Sunday, August 28, 2011

Bahya and Shitali: Control of the Autonomic Nervous System Through Breath

 George Gets Lost
     Prescribing pharmaceuticals to elderly clients requires an entirely different set of considerations for a physician. Often times, a physician has to make decisions as to which symptoms are the lesser of two, or perhaps more, evils. Hypertension provides us with a great example. Let's say George is an 80 year old patient who presents with a blood pressure of 141/95. After ruling out other possible causes the physician diagnoses George with primary hypertension (high blood pressure). This is not good. Because of George's advanced age, his blood vessels are less elastic. He's at increased risk of stroke because under that pressure the vessels in his brain could burst very easily. Hypertensive retinopathy may cause him to go blind, and hypertensive nephropathy may destroy his kidneys to the extent that he requires dialysis. So the physician prescribes a drug to lower his blood pressure. Maybe it's an ACE inhibitor or perhaps it's ARB. Doesn't matter much; the point is, his blood pressure goes down to a more acceptable 125/85. Unfortunately, George suddenly starts forgetting where he is and what he was doing. He loses the ability to pay attention for more than a short period of time. The decreased blood pressure in an elderly client often results in a decrease of cognitive ability, and so the choice is whether you prefer to think clearly, or be able to see and live without a machine to clean your blood a few times a week. It's not a pleasant circumstance to think about, but this does demonstrate the impact of blood pressure on cognition. That impact is not on the elderly alone either. Hypertension affects over 1/3 of the population worldwide. A 2004 study regarding high blood pressure related decline, performed at the University of Maine, demonstrated that adults young and old, both suffer from a significant decrease in visualization-fluid abilities. Hypotension (low blood pressure), while not as common as hypertension is still a highly prevalent condition, suffered by up to 16% of some age groups. Hypotension results in a decrease of cognitive ability particularly in the domains of attention and memory, such as in the case of our friend George above. Now let's flip this knowledge on its head. If a decrease in blood pressure results in an decrease in a particular cognitive ability, will an increase in blood pressure result in an increase in that ability? And those abilities decreased by an increased blood pressure... will they be increased by a decrease in blood pressure? I'm going to give a very tentative and conditional yes, which I'll explain further in the article. Assuming this to be the case, the ability to consciously adjust ones blood pressure would provide us with a means to boost particular cognitive functions at will. While playing chess or perhaps even driving at rapid speeds to elude law enforcement, one could intentionally decrease blood pressure in order to increase visualization-fluid abilities. While studying for a class or trying to remember everyone’s name at a party, one could willfully augment their attentiveness and short-term memory by a willful blood pressure spike. This begs the question, is it possible to control aspects of the autonomic nervous system like blood pressure at will? The answer is an emphatic yes, which certainly make conscious control of blood pressure an augment worth exploring. 
 Sri Swami Ram Shows Off

Sri Swami Ram was the first yogi to demonstrate under laboratory conditions his ability to voluntarily control autonomic processes such as his blood pressure, heart rate, and temperature. Scientists had long thought such control to be an impossibility akin to levitation. Swami Ram however demonstrated with 100% repeatability that such a feat is possible. This same remarkable control has been demonstrated countless times by other Yogis and now is accepted as fact. There are many paths to this control. A very promising path is that of biofeedback. Biofeedback is currently being used as a means to teach people to control their internal environment in a diverse number of ways. It has been shown to be efficacious in the treatment of everything from Diabetes Mellitus to urinary incontinence. This technology provides a great leap in terms of human augmentation and is something I will certainly address in a future blog. A much older and immediate method to learn control of one's autonomic system is through conscious control of breathing. In order to understand exactly how powerful controlled breathing is in influencing the autonomic nervous system in general, and blood pressure specifically, a little knowledge of anatomy and physiology is required. 
 A PNS That Branches

There are many factors that influence blood pressure and it's controlled by multiple systems. Many of the factors we can simply ignore. For example, both fluid volume and blood viscosity have a major impact on blood pressure. Sure, remaining hydrated is important but does nothing for us in terms of precise quick changes. Another powerful mechanism for blood pressure control is the renin-agiotensin system. It's a hormonal system that impacts both the diameter of blood vessels and controls fluid and electrolyte volumes. Yes, breathing impacts this system; however, as an endocrine component of control it's much slower. We want to be able to control our blood pressure now, not tomorrow. The mechanism that will be focused on is the Autonomic Nervous System.

The nervous system is categorized into two major divisions, the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS consists of the brain and spinal cord. The PNS is everything else. The PNS is further divided into the Somatic Nervous System and the Autonomic Nervous System (ANS). The SNS is the means by which we control our skeletal muscles and receive sensory input of which we are conscious. The ANS is how we involuntarily control such factors as blood pressure, heart rate, and the like primarily through modulation and control of smooth muscle and cardiac muscle. The ANS has a sensory branch which receives visceral input, and two motor branches, the Sympathetic Nervous System, also called the "Fight or Flight" system, and the Parasympathetic Nervous System, or the "Feed and Breed" system. Ok, I know that I've thrown a lot of jargon, but if one looks at a mind map of these things, it's pretty easy to understand.
The ANS gets even more confusing once we start taking into account different receptor types. One can't simply generalize that a sympathetic effect is always stimulatory and the parasympathetic is inhibitory. Some parts of the body are stimulated, but others instead relax. The muscles that control the pupils of the eye for example actually relax in response to sympathetic stimulation. As the wolf would say, "the better to see you with." Blood vessels which lead to skeletal muscles also dilate, providing better blood perfusion to run down prey; "The better to eat you with." The overall effect of the sympathetic nervous system though does result in an increase in total blood vessel resistance through vasoconstriction and an increase in heart rate, which leads to higher blood pressure. The overall systemic effect of the parasympathetic nervous system is to lower total vascular resistance through vasodilation, and to decrease heart rate, leading to a decrease in blood pressure. 
 The Diaphragm that Controls More than Conception

There is one exceptional muscle that deserves our attention now. This is the skeletal muscle known as the diaphragm. The diaphragm is a thin sheet of skeletal muscle which separates the thoracic cavity from the abdominal cavity. This muscle is what drives breathing. When the diaphragm contracts, it moves downward. This causes the volume in the chest to increase, decreasing the pressure in the lungs, and causing air to move inward. When we breathe out, it's because the diaphragm relaxes and the volume of the chest decreases. The most interesting aspect of the diaphragm is the way it's controlled. Under most circumstances, the diaphragm, and thus breathing is controlled autonomically. It's innervated via the phrenic nerve, which receives input from a few regions we'll explore in a moment. Unlike other autonomic processes however, the diaphragm also has elements of somatic control. We can decide to hyperventilate or hold our breaths, and because breathing has such a huge impact on the internal conditions of our bodies it provides us with the means we need to adjust the blood pressure at will. 
Baroreceptors and the Eight Limbs of Yoga

Let's take a look now at how the autonomic nervous system controls blood pressure. A great place to start is at the baroreceptors. Barorecptors are specialized neurons which are sensitive to changes in pressure. There is a baroreceptor of interest located in the Carotid artery which provides physicians with a simple method to drop a patients heart rate and blood pressure. Applying pressure to the carotid artery stimulates the baroreceptors. These baroreceptors communicate the increased pressure to the brain stem. The brain stem then inhibits the Sympathetic Nervous System causing a decrease in blood pressure and a decrease in heart rate. This is sometimes used successfully in emergency situations when a person has a dysrythmia such as tachycardia, but it's not terribly dependable. Lowering pressure to a baroreceptor results in exactly the opposite effect. If the carotid baroreceptor reports that pressure is lower than normal, it communicates this finding to the brainstem resulting in a disinhibition of the sympathetic nervous system. The sympathetic nervous system stimulates the heart rate to increase and for peripheral vessels to constrict, resulting in an increase in blood pressure.

The baroreceptor that we really need to focus on is the Aortic Baroreceptor. It's right on the aorta, close to where it emerges from the heart. It's inside the thoracic cavity with the lungs, so instead of having to rub our necks, we can influence the aortic baroreceptor through breathing alone. This brings us right back to the teachings of Yoga. The seminal text of yogic teachings is the Yoga Sutras of Patanjali. which date back the 2nd century BCE. I'll explore some of the other eight limbs taught in this work in other blogs, but the pertinent limb for this augment is the fourth limb: Pranayama. Pranayama teaches a plethora of breathing patterns purported to result in an increased lifespan and enhancement in our ability to perceive, as well as a steady mind with strong will power. According to Swami Chidananda Saraswati:

"Prana is a subtle invisible force. It is the life-force that pervades the body. It is the factor that connects the body and the mind, because it is connected on one side with the body and on the other side with the mind. It is the connecting link between the body and the mind. The body and the mind have no direct connection. They are connected through Prana only."

While I'll likely never have the opportunity to argue with the good Swami regarding this, it's interesting to note the parrallel between his statement, and our understanding of human physiology. There is no connection between the voluntary control systems and the involuntary control systems of the body, except for that which controls breathing. They are connected through the diaphragm alone. Well... mostly.
Let's take a quick look at lung volumes in order to have a clear understanding of how to perform the two pranayamas we are going to discuss. The normal breathing that people do every day is the tidal volume. This tidal volume is the amount of air exhaled from the top of a normal breath down to the bottom of a normal breath. The inspiratory reserve volume is the amount of air exhaled from the maximum amount of air you can inhale, down to the top of a normal breath. The expiratory reserve is the amount of air one can forcefully exhale from the bottom of a normal exhale. Once again, lots of jargon for something pretty simple. The picture should explain everything you need to know.

Bahya Pranayama

The first pranayama provides us with the ability to increase our blood pressure at will. It's called Bahya Pranayam. This is how Bahya is performed:

1. Practitioner begins with a full breath all the way up to the top of the inspiratory reserve volume. Lungs are completely full. Do not pause or hold the breath here.

2. All air is completely exhaled with the assistance of the abdominal muscles being pulled back towards the spine and upward towards the thoracic cage. This brings one to the very bottom of the expiratory reserve volume.

3. The air is held out for a count of 8-16 seconds. 

4. A controlled inhale fills the lungs all the way back to the top of the inspiratory reserve and then the exhale and holding is immediately repeated.  

A few important notes here about Bahya. If you already have high blood pressure, then never ever do this. In fact, you want to be cautious if you have any ailments as a person with an average blood pressure can expect systolic pressures as high as 240 mmhg. This breath is no joke. Women can miscarry, and those with high blood pressure may burst a vessel in their heads. For those healthy enough to practice Bahya Pranayam regularly though, there are some really powerful benefits. Research has indicated that it has long term benefits in increasing blood perfusion to abdominal organs.
This increased blood flow has been shown effective as a treatment for such ailments as diabetes, impotence, and constipation. More importantly, as discussed above, the temporary increase in blood pressure results in an increased ability for attentiveness and short-term memory formation. This breathing pattern provides one with a temporary augment in these skills. So the next time your studying or trying to remember names at a cocktail party, it might behoove you to step away for a few moments in order to practice a few rounds of Bahya Pranayam.
The way Bahya influences the body should be pretty simple to understand after the physiology overview above. When we exhale out all of our air and then pull the abdomen back, we create a strong negative pressure in the thorax. This negative pressure is detected by the baroreceptor located on the aortic arch. The baroreceptor then signals the brainstem to disinhibit the sympathetic nervous system. This sympathetic activation results in an increase in heart rate and an increase in overall vasoconstriction. The blood pressure is significantly increased. This pattern is effective in as little as 3 rounds, and should not be practiced for more than a total of 12. Because Bahya effects the sympathetic nervous system, it's a stimulatory breath that some find more effective than even a mug of joe.
Shitali Pranayama
If one is seeking the opposite effect, a decrease in blood pressure, the appropriate breathing pattern is called Shitali Pranayama. This is how Shitali is performed: 
1. Practitioner begins with a normal exhale to the bottom of tidal volume.

2. The tongue is curled curled into the shape of a tube.

3. Practitioner inhales slowly and steadily through the tube formed by the tongue until reaching the top of the inspiratory reserve volume. 

4. Breath is then held for 8-12 second.

5. Exhale is slow and steady to the bottom of the tidal volume and breath is repeated.

The video here isn't the greatest. Notice that she immediately exhales, which eliminates much of the patterns visceral effect. If you want to drop your blood pressure, make sure to hold your breath at the top. Shitali is much safer than Bahya. It can be performed safely by pretty much anyone, except for those suffering from low blood pressure. In fact, research has indicated that this is a pretty efficacious means for a person with hypertension to treat their disorder. This pattern also has a significant effect on body temperature. If one performs 9 rounds of Shitali, they can expect a decrease in heart rate, a drop in systolic blood pressure of around 20 to 30 mmhg, and a recordable drop in temperature. This breath pattern also has a tendency to calm, and as such may assist those who have difficulty sleeping.
Shitali influences the body in two ways. During inhalation, the tongue provides resistance. This resistance is not significant enough to trigger the baroreceptor however. Instead, the negative pressure functions to more fully inflate the alveoli of the lungs and thus assists in gas exchange, and provides a person with the ability to inhale more air than without the resistance. The holding of the breath at the top of the inspiratory reserve is what provides the autonomic effect. The expanded lungs create a strong positive pressure. This pressure is detected by the aortic barorecpetor, which reports high pressure to the brainstem. The brainstem then inhibits the sympathetic nervous system, resulting in a decrease in heart rate, and an increase in overall vasodilation. Thus, the blood pressure falls. This pattern of breathing should be effective in as little as 6 breaths, but can be practiced for as long as 5 minutes.
Further Resources
In writing this, I'm really focusing on how these techniques work. Because of the limited scope of this blog, there are some fine points that I'm not addressing and if after trying out the two basic techniques you find you'd like to learn more I advise investing in a few videos by Sri Swami Ram dev. He's a pretty famous guy in India. When I first watched his videos, my response was, "bullshit." He makes some pretty fantastic claims as to what pranayama can do. In fact, at one point his videos almost got pulled from being sold in America due to claims that certain Pranayamas can raise the CD-4 count in Aids patients. Amazingly, these claims have been confirmed through research, as have many of his other claims. What isn't debatable is that through pranayama and other yogic practices, people have found methods to control their Autonomic Nervous System. These methods are certainly augments worthy of consideration.

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