Ondine's curse

To the Editor:

We demonstrated, in our previous report, (1) that the row-a-boat phenomenon (RBP) of spontaneous upper-body movement in patients with advanced Duchenne muscular dystrophy (DMD), which occurs when these patients are sitting upright supported by a belt around the body, is a respiratory movement to compensate for the atrophied respiratory muscles in advanced DMD. The major mechanism to generate tidal volume in RBP is an active compression of the thorax and abdomen during expiration, which is done by making use of the belt. Despite the lack of arm movement, the motion looks as if the patient were rowing a boat. Here, we show a practical method to obtain an adequate tidal volume with RBP.

We used a tightly woven cotton belt 13.5 cm (5.3 inches) in width, which was tied around a patient in an electrical wheelchair to help maintain him in the upright position. The belt was positioned between the fourth/fifth and eighth/ninth ribs anterior to the axillary line of the patients. With the aim of assessing the effects of belt position on the efficacy of RBP, we compared respiration with the belt in its usual position and positioned 10 cm (3.9 inches) cephalad. Breath-to-breath ventilation and expiratory gases were measured with a respirometabolic monitoring system (MG-360, RM-300; Minato; Osaka, Japan) through a full face-mask. The subjects were six patients with DMD, 22 to 35 years of age, who were unable to ambulate and were dependent on mechanical ventilation 50 to 100% of the time. They started spontaneous RBP as soon as they were transferred from the bed to an upright position in a wheelchair with the ventilator temporarily stopped. During RBP with the belt in its usual position, tidal volume was 276 [+ or -] 69 mL per breath (mean [+ or -] SD) and respiratory rate was 30.3 [+ or -] 7.0 breaths/min. However, with the belt in the more cephalad position, tidal volume was significantly decreased, to 232 [+ or -] 71 mL per breath (p < 0.05), without any change in respiratory rate of 31.0 [+ or -] 7.8 breaths/min. The supplemental tidal volume exerted by an efficient RBP in these patients was approximately 20%. With the unusual belt position, all the patients felt uneasy on breathing due to a lack of freedom to utilize their upper body for RBP.

Breathing is controlled separately by the autonomic and voluntary pathways, which are, at least partially, anatomically different. Discrete syndromes of selective paralysis of autonomic or voluntary respiration, with the function of one pathway being paralyzed and the other being spared, were previously described by one of the authors. (2) The RBP is a backup mechanism exerted by the voluntary pathway to compensate for the paralyzed autonomic pathway, primarily the weakened diaphragm, in advanced DMD. Interestingly, we observed that RBP mostly occurred spontaneously in patients sitting in a wheelchair; the patients themselves did not notice the occurrence of RBP. This seems a wonderful example of the cleverness of the nervous system to be able to develop such curious compensatory responses in the face of lost function of autonomic respiration.

Correspondence to: Fumihiko Yasuma, MD, FCCP, Physician-in-Chief, Department of Internal Medicine, Suzuka National Hospital, 3-2-1 Kasado, Suzuka, 513-8501 Japan; e-mail: f-yasuma@mtb.biglobe.ne.jp

REFERENCES

(1) Yasuma F, Kato T, Matsuoka Y, et al. Row-a-boat phenomenon: respiratory compensation in advanced Duchenne muscular dystrophy, Chest 2001; 119:1836-1839

(2) Yasuma F, Okada A, Honda Y, et al. Ondine's curse and its inverse syndrome: respiratory failure in autonomic vs voluntary control. In: Hughson R, Cunningham DA, Duffin J, eds. Advances in modeling and control of ventilation. New York, NY: Plenum Press, 1998; 179-184

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