User:VanBuren/Misc

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Buteyko method

removed 02:28, 3 January 2011

Theory
Chronic Hyperventilation Syndrome has been discussed in the medical literature for most of the 20th century. In fact, DaCosta is thought to have been the first to describe some of the symptoms in 1871, following a bizarre symptoms complex (including chronic fatigue) he found in soldiers during the American Civil War. However, he did not associate these symptoms with over-breathing at that time. It was Goldman who discovered in 1922 that all of the symptoms, listed by DaCosta, were associated with involuntary hyperventilation.

In spite of the long history and many pages that have been written on the condition, chronic hyperventilation is rarely diagnosed by doctors. Chronic hyperventilation develops from any chronic stress on the body leading to a depletion of carbon dioxide (CO2) and bicarbonate (HCO3-). The respiratory center, situated in the brain stem, paces breathing in order to maintain pH according to the Henderson-Hasselbach equation:


 * $$\textrm{pH} = 6.1 - \log \left ( 0.03\frac{[\mbox{CO}_2]}{[\mbox{HCO}_3^{-}]}\right )$$

Hence, to maintain pH, the ratio of CO2 to bicarbonate in the cerebro-spinal fluid (CSF) needs to remain constant. Since the blood-brain barrier is extremely permeable to CO2, this is readily accomplished by regulation of breathing. If the body is stressed, breathing increases, CO2 is reduced and a state of alkalosis develops. If this stress is sustained, the kidneys compensate by dumping bicarbonate in order to reestablish normal pH in the blood. . However, the blood-brain barrier is only very slightly permeable to bicarbonate resulting in a very slow diffusion of bicarbonate from the CSF into the blood if the stress is sustained for a very long time (chronic stress). When the stress eventually dissipates, the CSF is left with a low bicarbonate concentration. To maintain pH the CO2 will also have to be kept low and a habituation to low CO2 will have taken place. The resulting low CO<SUB>2</SUB> and bicarbonate results in a profound derangement of normal body chemistry.

The late consultant chest physician Claude Lum, said that chronic hyperventilation “presents a collection of bizarre and often apparently unrelated symptoms which may affect any part of the body, and any organ or any system ... for we are dealing with a profound biochemical disturbance, which is as real as hypoglycemia, and more far-reaching in its effects.” From the Buteyko perspective, the inflammatory hyperresponsiveness and allergic hyper reactivity seen in asthma and bronchitis are the results of immune disturbances caused by chronic hyperventilation because of these biochemical derangements.

The second component of asthma, bronchospasm, is easier to understand from a teleological perspective. There is clearly a reason for the existence of the smooth muscle in the walls of the bronchioles. Their role is to optimize ventilation of the lungs so that over ventilated airways (low CO<SUB>2</SUB>) can be constricted and under ventilated airways can be dilated. Carbon dioxide is a known muscle relaxant. One of the well known symptoms in acute hyperventilation is carpopedal spasm, a condition in which the skeletal muscles of fingers and toes go into spasm. Smooth muscle in the walls of some arteries and bronchioles is affected too, by low carbon dioxide. The smooth muscle in the blood vessels going to the brain contract during hyperventilation eventually leading to fainting. Blood flow to the brain is reduced by 2% for every 1mm Hg reduction in arterial CO<SUB>2</SUB> tension.

The mechanism behind smooth muscle spasm is thought to be as follows: Carbon dioxide is involved in the transport of Calcium across the cell walls. During hyperventilation calcium is re-distributed through the tissues, depleting the extra-cellular fluid and accumulating inside the cells. Thus trapped, it is unable to participate in the process of relaxing the smooth muscle, which then remains in spasm. In people with a genetic predisposition to asthma, over breathing is known to cause bronchospasm. In fact, in asthmatics even a single deep breath of the kind taken for performing lung function tests, airway resistance is increased by 71% while arterial carbon dioxide tension is reduced by 7 to 16mmHg.

It follows that PEF and FEV1 lung function tests are not appropriate tests for testing asthmatics, because the testing procedure alters the quantity being measured.

There are many other effects of hyperventilation on the body. One of the most significant is poor oxygenation of the cells. Apart from constriction of blood vessels causing a reduction in blood flow, low CO<SUB>2</SUB> increases the affinity of hemoglobin for oxygen. This is known as the Bohr effect, and results in the hemoglobin not offloading its oxygen where it is needed, returning back to the lungs on a wasted trip. This is the cause of breathlessness and leads to more breathing, aggravating an already serious situation.

The Buteyko method is a simple educational program aimed at reversing chronic hyperventilation. In the same way as chronic stress leads to chronic hyperventilation, so too a deliberate reduction in breathing over a period of time reverses this process to restore CO<SUB>2</SUB> back to a normal level.