- Email: [email protected]
Counterpoint: Should Phrenic Nerve Stimulation Be the Treatment of Choice for Spinal Cord Injury? No
the time.2,20 Changes in common care models that encourage early pacer placement may avoid this complication, but for now, the ability to safely wean from invasive mechanical ventilation to respiratory pacing in a home environment can help to mitigate this concern.15 In summary, physicians should support the use of respiratory pacing in patients with SCI. Ethical, medical, and economic considerations support this hypothesis. To date, the application of respiratory pacing has been limited, and a commitment to more-aggressive care models should be considered. Lisa F. Wolfe, MD, FCCP Chicago, IL Affiliations: From the Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine. Financial/nonfinancial disclosures: The author has reported to CHEST the following conflicts of interest: ResMed in the area of complex apnea supported research, Hill-Rom and Philips Respironics for consulting in the area of airway clearance. The data in this article were presented in a pro-vs-con debate at CHEST 2011; October 22-26, 2011; Honolulu, HI. Correspondence to: Lisa F. Wolfe, MD, FCCP, Northwestern University, 675 N St Claire St, Ste 18-250, Chicago, IL 60611; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.13-0217
References 1. National Spinal Cord Injury Statistical Center. Spinal cord injury facts and figures at a glance. J Spinal Cord Med. 2010; 33(4):439-440. 2. DiMarco AF. Phrenic nerve stimulation in patients with spinal cord injury. Respir Physiol Neurobiol. 2009;169(2):200-209. 3. Onders RP, Khansarinia S, Weiser T, et al. Multicenter analysis of diaphragm pacing in tetraplegics with cardiac pacemakers: positive implications for ventilator weaning in intensive care units. Surgery. 2010;148(4):893-897. 4. DiMarco AF. Restoration of respiratory muscle function following spinal cord injury. Review of electrical and magnetic stimulation techniques. Respir Physiol Neurobiol. 2005;147(2-3): 273-287. 5. Synapse Biomedical Inc. Synapse biomedical fact sheet. Synapse Biomedical Inc website. http://www.synapsebiomedical. com/news/media/pdf/CompanyFactSheet-2011.pdf. Accessed March 12, 2013. 6. Avery Biomedical Devices, Inc. Advantages of breathing pacemakers: advantages of breathing pacemakers over positive pressure ventilation (PPV). Avery Biomedical Devices, Inc website. http://www.averybiomedical.com/breathing-pacemakers/ advantages.html. Accessed March 12, 2013. 7. White AC, O’Connor HH, Kirby K. Prolonged mechanical ventilation: review of care settings and an update on professional reimbursement. Chest. 2008;133(2):539-545. 8. Van de Velde D, Bracke P, Van Hove G, Josephsson S, Devisch I, Vanderstraeten G. The illusion and the paradox of being autonomous, experiences from persons with spinal cord injury in their transition period from hospital to home. Disabil Rehabil. 2012;34(6):491-502. 9. Hess DR. Facilitating speech in the patient with a tracheostomy. Respir Care. 2005;50(4):519-525.
10. Esclarín A, Bravo P, Arroyo O, Mazaira J, Garrido H, Alcaraz MA. Tracheostomy ventilation versus diaphragmatic pacemaker ventilation in high spinal cord injury. Paraplegia. 1994;32(10): 687-693. 11. Onders RP, Elmo M, Khansarinia S, et al. Complete worldwide operative experience in laparoscopic diaphragm pacing: results and differences in spinal cord injured patients and amyotrophic lateral sclerosis patients. Surg Endosc. 2009; 23(7):1433-1440. 12. Le Pimpec-Barthes F, Gonzalez-Bermejo J, Hubsch JP, et al. Intrathoracic phrenic pacing: a 10-year experience in France. J Thorac Cardiovasc Surg. 2011;142(2):378-383. 13. Ragnarsson KT. Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions. Spinal Cord. 2008;46(4):255-274. 14. Hirschfeld S, Exner G, Luukkaala T, Baer GA. Mechanical ventilation or phrenic nerve stimulation for treatment of spinal cord injury-induced respiratory insufficiency. Spinal Cord. 2008;46(11):738-742. 15. Onders RP, Elmo MJ, Ignagni AR. Diaphragm pacing stimulation system for tetraplegia in individuals injured during childhood or adolescence. J Spinal Cord Med. 2007;30(suppl 1): S25-S29. 16. Adler D, Gonzalez-Bermejo J, Duguet A, et al. Diaphragm pacing restores olfaction in tetraplegia. Eur Respir J. 2009; 34(2):365-370. 17. Illinois Department of Healthcare and Family Services. Summary of private duty nursing: net liability in identified medical programs for state fiscal year 2010. Illinois Department of Healthcare and Family Services website. http://www2.illinois. gov/hfs/PublicInvolvement/ccmn/Documents/090811_ccmn_ ncps.pdf. Accessed March 12, 2013. 18. Hagglund KJ, Clark MJ, Mokelke EK, Stout BJ. The current state of personal assistance services: implications for policy and future research. NeuroRehabilitation. 2004;19(2):115-120. 19. Bolikal P, Bach JR, Goncalves M. Electrophrenic pacing and decannulation for high-level spinal cord injury: a case series. J Spinal Cord Med. 2012;35(3):170-174. 20. Gater DR Jr, Dolbow D, Tsui B, Gorgey AS. Functional electrical stimulation therapies after spinal cord injury. NeuroRehabilitation. 2011;28(3):231-248.
Counterpoint: Should Phrenic Nerve Stimulation Be the Treatment of Choice for Spinal Cord Injury? No incidence of long-term ventilator assistance in Thepatients with spinal cord injury (SCI) has increased
from 1990, rising to 43,700 cases per year in 1998 likely because of better available treatment plans.1 More than $8 billion per year is spent on SCI care in the United States after the first year of injury, and respiratory complications comprise the number one cause of morbidity and mortality in SCI.2 The majority of patients with SCI are male, aged , 30 years, and, as expected, the leading causes of death are pneumonia, pulmonary emboli, and septicemia. As of February 2011, the National Spinal Cord Injury Statistical Center3 estimated that 232,000 to 316,000 patients
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in the United States are living with SCI. Of the 12,000 new cases per year, . 2,700 patients with tetraplegia will require extended ventilator support. Ultimately, 2,000 will wean from ventilators, and 500 high tetraplegic injuries will result in permanent mechanical ventilator dependency. A prospective multicenter case series of SCI identified a 67% rate of respiratory complications primarily involving atelectasis, pneumonia, and ventilatory failure. This finding relates strongly to the cord level of injury, with respiratory complications occurring at rates of 84% in high cervical, C1 to C4 injury compared with a rate of 60% at level C5 to C8.4 Another study showed that the pulmonary complications that occurred in 36% of patients within the first month, including (in decreasing frequency) atelectasis, pneumonia, edema, pulmonary embolism, and aspiration, accounted for 11% of all mortality.5 The major factors associated with overall mortality were higher mean age in nonsurvivors (52 vs 28 years), lower FVC, the Pao2 in the pulmonary complication group, intubation rate, and tracheotomy. There is supporting evidence that intensive care management improves outcomes after SCI, and one can define key parameters for successful cardiopulmonary support and resuscitation.6 In addition, the use of aggressive secretion clearance devices, such as the insufflator-exsufflator, has been shown to be effective in assisting cough in patients with SCI, results in a significant increase in objective pulmonary function, and helps to inflate atelectatic areas, but these devices may still be underused.7,8 Ventilatory assistance with noninvasive ventilation (NIV) should be considered the first-line therapy of care, allowing for the patient’s condition to be managed at a reduced cost compared with an invasive means of support. An early study in patients with SCI demonstrated the benefit of NIV in all forms, including mouth assist and mask NIV, and 17 of the 23 patients were actually able to have their tracheostomy closed and sustained for years.9 Another study in 28 patients with SCI over a 4-year period showed that when NIV was used to prevent respiratory failure or wean-off ventilation, invasive ventilation was avoided in 10 of 17.10 The diaphragm pacing support (DPS) data that Dr Wolfe offers come from limited studies, most of which were by paid consultants of DPS manufacturers.11 A complete bibliography of studies for DPS is available online.12 From 2000 to 2007, 50 patients with SCI were reported to receive DPS implantations at five sites; of these patients, 96% were able to use the DPS system for ventilation, replacing their mechanical ventilators as early as 3 months after their injury.11 Ten deaths were also reported as shown in Table 1. The authors went on to state that the DPS system is safe and effective and that in Ohio, it would
Table 1—Complications and Deaths From Diaphragm Pacing Support Complications and Causes of Death
No.
Internal electrode failure Superficial wire infection that stopped pacing temporarily Cause of death Not device related Urosepsis Cardiac (elderly patient, patient with long-term injury) Endocarditis Complications from decubiti Systemic mastocytosis Aspiration sepsis Recurrence of tumor and sepsis
1 1 10 3 3 1 2 1 1 1
save $13,000 per patient per month compared with tracheostomy and mechanical ventilation (NIV not compared). They claimed that no patients stopped pacing and all would recommend it; thus, the authors concluded that “all patients with intact phrenic nerves should be offered diaphragm pacing to allow natural diaphragm breathing.”11 A study in France from 1997 to 2007 reviewed DPS use in 19 patients with posttraumatic tetraplegia who required full-time ventilation.13 The authors achieved ventilatory weaning in all but two patients after a median conditioning time of 6 weeks (2 weeks-11 months). These authors also concluded that DPS is safe and should be done as soon as orthopedic and neurologic issues are stable, but complications were not detailed, and limited long-term follow-up data were provided. However, there is a downside of DPS for some patients. DPS is strictly paced, so patients cannot initiate breathing, and most with SCI note that with about a 900-mL tidal breath and a respiratory rate set at 12 to 14/min, a Passy-Muir valve circuit (Passy-Muir Inc) allows almost continuous speech, but a DPS system usually will not.12 The elimination of the fear of disconnection from the mechanical ventilator is simply replaced by battery or pacer failure, so many DPS users with SCI need a backup, and the care plan may require two systems. Potential long-term risks of prolonged pacing always include electrode dislodgement and breakage. Complications have been more clearly reported elsewhere, which include the fact that laparoscopic surgery has some associated risks, such as the development of pneumothorax and subcutaneous emphysema that may require chest tube drainage.14 Sometimes, chest pain is associated with stimulation and possibly shoulder pain during the maximum stimulation that like occurs as a consequence of the stimulation of phrenic nerve afferents. One subject with rhinosinusitis prior to his injury but not present when receiving mechanical ventilation had this recur when nasal airflow was restored during diaphragmatic pacing.
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Point/Counterpoint Editorials
Another had intermittent food aspiration likely related to the large negative airway pressure generated during DPS stimulation, and the problem was only eliminated by maintaining the tracheostomy with use of a PassyMuir valve during meals. I concede that great advances in the placement and management of DPS systems for patients with SCI have been made. These patients may appreciate the ability to be freed from their ventilator dependence for part of the day, but it is not clearly superior to NIV. There is a speculative advantage that DPS may, in some patients, gradually condition and strengthen the diaphragm to allow for more subsequent independent ventilation, but proponents will argue that NIV will not do this, despite having no evidence. On the contrary, I contend that this procedure is unproven and not inexpensive, with many patients carrying a substantial out-of-pocket burden. NIV seems more appropriate until better data are available to support the widespread use of DPS in patients with SCI. Rapid extrapolation to other indications, such as amyotrophic lateral sclerosis and diaphragmatic failure in patients with ARDS, are being urged at the patient’s expense without good studies and will lead to similar debates. To conclude, there is an excellent parallel perspective in the National Emphysema Treatment Trial that arose because of overzealous acceptance of lung volume reduction surgery (LVRS).15 This resulted in a surge of charges to Medicare, and clear-headed thinkers demanded a National Institutes of Healthsponsored randomized trial to prove efficacy. Despite the extensive study demonstrating that LVRS may result in benefit for selected patients, relatively few patients later underwent the procedure. By 2004, only 254 Medicare beneficiaries underwent LVRS at a limited number of approved centers, and between 2005 and 2006, only 225 Medicare beneficiaries underwent LVRS. Specific reasons for the underperformance of LVRS have been suggested and include restricting LVRS performance to certain centers and a perceived overly complicated assessment. Many physicians still remain unaware of the benefits of LVRS and what characterizes an appropriate patient candidate, and LVRS is perceived by many in the medical community as too costly. Sound familiar? The reader needs to discern which argument can support or refute the concept that DPS therapy has enough solid long-term outcome evidence to justify it as first-line therapy. I contend that we must demand more well-designed prospective outcome trials before we take the apparent dive into the alluring pool of unproven new technology. Peter C. Gay, MD, FCCP Rochester, MN
Affiliations: From the Mayo Clinic. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. The data in this article were presented in a pro-vs-con debate at CHEST 2011; October 22-26, 2011; Honolulu, HI. Correspondence to: Peter C. Gay, MD, FCCP, Mayo Clinic, 200 First St SW, Rochester, MN 55905; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.13-0219
References 1. Carter RE, Donovan WH, Halstead L, Wilkerson MA. Comparative study of electrophrenic nerve stimulation and mechanical ventilatory support in traumatic spinal cord injury. Paraplegia. 1987;25(2):86-91. 2. DiMarco AF, Onders RP, Ignagni A, Kowalski KE. Inspiratory muscle pacing in spinal cord injury: case report and clinical commentary. J Spinal Cord Med. 2006;29(2):95-108. 3. National Spinal Cord Injury Statistical Center. Spinal cord injury facts and figures at a glance. The University of Alabama at Birmingham website. https://www.nscisc.uab.edu/Public Documents/nscisc_home/pdf/Facts%202011%20Feb%20Final. pdf. Accessed March 12, 2013. 4. Jackson AB, Groomes TE. Incidence of respiratory complications following spinal cord injury. Arch Phys Med Rehabil. 1994;75(3):270-275. 5. Reines HD, Harris RC. Pulmonary complications of acute spinal cord injuries. Neurosurgery. 1987;21(2):193-196. 6. Casha S, Christie S. A systematic review of intensive cardiopulmonary management after spinal cord injury. J Neurotrauma. 2011;28(8):1479-1495. 7. Pillastrini P, Bordini S, Bazzocchi G, Belloni G, Menarini M. Study of the effectiveness of bronchial clearance in subjects with upper spinal cord injuries: examination of a rehabilitation programme involving mechanical insufflation and exsufflation. Spinal Cord. 2006;44(10):614-616. 8. Schmitt JK, Stiens S, Trincher R, et al. Survey of use of the insufflator-exsufflator in patients with spinal cord injury. J Spinal Cord Med. 2007;30(2):127-130. 9. Bach JR, Alba AS Noninvasive options for ventilatory support of the traumatic high level quadriplegic patient. Chest. 1990; 98(3):613-619. 10. Tromans AM, Mecci M, Barrett FH, Ward TA, Grundy DJ. The use of the BiPAP biphasic positive airway pressure system in acute spinal cord injury. Spinal Cord. 1998;36(7): 481-484. 11. Onders RP, Elmo MJ, Khansarinia S, et al. Complete worldwide operative experience in laparoscopic diaphragm pacing: results and differences in spinal cord injured patients and amyotrophic lateral sclerosis patients. Surg Endosc. 2009; 23(7):1433-1440. 12. Synapse Biomedical Inc. Phrenic nerve & diaphragm motor point stimulation bibliography. Synapse Biomedical Inc website. http://www.synapsebiomedical.com/support/PDFs/SCI_ Reimbursement/Synapse%20Bibliography%205%207%202012. pdf. Accessed March 12, 2013. 13. Le Pimpec-Barthes F, Gonzalez-Bermejo J, Hubsch JP, et al. Intrathoracic phrenic pacing: a 10-year experience in France. J Thorac Cardiovasc Surg. 2011;142(2):378-383. 14. DiMarco AF, Onders RP, Ignagni A, Kowalski KE, Mortimer JT. Phrenic nerve pacing via intramuscular diaphragm electrodes in tetraplegic subjects. Chest. 2005;127(2):671-678.
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15. Criner GJ, Cordova F, Sternberg AL, Martinez FJ. The National Emphysema Treatment Trial (NETT) part II: lessons learned about lung volume reduction surgery. Am J Respir Crit Care Med. 2011;184(8):881-893.
either mechanical ventilation or pacing. No one will be left untreated. We cannot hide from the costs in both dollars and quality of life. All of these patients will need to decide: ventilation or pacing? But will they all be offered the choice? Lisa F. Wolfe, MD, FCCP Chicago, IL
Rebuttal From Dr Wolfe
D
r Gay1 has shared some interesting points. Many of his arguments hinge on the assumption that all patients with tracheostomy and spinal cord injury (SCI) have the option of using an alternative to either mechanical ventilation or diaphragm pacing support (DPS). This alternative would be noninvasive ventilation (NIV) and aggressive airway clearance, including mechanical cough assist. In reality, those patients with SCI who do not require invasive mechanical ventilation are not even considered candidates for DPS. If even 4 h of spontaneous breathing is possible, DPS is excluded,2 and 24-h NIV when there is no use of hands is possible but may not be practical. Dr Gay1 also states that mechanical ventilation with a PassyMuir valve (Passy-Muir Inc) provides completely normal speech, but the use of a Passy-Muir valve may not be safe in all patients because of secretions that may obstruct the valve, and speech without the valve is unnatural because it occurs mainly during inhalation. In addition, many patients have an intolerance to the added resistance of the Passy-Muir valve, and fenestrated tubes are not an adequate compensation because they may promote aggressive leak compensation, even risking respiratory alkalosis and seizure. In the best of situations, leak speech using mechanical ventilation does not produce adequate speech.3 Many of Dr Gay’s points do not appropriately balance the risks. Device failure is an issue with both DPS and mechanical ventilation, but given that the battery life for a pacer is 500 h4 compared with the very common occurrence of disconnection or the insurmountable fear of electrical power outage, this comparison easily favors the DPS system. One patient’s rhinosinusitis cannot serve as a reason to deny all patients the ability to smell. One assertion that large tidal volumes cause aspiration is in contradiction to other data showing that lung volume recruitment improves the ability to swallow.5 Finally, it is important to remember that everyone would be in favor of a large North American trial for the DPS system, but Dr Gay’s allusion to the National Emphysema Treatment Trial is flawed. That trial’s final recommendation was to refer these many patients who do not benefit from lung volume reduction surgery for the more-expensive lung transplantation.6 The final global cost advantage comes only from the reality of a fixed number of organs, leaving most patients untreated. In the setting of SCI, all patients will receive
Affiliations: From the Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine. Financial/nonfinancial disclosures: The author has reported to CHEST the following conflicts of interest: ResMed in the area of complex apnea supported research, Hill-Rom and Philips Respironics for consulting in the area of airway clearance. The data in this article were presented in a pro-vs-con debate at CHEST 2011; October 22-26, 2011; Honolulu, HI. Correspondence to: Lisa F. Wolfe, MD, FCCP, Northwestern University, 675 N St Claire St, Ste 18-250, Chicago, IL 60611; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.13-0218
References 1. Gay PC. Counterpoint: should phrenic nerve stimulation be the treatment of choice for spinal cord injury? No. Chest. 2013;143(5):1203-1206. 2. Blue Cross Blue Shield Blue Care Network of Michigan. Phrenic nerve/diaphragm pacing. Blue Cross Blue Shield of Michigan website. http://www.bcbsm.com/mprApp/Medical PolicyDocument?fileId52047509. Effective November 1, 2012. Accessed March 4, 2013. 3. MacBean N, Ward E, Murdoch B, et al. Optimizing speech production in the ventilator-assisted individual following cervical spinal cord injury: a preliminary investigation. Int J Lang Commun Disord. 2009;44(3):382-393. 4. Synapse Biomedical Inc. Frequently asked questions (FAQs). Synapse Biomedical Inc website. http://www.synapsebiomedical. com/images/FAQ613.pdf. Accessed March 4, 2013. 5. Wheeler Hegland KM, Huber JE, Pitts T, Sapienza CM. Lung volume during swallowing: single bolus swallows in healthy young adults. J Speech Lang Hear Res. 2009;52(1):178-187. 6. Criner GJ, Cordova F, Sternberg AL, Martinez FJ. The National Emphysema Treatment Trial (NETT) part II: lessons learned about lung volume reduction surgery. Am J Respir Crit Care Med. 2011;184(8):881-893.
Rebuttal From Dr Gay
D
r Wolfe1 and I2 have discussed whether a diaphragm pacing support (DPS) system is the treatment of choice for patients with spinal cord injury (SCI) in terms of technical aspects, costs, safety, ethics, and, most importantly, data to answer the primary question of what is the treatment of choice. We will further examine these arguments, beginning with the technical issues, but the emphasis must be on the available data and whether treatment outcome issues are completely clarified to this date. I again contend that
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Point/Counterpoint Editorials
References 1. National Spinal Cord Injury Statistical Center. Spinal cord injury facts and figures at a glance. J Spinal Cord Med. 2010; 33(4):439-440. 2. DiMarco AF. Phrenic nerve stimulation in patients with spinal cord injury. Respir Physiol Neurobiol. 2009;169(2):200-209. 3. Onders RP, Khansarinia S, Weiser T, et al. Multicenter analysis of diaphragm pacing in tetraplegics with cardiac pacemakers: positive implications for ventilator weaning in intensive care units. Surgery. 2010;148(4):893-897. 4. DiMarco AF. Restoration of respiratory muscle function following spinal cord injury. Review of electrical and magnetic stimulation techniques. Respir Physiol Neurobiol. 2005;147(2-3): 273-287. 5. Synapse Biomedical Inc. Synapse biomedical fact sheet. Synapse Biomedical Inc website. http://www.synapsebiomedical. com/news/media/pdf/CompanyFactSheet-2011.pdf. Accessed March 12, 2013. 6. Avery Biomedical Devices, Inc. Advantages of breathing pacemakers: advantages of breathing pacemakers over positive pressure ventilation (PPV). Avery Biomedical Devices, Inc website. http://www.averybiomedical.com/breathing-pacemakers/ advantages.html. Accessed March 12, 2013. 7. White AC, O’Connor HH, Kirby K. Prolonged mechanical ventilation: review of care settings and an update on professional reimbursement. Chest. 2008;133(2):539-545. 8. Van de Velde D, Bracke P, Van Hove G, Josephsson S, Devisch I, Vanderstraeten G. The illusion and the paradox of being autonomous, experiences from persons with spinal cord injury in their transition period from hospital to home. Disabil Rehabil. 2012;34(6):491-502. 9. Hess DR. Facilitating speech in the patient with a tracheostomy. Respir Care. 2005;50(4):519-525.
10. Esclarín A, Bravo P, Arroyo O, Mazaira J, Garrido H, Alcaraz MA. Tracheostomy ventilation versus diaphragmatic pacemaker ventilation in high spinal cord injury. Paraplegia. 1994;32(10): 687-693. 11. Onders RP, Elmo M, Khansarinia S, et al. Complete worldwide operative experience in laparoscopic diaphragm pacing: results and differences in spinal cord injured patients and amyotrophic lateral sclerosis patients. Surg Endosc. 2009; 23(7):1433-1440. 12. Le Pimpec-Barthes F, Gonzalez-Bermejo J, Hubsch JP, et al. Intrathoracic phrenic pacing: a 10-year experience in France. J Thorac Cardiovasc Surg. 2011;142(2):378-383. 13. Ragnarsson KT. Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions. Spinal Cord. 2008;46(4):255-274. 14. Hirschfeld S, Exner G, Luukkaala T, Baer GA. Mechanical ventilation or phrenic nerve stimulation for treatment of spinal cord injury-induced respiratory insufficiency. Spinal Cord. 2008;46(11):738-742. 15. Onders RP, Elmo MJ, Ignagni AR. Diaphragm pacing stimulation system for tetraplegia in individuals injured during childhood or adolescence. J Spinal Cord Med. 2007;30(suppl 1): S25-S29. 16. Adler D, Gonzalez-Bermejo J, Duguet A, et al. Diaphragm pacing restores olfaction in tetraplegia. Eur Respir J. 2009; 34(2):365-370. 17. Illinois Department of Healthcare and Family Services. Summary of private duty nursing: net liability in identified medical programs for state fiscal year 2010. Illinois Department of Healthcare and Family Services website. http://www2.illinois. gov/hfs/PublicInvolvement/ccmn/Documents/090811_ccmn_ ncps.pdf. Accessed March 12, 2013. 18. Hagglund KJ, Clark MJ, Mokelke EK, Stout BJ. The current state of personal assistance services: implications for policy and future research. NeuroRehabilitation. 2004;19(2):115-120. 19. Bolikal P, Bach JR, Goncalves M. Electrophrenic pacing and decannulation for high-level spinal cord injury: a case series. J Spinal Cord Med. 2012;35(3):170-174. 20. Gater DR Jr, Dolbow D, Tsui B, Gorgey AS. Functional electrical stimulation therapies after spinal cord injury. NeuroRehabilitation. 2011;28(3):231-248.
Counterpoint: Should Phrenic Nerve Stimulation Be the Treatment of Choice for Spinal Cord Injury? No incidence of long-term ventilator assistance in Thepatients with spinal cord injury (SCI) has increased
from 1990, rising to 43,700 cases per year in 1998 likely because of better available treatment plans.1 More than $8 billion per year is spent on SCI care in the United States after the first year of injury, and respiratory complications comprise the number one cause of morbidity and mortality in SCI.2 The majority of patients with SCI are male, aged , 30 years, and, as expected, the leading causes of death are pneumonia, pulmonary emboli, and septicemia. As of February 2011, the National Spinal Cord Injury Statistical Center3 estimated that 232,000 to 316,000 patients
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in the United States are living with SCI. Of the 12,000 new cases per year, . 2,700 patients with tetraplegia will require extended ventilator support. Ultimately, 2,000 will wean from ventilators, and 500 high tetraplegic injuries will result in permanent mechanical ventilator dependency. A prospective multicenter case series of SCI identified a 67% rate of respiratory complications primarily involving atelectasis, pneumonia, and ventilatory failure. This finding relates strongly to the cord level of injury, with respiratory complications occurring at rates of 84% in high cervical, C1 to C4 injury compared with a rate of 60% at level C5 to C8.4 Another study showed that the pulmonary complications that occurred in 36% of patients within the first month, including (in decreasing frequency) atelectasis, pneumonia, edema, pulmonary embolism, and aspiration, accounted for 11% of all mortality.5 The major factors associated with overall mortality were higher mean age in nonsurvivors (52 vs 28 years), lower FVC, the Pao2 in the pulmonary complication group, intubation rate, and tracheotomy. There is supporting evidence that intensive care management improves outcomes after SCI, and one can define key parameters for successful cardiopulmonary support and resuscitation.6 In addition, the use of aggressive secretion clearance devices, such as the insufflator-exsufflator, has been shown to be effective in assisting cough in patients with SCI, results in a significant increase in objective pulmonary function, and helps to inflate atelectatic areas, but these devices may still be underused.7,8 Ventilatory assistance with noninvasive ventilation (NIV) should be considered the first-line therapy of care, allowing for the patient’s condition to be managed at a reduced cost compared with an invasive means of support. An early study in patients with SCI demonstrated the benefit of NIV in all forms, including mouth assist and mask NIV, and 17 of the 23 patients were actually able to have their tracheostomy closed and sustained for years.9 Another study in 28 patients with SCI over a 4-year period showed that when NIV was used to prevent respiratory failure or wean-off ventilation, invasive ventilation was avoided in 10 of 17.10 The diaphragm pacing support (DPS) data that Dr Wolfe offers come from limited studies, most of which were by paid consultants of DPS manufacturers.11 A complete bibliography of studies for DPS is available online.12 From 2000 to 2007, 50 patients with SCI were reported to receive DPS implantations at five sites; of these patients, 96% were able to use the DPS system for ventilation, replacing their mechanical ventilators as early as 3 months after their injury.11 Ten deaths were also reported as shown in Table 1. The authors went on to state that the DPS system is safe and effective and that in Ohio, it would
Table 1—Complications and Deaths From Diaphragm Pacing Support Complications and Causes of Death
No.
Internal electrode failure Superficial wire infection that stopped pacing temporarily Cause of death Not device related Urosepsis Cardiac (elderly patient, patient with long-term injury) Endocarditis Complications from decubiti Systemic mastocytosis Aspiration sepsis Recurrence of tumor and sepsis
1 1 10 3 3 1 2 1 1 1
save $13,000 per patient per month compared with tracheostomy and mechanical ventilation (NIV not compared). They claimed that no patients stopped pacing and all would recommend it; thus, the authors concluded that “all patients with intact phrenic nerves should be offered diaphragm pacing to allow natural diaphragm breathing.”11 A study in France from 1997 to 2007 reviewed DPS use in 19 patients with posttraumatic tetraplegia who required full-time ventilation.13 The authors achieved ventilatory weaning in all but two patients after a median conditioning time of 6 weeks (2 weeks-11 months). These authors also concluded that DPS is safe and should be done as soon as orthopedic and neurologic issues are stable, but complications were not detailed, and limited long-term follow-up data were provided. However, there is a downside of DPS for some patients. DPS is strictly paced, so patients cannot initiate breathing, and most with SCI note that with about a 900-mL tidal breath and a respiratory rate set at 12 to 14/min, a Passy-Muir valve circuit (Passy-Muir Inc) allows almost continuous speech, but a DPS system usually will not.12 The elimination of the fear of disconnection from the mechanical ventilator is simply replaced by battery or pacer failure, so many DPS users with SCI need a backup, and the care plan may require two systems. Potential long-term risks of prolonged pacing always include electrode dislodgement and breakage. Complications have been more clearly reported elsewhere, which include the fact that laparoscopic surgery has some associated risks, such as the development of pneumothorax and subcutaneous emphysema that may require chest tube drainage.14 Sometimes, chest pain is associated with stimulation and possibly shoulder pain during the maximum stimulation that like occurs as a consequence of the stimulation of phrenic nerve afferents. One subject with rhinosinusitis prior to his injury but not present when receiving mechanical ventilation had this recur when nasal airflow was restored during diaphragmatic pacing.
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Point/Counterpoint Editorials
Another had intermittent food aspiration likely related to the large negative airway pressure generated during DPS stimulation, and the problem was only eliminated by maintaining the tracheostomy with use of a PassyMuir valve during meals. I concede that great advances in the placement and management of DPS systems for patients with SCI have been made. These patients may appreciate the ability to be freed from their ventilator dependence for part of the day, but it is not clearly superior to NIV. There is a speculative advantage that DPS may, in some patients, gradually condition and strengthen the diaphragm to allow for more subsequent independent ventilation, but proponents will argue that NIV will not do this, despite having no evidence. On the contrary, I contend that this procedure is unproven and not inexpensive, with many patients carrying a substantial out-of-pocket burden. NIV seems more appropriate until better data are available to support the widespread use of DPS in patients with SCI. Rapid extrapolation to other indications, such as amyotrophic lateral sclerosis and diaphragmatic failure in patients with ARDS, are being urged at the patient’s expense without good studies and will lead to similar debates. To conclude, there is an excellent parallel perspective in the National Emphysema Treatment Trial that arose because of overzealous acceptance of lung volume reduction surgery (LVRS).15 This resulted in a surge of charges to Medicare, and clear-headed thinkers demanded a National Institutes of Healthsponsored randomized trial to prove efficacy. Despite the extensive study demonstrating that LVRS may result in benefit for selected patients, relatively few patients later underwent the procedure. By 2004, only 254 Medicare beneficiaries underwent LVRS at a limited number of approved centers, and between 2005 and 2006, only 225 Medicare beneficiaries underwent LVRS. Specific reasons for the underperformance of LVRS have been suggested and include restricting LVRS performance to certain centers and a perceived overly complicated assessment. Many physicians still remain unaware of the benefits of LVRS and what characterizes an appropriate patient candidate, and LVRS is perceived by many in the medical community as too costly. Sound familiar? The reader needs to discern which argument can support or refute the concept that DPS therapy has enough solid long-term outcome evidence to justify it as first-line therapy. I contend that we must demand more well-designed prospective outcome trials before we take the apparent dive into the alluring pool of unproven new technology. Peter C. Gay, MD, FCCP Rochester, MN
Affiliations: From the Mayo Clinic. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. The data in this article were presented in a pro-vs-con debate at CHEST 2011; October 22-26, 2011; Honolulu, HI. Correspondence to: Peter C. Gay, MD, FCCP, Mayo Clinic, 200 First St SW, Rochester, MN 55905; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.13-0219
References 1. Carter RE, Donovan WH, Halstead L, Wilkerson MA. Comparative study of electrophrenic nerve stimulation and mechanical ventilatory support in traumatic spinal cord injury. Paraplegia. 1987;25(2):86-91. 2. DiMarco AF, Onders RP, Ignagni A, Kowalski KE. Inspiratory muscle pacing in spinal cord injury: case report and clinical commentary. J Spinal Cord Med. 2006;29(2):95-108. 3. National Spinal Cord Injury Statistical Center. Spinal cord injury facts and figures at a glance. The University of Alabama at Birmingham website. https://www.nscisc.uab.edu/Public Documents/nscisc_home/pdf/Facts%202011%20Feb%20Final. pdf. Accessed March 12, 2013. 4. Jackson AB, Groomes TE. Incidence of respiratory complications following spinal cord injury. Arch Phys Med Rehabil. 1994;75(3):270-275. 5. Reines HD, Harris RC. Pulmonary complications of acute spinal cord injuries. Neurosurgery. 1987;21(2):193-196. 6. Casha S, Christie S. A systematic review of intensive cardiopulmonary management after spinal cord injury. J Neurotrauma. 2011;28(8):1479-1495. 7. Pillastrini P, Bordini S, Bazzocchi G, Belloni G, Menarini M. Study of the effectiveness of bronchial clearance in subjects with upper spinal cord injuries: examination of a rehabilitation programme involving mechanical insufflation and exsufflation. Spinal Cord. 2006;44(10):614-616. 8. Schmitt JK, Stiens S, Trincher R, et al. Survey of use of the insufflator-exsufflator in patients with spinal cord injury. J Spinal Cord Med. 2007;30(2):127-130. 9. Bach JR, Alba AS Noninvasive options for ventilatory support of the traumatic high level quadriplegic patient. Chest. 1990; 98(3):613-619. 10. Tromans AM, Mecci M, Barrett FH, Ward TA, Grundy DJ. The use of the BiPAP biphasic positive airway pressure system in acute spinal cord injury. Spinal Cord. 1998;36(7): 481-484. 11. Onders RP, Elmo MJ, Khansarinia S, et al. Complete worldwide operative experience in laparoscopic diaphragm pacing: results and differences in spinal cord injured patients and amyotrophic lateral sclerosis patients. Surg Endosc. 2009; 23(7):1433-1440. 12. Synapse Biomedical Inc. Phrenic nerve & diaphragm motor point stimulation bibliography. Synapse Biomedical Inc website. http://www.synapsebiomedical.com/support/PDFs/SCI_ Reimbursement/Synapse%20Bibliography%205%207%202012. pdf. Accessed March 12, 2013. 13. Le Pimpec-Barthes F, Gonzalez-Bermejo J, Hubsch JP, et al. Intrathoracic phrenic pacing: a 10-year experience in France. J Thorac Cardiovasc Surg. 2011;142(2):378-383. 14. DiMarco AF, Onders RP, Ignagni A, Kowalski KE, Mortimer JT. Phrenic nerve pacing via intramuscular diaphragm electrodes in tetraplegic subjects. Chest. 2005;127(2):671-678.
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15. Criner GJ, Cordova F, Sternberg AL, Martinez FJ. The National Emphysema Treatment Trial (NETT) part II: lessons learned about lung volume reduction surgery. Am J Respir Crit Care Med. 2011;184(8):881-893.
either mechanical ventilation or pacing. No one will be left untreated. We cannot hide from the costs in both dollars and quality of life. All of these patients will need to decide: ventilation or pacing? But will they all be offered the choice? Lisa F. Wolfe, MD, FCCP Chicago, IL
Rebuttal From Dr Wolfe
D
r Gay1 has shared some interesting points. Many of his arguments hinge on the assumption that all patients with tracheostomy and spinal cord injury (SCI) have the option of using an alternative to either mechanical ventilation or diaphragm pacing support (DPS). This alternative would be noninvasive ventilation (NIV) and aggressive airway clearance, including mechanical cough assist. In reality, those patients with SCI who do not require invasive mechanical ventilation are not even considered candidates for DPS. If even 4 h of spontaneous breathing is possible, DPS is excluded,2 and 24-h NIV when there is no use of hands is possible but may not be practical. Dr Gay1 also states that mechanical ventilation with a PassyMuir valve (Passy-Muir Inc) provides completely normal speech, but the use of a Passy-Muir valve may not be safe in all patients because of secretions that may obstruct the valve, and speech without the valve is unnatural because it occurs mainly during inhalation. In addition, many patients have an intolerance to the added resistance of the Passy-Muir valve, and fenestrated tubes are not an adequate compensation because they may promote aggressive leak compensation, even risking respiratory alkalosis and seizure. In the best of situations, leak speech using mechanical ventilation does not produce adequate speech.3 Many of Dr Gay’s points do not appropriately balance the risks. Device failure is an issue with both DPS and mechanical ventilation, but given that the battery life for a pacer is 500 h4 compared with the very common occurrence of disconnection or the insurmountable fear of electrical power outage, this comparison easily favors the DPS system. One patient’s rhinosinusitis cannot serve as a reason to deny all patients the ability to smell. One assertion that large tidal volumes cause aspiration is in contradiction to other data showing that lung volume recruitment improves the ability to swallow.5 Finally, it is important to remember that everyone would be in favor of a large North American trial for the DPS system, but Dr Gay’s allusion to the National Emphysema Treatment Trial is flawed. That trial’s final recommendation was to refer these many patients who do not benefit from lung volume reduction surgery for the more-expensive lung transplantation.6 The final global cost advantage comes only from the reality of a fixed number of organs, leaving most patients untreated. In the setting of SCI, all patients will receive
Affiliations: From the Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine. Financial/nonfinancial disclosures: The author has reported to CHEST the following conflicts of interest: ResMed in the area of complex apnea supported research, Hill-Rom and Philips Respironics for consulting in the area of airway clearance. The data in this article were presented in a pro-vs-con debate at CHEST 2011; October 22-26, 2011; Honolulu, HI. Correspondence to: Lisa F. Wolfe, MD, FCCP, Northwestern University, 675 N St Claire St, Ste 18-250, Chicago, IL 60611; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.13-0218
References 1. Gay PC. Counterpoint: should phrenic nerve stimulation be the treatment of choice for spinal cord injury? No. Chest. 2013;143(5):1203-1206. 2. Blue Cross Blue Shield Blue Care Network of Michigan. Phrenic nerve/diaphragm pacing. Blue Cross Blue Shield of Michigan website. http://www.bcbsm.com/mprApp/Medical PolicyDocument?fileId52047509. Effective November 1, 2012. Accessed March 4, 2013. 3. MacBean N, Ward E, Murdoch B, et al. Optimizing speech production in the ventilator-assisted individual following cervical spinal cord injury: a preliminary investigation. Int J Lang Commun Disord. 2009;44(3):382-393. 4. Synapse Biomedical Inc. Frequently asked questions (FAQs). Synapse Biomedical Inc website. http://www.synapsebiomedical. com/images/FAQ613.pdf. Accessed March 4, 2013. 5. Wheeler Hegland KM, Huber JE, Pitts T, Sapienza CM. Lung volume during swallowing: single bolus swallows in healthy young adults. J Speech Lang Hear Res. 2009;52(1):178-187. 6. Criner GJ, Cordova F, Sternberg AL, Martinez FJ. The National Emphysema Treatment Trial (NETT) part II: lessons learned about lung volume reduction surgery. Am J Respir Crit Care Med. 2011;184(8):881-893.
Rebuttal From Dr Gay
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r Wolfe1 and I2 have discussed whether a diaphragm pacing support (DPS) system is the treatment of choice for patients with spinal cord injury (SCI) in terms of technical aspects, costs, safety, ethics, and, most importantly, data to answer the primary question of what is the treatment of choice. We will further examine these arguments, beginning with the technical issues, but the emphasis must be on the available data and whether treatment outcome issues are completely clarified to this date. I again contend that
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Point/Counterpoint Editorials