ABSTRACT
Electrophrenic respiration was developed in 1948 by Sarnoff et al. (1) who reported successful ventilation among dogs, cats, rabbits, and monkeys when electrodes were attached directly to their phrenic nerves. In these studies they were able to achieve minute ventilation and blood gases comparable to those measured during periods of unassisted ventilation, noting the relationship between the applied voltage and the resultant respiratory volumes. In these animals electrophrenic respiration could maintain satisfactory blood gases for up to 22 hours (1). Since diaphragmatic stimulator implant surgery was developed for chronic ventilatory support in 1968, several thousand patients worldwide have benefited from its use (2). In 1973 Glenn and colleagues first reported on the effectiveness of diaphragmatic pacing among patients with quadriplegia and those with chronic alveolar hypoventilation (3). Commercially available systems are currently accessible from three sources worldwide-Avery Biomedical DevicesTM in the United States, AtrotechTM in Finland, and MedImplantTM in Austria. The only system approved for use by the FDA is the Avery Biomedical Devices system. At present this company is following 300 patients, 200 of whom are residents of the United States and 17 of whom are based in Canada. This number is small when considering that in the United States 4% of the annual 10,000 new spinal injury patients require mechanical ventilation (4) and that quadriplegia is not the only indication for phrenic pacing.
