Phrenic Nerve Pacing Via Intramuscular Diaphragm Electrodes in Tetraplegic Subjects

doi:10.1378/chest.127.2.671

Chest

Volume 127, Issue 2, February 2005, Pages 671-678

https://doi.org/10.1378/chest.127.2.671 Get rights and content

Context

Diaphragm pacing in ventilator-dependent tetraplegic subjects is usually achieved by the placement of phrenic nerve electrodes via thoracotomy. However, this technique may be accomplished less invasively via laparoscopic placement of IM electrodes, at a lower cost and with less risk of injury to the phrenic nerve.

Objective

To assess the feasibility of laparascopic placement of IM diaphragm electrodes to achieve long-term ventilatory support in ventilator-dependent tetraplegic subjects.

Design, setting, and participants

Two IM diaphragm electrodes were placed laparoscopically in each hemidiaphragm in five subjects with ventilator-dependent tetraplegia. Studies were performed either on an outpatient basis or with a single overnight hospitalization. Ventilator-dependent tetraplegic subjects were identified in whom bilateral phrenic nerve function was present, as determined by phrenic nerve conduction studies. Following electrode placement, subjects participated in a conditioning program to improve the strength and endurance of the diaphragm over a period of 15 to 25 weeks. The duration of the study was variable depending on the time necessary to determine the maximum duration that individuals could be maintained without mechanical ventilation support.

Main outcome measures

Magnitude of inspired volume generation and duration of ventilatory support with bilateral diaphragm pacing alone.

Results

In four of the five subjects studied, initial bilateral diaphragm stimulation resulted in inspired volumes between 430 and 1,060 mL. Reconditioning of the diaphragm over several weeks resulted in substantial increases in inspired volumes to 1,100 to 1,240 mL. These subjects were comfortably maintained without mechanical ventilatory support for prolonged time periods by diaphragm pacing, by full-time ventilatory support in three subjects, and 20 h per day, in the fourth subject. No response to stimulation was observed in one subject, most likely secondary to denervation atrophy.

Conclusions

Diaphragm pacing in ventilator-dependent tetraplegic subjects can be successfully achieved via laparascopic placement of IM electrodes.

Section snippets

Subjects

Five subjects with trauma-induced high cervical spinal cord injury who required long-term mechanical ventilatory support were studied. All subjects were in stable condition at the time of study (ie, free of significant lung, cardiovascular, or brain disease). Highly motivated subjects with sufficient caregiver support were recruited for this study. This investigation was approved by the US Food and Drug Administration (Investigational Device Exemption G920162) and also by the institutional

Results

Maximum changes in inspired volume resulting from separate left and right hemidiaphragm stimulation and bilateral stimulation, at various intervals during the reconditioning period, are superimposed for one subject in Figure 2. There were progressive increases in inspired volume generation during unilateral and bilateral diaphragm stimulation. Since the inspiratory time was constant at 1.1 s under all conditions, increases in inspired volume were achieved by increases in inspiratory flow rate.

Discussion

In a previous case report,¹⁵ we described the first tetraplegic subject in whom full-time diaphragm pacing could be maintained via IM diaphragm electrodes. In the current report, additional clinical experience with this technique and a modification of the method of electrode insertion has been presented. The results indicate that artificial ventilation via IM diaphragm pacing provides a similar degree of ventilatory support and clinical benefit to ventilator-dependent tetraplegic subjects when

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Citation Excerpt :
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Patients with high cervical Spinal Cord Injury (SCI) usually require mechanical ventilation support. Phrenic Nerve Stimulation (PNS) both direct and indirect is the main alternative for these patients to wean off ventilator although PNS has several limitations and phrenic nerve could be also damaged after cervical spinal cord injury.
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Results demonstrate that EES at T2-T5 substantially increase the inspired volume. The results of this study also demonstrate that EES at spinal segments T2-T5 can bring patients dependent from mechanical ventilation to pressure support (on CPAP), preventing Baro-trauma and other complications related to mechanical ventilation.
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Spinal cord injury (SCI) often results in impaired respiratory function. Paresis or paralysis of inspiratory and expiratory muscles can lead to respiratory dysfunction depending on the level and severity of the injury, which can affect the management and care of SCI patients. Respiratory dysfunction after SCI is more severe in high cervical injuries, with vital capacity (VC) being an essential indicator of overall respiratory health. Respiratory complications include hypoventilation, a reduction in surfactant production, mucus plugging, atelectasis, and pneumonia. Respiratory management includes mechanical ventilation and tracheostomy in high cervical SCI, while noninvasive ventilation is more common in patients with lower cervical and thoracic injuries. Mechanical ventilation can negatively impact the function of the diaphragm and weaning should start as soon as possible. Patients can sometimes be weaned from mechanical ventilation with assistance of electrical stimulation of the phrenic nerve or the diaphragm. Respiratory muscle training regimens may also improve patients’ inspiratory function following SCI. Despite the critical advances in preventing, diagnosing, and treating respiratory complications, they continue to significantly affect persons living with SCI. Additional studies of interventions to reduce respiratory complications are likely to further decrease the morbidity and mortality associated with these injuries.

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Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: [email protected]).

This work was supported by US Food and Drug Administration grant FD-R-001839 and by the Rehabilitation Research Service of the Veterans Affairs.

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Chest

Selected ReportsPhrenic Nerve Pacing Via Intramuscular Diaphragm Electrodes in Tetraplegic Subjects

Context

Objective

Design, setting, and participants

Main outcome measures

Results

Conclusions

Section snippets

Subjects

Results

Discussion

J Pediatr Surg

Ventilatory support by pacing of the conditioned diaphragm in quadriplegia

N Engl J Med

Diaphragmatic pacing

Am Rev Respir Dis

Phrenic nerve stimulation in tetraplegia: a new regimen to condition the diaphragm for full-time respiration

Scand J Rehabil Med

Multichannel stimulation of phrenic nerves by epineural electrodes: clinical experience and future developments

ASAIO J

Electrophrenic respiration

Science

Twenty years of experience in phrenic nerve stimulation to pace the diaphragm

Pacing Clin Electrophysiol

Diaphragm pacing in patients with spinal cord injury

Topics Spinal Cord Injury Rehabil

Diaphragm pacing by electrical stimulation of the phrenic nerve

Neurosurgery

Central hypoventilation: long-term ventilatory assistance by radiofrequency electrophrenic respiration

Ann Surg

Diaphragm activation with intramuscular stimulation in dogs

Am Rev Respir Dis

Intramuscular electrical activation of the phrenic nerve

IEEE Trans Biomed Eng

Selected Reports
Phrenic Nerve Pacing Via Intramuscular Diaphragm Electrodes in Tetraplegic Subjects