Long‐Term Follow‐Up of Pacing of the Conditioned Diaphragm in Quadriplegia

Abstract

The authors have previously shown that conditioning of the diaphragm for continuous bilateral pacing is a feasible and effective means of ventilation in patients with complete respiratory paralysis from high cervical (above C3) quadriplegia. The present study reports the long-term results of continuous diaphragmatic pacing. Twelve quadriplegia patients underwent bilateral phrenic nerve pacemaker placement and diaphragm conditioning from 1981 to 1987. Pacing was initiated at 11 Hz and progressively decreased to 7.1 Hz. A pulse train duration of 1.3 seconds for adults and 0.9 seconds for children was used. Long-term follow-up information obtained included pacing status (full-time, part-time, or mechanical ventilation), ventilation parameters, and social circumstances. Of the 12 patients, 6 continued to pace full time (mean 14.8 years); all were living at home. Three patients paced for an average of 1.8 years before stopping; two were institutionalized. One patient who paced full time for 6.5 years before lapsing to part time, lived at home. Two patients were deceased; one paced continuously for 10 years before his demise, the other stopped pacing after 1 year. Patients who stopped full-time pacing did so mainly for reasons of inadequate social or financial support or associated medical problems. All patients demonstrated normal tidal volumes and arterial blood gases while pacing full time. Despite theoretical concerns about long-term nerve damage, no patient lost the ability to pace the phrenic nerve. Threshold currents did not increase over time (original/follow-up: 0.46/0.47 for right, 0.45/0.46 for left), nor did maximal currents (original/follow-up: 1.16/1.14 for right, 1.37/1.26 for left). This follow-up confirms that quadriplegic patients are able to meet long-term, full-time ventilation requirements using phrenic nerve stimulation of the conditioned diaphragm. Careful review of diaphragmatic pacing candidates with respect to associated medical conditions, social support, and motivation is essential for appropriate patient selection and successful long-term results.

Diaphragm Pacing (Phrenic Nerve Stimulation) in a High Cervical Spinal Cord Injury in Quadriplegic Patient

“…Van Heekran and Glenn first introduced electrophrenic stimulation in 1966 in patients with Ondyne's curse. 2 Phrenic nerve stimulation can be done at the neck through a suprascapular approach either on single side or on both sides (as in our patient). The long distance between the electrode and muscle and technical challenges in anchoring the electrodes made this more difficult to maintain for long periods.…”

Functional Electrical Stimulation in Spinal Cord Injury Respiratory Care

“…The Avery Mark IV device has a unique optional interface that allows biofeedback control from pulse oximetry and CO 2 monitoring. 31,32 In addition, trans-telephonic monitoring is available, allowing the electronic output and phrenic nervediaphragm neurophysiologic response to be monitored by telephone. 31 Atrotech (Tampere, Finland) and Medimplant (Vienna, Austria) systems differ from the Avery system in the electrode technology.…”

“…31,32 In addition, trans-telephonic monitoring is available, allowing the electronic output and phrenic nervediaphragm neurophysiologic response to be monitored by telephone. 31 Atrotech (Tampere, Finland) and Medimplant (Vienna, Austria) systems differ from the Avery system in the electrode technology. 11,20,33,34 The Atrotech system has the ability to stimulate different portions of the nerve each time with the intention of reducing muscle fatigue.…”

Diaphragmatic Pacemaker

“…47.27% of patients had success, whereas 34.54% of patients had significant support, and approximately 16% of patients had failure or minimal support. In another paper by Glenn et al [21], they reported the long-term follow-up of pacing of the conditioned diaphragm in twelve quadriplegic patients. All twelve patients were successfully conditioned and they all were able to achieve full ventilation.…”

“…Electrical pulses of 150 microsecond duration are delivered with varying amplitude, based on the patient's requirements. A pulse train of 1.3 second and 0.9 second is used for adult and pediatric patients respectively [21]. In order to allow time for the postoperative edema to subside, the diaphragm conditioning is not initiated for at least 12 days after implantation of the second unit.…”