Incidence and treatment of diaphragmatic paralysis after cardiac surgery in children.

OBJECTIVE: Diaphragmatic paralysis (DP) caused by phrenic nerve injury is potentially life-threatening in infants. Phrenic nerve injury due to thoracic surgery is the most common cause of DP in children. We retrospectively analyzed incidence, surgical details, management and follow-up of our patients with DP after cardiac surgery to develop an algorithm for the management and follow-up. METHODS: Retrospective analysis of 43 patients with DP after cardiac surgery performed between 1996 and 2000. RESULTS: Median age at cardiac surgery was 1 month (range 3 days to 9 years). Incidence of DP was 5.4%. A trend towards higher incidences of DP were observed after arterial switch operation (10.8%, P=0.18), Fontan procedure (17.6%, P=0.056) and Blalock-Taussig Shunt (12.8%, P=0.10). Median time from cardiac surgery to surgical plication was 21 days (range 7-210 days). Transthoracic diaphragmatic plication was performed in 29/43 patients, no plication was done in 14/43 patients. Patients in whom diaphragmatic plication was required were younger (median age 2 months, range 21 days to 53 months versus 17.5 months, range 4 days to 110 months; P<0.001). Indications for plication were failure to wean from ventilator (n=22), respiratory distress (n=4), cavopulmonary anastomosis (n=2), and failure to thrive (n=1). All these symptoms resolved after diaphragmatic plication, however, 8/29 patients with plication and 2/14 without plication died. Cause of death was not related to diaphragmatic plication in any patient. Position of plicated diaphragm was normal in 18/21 surviving patients 1 month after plication. In 2/12 surviving patients without plication hemidiaphragm showed a normal position 1 year after surgery. The rate of pulmonary infections was not significantly different during 12-60 months follow-up. CONCLUSIONS: DP is an occasional complication of cardiac surgery. High incidences of DP were seen after arterial switch operation, Fontan procedure and Blalock-Taussig shunt (BT). Respiratory insufficiency requires diaphragmatic plication in most infants with DP whereas older children may tolerate DP. Transthoracic diaphragmatic plication is an effective treatment of DP and achieves relief of respiratory insufficiency in most patients. Spontaneous recovery from postsurgical DP is rare.     

Phrenic nerve paralysis after pediatric cardiac surgery. Retrospective study of 125 cases

Phrenic nerve paralysis was diagnosed in 125 children (1.6%) from a series of 7,670 cardiac surgical procedures in infants and children during a 12 year period. The incidence was 1.9% for open heart and 1.3% for closed heart operations. In order of decreasing incidence, the open heart procedures included Mustard procedure (6.7%), right ventricular outflow tract reconstruction (5.6%), and repair of tetralogy of Fallot (2.7%). The closed heart procedures included Glenn anastomosis (6.2%), Blalock-Hanlon atrial septectomy (5.9%), and right Blalock-Taussig shunt (5.1%). Procedures following previous operations or thoracotomies had almost twice the incidence of phrenic nerve paralysis: Mustard procedure 9.9%, right ventricular outflow tract reconstruction 10.8%, and tetralogy repair 5.5%. Seven patients (5.6%) with phrenic nerve paralysis died. Patients less than 2 years old with phrenic nerve paralysis were intubated for 0 to 57 (average 15.7) days after their cardiac operations and those over 2 years old for 13 to 35 (average 7.2) days (p less than 0.001). Twelve patients had diaphragmatic plication without mortality and were extubated 0 to 6 (average 2.3) days after plication. We have made the following conclusions: (1) Phrenic nerve paralysis may occur after both open and closed cardiac procedures and is more common in children requiring reoperation; (2) it is associated with considerable morbidity; (3) eventual recovery of phrenic nerve function occurs in 84% of children; and (4) diaphragmatic plication is safe, reliable, and of most value in patients who are under 2 years of age and require mechanical ventilation for more than 2 weeks.     

Phrenic nerve injury after blunt trauma

Phrenic nerve injury resulting from blunt trauma is unusual and may closely mimic diaphragmatic rupture. Diagnosis remains difficult and is often delayed. A prompt diagnosis requires a high index of suspicion. We describe one patient with phrenic nerve injury in whom the diagnosis was made late at the time of injury. Radiograph, ultrasonography, and computed tomography were helpful in the diagnosis. Video-assisted thoracic surgery was performed on our patient for diagnostic purposes. Left phrenic nerve injury and pericardial injury were found. Diaphragmatic plication was performed through a miniature left posterolateral thoracotomy. This case was presented to show the unusual nature of phrenic nerve injury.     

Phrenic nerve injury following cardiac surgery: a review

Phrenic nerve injury following cardiac surgery is variable in its incidence depending on the diligence with which it is sought. Definitive studies have shown this complication to be related to cold-induced injury during myocardial protection strategies and possibly to mechanical injury during internal mammary artery harvesting. The consequences are also variable and depend to a large extent on the underlying condition of the patient, particularly with regard to pulmonary function. The response of the patient may range from an asymptomatic radiographic abnormality to severe pulmonary dysfunction requiring prolonged mechanical ventilation and other associated morbidities and even mortality. Two cases are presented to demonstrate the variability in clinical responses to diaphragmatic dysfunction secondary to phrenic nerve injury from cardiac surgery. In addition, treatment strategies are reviewed including early tracheostomy and diaphragmatic plication, which appear to be the most effective options for patients who are compromised by phrenic injuries.     

Phrenic nerve conduction disorder after open heart surgery--electrophysiological study

In 32 consecutive adult patients undergoing heart surgery, the induced diaphragmatic muscle action potential was measured. Phrenic nerve conduction disorder was defined as disappearance of muscle action potential (Edi) and conduction time (CT). Phrenic nerve conduction disorder was observed in 10 patients (31%); 8 patients on the left side and 2 patients on both sides. In non-conduction disorder group (22 patients), Edi and CT were measured. Edi of the right side decreased significantly from preoperative value of 705 +/- 318 microV to 445 +/- 285 microV at 1-3 days after operation (stage I) and to 559 +/- 314 microV at 7-10 days after operation (stage II) (p less than 0.05). CT of the right side prolonged significantly from 7.1 +/- 0.7 msec before operation to 7.44 +/- 0.97 msec at postoperative stage I and to 7.40 +/- 0.21 msec at postoperative stage II (p less than 0.05). For the left phrenic nerve, Edi showed significant (p less than 0.05) decrease from 803 +/- 338 microV before operation to 429 +/- 251 microV at the postoperative stage I and 620 +/- 350 microV at the postoperative stage II. In the conduction disorder group, incidence of atelectasis, diaphragm elevation and pleural effusion as documented by chest roentgenographic findings were higher than those of non-conduction disorder group (p less than 0.01). Moreover, the lowest temperature of the myocardium during operation was significantly (p less than 0.05) lower for conduction disorder group as compared to non-conduction disorder group. We believed that it is necessary to develop a innovative method for preventing the phrenic nerve from cold injury.     

Topical cooling for myocardial protection: the results of a prospective randomized study of the "shallow technique"

INTRODUCTION AND BACKGROUND: Respiratory distress following cardiac surgery is a troublesome complication. In several cases it is associated to cool-related phrenic nerve injury (PNI) after adoption of iced slush or hypothermic cardiopulmonary bypass. We compare two different strategies for myocardial protection: the "shallow technique" (ST) (dripping and prompt removal of cold saline solution from the epicardial surface) plus normothermic cardiopulmonary bypass, versus mild hypothermic cardiopulmonary bypass plus iced slush. METHODS: Two hundred forty-nine patients undergoing elective cardiac surgery were randomly assigned to receive either ST (Group A) or iced slush (Group B). Occurrence of postoperative PNI (abnormal diaphragmatic movement plus alteration of nerve conduction) was evaluated. Multivariate analysis was performed for identification of factors associated to PNI. Patients had a 6-month follow-up. RESULTS: PNI and failure of extubation occurred more frequently in Group B (p = 0.009 and p = 0.034, respectively), but there was no statistically significant difference in mean intensive care unit stay. Diabetes and the use of iced slush were independent predictors of phrenic dysfunction, while internal thoracic artery (ITA) harvest was a significant risk factor only among Group B patients. Abnormal diaphragmatic movement was persistent at 6 months only in 30% of Group B individuals who suffered this complication in the early postoperative. CONCLUSIONS: ST likely reduces the incidence of postoperative PNI and might be protective mainly in the event of ITA harvest. It should be considered as a valuable tool for myocardial protection protocols.     

Bedside assessment of phrenic nerve function in infants and children

Phrenic nerve damage is widely recognized after cardiac operations and is associated with an increased morbidity and mortality. Retrospective studies in children have estimated a prevalence of phrenic damage of between 0.5% and 2.2%, but all these studies have limited their investigations to patients who have clinical problems postoperatively, and they have all used clinical or radiologic methods to diagnose the damage. These methods are indirect and hard to evaluate, making the accurate early diagnosis of phrenic nerve damage very difficult. Measurement of phrenic nerve conduction time (phrenic latency) allows direct evaluation of phrenic function and integrity, making it potentially much more specific than indirect methods. Using a simplified method of direct phrenic nerve stimulation, we have developed a method of measuring phrenic latency at the bedside in infants and children. A 1 Hz electrical stimulus is applied over the phrenic nerve in the neck and a diaphragmatic electromyogram from the seventh and eighth intercostal spaces is displayed on a storage oscilloscope. Phrenic latency can be measured directly from the screen. Using these methods we have now studied 37 children (aged 2 days to 15 years) before and after cardiac operations. Mean phrenic latency was 5.4 +/- 1.0 msec on the right and 5.4 +/- 1.0 msec on the left. Prolongation of phrenic latency by more than 2 msec was found in seven of 66 postoperative measurements (10.6%). These patients had a substantially worse postoperative course. We believe this technique to be an important contribution to the diagnosis of postoperative phrenic nerve damage, and one that can help in clinical practice to elucidate an important cause of postoperative morbidity and mortality.     

Phrenic nerve injury associated with high free right internal mammary artery harvesting

BACKGROUND: The right phrenic nerve is at risk of injury during high mobilization of the right internal mammary artery (RIMA). The incidence and implications of this injury have not been previously defined. METHODS: Prospectively collected data on all patients who underwent RIMA harvesting between January 1995 and February 2002 were analyzed. Thirty-one patients with right phrenic nerve injury were identified and the medical charts reviewed. Phrenic nerve injury was diagnosed when a postoperative chest roentgenogram showed the right hemidiaphragm to be two or more intercostal spaces higher than the left, or transection of the nerve was seen intraoperatively. Investigations included fluoroscopy and spirometry in upright and supine positions. Diaphragm plication was offered for symptom control. Subsequent follow-up was undertaken to determine the incidence of spontaneous recovery of diaphragm function and the benefits of diaphragm plication. RESULTS: Seven hundred and eighty-three patients underwent high mobilization of the RIMA with proximal detachment for use as a free graft. Thirty-one patients with right hemidiaphragm dysfunction were identified in the postoperative period providing an injury incidence of 4% (confidence interval, 2.6% to 5.3%). Of these, 12 patients underwent diaphragm plication (4 early and 8 late), 14 patients achieved spontaneous recovery, and 5 patients were lost to follow-up. The supine to upright forced vital capacity ratios at the time of phrenic nerve dysfunction, after diaphragm plication, and after spontaneous recovery were 0.79, 0.90, and 0.96 respectively. CONCLUSIONS: The incidence of phrenic nerve injury associated with high RIMA harvesting was 4% but spontaneous recovery may be anticipated in two thirds (14 of 22) of patients in whom the injury is identified postoperatively. High RIMA harvesting should be used with caution in patients with preoperative pulmonary dysfunction in whom phrenic nerve injury would be poorly tolerated.     

Phrenic nerve paralysis following lung transplantation

Phrenic nerve paralysis is a well-documented complication of cardiac operation, but there is less commonly reported after lung transplantation. A retrospective study of 49 lung transplantation was done at Okayama University Hospital. Phrenic nerve paralysis (unilateral in 3 patients and bilateral in 1) was found in 4 patients (8.2%). All of these paralyses were transiently recovered. The average length of ventilation, intensive care unit stay and hospitalization for recipients with phrenic nerve paralysis was not significantly longer than the other (no diaphragmatic paralysis) recipients, but there was a tendency to be longer. Diaphragmatic paralysis is most likely related to difficulty in detecting the phrenic nerve caused by adhesions, injury due to dissection, thermal injury by electrocartery, or local topical hypothermia using ice-slush. Therefore, it is important to take care of avoiding the injury of the nerve during the operation.     

Diaphragmatic paralysis: pathology at the reach of the pediatric surgeon

The phrenic nerve is the only motor nerve in the diaphragm. The injury will lead to a diaphragmatic paralysis or eventration with paradoxical movements during breathing. The aim of this review is to analyze the diagnostic criteria, surgical indications, and the patients that are not treated by surgery. We review 53 cases with diaphragmatic pathology in the last 5 years; 19 females and 20 males. One was a diaphragmatic rupture, 13 were diaphragmatic hernias, and 39 had diaphragmatic paralysis. Diaphragmatic paralysis was diagnosed by fluoroscopy in 97%, electromiography 5.1% or ultrasounds. The ethiology was 64% after cardiac surgery and 10% after thoracic oncologic surgery. The age at diagnosis was less than 1 month in 41% cases. In 29 patients the paralysis was well tolerated and were extubated between 24 h and 4 days after the diagnosis, frequently was in the first 48 h. 4 patients need a traqueostomy and 2 went to another hospital. In 5 we performed a diaphragmatic plication because the inability to be extubated or the persistence of respiratory distress. The paralysis was demonstrated by fluoroscopy. 2 patients are asymptomatic, 2 are in mechanical ventilation and 1 died (sepsis). The most frequent cause of diaphragmatic paralysis was related to cardiac or thoracic surgery. In general, is well tolerated, almost asymptomatic, the patients were extubated between 24 or 48 h. In pediatric population they are few cases that need surgical treatment. The patients that we operated on were less than 2 months old, because is at that age were the repercussion is more important. We must follow strict criteria, without precipìtation for the surgical indications.     

Eventration of the diaphragm in children

Diaphragmatic plication is a safe, well tolerated procedure for congenital diaphragmatic eventration. It is the treatment of choice in neonates with respiratory distress following phrenic nerve injury. The abdominal approach is as good as the thoracic and may be safer in cases with central eventration and when the diagnosis of congenital diaphragmatic hernia cannot be excluded with confidence. However, in phrenic nerve paralysis the thoracic approach is superior in showing the anatomical distribution of the phrenic nerve. Experience with eight paediatric patients treated for diaphragmatic eventration is reported. Five had congenital eventration of the diaphragm and three had acquired eventration. All patients except one required surgical plication of the diaphragm. Three patients developed minor postoperative complications and all patients were alive and well on follow-up. It appears that diaphragmatic plication is a safe and well tolerated procedure for symptomatic diaphragmatic eventration.     

Phrenic nerve paralysis following pediatric cardiac surgery. Role of diaphragmatic plication

Eighteen children sustained unilateral phrenic nerve paralysis (PNP) after cardiac surgical procedures. Ten (Group I), under 7 months (mean: 2.9 +/- 2.2), required long-term ventilatory assistance (mean: 23.9 +/- 13.0 days); they failed to be weaned from the ventilator. All underwent diaphragmatic plication (DP). DP was performed late in 7 cases (Group Ia) with a mean time of 30.8 days between surgery and DP, and early in 3 others (Group Ib) with a mean time of 10.2 days. Eight children (Group II), older than 1 year, tolerated PNP better and could be extubated early without diaphragmatic plication. In Group Ia severe lung infections were recorded in 5 before or/and after DP, and two died at 3 and 30 days after plication. Five children from Group Ia and all 3 from Group Ib were late survivors. They could be weaned from ventilatory support in a mean time of 3 days after DP, although those with severe lung infection (Group Ia) took the longest time. All from Group II were late survivors. We conclude: PNP is well tolerated without plication in children older than 1 year. However early DP offers excellent and immediate results in infants with PNP. Early DP in these children avoids or reduces severe lung infections and death.     

Bilateral diaphragmatic plication for an adult patient

Bilateral phrenic nerve paralysis is a very rare complication in open-heart surgery. An 65-year-old woman sustained respiratory distress after coronary artery bypass grafting because of bilateral phrenic nerve paralysis. Bilateral diaphragmatic plication was performed on the 43rd postoperative day. She successfully weaned from ventilator support without difficulty a few days after plication. We believe that surgical plication of the diaphragm is a safe and effective technique for a distressed adult patient with paralyzed diaphragm.     

Combination of diaphragmatic plication with major abdominal surgery in patients with phrenic nerve palsy

The role of simultaneous prophylactic diaphragmatic plication during major abdominal operations is evaluated. In five patients with a history of phrenic nerve injury, postoperative ventilation requirements and hospital stay were significantly reduced when synchronous diaphragmatic plication was performed, compared with corresponding values obtained during previous abdominal operation without diaphragmatic plication. In addition, diaphragmatic plication was associated with postoperative improvement of respiratory mechanics and blood gas exchange.     

Effects of lobar pulmonary blood flow on the evolution of oleic acid lung injury in dogs

We studied the effects of interruption of the pulmonary blood flow to the left diaphragmatic lung lobe on the evolution of canine oleic acid lung injury. We compared the morphology and edema of the left diaphragmatic lobe, whose pulmonary artery was ligated immediately after oleic acid injury, with the right diaphragmatic lobe, in which the blood supply was intact. The injury plus ligation resulted in hypoxemia and pulmonary hypertension with PaO2 falling from 98 +/- 4 to 72 +/- 21 torr (P less than 0.05) and pulmonary artery pressure increasing from 11 +/- 3 to 18 +/- 4 mm Hg (P less than 0.05). Animals were sacrificed 48 hr following the injury. Morphological examination of right and left lobes showed no consistent differences although wet/dry ratios indicated significantly greater edema (P less than 0.01) for the right diaphragmatic lobes (7.66 +/- 1.23) than the left (6.80 +/- 0.59). Both right and left lobes were substantially more edematous than our laboratory normal value of 4.74 +/- 0.54 (P less than 0.001 for both). We conclude that interruption of pulmonary arterial blood flow protects against edema formation in oleic acid injury but does not alter the morphologic evolution of the injury.     

Impact of diaphragmatic paralysis after cardiothoracic surgery in children.

OBJECTIVES: We sought to determine the prevalence and clinical impact of diaphragmatic paralysis caused by phrenic nerve injury after cardiothoracic surgery in children. METHODS: A search of cardiology, radiology, and hospital databases identified 170 episodes of diaphragmatic paralysis after cardiothoracic surgery in 168 children operated on from 1985 to 1997. Medical records were reviewed to determine demographics, details of the operation and postoperative course, diagnostic features and management of diaphragmatic paralysis, and follow-up status. RESULTS: The prevalence of diaphragmatic paralysis was 1.6% (95% confidence interval 1.4%-1.8%). Median age at operation was 6 months (range <1 day-14.4 years). Median time from the operation to the initial investigation was 5 days (range <1 day-61 days), with 57% of patients receiving mechanical ventilation at diagnosis. Diaphragmatic plication was performed in 40% of the patients at a median interval from the initial investigation of 15 days (range 3 days-11.1 months). Significant independent factors associated with increased postoperative hospital stay were lower patient weight at operation, previous cardiothoracic operations, bilateral diaphragmatic paralysis, increased interval from operation to investigation, mechanical ventilation at the time of investigation, and diaphragmatic plication. Confirmed recovery of diaphragmatic function was noted before hospital discharge in only 15 episodes. CONCLUSIONS: Diaphragmatic paralysis complicating cardiothoracic surgery continues to occur in the current era, with a significant impact on morbidity. Smaller patients with bilateral hemidiaphragmatic paralysis, requiring mechanical ventilation, may represent a higher risk subgroup to target for increased diagnostic suspicion and more aggressive management; early spontaneous recovery is rare.     

臂丛撕脱伤患者同侧膈神经诱发电位的研究

目的研究臂丛撕脱伤患者同侧膈神经的功能状态，为临床选用膈神经移位治疗臂丛撕脱伤提供依据。方法测定１００例臂丛神经撕脱伤膈肌诱发电位的潜伏期、波幅，并对其功能进行评价。将表面电极置在胸锁乳突肌后缘，在平环状软骨水平进行电刺激，于腋前线水平在第７、８肋间记录肌肉诱发电位。同时在膈神经移位术中取一段膈神经，观察其病理变化。结果诱发电位的资料证实，有１８例膈神经存在不同程度的损伤，其中１１例为完全损伤，７例为不全损伤。病理学观察发现膈神经部分损伤时，光镜下见神经纤维部分髓鞘崩解，髓鞘之间散在性地分布着瘢痕化组织。膈神经完全损伤时，可见神经髓鞘崩解，髓鞘之间布满瘢痕化组织。结论１００例臂丛撕脱伤中１８％的膈神经有损伤，其中７％为不全损伤。应重视这部分病例中膈神经的部分损伤，以便改进手术方法，提高移位术的疗效     

Diaphragmatic plication in adult patients with diaphragm paralysis after cardiac surgery.

OBJECTIVE: We investigated the benefit of diaphragmatic plication for weaning from mechanical ventilation in these adult patients. PATIENTS AND METHODS: Four patients underwent diaphragmatic plication for difficulty of weaning from mechanical ventilation due to diaphragmatic paralysis. They were all men with an average age of 70.5 +/- 6.3 years. Three of the patients had undergone cardiac surgeries for coronary artery bypass grafting and one patient ascending aortic replacement for pseudoaneurysm after coronary revascularization. Right diaphragmatic plication (muscle sparing procedure) was performed between 30 to 61 days after cardiac surgery. RESULTS: The mean forced tidal volume improved dramatically from 216 to 415 ml after plication in all patients, and it was possible to discontinue mechanical ventilation from 2 to 12 days after plication. One patient with obstructive respiratory dysfunction died from aspiration pneumonia 15 days after plication. However, postoperative tidal volume in this patient improved to 420 ml and he was able to be weaned from ventilatory support five days after plication. The other three patients were discharged between 26 to 58 days after plication and continue to do well without symptoms. CONCLUSION: Diaphragmatic plication is a useful procedure for treatment of diaphragmatic paralysis in adults as well in children.     

Phrenic nerve stimulation in normal subjects and in patients with diaphragmatic weakness.

Phrenic nerve stimulation is often considered to be difficult and unreliable. The time taken for the phrenic nerves to be located and adequately stimulated was measured in 110 subjects, aged 21-89 years, 26 of whom had diaphragmatic weakness; and phrenic nerve conduction time was recorded in 76 of these individuals. Each phrenic nerve was stimulated transcutaneously in the neck with square wave impulses 0.1 ms in duration at 1 Hz and 80-160 volts while diaphragmatic muscle action potentials were recorded with surface electrodes. The time taken to locate either phrenic nerve ranged from two seconds to 22 minutes (median 10s). Both nerves were located in 83 of the 84 control subjects (99%) and in 21 of the 26 patients with diaphragmatic weakness (81%). Mean (SD) phrenic nerve conduction time in the control subjects was 6.94 (0.77) ms on the right and 6.61 (0.77) ms on the left. A weak relationship was found between conduction time and the subjects' age and height. Four out of 24 patients with diaphragmatic weakness had a prolonged phrenic nerve conduction time. Transcutaneous stimulation of the phrenic nerves was not a time consuming procedure, and it was well tolerated, reproducible, and successful in 95% of subjects.     

Thoracoscopic placement of phrenic nerve electrodes for diaphragmatic pacing in children

Background/Purpose: Diaphragmatic pacing can provide chronic ventilatory support for children who suffer from congenital central hypoventilation syndrome (CCHS) or cervical spinal cord injury. The authors report a new thoracoscopic approach for establishing diaphragm pacing. Methods: Between 1997 and 2000, 9 children ranging in age from 5 to 15 years and suffering from these disorders underwent thoracoscopic placement of bilateral phrenic nerve electrodes. A 3- or 4-trocar technique was used to dissect the phrenic nerve in the midchest and suture a phrenic nerve electrode (Avery Laboratories I-110A, Commack, NY) into place. The electrode was tunneled to a subcutaneous pocket in the upper abdomen and attached to an implanted pacing unit. Results: Bilateral electrodes were placed successfully into all patients. The average procedure time was 3.3 hours (range, 2.5 to 4.6), and average hospital stay was 4.2 days (range, 3 to 5). Four patients experienced postoperative complications (pneumonia, atelectasis, bradycardia, and pneumothorax). Average follow-up has been 30 months (range, 15 to 49). Eight patients have reached their long-term pacing goals. Conclusions: Phrenic nerve electrodes can be implanted thoracoscopically and allow the successful use of diaphragmatic pacing therapy. Avoidance of thoracotomy with its associated perioperative morbidity and scarring may encourage wider utilization of diaphragmatic pacing in children. J Pediatr Surg 37:974-978.