Am. J. Respir. Crit. Care Med., Vol 150, No. 4, Oct 1994, 934-940.
Evaluation of intercostal pacing to provide artificial ventilation in quadriplegics
AF DiMarco, GS Supinski, JA Petro and Y Takaoka
Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
The purpose of this study was to assess the utility of intercostal muscle
pacing by spinal cord stimulation (SCS) to provide artificial ventilation
in ventilator-dependent quadriplegic patients. Five ventilator-dependent
quadriplegics with phrenic nerve injury (and therefore not candidates for
phrenic nerve pacing) were studied. During an initial surgical procedure, a
quadripolar epidural disc electrode was positioned on the ventral portion
of the upper thoracic spinal cord via a hemilaminectomy and subsequently
connected to a radio-frequency receiver implanted subcutaneously over the
anterior rib cage. In four of the five patients, initial SCS stimulation
resulted in inspired volumes between 150 and 240 ml. Stimulation resulted
in no effect in one patient, due to probable cystic degeneration of the
thoracic spinal cord. Reconditioning of the intercostal muscles caused
substantial increases in inspired volume in three of four patients of 670
to 850 ml. In one patient, reconditioning resulted in a much smaller
increase (to 470 ml). The maximum duration that ventilation could be
sustained by low-frequency (13 Hz) intercostal pacing ranged between 20 min
and 2 3/4 h. Our findings indicate that intercostal pacing via SCS does not
result in sufficient inspired volume production to support ventilation for
prolonged periods. However, this modality may be a useful adjunct to
enhance tidal volume in patients with suboptimal inspired volume by phrenic
nerve pacing.
