Anthony R. Ignagni

Natural orifice transluminal endoscopic surgery (NOTES) as a diagnostic tool in the intensive care unit

BackgroundAutopsy studies confirm that many intensive care unit (ICU) patients die from unrecognized sources of abdominal sepsis or ischemia. Computed tomography (CT) scans can be of limited use for these diagnoses and difficult to obtain in critically ill patients who require significant support for transport. Bedside laparoscopy has been described but still is cumbersome to perform. Bedside flexible endoscopy as a diagnostic tool or for placement of gastrostomy tubes is a standard ICU procedure. Natural orifice transluminal endoscopic surgery (NOTES) can provide access to the peritoneal cavity as a bedside procedure and may decrease the number of patients with unrecognized intra-abdominal catastrophic events.MethodsPigs were anesthetized and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery, and balloon dilatation. The transgastric endoscope was used to explore all quadrants of the abdominal cavity. The small bowel was visualized to complete the exploration. The transgastric access location was then managed with the use of a gastrostomy tube. The animals were euthanized and analyzed.ResultsEight pigs were studied and complete abdominal exploration, including diaphragm visualization, was possible in all cases. Endoscopy-guided biopsies were performed, adhesions lysed, and the gallbladder successfully drained percutaneously. The small bowel was run successfully with percutaneous needlescopic suture graspers.ConclusionsThese animal studies support the concept that NOTES, with management of the gastric opening with a gastrostomy tube, may be another approach for finding unrecognized sources of abdominal sepsis or mesenteric ischemia in difficult ICU patients. These encouraging results warrant a prospective human trial to assess safety and efficacy.

Diaphragm pacing stimulation system for tetraplegia in individuals injured during childhood or adolescence.

Abstract Background: Children with cervical spinal cord injury and chronic respiratory insufficiency face the risks and stigma associated with mechanical ventilators. The Diaphragm Pacing Stimulation (DPS) System for electrical activation of the diaphragm is a minimally invasive alternative to mechanical ventilation. Methods: Review of patients in a prospective Food and Drug Administration trial of the DPS System in individuals who were injured at age 18 years or younger. The procedure involved laparoscopic mapping to locate the diaphragm motor points with electrode implantation. Two weeks after surgery, stimulus/output characteristics of each electrode were determined to obtain an adequate tidal volume for ventilation. A home-based weaning protocol from the ventilator was used. Results: Of 28 patients implanted with the DPS System, 10 had sustained cervical SCI as children or adolescents. Average age at injury was 13 years (range 1.5 to 17 y). Age at implantation ranged from 18 to 34 years. Length of time from injury to implantation averaged 9.7 years (0.8 to 19y). All patients tolerated the implantation procedure. Four patients utilize DPS continuously (24/7), 4 patients pace daytime only, and 2 patients are still actively conditioning their diaphragms. Two patients required surgical correction of scoliosis prior to implantation. All patients prefer breathing with the DPS and would recommend it to others; 4 patients specifically identified that attending college or church without a ventilator eases their integration into society. Conclusions: The results show that the laparoscopic DPS system can be safely implanted in tetraplegics injured as children and used in a home-based environment to wean them off of mechanical ventilation.

Inspiratory Muscle Pacing in Spinal Cord Injury: Case Report and Clinical Commentary

Abstract Background/Objective: A significant fraction of patients with cervical spinal cord injury suffer from respiratory muscle paralysis and dependence on chronic mechanical ventilation. In selected patients, diaphragm pacing (DP) through electrical stimulation of the phrenic nerves provides an alternative to mechanical ventilation with significant advantages in life quality. Methods: A case report of an individual who successfully underwent DP using intramuscular diaphragm electrodes. A brief review of the state of the art of DP including the clinical benefits of DP, patient selection and evaluation, description of equipment, methods of transition from mechanical ventilation to DP, potential complications and side effects, long-term outcome, and potential future developments in this field is included. Results: Several available DP systems are available, including conventional ones in which electrodes are positioned directly on the phrenic nerves through thoracotomy and less invasive systems in which electrodes are placed within the diaphragm through laparoscopy. For patients with only unilateral phrenic nerve function, a combined intercostal and unilateral diaphragm pacing system is under development. Conclusions: In patients with ventilator-dependent tetraplegia, there are alternative methods of ventilatory support, which offer substantial benefits compared to mechanical ventilation.

Diaphragm pacing improves sleep in patients with amyotrophic lateral sclerosis

Abstract In amyotrophic lateral sclerosis (ALS) patients, respiratory insufficiency is a major burden. Diaphragm conditioning by electrical stimulation could interfere with lung function decline by promoting the development of type 1 muscle fibres. We describe an ancillary study to a prospective, non-randomized trial (NCT00420719) assessing the effects of diaphragm pacing on forced vital capacity (FVC). Sleep-related disturbances being early clues to diaphragmatic dysfunction, we postulated that they would provide a sensitive marker. Stimulators were implanted laparoscopically in the diaphragm close to the phrenic motor point in 18 ALS patients for daily conditioning. ALS functioning score (ALSFRS), FVC, sniff nasal inspiratory pressure (SNIP), and polysomnographic recordings (PSG, performed with the stimulator turned off) were assessed before implantation and after four months of conditioning (n = 14). Sleep efficiency improved (69 ± 15% to 75 ± 11%, p = 0.0394) with fewer arousals and micro-arousals. This occurred against a background of deterioration as ALSFRS-R, FVC, and SNIP declined. There was, however, no change in NIV status or the ALSFRS respiratory subscore, and the FVC decline was mostly due to impaired expiration. Supporting a better diaphragm function, apnoeas and hypopnoeas during REM sleep decreased. In conclusion, in these severe patients not expected to experience spontaneous improvements, diaphragm conditioning improved sleep and there were hints at diaphragm function changes.

Peripheral Hyperstimulation Alters Site of Disease Onset and Course in SOD1 Rats

In amyotrophic lateral sclerosis (ALS), the exogenous temporal triggers that result in initial motor neuron death are not understood. Overactivation and consequent accelerated loss of vulnerable motor neurons is one theory of disease initiation. The vulnerability of motor neurons in response to chronic peripheral nerve hyperstimulation was tested in the SOD1(G93A) rat model of ALS. A novel in vivo technique for peripheral phrenic nerve stimulation was developed via intra-diaphragm muscle electrode implantation at the phrenic motor endpoint. Chronic bilateral phrenic nerve hyperstimulation in SOD1(G93A) rats accelerated disease progression, including shortened lifespan, hastened motor neuron loss and increased denervation at diaphragm neuromuscular junctions. Hyperstimulation also resulted in focal decline in adjacent forelimb function. These results show that peripheral phrenic nerve hyperstimulation accelerates cell death of vulnerable spinal motor neurons, modifies both temporal and anatomical onset of disease, and leads to involvement of disease in adjacent anatomical regions in this ALS model.

A Preliminary Feasibility Study of Different Implantable Pulse Generators Technologies for Diaphragm Pacing System

Diaphragm pacing stimulation (DPS) for ventilator‐dependent patients provides several advantages over conventional techniques such as phrenic nerve pacing or mechanical ventilator support. To date, the only existing system for DPS uses lead electrodes, percutaneously attached to an external pulse generator (PG). However, for a widespread use of this technique it would be more appropriate to eliminate the need for percutaneous wire and use a totally implantable system. The aim of this study was to determine if it were feasible to replace the external PG by an implantable system. We present here the results of a preliminary study of two different PG, currently used in other electrical stimulation (ES) clinical applications, which could be used as implantable DPS systems. One radio‐frequency‐powered PG, one rechargeable battery‐powered PG, and the current external PG were tested. Each was attached to the externalized part of the wires, connected to the diaphragm and tidal volume (TV) was measured in one ventilator‐dependent patient who has been using the current percutaneous stimulator for 3 years. Results indicated that both implantable PGs could achieve equivalent ventilatory requirements to the current external stimulator. No significant differences were observed between the three PG systems when stimulating the electrodes as used in the patients own chronically attached PG system. We found that TV increased with increases in charge and frequency as expected when stimulating the patients electrodes individually and in combination with each PG system. These results are a significant step toward developing a totally implantable DPS system for the ventilator‐dependant patients. Further clinical tests to demonstrate the safety and efficacy of a fully implanted DPS system are warranted.