary/Essential & Secondary
    • Primary or Essential
      • which basically means we can’t be very specific as to why you have elevated BP.
      • This is because the control of BP is complicated (as mentioned above) and many things can increase your BP. Behavioural, psychological and physical factors all weigh in on claiming part that BP number you see when you go to the doctor’s office. Which mechanism is contributing how much to your overall BP is hard to say.
      • Central to the development of essential hypertension is autonomic imbalance (i.e., sympathetic overactivity and underactivity of the parasympathetic nervous system; (Brook & Julius, 2000)
    • Secondary
      • common secondary causes include sleep apnea, kidney disease, certain medications and hormonal issues.
      • That is, hypertension is secondary to those primary diseases.
Hypertension affects 7.5 million Canadians, and is among the leading causes of death and disability worldwide (www.hypertension.ca)
  • Hypertension is a major risk factor for atherosclerosis (or plugging of the arteries with biological debris)
  • Your organs depend on blood flow to sustain their function; if this is compromised, their function is compromised. That is, wherever your blood vessels go, so do the potential consequences of hypertension.
  • Common consequences that have been linked to hypertension are coronary artery disease, heart failure, stroke, kidney failure and many more.
None of the following can be said to cause hypertension, just that if you have any of these, your risk of having hypertension is higher (NHANES 3):
    • Increasing age
    • Obesity
    • Other medical problems, e.g., type 2 diabetes and high cholesterol
    • Alcohol intake beyond the “safe drinking guidelines”
    • high salt diet
    • Inactivity
    • Quit smoking
    • African-American ancestry
    • Family history of elevated BP
    • Psychological factors
      • Exposure to harsh conditions during childhood (Lehman, Kiefe, Taylor, Seeman, 2009)
      • Chronic sense of time urgency and hostility (CARDIA, Yan et al., 2003)
      • The mechanism by which stress affects BP is uncertain but because of the discussion above, autonomic function, as indexed by Heart Rate Variability (HRV) has received a lot of attention (Hughes & Stoney, 2000)
    • Regular Exercise: 30-60 minutes of moderate intensity dynamic exercise (e.g., walking, jogging, cycling, or swimming) 4-7 days per week in addition to the routine activities of daily living. Note: vacuuming does not count as part of those 30-60 minutes. Higher intensities of exercise are not more effective for BP prevention/improvement. When you exercise, your muscles need more blood so the blood vessels going to them dilate. This lowers the TPR and, in turn, the BP.
    • Salt reduction: ~ 30% of patients have hypertension that goes up and down in accordance with their salt intake; the more salt they eat, the more their BP goes up, and vice versa. By reducing salt intake to less than 2000 mg of sodium/day, MAP decreases by greater than 10mmHg and cardiovascular events by 25%. (Chobanian & Hill, 2000)
    • DASH diet: this is a dietary scheme that in general sees people eating more fruits and vegetables and low in fat. In and of itself, it reduces BP and its consequences. (Levitan, Wok, Mittleman, 2009)
    • Maintain a healthy body weight: BMI of 18.5 to 24.9 kg/m2, and waist circumference <102 cm for men and <88 cm for women is recommended
    • Maintain alcohol consumption within the “Safe Drinking Guidelines”: ≤2 drinks per day and consumption should not exceed 14 standard drinks per week for men and 9 standard drinks per week for women.
      • Note: One standard drink is considered to be equivalent of 13.6 g or 17.2 mL of ethanol or approximately 44 mL [1.5 oz] of 80 proof [40%] spirits, 355 mL [12 oz] of 5% beer, or 148 mL [5 oz] of 12% wine.
    • Stress Management: This has been discussed in previous articles on mindfulness, CBT-i, Biofeedback, relaxation strategies, stress management, therapeutic activities, energy management, etc.
    • To put it succinctly:
      • Biofeedback: Improve the regulation of your autonomic nervous system by learning to hone relaxation strategies
        • Thermal Biofeedback has been shown to be effective in the treatment of HTN (Nakao et al., 2003; Linden & Mosley, 2006).
          • Thermal biofeedback involves learning to dilate your blood vessels to reduce the TPR (i.e., the tubes get wider so the fluid [blood] in the tubing exerts less pressure on the tube’s wall).
          • HRV training increases the sensitivity of your pressure sensor cells and helps restore the balance between the sympathetic and parasympathetic nervous system (Reyes del Paso et al., 2006; Lin et al., 2012)
        • As this is a skill that is being taught, people tend to get better with time. In fact, BP continues to improve even after active treatment (linden, 2006)
      • Cognitive Behavioural Therapy: this is a more involved process that is usually done by specialized psychologists. While effective, it can be time-consuming and costly. (Linden, 2006)
    • To elaborate further:
      • As mentioned earlier, many factors weigh in on that BP number you get in the doctor’s office: your behaviour (e.g., diet, exercise habits, etc.), your psychology (e.g., stress management skills) and your physical health (e.g., overweight, sleep apnea, etc.).
      • Because so many factors weigh in, their contributions to your BP get “all mixed together” and so it’s not possible to apportion, for example, 50% of the blame on psychological factors, 20% on physical and 30% on behavioural.
      • However, the epidemiological evidence for the link between stress and HTN is convincing: Over 100 randomized controlled trials show that behavioural therapy reduces BP to a modest degree and that the change is greater than what is seen in waiting-list or other inactive controls (Andrasik, Schwartz 2016). However, the definitive psychological pathway that would explain how stress can lead to HTN is still wanting. (Schwartz and Andraski, 2016; Linden 2005)
    • To answer this question, we have to look at our goal. What is our goal?
      • To decrease our risk of death and disease
    • What are the factors that lead to death and disease?
      • It is not just HTN. There are many other factors.
    • So does that mean that if people have other health problems that can lead to cardiovascular disease, they should have lower BP than those without these same health problems
      • Generally, yes. For example, a diabetic should have a lower BP than a non-diabetic. A diabetic that has kidney damage as seen by proteins spilling out in the urine should have a target lower BP than a diabetic without this problem.
    • I hear anything above 140/90 is hypertension. Is this true?
      • In a patient without any other risk factors, 140/90 is the most widely accepted threshold for HTN. But 130/80 and above is still not ideal and it’s better to stay lower than this.
    • We treat patients with biofeedback regularly to help achieve treatment goals in concussion rehabilitation. As biofeedback is just used to retrain aspects of the nervous system, this treatment is useful in the non-concussed population. In fact, many professional sports teams use this technology to enhance performance.
    • Because of our skill in training autonomic nervous system control using psychophysical techniques, we have started a Blood Pressure Biofeedback Program for any patient with HTN, not just those with concussions.
  • The consultation with the MD is funded by OHIP. The MD then relays the information to your GP who remains your principal care provider for HTN: monitoring and prescribing drugs if needed.
  • The rehabilitation sessions are covered by your extended health benefits for physiotherapy or chiropractic therapy.
Make a consultation request on our website by clicking here. Our office will then send you an intake questionnaire. Upon receiving your completed questionnaire, we will arrange for a consultation.
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Research & writing: Mojtaba Garshasb & Dr. Taher Chugh

Last update: February 2019