Difficult Decisions in Thoracic Surgery - part 8 pptx

360 M. Alifano 44.2. Surgical Technique Morrison published a report of the fi rst surgical repair in 1923. 22 Since this initial description, different surgical techniques have been proposed. Plication can be carried out by thoracic or abdominal access; open surgery or video-assisted techniques have been proposed. 44.2.1. Open Approaches It is generally believed that a phrenic nerve injury complicating cardiac surgery in children, if rec- ognized intraoperatively, should prompt immediate plication through the sternotomy. 1,13 There is no consensus or suffi cient data about plication in similar circumstances in adults. In any other setting sternotomy is obviously not an option. A midline laparotomy has been employed in cases of bilateral diaphragmatic elevation or infracardiac involvement, although such an approach is occasionally employed in case of pure unilateral diaphragmatic elevation. 1 The exception is represented by patients with diaphragmatic eventration associated with an intra- abdominal disease requiring surgery. In these cases laparotomy is adequate in dealing with both conditions. 23 Transthoracic plication has been generally performed by a standard posterolateral thoracotomy. Simple plication is generally employed because it is faster and avoids entry into the peritoneal cavity. The technique described by Schwartz and Filler 24 (sometimes slightly modi- fi ed) is usually employed: the slack portion of the diaphragm is pulled in a radial direction and pleats are created by full-thickness nonabsorb- able mattress sutures. The surgeon should aim at repositioning the dome of the diaphragm one or two intercostal spaces below where it should ulti- mately be located. The more frequently employed alternative technique is represented by resection of the excess aponeurotic portion of the diaphragm with a two-layer overlapping approximation of peripheral muscle. This technique offers the advantage of avoiding inadvertent injury to abdominal organs but it involves the frequent section of phrenic nerve branches. Cases of suture dehis- cence have been reported. 1 Repair of congenital eventration in children may present some challenges: a possibly associated pulmonary sequestration should be resected and the possible absence of the medial component of the diaphragm may be corrected by using the diaphragmatic portion of the pericardium rather than a prosthetic material. Furthermore, if abdominal organs cannot be reduced in the peritoneal cavity, creation of a temporary ventral hernia may be performed. 1 44.2.2. Video-Assisted Thoracic Surgery In 1996, Mouroux and colleagues 18 proposed plication through a video-assisted thoracic surgery (VATS) approach. Two 5-mm thoracic ports and a 4-cm minithoracotomy in the ninth intercostal space were employed. In the majority of cases no rib retraction is necessary. The apex of the eventration is invaginated into the abdomen, thus creating a transverse fold from the periphery to the cardio- phrenic angle behind the prenic nerve. This fold is closed by two superposed series of transverse back- and-forth continuous sutures with a nonresorbable material. This fi rst suture allows the surgeon to maintain the excess of diaphragm within the abdomen; the second row of stitches is inserted through more peripheral portions of diaphragm in order to obtain the desired tension. Since the initial publication of Mouroux and colleagues, other authors reported their experience with the same or very similar techniques. 25,26 Several reports and some series have reported on the experiences of different centers in both adult and pediatric patients. Van Smith 26 successfully treated a newborn weighting 3 kg. Totally endo- scopic approaches have also been described. 7,27 The obvious advantage of VATS methods over open surgery is the minimal invasiveness which would facilitate postoperative recovery and respiratory muscle retraining. Plication should be carried out by transthoracic approach in the absence of indication for an abdominal approach (bilateral or infracardiac involvement, associated intra-abdominal disease; level of evidence 4; recommendation grade C). Plication for eventration is technically feasible by VATS; the operation is bloodless and rapid, and the desired tension can be applied to the plicated diaphragm (level of evidence 4). 44. Plication for Diaphragmatic Eventration 361 44.3. Results The results expected from plication are obviously different depending on the clinical context. As stated earlier in this chapter, children often undergo plication because of congenital or acquired elevation of the diaphragm that is responsible for serious respiratory impairment, and the goal of the operation is in most cases weaning from mechanical ventilation. In adulthood, respiratory function is generally much less compromised, and surgery is indicated to improve dyspnea or digestive symptoms. 44.3.1. Childhood 44.3.1.1. Postoperative Outcome There are several studies evaluating the outcome of pediatric patients treated by diaphragmatic plication, generally for phrenic nerve injury. They are summarized in Table 44.1. These studies aimed at evaluating operative mortality, the impact of the procedure on weaning patients from respiratory support, and, in some cases, improvement in clinical and/or radiologic status. In the retrospective series by Tsugawa and colleagues 11 dealing with 25 children with phrenic nerve injury treated by thoracotomy and plication, weaning from respiratory support (mechanical ventilation or supplemental oxygen) was possible in a short period (0–6 days) in 15/17 patients; the two failures were managed by redo plication that was successful in one instance. In the same study, 25 other patients underwent plication for congenital eventration and 4 of them were mechanically ventilated prior to operation; weaning was possible in all the cases from 1 to 61 days postoperatively. Similar results are reported in the retrospective study by Simansky and colleagues. 7 Among the 10 children with postsurgical phrenic nerve injury responsible for respiratory failure and treated by open plication, 7 could be weaned from mechanical ventilation (within 8 days in 6 cases). The remaining three died in spite of a radiographically successful plication, mainly because of intracta- ble underlying cardiac disease. No deaths were reported in the series by Tonz and coworkers, 15 who operated on 11 out of 25 patients with postsurgical phrenic nerve injury (the remaining patients were managed nonoperatively), because of failure to wean from mechanical ventilation or respiratory distress after extubation. Weaning was possible in all the cases (in all but two patients within a week) and respiratory distress could be managed successfully in all the cases. Plication should be carried out by transthoracic approach in the absence of indication for an abdominal approach (bilateral or infracardiac involvement, associated intra-abdominal disease) (level of evidence 4; recommendation grade C). Plication for eventration is technically feasible by VATS; the operation is bloodless and rapid, and the desired tension can be applied to the plicated diaphragm (level of evidence 4; recommendation grade C). TABLE 44.1. Outcome of plication in children. Weaning Overall Mortality Duration of from Year of Period Design No. of operative related to follow-up respiratory Radiological Clinical Reference publication of study of study patients mortality plication (years) support improvement improvement Tonz 15 1996 1983–1992 Retrospective 11 0/11 0/11 3.2 (mean) 11/11 10/11 9/9 Tzugawa 11 1997 1971–1996 Retrospective 25 5/25 0/25 1–25 – 20/20 20/20 De Vries 14 1998 1986–1997 Retrospective 14 0/14 0/14 – 9/9 – 14/14 De Leeuw 13 1999 1985–1997 Retrospective 68 4/68 0/68 – 49/50 – – Simansky 7 2002 1988–2000 Retrospective 10 3/10 0/10 – 7/7 a – – Hines 9 2003 – Retrospective 5 0/5 0/5 – 2/2 5/5 5/5 Joho- 2005 1996–2000 Retrospective 29 8/29 0/29 1 – 13/21 – Arreola 10 a Not taking into account operative mortality. 362 M. Alifano A more consistent experience, albeit retrospective, can be drawn from the study by de Leeuw and associates, 13 also dealing with postsurgical phrenic nerve paralysis. In their experience 40% of 170 children with this condition underwent open plication. The indication for operation was respiratory insuffi ciency in almost all of the cases, with most patients being mechanically ventilated at the time of plication. The median time to fi nal extubation after plication was 4 days, with a range of 1 to 65 days. Multivariate analysis showed that independent factors associated with a longer time to extubation were bilateral paralysis and a longer interval from the initial operation to diagnosis. There were 4 in- hospital deaths, but none of these was considered related to the procedure. As in all the other above- mentioned pediatric series, all the deaths were considered secondary to underlying diseases. Further evidence that the plication per se is not associated with mortality or major morbidity is provided by the experience of de Vries Reillingh and colleagues, 14 who performed the operation with an open approach in 13 patients with phrenic nerve injury, in almost all the cases resulting from an obstetrical trauma (therefore with no associated cardiac or pulmonary malformations). Respiratory distress requiring mechanical ventilation was present in most cases. Dramatic improvement was observed in all the patients, with discontinuation of mechanical ventilation possible within a few days and return to normal gas values in all the cases. A small series of diaphragmatic plication in children by VATS has been recently published. 9 The authors reported on fi ve children weighing 3.2 to 13.2 kg with congenital or postsurgical diaphragmatic eventration responsible for re - spiratory insuffi ciency or recurrent respiratory infections. Satisfactory clinical and radiologic results were observed in all the cases. In particular, weaning from mechanical ventilation was achieved within 3 days in both patients undergo- ing surgery for this indication. 44.3.1.2. Long-term Outcome In some surgical series of pediatric patients, information about long-term follow-up is available. Tonz and colleagues 15 reported no late death related to diaphragmatic paralysis and good radiologic results in 10 out of 11 patients. No children had respiratory symptoms at late follow-up. Similarly, Tsugawa and coworkers 11 observed fully satisfactory clinical and radiologic results in all the patients available at follow-up after plication for either phrenic nerve injury or congenital eventration. On the other hand, in the study by Joho-Arreola and associates, 10 6 out of 21 patients had elevated diaphragm at 1-year follow- up; unfortunately, the percentage of patients with respiratory symptoms in that study is not stated. Overall, diaphragmatic elevation secondary to phrenic nerve injury in children may be satisfac- torily managed by plication: in almost all the instances weaning from respiratory support is possible, in many instances within a short delay. Mortality is generally related to the underlying disease and not to the operation itself. Similarly, long-term outcome is fi xed by the possibly associated comorbidities, as the operation allows a permanent improvement of respiratory function (level of evidence 4). 44.3.2. Adulthood As adults with unilateral diaphragmatic elevation generally present with mild respiratory insuffi ciency, weaning from mechanical ventilation is a rare indication for plication. In the recent prospective study by Mouroux and coworkers, 4 the operation (by video-assisted surgery) was performed for this indication in only two patients and both were successfully weaned within 1 week. In contrast, only one among the four mechanically ventilated patients in the series by Simanski and colleagues 7 (dealing with patients with phrenic nerve injury) could be weaned. When the operation is performed because of less severe respiratory symptoms or because of digestive problems, satisfactory results are uni- formly observed (Table 44.2). In the above- mentioned retrospective study by Simanski and colleagues, all of the seven nonventilated patients experienced an improvement of ATS dyspnea score of 2 or 3 levels at their 3-month re-evaluation. At long-term follow-up (11–114 months), all were completely asymptomatic from a respiratory point of view [7]. 44. Plication for Diaphragmatic Eventration 363 In the experience of Graham and coworkers dealing with 17 patients treated by thoracotomy and plication between 1979 and 1989, improvement was observed in all the patients in both subjective (dyspnea score) and objective measurements. In particular, the operation resulted in signifi cant improvement in terms of postoperative forced vital capacity (FVC), total lung capacity (TLC), diffusing capacity of carbon monoxide (DLCO), PO 2 , and PCO 2 . These satisfactory results were still present in all the six patients who could be reassessed at long-term (>5 years) follow-up. 17 In the retrospective study by Ribet and Linder, 12 9 out of 11 patients were persistently asymptomatic after the operation (3 months–18 years follow- up), 1 was mildly dyspneic, and 1 had persistent digestive symptoms. Of note, chest X rays showed a persistently elevated (though at a lesser extent) diaphragm in fi ve cases. In this study only fi ve patients had both preoperative and postoperative functional assessment, and an improvement in both FVC and forced expiratory volume in 1 s (FEV 1 ) was observed in all the cases. In the prospective study of Nice University Hospital dealing with 12 adult patients treated by video-assisted plication for diaphragmatic elevation of miscellaneous origin (post-traumatic in most instances), 4 all the patients experienced a complete disappearance of symptoms shortly after the operation and no radiologic relapse was observed at a follow-up of more than 64 months. A signifi cant improvement in both FEV 1 and FVC was observed at late spirometry in all the cases. Regardless of the surgical technique, diaphragmatic plication in nonventilated adult patients carries a low morbidity and a very low, if any, mortality (level of evidence 4). Functional results are fully satisfactory in almost all the cases, regardless of the surgical approach (level of evidence 4). Plication by VATS achieved results similar to those obtained by conventional surgery. 4 Unfor- tunately the rarity of eventration precludes the possibility of performing randomized studies to enable accurate comparisons. This technique can be proposed as an alternative to conventional plication through standard thoracotomy. References 1. Frechette E, Cloutier R, Deslauriers J. Congenital eventration and acquired elevation of the diaphragm. In: Shields TW, ed. General Thoracic Surgery. Chicago: Lippincott Williams & Wilkins; 2004:1537–1549. 2. Schumpelick V, Steinau G, Schluper I, Prescher A. Surgical embriology and anatomy of the diaphragm with surgical applications. Surg Clin North Am 2000;80:213–239. 3. Wright CD, Williams JG, Ogilvie CM, Donnelly RJ. Results of the diaphragm plication for unilateral diaphragmatic paralysis. J Thorac Cardiovasc Surg 1985;90:195–198. 4. Mouroux J, Venissac N, Leo F, Alifano M, Guillot F. Surgical treatment of diaphragmatic eventration using video-assisted thoracic surgery: a prospective study. Ann Thorac Surg 2005;79:308–312. 5. Clague HW, Hall DR. Effect of posture on lung volume: airway closure and gas exchange in hemi- diaphragmatic paralysis. Thorax 1979;34:523–526. 6. Dor J, Richelme H, Aubert J, Boyer R. L’éventration diaphragmatique. J Chir 1969;97:399–432. 7. Simansky DA, Paley M, Refaely Y, Yellin A. Dia- phragm plication following phrenic nerve injury: a comparison of paediatric and adult patients. Thorax 2002;57:613–616. 8. Huttl TP, Wichmann MW, Reichart B, Geiger TK, Schildberg FW, Meyer G. Laparoscopic diaphragmatic plication. Surg Endosc 2004;18:547–551. T ABLE 44.2. Outcome of plication in adults (nonventilated patients). Duration of Year of Period Design No. of Operative follow-up Improvement Reference publication of study of study patients mortality (years) Clinical Radiologic Functional Wright 3 1985 – Retrospective 7 0 0.3–4 7/7 7/7 7/7 Graham 17 1990 1979–1989 Retrospective 17 0 5–7 6/6 6/6 6/6 Ribet 12 1992 1968–1988 Retrospective 11 0/11 8.5 (mean) 9/11 6/11 5/5 Simansky 7 2002 1988–2000 Retrospective 7 0/7 7.3 (mean) 7/7 7/7 7/7 Higgs 16 2002 1983–1990 Retrospective 19 0/19 7–14 (n = 15) 14/15 14/15 15/15 Mouroux 4 2005 1992–2003 Prospective 10 0/10 6.3 (mean) 10/10 10/10 10/10 364 M. Alifano 9. Hines MH. Video-assisted diaphragm plication in children. Ann Thorac Surg 2003;76:234–236. 10. Joho-Arreola AL, Bauersfeld U, Stauffer UG, Baenziger O, Bernet V. Incidence and treatment of diaphragmatic paralyisis after cardiac surgery in children. Eur J Cardiothorac Surg 2005;27:53– 57. 11. Tsugawa C, Kimura K, Nishijima E, Muraji T, Yamaguchi M. Diaphragmatic eventration in infants and children. Is conservative treatment justifi ed? J Pediatr Surg 1997;32:1643–1644. 12. Ribet M, Linder JL. Plication of the diaphragm for unilateral eventration or paralysis. Eur J Cardio- thorac Surg 1992;6:357–360. 13. de Leeuw M, Williams JM, Freedom RM, Williams WG, Shemie SD, McCrindle BW. Impact of diaphragmatic paralysis after cardiothoracic surgery in children. J Thorac Cardiovasc Surg 1999;118: 510–517. 14. de Vries Reilingh TS, Koens BL, Vos A. Surgical treatment of diaphragmatic eventration caused by phrenic nerve injury in the newborn. J Pediatr Surg 1988;33:602–605. 15. Tonz M, von Segesser LK, Mihaljevic T, Arbenz U, Stauffer UG, Turina MI. Clinical implications of phrenic nerve injury after pediatric cardiac surgery. J Pediatr Surg 1996;31:1265–1267. 16. Higgs SM, Hussain A, Jackson M, Donnelly RJ, Berrisford RG. Long term results of diaphragmatic plication for unilateral diaphragmatic paralysis. Eur J Cardiothorac Surg 2002;21:294–297. 17. Graham DR, Kaplan D, Evans CC, Hind CRK, Donelly RJ. Diaphragm plication for unilateral diaphragmatic paralysis: a 10-year experience. Ann Thorac Surg 1990;49:248–252. 18. Mouroux J, Padovani B, Poirier NC, et al. Tech- nique for the repair of diaphragmatic eventration. Ann Thorac Surg 1996;62:905–907. 19. Pielher JM, Pairolero PC, Gracey DR, Bernatz PE. Unexplained diaphragmatic paralysis: a harbin- ger of malignant disease? J Thorac Cardiovasc Surg 1982;84:861–864. 20. Efthimiou J, Butler J, Benson MK, Westaby S. Bilateral diaphragm paralysis after cardiac surgery with topical hypothermia. Ann Thorac Surg 1991;52:1005–1008. 21. Deng Y, Byth K, Paterson H. Phrenic nerve injury associated with high free right internal mammary artery harvesting. Ann Thorac Surg 2003;76:459– 463. 22. Morrison JMW. Eventration of diaphragm due to unilateral phrenic nerve paralysis. Arch Radiol Electrother 1923;28:72–75. 23. Smyrniotis V, Arkadopoulos N, Kostopanagiotou G, Gamaletsos E, Pistioli L, Kostopanagiotou E. Combination of diaphragmatic plication with major abdominal surgery in patients with phrenic nerve palsy. Surgery 2005;137:243–245. 24. Schwartz MZ, Filler RM. Plication of the diaphragm for symptomatic phrenic nerve paralysis. J Pediatr Surg 1978;13:259–263. 25. Lai DTM, Paterson HS. Mini-thoracotomy for diaphragmatic plication with thoracoscopic assis- tance. Ann Thorac Surg 1999;68:2364–2365. 26. Van Smith C, Jacobs JP, Burke RP. Minimally inva- sive diaphragm plication in a infant. Ann Thorac Surg 1998;65:842–844. 27. Cherian A, Stewart RJ. Thoracoscopic repair of diaphragmlatic eventration. Pediatr Surg Int 2004; 20:872–874. 365 45 Pacing for Unilateral Diaphragm Paralysis Raymond P. Onders surgeries), and trauma. Although sniff tests and phrenic nerve conduction studies with fl uoroscopic observation can identify intact phrenic nerves, the negative results of these tests do not necessarily determine the extent or location of damage. Localized damage to the myelin sheath or acute edema will result in negative results and loss of central control of the diaphragm. Re- myelinization or resolution of the edema may occur over a number of days to years. 1 Diaphragm pacing for ventilatory support has been in use for over 30 years since fi rst reported by Glenn. 2 There are several diaphragm pacing systems available including the conventional ones in which phrenic nerve cuff electrodes are placed with staged bilateral thoracotomies. The cervical electrode placement while utilized in the past is discouraged for the following reasons: there is an accessory branch from the lower segment of the cervical spinal cord that joins the phrenic nerve trunk in the thorax so that neck stimulation may result in incomplete diaphragm activation; brachial plexus nerves are in close proximity and may be activated resulting in pain or undesirable movement; and neck movements can increase mechanical stress on the nerve/electrode system which may increase the risk of nerve injury. There have been recent reports of placing the system thorascopically. 3,4 Diaphragm pacing with direct phrenic nerve electrodes is underuti- lized because of the scope of the operation, risk of phrenic nerve injury, and theoretical concerns about using it 24 h/day. There is a more recent option that involves laparoscopic implantation of intramuscular electrodes at the motor point of Symptoms of unilateral diaphragmatic paralysis can range from sleep-related symptoms to exert ional dyspnea or orthopnea. At times unilateral diaphragm paralysis is found on routine chest radiograph alone when an elevated hemi- diaphragm is seen. Ventilatory failure will usually only result if there is bilateral diaphragmatic involvement. When diaphragmatic paralysis is suspected, confi rmatory testing is done by inspiratory fl uoroscopy (sniff test) and electromyography of the phrenic nerve. To determine if the conduction path of the phrenic nerve is intact from the cervical region to the diaphragm, the key test is fl uoroscopic visualization of the diaphragm with transcutaneous stimulation of the phrenic nerve in the neck. If the diaphragm moves during stimulation then the phrenic nerve is intact, but there is a disruption of the signal pathway from the respiratory center in the brain to the phrenic nerve causing the diaphragm not to function. With the use of fl uoroscopic visualization during stimulation, false-positive phrenic nerve conduction studies are virtually eliminated. However, because of diffi culties in locating the phrenic nerve in the cervical region there is a signifi cant potential for false-negative studies, especially in inexperienced hands. The most common causes of an intact phrenic nerve with diaphragm paralysis are high cervical spinal cord injury or central hypoventila- tion syndrome (CHS or Ondine’s Curse). In almost all of these cases the diaphragm paralysis is bilateral. Unilateral paralysis of the diaphragm usually involves a nonfunctioning phrenic nerve with the causes in decreasing order of frequency: idio- pathic, postsurgical (cardiac, neck, and thoracic 366 R.P. Onders the diaphragm. 5 This has been implanted in 18 spinal cord patients with excellent results. This is an outpatient operation with no risk of phrenic nerve injury and allows 24-h use with the longest patient continuing to pace full-time for over 5 years. In brief, this procedure involves laparoscopic mapping of the diaphragm to identify the motor point which is the area where a electrical stimulus can cause maximal contraction of the diaphragm. 6 Two electrodes are then placed on each hemi-diaphragm with a specially designed laparoscopic implant instrument (Synapse Bio- medical, Oberlin, OH) and tunneled externally to the power source. 7 Both the phrenic nerve cuff electrode system and the laparoscopic motor point diaphragm pacing stimulation system require an intact phrenic nerve. The conduction pathway is the phrenic nerve and if that is not intact none of the systems can deliver a stimulus to the target diaphragm muscle. Almost all causes of unilateral diaphragm paralysis in non-spinal-cord-injured patients involve a phrenic nerve that is nonfunctional, at least to some extent, below the cervical region. The medical literature describes nerve transfers to the phrenic nerve and use of a diaphragm pacing system 8 as an option in patients with an injured phrenic nerve. This procedure essentially involves the coaption of a proximal foreign nerve to the distal denervated nerve to reinnervate the latter by the donated axons. Cortical plasticity appears to play an important physiological role in the functional recovery of the reinnervated muscles. An independent electrical pacing system is necessary because the nerve that is transferred has no con- nection to the central respiratory system so it must be stimulated to cause independent diaphragm contraction to augment respiration. This chapter will review the extant evidence to assess whether diaphragm pacing is an option for patients with unilateral paralysis of the diaphragm when there is an intact phrenic nerve and when there is no intact nerve. 45.1. Available Evidence The initial review will assess the evidence of diaphragm pacing when there is diaphragmatic dysfunction but an intact phrenic nerve. Over the past 30 years, electrical activation of the phrenic nerves has been used to provide artifi cial ventilation in patients with chronic respiratory insuffi - ciency. Despite their clinical effectiveness, their use has been limited to a carefully selected group of patients with bilateral diaphragmatic dysfunction and intact phrenic nerves. The benefi ts of diaphragm pacing have been well described in large series and include: decreased barotrauma with the use of natural negative pressure ventilation with their own diaphragm; increased mobil- ity without need for ventilator; improved speech; improved olfactory sensation; and decreased risk for pulmonary infection. 9–14 In some of the early series, diaphragm pacing was considered successful for ventilatory support in only 50% of patients. 11,15,16 These early studies are not refl ec- tive of the modern-day experience with diaphragm pacing, as the technology and patient selection methods were not well defi ned. There have been few reports of modern-day success rates though several papers describe the use of diaphragm pacing for over 15 years. 17,18 Three commercial systems are in current use for trans-thoracic direct phrenic nerve stimulation: Avery Biomedical Devices (Commack, NY), Atrotech OY (Tampere, Finland), and Medim- plant Biotechnisches Labor (Vienna, Austria). These systems differ primarily in the electrode design and stimulus parameters. Phrenic pacers have been implanted in over 1500 patients world- wide. Drawbacks to these systems include the risk of injury to the phrenic nerve either by surgical manipulation or by the electrode itself, system component failure, and the high cost of the systems. Although the risk of injury to the nerve has decreased, it does exist because a section of the nerve must be mobilized for electrode placement. The incidence of component failure has declined as the systems have undergone revi- sions. However, all three require some extracor- poreal component. Unlike the cardiac pacemaker, traditional phrenic pacers require an external transmitter and antenna to transmit both the power and control signal to an implanted receiver/ stimulator. Also, at present, none of the systems has any feedback or timing mechanism to make them physiologically responsive, nor are they synchronized with the upper airway. Develop- ment of such a mechanism would be an added 45. Pacing for Unilateral Diaphragm Paralysis 367 benefi t to phrenic pacers over conventional mechanical ventilators. Cost is perhaps a larger hurdle to overcome. The phrenic nerve electrode pacing systems available today cost nearly $100,000 (for the system, implant, and rehabilita- tion). Unlike cardiac pacemakers, because of the low number of potential candidates for these systems and the relatively low profi t potential, there is little interest from major manufacturers of medical devices. This may explain the limited effort to develop improved pacing systems. An alternative to the trans-thoracic phrenic nerve stimulation is the laparoscopic diaphragm pacing stimulation (DPS) system. There have been 22 human subjects implanted with the DPS system [18 spinal cord injury patients and 4 amyotrophic lateral sclerosis (ALS) patients]. The results of the DPS system for spinal cord patients indicated that the DPS system produced a signifi - cant mean percentage increase in tidal volume relative to the basal required tidal volume. 19 The procedure has overcome the learning curve for the operation, with the implantation standard- ized in an outpatient surgical procedure. 20 Overall there has been a 94% success rate for the spinal cord injured patients with the only failure being the second patient who had a false-positive inclu- sion criterion. The laparoscopic motor point electrode DPS system is an easy application for diaphragmatic stimulation when the phrenic nerve is intact. It overcomes many of the short- comings of the available phrenic nerve electrode systems. The development of a totally implant- able system is feasible and under way. 21 It would be a signifi cant advancement over presently available systems. For patients with nonfunctioning phrenic nerves, electrical activation of the intercostal muscles is one approach to treat respiratory insuffi ciency. Unlike the diaphragm, these muscles are innervated by a group of nerves (intercostal nerves originating from the ventral rami of T2–T12). However, by placing a single electrode in the epidural surface of the spinal cord through a dorsal laminectomy, this group of nerves/muscles can be activated which can provide up to 40% of vital capacity through the parasternal and external intercostals that are primarily inspiratory. Electrical activation of the intercostal muscles alone has been used in patients, however, the maximum duration of intercostal pacing (without mechanical ventilation or spontaneous breathing activity) remained relatively short (<3 h) and is not a viable option on its own. 22 Based on this, individuals with only one intact phrenic nerve had a combined intercostal system with a conventional diaphragm pacing system placed unilaterally. This system was successful in maintaining long-term ventilatory support in the four patients but presently is not in any further trials. 23 In those patients with a nonfunctioning phrenic nerve, diaphragm pacing is not an option unless a nerve is transferred to the phrenic nerve to re-animate the diaphragm. With advances in microsurgical techniques for neural anastomosis and a better understanding of axonal degenera- tion and regeneration, the repair or transfer of a nerve to the phrenic nerve and subsequent rein- nvervation of the diaphragm is a possibility. With a viable nerve, diaphragmatic pacing is then an option. Krieger successfully described transfer- ring a brachial nerve to the phrenic nerve in cats in 1983. 8 After a recovery period to allow for growth of axons down the anastomosed phrenic nerve (16–32 weeks), they were able to stimulate the nerve and have adequate diaphragm contrac- tions. Following this initial study, Krieger and colleagues investigated using an intercostals nerve in place of the brachial nerve for the anastomosis. The intercostals nerve was a good donor because of its proximity to the phrenic nerve (reducing the time for axonal regeneration), its physiological function (activation of skeletal muscle for respiration), and its size (comparable to the phrenic nerve). The initial article describes a single case and a letter to the editor describes two additional cases. 24,25 Subsequently a series of six patients was then described in 2000. 26 All of the patients had spinal cord injury with the time from injury to nerve transfer ranging from 6 months to 3 years. In this series of six patients there were a total of 10 nerve transfers. Two patients only had single nerve transfer because the other nerve on direct exploration was found to be intact. Only four patients were available for study. The fi fth patient is on a progressive pacing schedule and the sixth patient was only 1 month postoperative and with accepted growth of regen- erating axons of 1 mm per day the distance from 368 R.P. Onders the anastomosis to the diaphragm of 50 mm could not have been covered. In this series the average time for diaphragmatic response was 7 months with the shortest 6 months and the longest 13 months, so the true growth rate can be as slow at 1 mm every 8 days. Two of the patients are classi- fi ed as capable of pacing but presently are not being paced because of depression in one and one died of unrelated causes. In neither of these cases were the tidal volumes or diaphragmatic movement with stimulation given. Two patients (a total of three nerve transfers) are using the system 24 h/day, but again no data are given concerning the tidal volumes or diaphragmatic excursion with stimulation. Overall, of the eight nerve transfers that could be studied, all eight showed diaphragm motion with stimulation, which is impressive given the authors’ own description of the operation as diffi cult because of the angles and the fact the anastomosis occurs on the beating heart. There is some concern of the long-term viability of this technique in these patients, though. There was a letter to the editor by a sepa- rate physician stating that one of the patients that was reported as a success is in actuality not using the system at all. 27 To date there has been no other reports of this technique in the literature although it is mentioned often in the literature as a possibility both for spinal cord–injured patients and also patients with isolated phrenic nerve injuries. 45.2. Summary of Evidence and Current Recommendations Overall, none of the available data concerning diaphragm pacing specifi cally identify its use with unilateral diaphragm paralysis. The reason for this is that unilateral paralysis usually involves an injured phrenic nerve and therefore the diaphragm cannot be paced unless the diaphragm is re-innervated with a nerve transfer. So let us fi rst look at the evidence for diaphragm function with intercostal transfer and diaphragm pacing. The level of evidence for diaphragm pacing using an intercostal nerve transfer is level 4 because it is a case series that only measured end results with tidal volumes with stimulation and measurements of outcomes in less than 80% of the patients. Without more centers reporting their results or this series re-analyzing their results with a long-term follow-up, the recommendation grade is C. With this scarcity of evidence patients should not be given the hope of diaphragm pacing for a unilateral paralysis of the diaphragm unless they have an intact nerve. Patients should not be given the hope of diaphragm pacing for a unilateral paralysis of the diaphragm unless they have an intact nerve (level of evidence level 4; recommendation grade C). The results of diaphragm pacing when the phrenic nerve is intact are excellent. The evidence for the ability to pace the diaphragm and provide tidal volumes is level 1 because of the long history of success of pacing in multiple centers and the all or none ability to assess the results. The patient’s diaphragm either provides a tidal volume for ventilation with stimulation or is nonfunctional and the patient requires a mechanical ventilator when the device is turned off. The major change in diaphragm pacing is that it can now be done more safely and as an outpatient through the laparoscopic motor point stimulation technique with a higher success rate. The recommendation grade is A for bilateral diaphragm pacing when both phrenic nerves are intact. When both phrenic nerves are intact, results of bilateral diaphragm pacing are excellent (level of evidence 1; recommendation grade A). For unilateral diaphragm paralysis pacing is not benefi cial because the phrenic nerve is usually not functional (level of evidence 5; recommendation grade D). Unfortunately, for unilateral diaphragm paralysis there is no evidence that pacing is done because the phrenic nerve is usually not functional. If the nerve is intact but the diaphragm is nonfunctional then the level of evidence for 45. Pacing for Unilateral Diaphragm Paralysis 369 pacing is 5 and the recommendation grade is D because it is only based on the physiology of the system and has not been reported in the literature. Presently, the discussions of an earlier chapter in this text concerning diaphragm plication may offer the most hope for patients with unilateral dennervated diaphragms. 45.3. Future Research Future research should involve ways to help a damaged phrenic nerve recover in unilateral paralysis. When diaphragmatic dysfunction is identifi ed after a thoracic or cardiac procedure, instead of waiting to see if recovery occurs we should be proactive in trying to help that recovery process. Functional electrical stimulation has been shown to help recovery of injured nerves and, with the intramuscular laparoscopic diaphragm pacing technique now in clinical use, we may have a way to stimulate the diaphragm so that some afferent affects along the nerve will promote recovery. There is now some preliminary data in a disease where the phrenic nerve is dying at a set rate – amyotrophic lateral sclerosis (Lou Gehrig’s disease; unpublished results). By beginning a process of conditioning the diaphragm with the DPS system, we have been able to maintain diaphragmatic function in our early patients. This is partly due to the afferent effects of electrical stimulation but also preserving and strengthening the motor units that are left. The continuous decline in forced vital capacity of these initial patients has decreased which will increase their expected lifespan. This technique of using DPS can be expanded into acutely injured phrenic nerves in the hopes of reversing or improving the affects of acute phrenic nerve injuries. This technique would not require any nerve transfers and if the nerve recovers it can be easily removed. A prospective trial of using DPS is necessary to show if this would help. There is also a signifi cant number of patients who were told they have a negative phrenic nerve conduction test (a nonfunctioning nerve) when, on repeat evaluation in our laboratory, we were able to show diaphragmatic movement with a nerve conduction study. Phrenic nerve studies are diffi cult to reproduce, especially in patients that are overweight or have thick necks. We were able to subsequently implant these patients with the laparoscopic motor point electrode system. With a simple laparoscopic mapping stimulation tool, before giving up on diaphragmatic function or prior to plication, the diaphragm should be surgically studied. If at the time of plication the diaphragm responds to intraoperative stimulation, a motor point electrode with the DPS system should be placed and diaphragm function main- tained. This may be a better long-term option than plication. This hopefully will be an option in our armentarium for unilateral diaphragm function in the future. References 1. Oo T, Watt JW, Soni BM, Sett PK. Delayed diaphragm recovery in 12 patients after high cervical spinal cord injury. A retrospective review of the diaphragm status of 107 patients ventilated after acute spinal cord injury. Spinal Cord 1999;37:117– 122. 2. Glenn WW, Holcomb WG, Hogan J, et al. Dia- phragm pacing by radiofrequency transmission in the treatment of chronic ventilatory insuffi ciency. Present status. J Thorac Cardiovasc Surg 1973;66: 505–520. 3. Morgan JA, Ginsburg ME, Sonett JR, et al. Advanced thoracoscopic procedures are facili- tated by computer-aided robotic technology. Eur J Cardiothorac Surg 2003;23:883–887; discussion 887. 4. Shaul DB, Danielson PD, McComb JG, Keens TG. Thoracoscopic placement of phrenic nerve electrodes for diaphragmatic pacing in children. J Pediatr Surg 2002;37:974–978; discussion 978. 5. DiMarco AF, Onders RP, Kowalski KE, Miller ME, Ferek S, Mortimer JT. Phrenic nerve pacing in a tetraplegic patient via intramuscular diaphragm electrodes. Am J Respir Crit Care Med 2002;166: 1604–1606. 6. Onders RP, Aiyar H, Mortimer JT. Characteriza- tion of the human diaphragm muscle with respect to the phrenic nerve motor points for diaphragmatic pacing. Am Surg 2004;70:241–247; discussion 247. 7. Aiyar H, Stellato TA, Onders RP, Mortimer JT. Laparoscopic implant instrument for the placement of intramuscular electrodes in the diaphragm. IEEE Trans Rehabil Eng 1999;7:360–371. 8. Krieger AJ, Danetz I, Wu SZ, Spatola M, Sapru HN. Electrophrenic respiration following anastomosis [...]... following blunt trauma and found that all of the patients had associated injuries, and 84 % had injury to abdominal organs.7 Similarly, in 65 patients diagnosed with traumatic rupture due to blunt or penetrating injury, Mihos and coworkers found associated injuries in 95% with the majority being injury to 379 380 abdominal organs, most commonly liver, spleen, or intestine This study also described an increase... of a tracheostomy In his original series,10 which included 66 patients ( 28 with benign strictures) and a mean follow-up of 3 months, he gave a preliminary outcome describing the feasibility and safety of this stent In his follow-up study11 of four institutions and 10 58 patients, 263 of them had benign stenosis In the benign group, complications included migration in 18% , obstruction in 5.7%, and granulation... experience in phrenic nerve stimulation to pace the diaphragm Pacing Clin Electrophysiol 1 986 ;9: 780 – 784 Carter RE, Donovan WH, Halstead L, Wilkerson MA Comparative study of electrophrenic nerve stimulation and mechanical ventilatory support in traumatic spinal cord injury Paraplegia 1 987 ;25 :86 –91 Weese-Mayer DE, Silvestri JM, Kenny AS, et al Diaphragm pacing with a quadripolar phrenic nerve electrode: an international... descending aortic injures This argument is supported by findings in a paper by Meyers and colleagues, in which 12 out of 54 patients underwent thoracotomy either alone in combination with S.D Force laparotomy (level of evidence 3) Their reasons for choosing thoracotomy included further evaluation for positive pericardial window, persistent thoracic bleeding, bleeding from dome of liver, aortic injury,... regarding diagnosis and treatment rely more on clinical opinion than on scientific results Based on the evidence, recommendation grade D exists for laparotomy as choice for exposure in the majority of patients who have suffered a traumatic diaphragmatic injury The exceptions include isolated right diaphragmatic injuries and diaphragmatic injuries occurring in the setting of other thoracic injuries requiring... Missed diaphragmatic injuries and their long-term sequelae J Trauma 19 98; 44: 183 – 188 3 Feliciano DV, Cruse PA, Mattox KL, et al Delayed diagnosis of injuries to the diaphragm after penetrating wounds J Trauma 1 988 ; 28: 1135 4 Carter BN, Giuseffi J, Felson B Traumatic diaphragmatic hernia AJR Am J Roentgenol 1951;65: 56 82 5 Williams M, Carlin A, Tyburski JG, et al Predictors of mortality in patients with... Pacing Clin Electrophysiol 1996;19:1311–1319 Elefteriades JA, Quin JA Diaphragm pacing Chest Surg Clin North Am 19 98; 8:331–357 Elefteriades JA, Hogan JF, Handler A, Loke JS Long-term follow-up of bilateral pacing of the diaphragm in quadriplegia N Engl J Med 1992;326: 1433–1434 19 DiMarco AF, Onders RP, Ignagni A, Kowalski KE, Mortimer JT Phrenic nerve pacing via intramuscular diaphragm electrodes in. .. diaphragmatic injuries requiring immediate repair (level of evidence 3) Thirtyfour patients underwent thoracotomy to repair the defect, including 27 left-sided injuries and 7 right-sided injuries However, the authors do not explain their reason for choosing thoracotomy as the preferred exposure in these patients.26 Possible explanations for a thoracotomy approach may have included other intrathoracic pathology... injuries of the diaphragm Br J Surg 1 988 ;75;226 26 Galan G, Penalver JC, Paris F, et al Blunt chest injuries in 1696 patients Eur J Cardiothorac Surg 1992;6: 284 – 287 S.D Force 27 Meyers BF, McCabe CJ Traumatic diaphragmatic hernia: occult marker of serious injury Ann Surg 1993;2 18: 783 –790 28 Rizoli SB, Brenneman FD, Boulander BR, Maggisano R Blunt diaphragmatic and thoracic aortic rupture: an emerging... associated with increased risk in patients with insufficient tracheobronchial length for an end-to-end, 387 388 L Kabbani and T.L Weigel TABLE 48. 1 Potential indications for stent placement in benign tracheobronchial disease Tracheal stenosis Congential Endotracheal tube injury (PIS) Post-tracheotomy related (PTS) Secondary to systemic disease Wegener’s syndrome Relapsing polychrondritis Amyloidosis . Video-Assisted Thoracic Surgery In 1996, Mouroux and colleagues 18 proposed plication through a video-assisted thoracic surgery (VATS) approach. Two 5-mm thoracic ports and a 4-cm minithoracotomy. weaned from mechanical ventilation (within 8 days in 6 cases). The remaining three died in spite of a radiographically successful plication, mainly because of intracta- ble underlying cardiac disease achieved within 3 days in both patients undergo- ing surgery for this indication. 44.3.1.2. Long-term Outcome In some surgical series of pediatric patients, information about long-term follow-up is

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