Observational study of early diaphragm pacing in cervical spinal cord injured patients to decrease mechanical ventilation during the COVID-19 pandemic.

BACKGROUND: Decreasing the burden of mechanical ventilation for spinal cord injuries was never more relevant than during the COVID-19 pandemic. Data have shown diaphragm pacing can replace mechanical ventilation, decrease wean times, improve respiratory mechanics, and decrease hospital costs for patients with spinal cord injuries. This is the largest report of diaphragm pacing during the pandemic. METHODS: This is a retrospective analysis of prospective Institutional Review Board approved databases of nonrandomized interventional experience at a single institution. Subgroup analysis limited to traumatic cervical spinal cord injuries that were implanted laparoscopically with diaphragm electrodes within 30 days of injury. RESULTS: For the study group of early implanted traumatic cervical spinal cord injuries, 13 subjects were identified from a database of 197 diaphragm pacing implantations from January 1, 2020, to December 31, 2022, for all indications. All subjects were male with an average age of 49.3 years (range, 17-70). Injury mechanisms included falls (6), motor vehicle accident (4), gunshot wound (2), and diving (1). Time from injury to diaphragm pacing averaged 11 days (range, 3-22). Two patients are deceased and neither weaned from mechanical ventilation. Nine of the remaining 11 patients weaned from mechanical ventilation. Four patients never had a tracheostomy and 3 additional patients had tracheostomy decannulation. Three of these high-risk pulmonary compromised patients survived COVID-19 infections utilizing diaphragm pacing. CONCLUSION: Diaphragm pacing successfully weaned from mechanical ventilation 82% of patients surviving past 90 days. Forty-four percent of this group never underwent a tracheostomy. Only 22% of the weaned group required long term tracheostomies. Early diaphragm pacing for spinal cord injuries decreases mechanical ventilation usage and tracheostomy need which allows for earlier placement for rehabilitation.

Spinal cord injury level and Phrenic Nerve Conduction Studies do not predict diaphragm pacing success or failure- all patients should undergo diagnostic laparoscopy.

BACKGROUND: Diaphragm Pacing(DP) demonstrates benefits over mechanical ventilation(MV) for spinal cord injured(SCI) patients. The hypothesis of this report is that phrenic nerve conduction study(PNCS) results cannot differentiate success or failure in selection of patients for DP. Direct surgical evaluation of the diaphragm should be performed. METHODS: Observational report of prospective databases of patients undergoing laparoscopic evaluation of their diaphragms to assess for ability to stimulate to cause contraction for ventilation. RESULTS: In 50 SCI patients who could not be weaned from MV, PNCS results showed latencies in stimulated patients (n = 44) and non-stimulated(n = 6) overlapped (7.8 ± 2.5 ms vs 9.4 ± 2.8 ms) and the null hypothesis cannot be rejected (p-value>0.05). Amplitudes overlapped (0.4 ± 0.2 mV vs 0.2 ± 0.2 mV) and the null hypotheses cannot be rejected (P-value >0.05). In 125 non SCI patients with diaphragm paralysis, there were 78(62.4%) with false negative PNCS. CONCLUSION: PNCS are inadequate pre-operative studies. Direct laparoscopic evaluation should be offered for all SCI patients to receive the benefit of DP.

Long-term experience with diaphragm pacing for traumatic spinal cord injury: Early implantation should be considered.

BACKGROUND: Cervical spinal cord injury can result in catastrophic respiratory failure requiring mechanical ventilation with high morbidity, mortality, and cost. Diaphragm pacing was developed to replace/decrease mechanical ventilation. We report the largest long-term results in traumatic cervical spinal cord injury. METHODS: In this retrospective review of prospective institutional review board protocols, all patients underwent laparoscopic diaphragm mapping and implantation of electrodes for diaphragm strengthening and ventilator weaning. RESULTS: From 2000 to 2017, 92 patients out of 486 diaphragm pacing implants met the criteria. The age at time of injury ranged from birth to 74 years (average: 27 years). Time on mechanical ventilation was an average of 47.5 months (range, 6 days to 25 years, median = 1.58 years). Eighty-eight percent of patients achieved the minimum of 4 hours of pacing. Fifty-six patients (60.8%) used diaphragm pacing 24 hours a day. Five patients had full recovery of breathing with subsequent diaphragm pacing removal. Median survival was 22.2 years (95% confidence interval: 14.0-not reached) with only 31 deaths. Subgroup analysis revealed that earlier diaphragm pacing implantation leads to greater 24-hour use of diaphragm pacing and no need for any mechanical ventilation. CONCLUSION: Diaphragm pacing can successfully decrease the need for mechanical ventilation in traumatic cervical spinal cord injury. Earlier implantation should be considered.

Completed FDA feasibility trial of surgically placed temporary diaphragm pacing electrodes: A promising option to prevent and treat respiratory failure.

BACKGROUND: Etiologies contributing to failure to wean from mechanical ventilation (MV) are multiple, resulting in morbid and costly outcomes. Diaphragm pacing (DP) is used in spinal cord injury to replace MV. Temporary DP could be utilized in acute respiratory failure to reduce MV. METHODS: A prospective FDA feasibility trial evaluated temporary DP electrodes implanted in each hemi-diaphragm during a subject's primary procedure. Objectives included: ability to provide ventilation, stability analysis with diaphragm electromyography, and adverse event monitoring. RESULTS: Twelve patients underwent successful implantation via median sternotomy, laparoscopy or laparotomy. Electrode stimulation exceeded ideal tidal volumes by an average of 37% (0%-95%) confirming ability to prevent atrophy. Daily electromyography confirmed stability of placement and was useful in evaluating hypoventilation. There were no complications and all 48 study electrodes remained intact until complete removal. CONCLUSION: This trial demonstrates ease of placement, removal, functionality and safety of temporary DP electrodes which therapeutically decreases diaphragm atrophy.

Identification of unexpected respiratory abnormalities in patients with amyotrophic lateral sclerosis through electromyographic analysis using intramuscular electrodes implanted for therapeutic diaphragmatic pacing.

BACKGROUND: Amyotrophic lateral sclerosis patients have significant respiratory abnormalities with incomplete understanding of respiratory control. This study analyzes electromyography (EMG) of the diaphragm (dEMG) using implanted diaphragm pacing (DP) electrodes. METHODS: Retrospective analysis of dEMG data were obtained during Institutional Review Board and US Food and Drug Administration approved trials. The electrodes were used to analyze epochs of dEMG during multiple respiratory cycles. RESULTS: Fifty-three patients were implanted. Thirty-six had bilateral dEMG assessments, 18 had continuous overnight readings with pulse oximetry, and 19 had serial analysis. Several findings revealed an alteration in the central respiratory drive including central apnea, hypoventilation, and hypercarbia. The electrodes showed unilateral dysfunction and demonstrated noninvasive ventilation suppression of diaphragm activity. DP can be used for serial monitoring, to decrease hypercarbia, improve sleep, and decrease atrophy. CONCLUSIONS: Multiple abnormalities of respiratory control can be seen in amyotrophic lateral sclerosis patients using dEMG through therapeutic DP electrodes. DP is used to overcome instability of respiratory control when there are intact diaphragm motor units leading to improved survival.

Extended use of diaphragm pacing in patients with unilateral or bilateral diaphragm dysfunction: a new therapeutic option.

BACKGROUND: Diaphragm dysfunction (DD) can cause sleep abnormalities, dyspnea, atelectasis, and respiratory failure. Historical treatments, including positive pressure ventilation or diaphragm plication, may alleviate symptoms but do not restore physiologic diaphragm function. Diaphragm pacing (DP) is approved for spinal cord-injured patients and in amyotrophic lateral sclerosis. We report a series of DD patients undergoing use of DP outside of these initial indications. METHODS: This report involves a prospective, nonrandomized, interventional trial under institutional review board approval at a single institution. DP involves laparoscopic motor point mapping with implantation of intramuscular electrodes in each hemidiaphragm. Postoperatively, diaphragm conditioning ensues. RESULTS: Twenty-seven patients were evaluated; all patients had symptomatic and objective hypoventilation for an average of 36 months of symptoms. Causes included idiopathic (n = 13), chest surgery (n = 5), shoulder surgery or trauma (n = 6), and others (n = 3); 17 had bilateral involvement, 6 had nonstimulable diaphragms and were not implanted, and 21 were implanted. Thirteen (62%) had substantial clinically relevant respiratory improvements. Four ventilator patients were weaned completely. Four had partial improvement, 3 had no improvement, and 1 patient was lost to follow-up for objective analysis. CONCLUSION: This is the first report of DP being used to treat diverse causes of DD. Eighty-one percent of implanted patients experienced improvements. This success suggests a potential for a wider use of DP and areas for future research.

Final analysis of the pilot trial of diaphragm pacing in amyotrophic lateral sclerosis with long-term follow-up: diaphragm pacing positively affects diaphragm respiration.

BACKGROUND: Respiratory insufficiency is the major cause of mortality in patients with amyotrophic lateral sclerosis or Lou Gehrig's disease. This is the final report of the diaphragm pacing (DP) pilot trial. METHODS: Patients underwent laparoscopic diaphragm electrode implantations and subsequent conditioning of diaphragms. Serial respiratory function tests were performed in the initial year and followed until death. RESULTS: Sixteen patients were implanted with no perioperative or unanticipated device-related adverse events. There were 452 implant-months of follow-up. DP allowed greater movement of the diaphragm under fluoroscopy, increased muscle thickness, and decreased the decline in forced vital capacity. Median survival from implant was 19.7 months with the cause of death respiratory in only 31%. CONCLUSIONS: Long-term analysis of DP in amyotrophic lateral sclerosis showed no safety issues and can positively influence diaphragm physiology and survival. This formed the initial basis for subsequent US Food and Drug Administration approval.

First reported experience with intramuscular diaphragm pacing in replacing positive pressure mechanical ventilators in children.

PURPOSE: Diaphragm pacing (DP) has been shown to successfully replace mechanical ventilators for adult tetraplegic patients with chronic respiratory insufficiency. This is the first report of DP in ventilator-dependent children. METHODS: This was a prospective interventional experience under institutional review board approval. Diaphragm pacing involves outpatient laparoscopic diaphragm motor point mapping to identify the site where stimulation causes maximum diaphragm contraction with implantation of 4 percutaneous intramuscular electrodes. Diaphragm conditioning ensues to wean the child from the ventilator. RESULTS: Six children were successfully implanted ranging from 5 to 17 years old with the smallest 15 kg in weight. Length of time on mechanical ventilation ranged from 11 days to 7.6 years with an average of 3.2 years. In all patients, DP provided tidal volumes above basal needs. Five of the patients underwent a home-based weaning program, whereas one patient who was implanted only 11 days post spinal cord injury never returned to the ventilator with DP use. Another patient was weaned from the ventilator full time but died of complications of his underlying brain stem tumor. The remaining patients weaned from the ventilator for over 14 hours a day and/or are actively conditioning their diaphragms. CONCLUSION: Diaphragm pacing successfully replaced mechanical ventilators, which improves quality of life.

Amyotrophic lateral sclerosis: the Midwestern surgical experience with the diaphragm pacing stimulation system shows that general anesthesia can be safely performed.

BACKGROUND: There is a paucity of literature concerning general anesthesia and surgery in patients with amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). This report summarizes the largest series of surgical cases in ALS during multicenter prospective trials of the laparoscopic diaphragm pacing system (DPS) to delay respiratory failure. METHOD: The overall strategy outlined includes the use of rapidly reversible short-acting analgesic and amnestic agents with no neuromuscular relaxants. RESULTS: Fifty-one patients were implanted from March 2005 to March 2008 at 2 sites. Age at implantation ranged from 42 to 73 years and the percent predicted forced vital capacity (FVC) ranged from 20% to 87%. On preoperative blood gases, Pco(2) was as high as 60. Using this protocol, there were no failures to extubate or 30-day mortalities. The DPS system increases the respiratory system compliance by decreasing posterior lobe atelectasis and can stimulate respirations at the end of each case. CONCLUSIONS: Laparoscopic surgery with general anesthesia can be safely performed in patients with ALS undergoing DPS.

Complete worldwide operative experience in laparoscopic diaphragm pacing: results and differences in spinal cord injured patients and amyotrophic lateral sclerosis patients.

BACKGROUND: Diaphragm movement is essential for adequate ventilation, and when the diaphragm is adversely affected patients face lifelong positive-pressure mechanical ventilation or death. This report summarizes the complete worldwide multicenter experience with diaphragm pacing stimulation (DPS) to maintain and provide diaphragm function in ventilator-dependent spinal cord injury (SCI) patients and respiratory-compromised patients with amyotrophic lateral sclerosis (ALS). It will highlight the surgical experiences and the differences in diaphragm function in these two groups of patients. METHODS: In prospective Food and Drug Administration (FDA) trials, patients underwent laparoscopic diaphragm motor point mapping with intramuscular electrode implantation. Stimulation of the electrodes ensued to condition and strengthen the diaphragm. RESULTS: From March of 2000 to September of 2007, a total of 88 patients (50 SCI and 38 ALS) were implanted with DPS at five sites. Patient age ranged from 18 to 74 years. Time from SCI to implantation ranged from 3 months to 27 years. In 87 patients the diaphragm motor point was mapped with successful implantation of electrodes with the only failure the second SCI patient who had a false-positive phrenic nerve study. Patients with ALS had much weaker diaphragms identified surgically, requiring trains of stimulation during mapping to identify the motor point at times. There was no perioperative mortality even in ALS patients with forced vital capacity (FVC) below 50% predicted. There was no cardiac involvement from diaphragm pacing even when analyzed in ten patients who had pre-existing cardiac pacemakers. No infections occurred even with simultaneous gastrostomy tube placements for ALS patients. In the SCI patients 96% were able to use DPS to provide ventilation replacing their mechanical ventilators and in the ALS studies patients have been able to delay the need for mechanical ventilation up to 24 months. CONCLUSION: This multicenter experience has shown that laparoscopic diaphragm motor point mapping, electrode implantation, and pacing can be safely performed both in SCI and in ALS. In SCI patients it allows freedom from ventilator and in ALS patients it delays the need for ventilators, increasing survival.

Phrenic nerve conduction studies in spinal cord injury: applications for diaphragmatic pacing.

The diaphragm pacing system (DPS) is a minimally invasive alternative to mechanical ventilation in patients with quadriplegia due to cervical myelopathy primarily caused by high cervical spinal cord injury. We evaluated 36 patients, 29 of whom had traumatic spinal cord injury, two who had a history of remote meningitis and demyelinating disease, and five who had cervical myelopathies of unknown etiology. Phrenic nerve conduction studies were performed with simultaneous fluoroscopic observation of diaphragm excursion to assess diaphragm viability. In the preoperative evaluation, diaphragm compound muscle action potentials (CMAPs) were recorded only when the diaphragm moved on fluoroscopy with ipsilateral stimulation. Twenty-six patients who were determined to have a viable diaphragm underwent DPS. Following DPS the primary outcome was the time (hours per day) that patients were able to pace and stay off the ventilator. Of 26 implanted patients, 96% (25 patients) were able to pace and tolerate being off the ventilator for more than 4 h per day. This study demonstrates that the presence of a diaphragm CMAP is associated with diaphragm movement observed by fluoroscopy in cervical myelopathy. In addition, DPS can help patients with cervical spinal cord injury to breathe unassisted by a ventilator.