Yoga and chemoreflex sensitivity

CORRESPONDENCE

171 m altitude

Yoga trainees Controls

1

2600 m altitude

PaO2 (mm Hg)

PaCO2 (mm Hg)

PaO2 (mm Hg)

PaCO2 (mm Hg)

84·88 (5·0) 85·25 (3·4)

38·0 (1·51) 36·88 (1·81)

75·38 (4·03) 75·13 (3·14)

34·0 (1·41) 33·0 (1·2)

2

PaO2=partial pressure of oxygen; PaCO2=partial pressure of carbon dioxide.

Mean (SD) partial pressure of oxygen and carbon dioxide by altitude 3

Yoga and chemoreflex sensitivity Sir—Lucia Spicuzza and colleagues (Oct 28, p 1495)1 conclude that yoga trainees have a generalised reduction in chemoreflex to hypoxia in laboratory conditions. These findings are useful to mountaineers. To verify Spicuzza and colleagues’ conclusions, we investigated eight healthy experienced yoga trainees (all male, mean age 35·5 years [SD 6·3], mean years of practice 5·1 [SD 1·7]) and eight matched controls at 171 m altitude and 2 days later after cable-car transport to 2600 m. We took arterial blood samples from the ear lobe after 2 h rest and measured spontaneous breathing.2 Arterial oxygen and carbon dioxide partial pressures were analysed. The results of blood gas analysis at both altitudes are shown in the table. Partial pressure of oxygen and of carbon dioxide were similar in the two groups at both altitudes. We did not measure respiration directly, but our data suggest that yoga trainees and controls had equally adequate ventilatory response to mild hypobaric hypoxia at moderate altitude. By contrast with Spicuzza and colleagues’ data, participants were not exposed to normobaric hypoxia in a laboratory, but to hypobaric hypoxia at moderate altitude. We could not, therefore, verify their findings under in-vivo conditions. *Georg Röggla, Stylianos Kapiotis, Hannelore Röggla Municipal Hospital of Neunkirchen, A-2620 Neunkirchen, Austria 1

2

Spicuzza L, Gabutti A, Porta C, Montano N, Bemardi L. Yoga and chemoreflex response to hypoxia and hypercapnia. Lancet 2000; 356: 1495–96. Röggla G, Röggla H, Röggla M, Binder M, Laggner AN. Effect of alcohol on acute ventilatory adaptation to mild hypoxia at moderate altitude. Ann Intern Med 1995; 122: 925–27.

Authors’ reply Sir—To verify whether or not yoga trainees have a reduced ventilatory response, ventilation should be measured as well as blood gases. Chemoreflex sensitivity, by definition, involves measurement of both. Similar

THE LANCET • Vol 357 • March 10, 2001

blood gas values might result from different respiratory patterns. Without information about ventilation and breathing rates (whose importance we underlined in our report) Röggla and colleagues cannot predict chemoreflex sensitivity. Furthermore, the altitude of 2600 m is probably an insufficient stimulus, as shown by the still high values of partial pressure of oxygen; because of the inverse curvilinear relation linking minute ventilation to this variable, the change should induce only minor or no change in ventilation.1 Our finding of a blunted chemoreflex in yoga trainees is fully supported by the findings of another study.2 We agree that adequate partial pressure of oxygen at low and moderate altitude is evidence of adequate ventilation. We noted that yoga training, rather than impairing ventilation (as Röggla and co-workers incorrectly infer from our report), produces a more efficient breathing pattern.3 Röggla and co-workers’ data actually support this conclusion because the efficiency of the breathing pattern can maintain adequate partial pressure of oxygen despite lower minute ventilation. Their findings of slightly increased carbon dioxide in yoga trainees, at 171 m and 2600 m, suggests some relative hypoventilation compared with controls, which also supports our and others’ findings. Finally, we also tested yoga trainees at higher altitude, and measured ventilatory parameters: in a first study,4 we measured ventilatory parameters at baseline and at a simulated altitude of 5000 m in ten yoga trainees. There was a blunted increase in ventilation and oxygen saturation was preserved at altitude. These conclusions were later confirmed in the field at the same altitude. We argue that a reduced hypoxic ventilatory response is not necessarily evidence of an impaired ventilation, as inferred by Röggla and co-workers. Endurance athletes are a typical example of this effect.5 *Luciano Bemardi, Lucia Spicuzza, Cesare Portal, Alessandra Gabutti, Nicola Montano *Department of Internal Medicine, University of Pavia and IRCCS Ospedale S Matteo, 27100 Pavia, Italy; Institute of Respiratory Diseases, Catania, Italy; and Centro Ricerche Cardiovascolari, Milan, Italy

4

5

Ward W, Milledge JS, West JB. High altitude medicine and physiology, 2nd edn. London: Chapman and Hall, 1995. Stanescu DC, Nemery B, Veritier C, Marecal C. Pattern of breathing and ventilatory response to C02 in subjects practising hata-yoga. J Appl Physiol. 1981; 51: 1625–29. Bemardi L, Spadacini G, Bellwon J, Hajiric R, Roskamm H, Frey AW. Effect of breathing rate on oxygen saturation and exercise performance in chronic heart failure. Lancet 1998; 351: 1308–11. Bemardi L, Passino Q Wilmerding V, et al. Breathing patterns and cardiovascular autonomic modulation during hypoxia induced by simulated altitutde. J Hypertens (in press). Levine BD, Friedman DB, Engfred K, et al. The effect of normoxic or hypobaric hypoxic endurance training on the hypoxic ventilatory response. Med Sci Sports Exerc 1992; 24: 769–75.

Relapse of systemic lupus erythematosus Sir—Ann E Traynor and colleagues (Aug 26, p 701)1 report on the efficacy of high-dose chemotherapy and haemopoietic stem-cell transplantation (HSCT) in patients with refractory systemic lupus erythematosus (SLE). In follow-up of 12–40 months no relapse was described. We studied three patients with refractory SLE (follow-up 20–28 months, and have seen a clinical relapse in one man aged 39 years, 18 months after HSCT.2 The patient had developed multiple-organ manifestations over 11 years and he received HSCT for persistent active disease with severe lupus nephritis (WHO class IV) expressing nephrotic syndrome, high titres of antibodies to double stranded, DNA, and low C3 and C4 concentrations despite pulses of methylprednisolone and intravenous cyclophosphamide. After HSCT, clinical symptoms resolved for the first time, autoantibodies became negative, and the complement concentrations became normal. Accordingly, the score of the disease activity index SLE daily activity index was zero at that time. 15 months after HSCT the antinuclear antibodies remained negative (<1:160). However, at 18 months after HSCT, lupus-nephritis and erythema had reoccurred, probably triggered by sun exposure. Simultaneously, a striking increase of autoantibody titres and decline in complement concentrations were noted (table). At 21 months after HSCT, lupus activity remains uncontrolled despite high doses of steroids and monthly cycles of intravenous cyclophosphamide reflected by a further

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For personal use only. Reproduce with permission from The Lancet Publishing Group.