Diaphragm pacing with a spinal cord stimulator

BACKGROUND: Diaphragm pacing with electrical stimulation of the phrenic nerve is an established treatment for central hypoventilation syndrome. The device, however, is not readily available in Japan. For pain control, we applied the spinal cord stimulator to bring about phrenic nerve stimulation. The purpose of this study is to evaluate the efficacy and feasibility of phrenic pacing using the compromise method. METHOD AND PATIENTS: We implanted a spinal cord stimulator in five patients with chronic central hypoventilation. The stimulation electrode was placed along the phrenic nerve in the neck, and the device was implanted in the anterior chest. We used the cyclic mode, and set the parameters at 1 second ramp up, 2 second on, 3 second off. The pulse width and the frequency were set at 150 mu sec and 21 Hz respectively. The amplitude was adjusted to obtain sufficient tidal volume and to maintain PaCO2 at around 40 mmHg. RESULT: During the follow-up period from 3 to 34 months (mean 23), stable and sufficient ventilation was observed in all patients without complications. CONCLUSION: Though longer follow-up is necessary, diaphragm pacing with the spinal cord stimulator is feasible as a treatment for central hypoventilation syndrome.     

Diaphragm pacing using the minimally invasive cervical approach

Context:The implantation of commercially available phrenic nerve/diaphragm pacers has been available for more than 40 years and has enabled thousands of patients in over 40 countries to achieve freedom from invasive mechanical ventilation.Objective:The cervical approach to implantation of these pacers is described, as are the pros and cons of using this technique compared to intrathoracic and sub-diaphragmatic.Methods:Study design was a retrospective review of 1,522 subjects from the Avery Biomedical Devices (ABD) database who were implanted with the Avery diaphragm pacer. Long term statistics from patients implanted with diaphragm pacers are presented as well.Results:17% of cervically placed electrodes required at least one replacement compared to 18% of electrodes placed thoracically. Devices implanted cervically show no significant difference in their longevity than those implanted using the thoracic approach (P value of 0.9382 using Two-Sample t-Test). The mean longevity for both approaches was found to be 6.4 years. The majority of electrodes implanted have never required replacement. A majority of CCHS patients were implanted using the thoracic approach and only find it necessary to use the device during sleeping hours. Most of the cervically implanted patients are found to be older at the time of implantation and implanted for diagnoses that require longer daily use of the device.Conclusion:The cervical approach for the implantation of phrenic nerve/diaphragm pacers is the most minimally invasive, but underutilized, technique that allows for the use of local or monitored anesthesia, does not require entering any body cavities, and keeps incision size small.     

Diaphragm pacing by electrical stimulation of the phrenic nerve

Sophisticated techniques for electrical stimulation of excitable tissue to treat neuromuscular disorders rationally have been developed over the past 3 decades. A historical review shows that electricity has been applied to the phrenic nerves to activate the diaphragm for some 200 years. Of the contemporary methods for stimulating the phrenic nerve in cases of ventilatory insufficiency, the authors prefer stimulation of the phrenic nerve in the thorax using a platinum ribbon electrode placed behind the nerve and an attached subcutaneously implanted radiofrequency (RF) receiver inductively coupled to an external RF transmitter. Instructions are given for implanting the electrode-receiver assembly, emphasizing atraumatic handling of the phrenic nerve and strict aseptic techniques. Diaphragm pacing is conducted with low frequency electrical stimulation at a slow repetition (respiratory) rate to condition the diaphragm muscle against fatigue and maintain it fatigue-free. Candidates for diaphragm pacing are those with ventilatory insufficiency due to malfunction of the respiratory control center or interruption of the upper motor neurons of the phrenic nerve. In the Yale series, there were 77 patients treated by diaphragm pacing; 63 (82%) started before 1981 and thus were available for follow-up for at least 5 years; 33 (52%) were paced for 5 to 10 years, and 15 (24%) were paced for 10 to 16. Long term stimulation of the phrenic nerves to pace the diaphragm is an effective method of ventilatory support in selected cases.     

Diaphragm pacing. Application to a patient with chronic obstructive pulmonary disease.

In a 66-year-old patient with chronic obstructive pulmonary disease (COPD) complicated by arterial hypoxemia and repeated episodes of respiratory and right ventricular failure, a satisfactory level of oxygenation could not be maintained despite controlled oxygen therapy. To enable oxygen to be administered without depression ventilation, artificial respiration by means of phrenic nerve stimulation (diaphragm pacing) has been employed. Evidence of clinical improvement since pacing was begun 32 months ago include fewer episodes of respiratory failure and better control of congestive heart failure despite a gradual worsening of pulmonary function.     

Diaphragm pacing with natural orifice transluminal endoscopic surgery: potential for difficult-to-wean intensive care unit patients

Background Up to 50% of the patients in the intensive care unit (ICU) require mechanical ventilation, with 20% requiring the use of a ventilator for more than 7 days. More than 40% of this time is spent weaning the patient from mechanical ventilation. Failure to wean from mechanical ventilation can in part be attributable to rapid onset of diaphragm atrophy, barotrauma, posterior lobe atelectasis, and impaired hemodynamics, which are normally improved by maintaining a more natural negative chest pressure. The authors have previously shown that laparoscopic implantation of a diaphragm pacing system benefits selected patients. They now propose that an acute ventilator assist with interventional neurostimulation of the diaphragm in the ICU is feasible and could facilitate the weaning of ICU patients from mechanical ventilation. Natural orifice transluminal endoscopic surgery (NOTES) has the potential to expand the benefits of the diaphragm pacing system to this acute patient population by allowing it to be performed at the bedside similarly to insertion of the common gastrostomy tube. This study evaluates the feasibility of this approach in a porcine model. Methods Pigs were anesthetized, and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery, and balloon dilation. The diaphragm was mapped using a novel endoscopic electrostimulation catheter to locate the motor point (where stimulation provides complete contraction of the diaphragm). An intramuscular electrode then was placed at the motor point with a percutaneous needle. The gastrotomy was managed with a gastrostomy tube. Results Four pigs were studied, and the endoscopic mapping instrument was able to map the diaphragm to identify the motor point. In one animal, a percutaneous electrode was placed into the motor point under transgastric endoscopic visualization, and the diaphragm could be paced in conjunction with mechanical ventilation. Conclusions These animal studies demonstrate the feasibility of transgastric mapping of the diaphragm and implantation of a percutaneous electrode for therapeutic diaphragmatic stimulation. Presented at the 2006 Scientific Session of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) April 2006, Dallas, TX, USA     

Diaphragm

The diaphragm is the muscle separating the thoracic and abdominal cavities; it is unique to mammals. It arises from the crura, the arcuate ligaments, the costal margin and the posterior aspects of the xiphoid and has a central trefoil-shaped tendon. It has three major openings for the aorta, inferior vena cava and oesophagus. Its entire motor supply and principal sensory supply is from the phrenic nerve (cervical segments 3, 4 and 5). Division of the phrenic nerve results in complete paralysis of the hemidiaphragm, which is elevated by the intra-abdominal pressure. At rest, the diaphragm is at the level of the fifth rib in the mid-clavicular line. In quiet inspiration it descends by about 1.5 cm, but this can increase almost ten-fold in maximal inspiration. Movement of the diaphragm accounts for about 60–75% of the total tidal volume. In quiet respiration it accounts for most, if not all, respiratory movement. The diaphragm also helps to raise the intra-abdominal pressure in defaecation, micturition, vomiting and parturition.     

Diaphragm

The diaphragm is the muscle separating the thoracic and abdominal cavities; it is unique to mammals. It arises from the crura, the arcuate ligaments, the costal margin and the posterior aspects of the xiphoid and has a central trefoil-shaped tendon. It has three major openings for the aorta, inferior vena cava and oesophagus. Its entire motor supply and principal sensory supply is from the phrenic nerve (cervical segments 3, 4 and 5). Division of the phrenic nerve results in complete paralysis of the hemidiaphragm, which is elevated by the intra-abdominal pressure. At rest, the diaphragm is at the level of the fifth rib in the mid-clavicular line. In quiet inspiration it descends by about 1.5 cm, but this can increase almost ten-fold in maximal inspiration. Movement of the diaphragm accounts for about 60-75% of the total tidal volume. In quiet respiration it accounts for most, if not all, respiratory movement. The diaphragm also helps to raise the intra-abdominal pressure in defecation, micturition, vomiting and parturition.