Posted by: barn owl | May 15, 2008

Anatomy Week: Stupid Yogi Tricks, the Valsalva Maneuver, and Hypoxia

ResearchBlogging.org
Health care professionals working with a variety of patients have reported beneficial effects from yoga and meditation practice. For example, an integrated yoga program was found to reduce anxiety, perceived stress, depression, and even DNA damage levels, in patients undergoing radiotherapy for breast cancer (Banerjee et al., 2007). Similarly, Kjellgren and colleagues (2007) found that a relaxation program of yoga and yogic breathing exercises reduced stress and increased the feeling of wellness in healthy volunteers.

However, there are some seriously weird “purification” and “seal” routines described in various yoga texts, summarized in The Yoga Tradition by the scholar Georg Feuerstein, which essentially amount to stupid human tricks. According to the sage Gheranda, there are six classes of purification practices, including swallowing the breath and expelling it through the anus, completely filling the stomach with water, prolapsing the intestines and washing them, cleansing the throat with a plantain stalk, inserting a thread into one nostril and passing it through the mouth, and staring at a small object until tears flow. The “seals and locks” comprise the third limb of Hatha-Yoga, and include such anatomically interesting exercises as the “thunderbolt seal”, which involves raising oneself off the ground while winding the legs around the neck, and the “elephant seal”, performed by standing neck-deep in water, inhaling water through the nose, and expelling it through the mouth. Not surprisingly, emergency medicine physicians have reported on the consequences of such yogic anatomical folly: one case, in Pune, involved a 40-year-old yoga practitioner who managed to introduce air into his retropharyngeal and parapharyngeal spaces, as well as into the mediastinum of his chest. He presented in the ER with respiratory distress and swelling of the face and neck, induced by overenthusiastic practice of yogic pranayama, or breath control exercises (Kashyap 2006).

chakras

Yogic chakras (from Yoga.net.au)

The retropharyngeal dissection is one of my favorite in gross anatomy, and it involves disarticulating the head of the cadaver from the first cervical vertebra (the atlas), and separating the back wall of the pharynx from the prevertebral muscles and fascia by opening the retropharyngeal space with your fingers. In a healthy person, the retropharyngeal space should only contain a very thin layer of fluid and gossamer connective tissue between fascia, but it can be a site of infection, or of tumor growth. The patient described above introduced air into this space, pathologically, by performing a vigorous Valsalva maneuver, which is essentially a forced expiration of air against a closed glottis, nose, and mouth. The Valsalva maneuver, named after a 17th century Italian physician, was used therapeutically in that time to expel fluid or foreign objects from the middle ear. In modern times, it has been used to evaluate cardiac autonomic function, as it causes alternating increases and decreases in heart rate, as well as reductions and elevations in arterial pressure (Junquiera, 2007). In pranayama, the Valsalva maneuver can be achieved through the “sun-piercing retention”, which involves inhalation through the right nostril, exhalation through the left nostril, and breath retention with the jalandhara-bandha (throat lock) in-between.

valsalva

Changes in arterial pressure and in heart rate, during a Valsalva maneuver (from Junquiera, 2007)

However, yogic breathing practices, which involve more engagement of the diaphragm and muscles of the thorax, can be beneficial in some circumstances, such as adaptation to high altitude conditions. A recent paper by Bernardi et al. compares the physiological responses to high altitude hypoxic (low oxygen) conditions in four groups of human subjects: control Caucasian subjects (n=12), Caucasian yoga practitioners (n=12), Nepalese native Sherpas, with an active lifestyle (n=38), Nepalese Buddhist monks, all yoga practitioners (n=13). For the Caucasian subjects, measurements were obtained at baseline (in Kathmandu, 1300 m elevation), and after two weeks adaptation to the high altitude conditions at Pyramid Laboratory (Khumbu Valley, 5050 m); the Nepalese native subjects all lived permanently at 3800-4200 m, and were studied at the Pyramid Laboratory. A rebreathing apparatus was used to measure the ventilation responses, including oxygen saturation, ventilation (VE; liters per minute), breathing rate, hypoxic ventilatory response (HVR), and ventilatory efficiency (the ratio of oxygen saturation to VE). Hemoglobin concentration, hematocrit, and red and white blood cell counts were also determined.

At 5050 m, Caucasian yoga practitioners exhibited a slight increase in ventilation, and no change in breathing rate, yet maintained oxygen saturation (high ratio of oxygen saturation/VE); in contrast, VE and breathing rate increased markedly in control subjects at the high altitude. The hematological parameters-hemoglobin, red blood cell count, albumin concentration-increased more markedly in controls than in yoga practitioners. At high altitude, Caucasian yoga trainees had ventilatory efficiency comparable to that of the native Sherpas and Buddhist monks, and the monks displayed lower HVR and decreased hematological responses to the hypobaric hypoxia than did the Sherpas. In other words, the cardiorespiratory control achieved by the practice of yogic breathing allowed highly efficient ventilation, and adaptation to acute hypoxia at high altitude. Bernardi and colleagues suggest that patients with chronic heart failure may benefit from training in yogic breathing, to increase ventilation during mild exercise.

References:

Banerjee, B., Vadiraj, H.S., Ram, A., et al. (2007) Effects of an integrated yoga program in modulating psychological stress and radiation-induced genotoxic stress in breast cancer patients undergoing radiotherapy. Integr. Cancer Ther. 6, 242-250.

Junquiera, L.F. (2007) Teaching cardiac autonomic function dynamics employing the Valsalva (Valsalva-Weber) maneuver. Adv. Physiol. Educ. 32, 100-126.

Kashyap, A.S., Anand, K.P., and Kashyap, S. (2006) Complications of yoga. Emergency Medicine J. 24, 231.

Kjellgren, A., Bood, S.A., Axelsson, K., Norlander, T., and Saatcioglu, F. (2007) Wellness through a comprehensive yogic breathing program – a controlled pilot trial. BMC Complementary Altern. Med. 7, 43.

Bernardi, L., Passino, C., Spadacini, G., Bonfichi, M., Arcaini, L., Malcovati, L., Bandinelli, G., Schneider, A., Keyl, C., Feil, P., Greene, R.E., Bernasconi, C. (2007). Reduced hypoxic ventilatory response with preserved blood oxygenation in yoga trainees and Himalayan Buddhist monks at altitude: evidence of a different adaptive strategy?. European Journal of Applied Physiology, 99(5), 511-518. DOI: 10.1007/s00421-006-0373-8

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