[Plication of diaphragm for postoperative phrenic nerve injury in infants and young children]

Paralysis of the diaphragm may cause life-threatening respiratory distress in infants and young children because of paradoxical motion of the affected diaphragm and contralateral shift of the mediastinum during expiration. Phrenic nerve injury (PNI) may follow chest operations. 10 children with diaphragmatic paralysis and severe respiratory distress underwent plication of the diaphragm. Ages ranged from 14 days to 5 years. 9 had PNI after operations for congenital heart disease and 1 after resection of an intraspinal cervical lipoma. The right side was affected in 7, the left in 3. Indication for surgery was inability to wean from mechanical ventilation, which had ranged from 11 to 152 days (median 35). 8 underwent plication via a thoracic approach and 2 via an abdominal approach. There were no complications directly related to the operation. The interval from plication to weaning from mechanical ventilation ranged from 2 to 140 days (median 4). 1 patient died 2 hours after plication due to severe heart failure and 2 after prolonged hospitalization due to sepsis and multi-organ failure. 6 were extubated 2-8 days (median 4) after plication and 1 only after 40 days. Early diaphragmatic plication is simple and avoids more serious surgery. While effective in ventilator-dependent infants and young children, it should not be used in those with multi-organ failure. Early plication may prevent the complications of prolonged mechanical ventilation.

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.

Multivascular trauma on an adolescent. Perioperative management

Penetrating vascular injury, in particular at the neck, is a life-threatening trauma not only of the nature and the anatomic proximity of cardiovascular, aerodigestive, glandular and neurologic system but also of the development of early and late complications. The following case report describes our experience with a penetrating wound patient, who was admitted to our emergencies twelve hours after the accident. The only demonstrable objective signs included a large hematoma at the right-side of the neck and distended mediastinum on the chest X-ray. As the patient was cardiovascularly unstable he was immediately transported to the theater without any angiography. The mandatory operative exploration was initially unsuccessful and a median sternotomy with a standard cardiopulmonary bypass and deep hypothermia circulatory arrest was established to restore all the vascular lesions. Actually, the patient was in critical condition with a rupture of the right internal jugular vein, a large pseudoaneurysm of the innominate artery and an avulsion of the ascending aorta with the suspicion of a cardiac tamponade. The postoperative period lasted two full months, while complications appeared. The substantial message from this multivascular trauma is the early diagnosis of the life-threatening complications as exsanguinations, ventricular fibrillation and the ability to minimize postoperative complications, which will impair the normal functional life of the patient.

Ventilatory muscle recruitment and work of breathing in patients with respiratory failure after thoracic surgery

OBJECTIVES

Increased work of breathing (WOB) and respiratory muscle weakness have been identified as major causes of respiratory failure after thoracic surgery. This study was undertaken firstly to characterize the mechanical impairment in patients with respiratory failure after cardio-thoracic surgery, and secondly, to determine how diaphragmatic paralysis affects deterioration in the ventilatory mechanics.

METHODS

We evaluated the respiratory mechanics of 24 patients following cardiac and thoracic surgery. Ten patients without respiratory problems were examined as control subjects. There were nine patients with phrenic nerve injury and five patients without phrenic nerve injury who required mechanical ventilation for more than 7 days. Phrenic nerve injury was assessed with a phrenic nerve stimulation test. We measured the respiratory variables, the esophageal, gastric and transdiaphragmatic pressure swing (deltaPes, deltaPga and deltaPdi, respectively), and the work of breathing during quiet tidal breathing.

RESULTS

Both the groups requiring mechanical ventilation exhibited abnormally negative deltaPga/deltaPes values, compared with the control subjects. A significant increase in WOB with the normal generation of deltaPdi was seen in the patients without phrenic nerve injury. In contrast, the poor generation of deltaPdi with a slight increase in work of breathing was noted in patients with phrenic nerve injury.

CONCLUSIONS

These results demonstrated two different types of respiratory failure in thoracic surgery patients, focusing on the impact of phrenic nerve paralysis. Diaphragmatic dysfunction should not be overlooked in postoperative care, and the amelioration of this compromise in respiratory mechanics is an important aspect of good patient management.

Postoperative atelectasis

Postoperative atelectasis is a common problem following any surgery. Limited atelectasis is usually well-tolerated and easily reversible. However, complete atelectasis of the remaining lung following partial lung resection may be poorly tolerated. Thoracic surgical procedures increase the risk because pain, thoracic muscle injury, chest wall instability, and diaphragmatic dysfunction impair clearance of secretions by cough. In addition, patients with lung diseases are prone to increased bronchial secretions. Prophylaxis includes preoperative and postoperative physiotherapy and medications, which should be graded in accordance to the individual patient's risk factors. Large atelectasis requires bronchoscopy to remove mucous plugs. Tracheostomy should be considered in patients with relapsing atelectasis or swallow disorders.

Thoracoscopic diaphragmatic plication

We report on thoracoscopic plication of the the paralyzed right hemidiaphragm of a 33-year-old woman with a history of reactive airway disease. The paralysis was secondary to transection of the phrenic nerve during right first rib resection for thoracic outlet syndrome 1 year prior to evaluation. By use of video-assisted thoracoscopic surgery (VATS), the diaphragm was plicated as with open thoracotomy. Postoperative recovery was uneventful, with minimal pain and early discharge. Preoperative symptoms of exertional dyspnea and orthopnea were significantly improved.

Post cardiac surgery phrenic nerve palsy: value of plication and potential for recovery

OBJECTIVES

Evaluation of an aggressive policy for the treatment of phrenic nerve palsy (PNP), following cardiac operations, with emphasis on early diaphragmatic plication. Attention was given to the incidence and predisposing factors for PNP and the potential for recovery following plication.

METHODS

From 1 June 1991 to 1 January 1996 we prospectively screened patients for PNP following cardiac surgery. The diagnosis was suspected if difficulty was experienced in weaning the child from the ventilator. If abnormal elevation of the hemidiaphragm was present diaphragmatic plication was performed. Echocardiography was used to assess subsequent return of diaphragmatic function.

RESULTS

Seventeen children (nine boys, eight girls), out of 867 (1.9%) children younger than 16 years of age, undergoing cardiac operations were found to have PNP. The mean age was 66 days (range 1-17 months) with 16 patients below 1 year out of a total of 285 patients (incidence 5.6%) and one patient 17 months old. The incidence following open procedures was 11/190, following closed procedures 2/95 and following reoperation 4/83. PNP was diagnosed from 2 to 44 days (mean 14 days) following surgery. It was present on the right side in seven cases, the left in nine and was bilateral in one patient. Two patients were extubated at the time of diagnosis, one patient could be extubated shortly thereafter. Fourteen children underwent diaphragmatic plication, at a median 5 days post diagnosis. Extubation was possible 1-60 days (mean 4 days) after plication. Mean follow-up was 19 +/- 5 months. Subsequent recovery of diaphragmatic movement was documented in seven (41%) children. Time to recovery following plication was 16 months, without plication 38 months.

CONCLUSION

Prospective screening for PNP revealed an incidence in children younger than 1 year of 6%. Early plication substantially reduces the duration of ventilation, with its associated reduced morbidity and ICU stay.

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.

Surgical anatomy of the diaphragm and the phrenic nerve

In this article, the anatomy of the diaphragm and phrenic nerves is discussed, together with related surgical implications. Since the major cause of phrenic nerve injury is surgery, usually for congenital or acquired heart disease, incisions in the diaphragm that do not injure major branches of the phrenic nerve are also discussed. Diaphragmatic plication is usually required in infants less than 3 months of age, and older children may be managed by ventilatory support if electrophysiologic studies document the possibility of return of nerve function. In adults with normal pulmonary function, unilateral diaphragmatic paralysis is usually asymptomatic.

Surgical treatment of diaphragmatic eventration caused by phrenic nerve injury in the newborn

BACKGROUND

Phrenic nerve palsy in infants and young children usually results from birth injury or iatrogenic damage. The newborn almost invariably presents with severe respiratory distress, diaphragmatic elevation, and paradoxical movement at the affected side.

METHODS/RESULTS

In this retrospective analysis a group of 23 patients below the age of 1 year with an obstetric or postoperative phrenic nerve injury was studied and compared with cases in the literature. All patients were admitted between 1986 and 1997 to the Pediatric Surgical Center, Amsterdam. Thirteen of 18 patients with an obstetric phrenic nerve injury underwent plication of the diaphragm after an average observation period of 100 days. In the remaining five children with an obstetric phrenic nerve injury, spontaneous recovery appeared within 1 month. Only one of five patients with a phrenic nerve palsy after a cardiac surgical procedure underwent plication of the diaphragm. Fifteen of the 34 patients described in the literature underwent plication of the diaphragm after an average of 54 days.

CONCLUSIONS

If after 1 month no spontaneous recovery of the diaphragmatic paralysis caused by a phrenic nerve injury occurs, plication of the diaphragm is indicated. This operation proved to be successful for relief of symptomatic phrenic nerve injury in all cases. If the condition of the patient clinically deteriorates during this first month of life, the patient should be operated on immediately.

Minimally invasive diaphragm plication in an infant

We report the use of video-assisted thoracic surgery to plicate the diaphragm after phrenic nerve injury associated with an operation for congenital heart disease. Right diaphragm paresis developed in a cyanotic newborn girl with pulmonary atresia and intact ventricular septum after a right modified Blalock-Taussig shunt. Diaphragm plication was performed endoscopically and the patient recovered. Refinement of technique and instrumentation may allow wider application of video-assisted thoracoscopic plication of the diaphragm in neonatal and pediatric patients.

Phrenic nerve injury after coronary artery bypass grafting: will it go away?

BACKGROUND

Phrenic nerve injury after coronary artery bypass grafting resolves in most cases. The purpose of this study was to analyze the causes and effects of persistent phrenic nerve injury after coronary artery bypass grafting.

METHODS

From a registry of patients with chronic obstructive pulmonary disease who underwent coronary artery bypass grafting, 64 patients were identified who experienced phrenic nerve injury during their operation. Fifteen patients either died during follow-up (n = 9) or were lost to follow-up (n = 6). At the last follow-up visit, all the patients underwent an ultrasound evaluation of the diaphragm and were divided into those who had persistent dysfunction (group I) and those who had normal function (group II). The groups were compared for preoperative and operative risk factors, acute and midterm postoperative results, and quality of life at last follow-up.

RESULTS

There were 13 patients in group I and 36 in group II. There were no significant differences in preoperative and operative risk factors between the groups. The length of hospitalization was similar for both groups (9.2 +/- 4.5 versus 8.5 +/- 3.3 days, respectively; p = 0.77). More patients in group I required reintubation (23% versus 14%, respectively; p = 0.04). The mean duration of follow-up was 32.7 +/- 9.2 months. At that time, both groups suffered a reduction of forced expiratory volume in 1 second compared with preoperative values. Group I had a greater reduction in forced expiratory volume in 1 second (p = 0.05). There were a total of 125 postoperative readmissions during the follow-up period, 36 in group I and 89 in group II. There were more admissions because of pulmonary problems in group I (85% versus 53%; p = 0.04). Of the 49 patients, 21 perceived a decline in quality of life after operation. More patients in group I (46% versus 22%; p = 0.05) complained of this decrease.

CONCLUSIONS

A significant number of patients who incur phrenic nerve injury after coronary artery bypass grafting have persistent phrenic nerve injury. Patients with persistent phrenic nerve injury have increased acute and midterm morbidity after operation, as well as reduced quality of life.

Glial changes in the phrenic nucleus following superimposed cervical spinal cord hemisection and peripheral chronic phrenicotomy injuries in adult rats

The objective of the present study was to characterize the microglial and astroglial reaction in the phrenic nucleus following either an ipsilateral C2 spinal cord hemisection, a peripheral phrenicotomy, or a combination of the two injuries in the same adult rat. The present study used three different fluorescent markers and a confocal laser image analysis system to study glial cells and phrenic motoneurons at the light microscopic level. Young adult female rats were divided into one combined injury group (left phrenicotomy and left C2 spinal hemisection with periods of 1 to 4 weeks between injuries, N = 12) and three other groups consisting of noninjured animals (N = 3), animals that received C2 hemisection only (N = 3), and animals with phrenicotomy only (survival periods of 2 (N = 3) and 4 (N = 3) weeks after phrenicotomy). Fluorogold was injected into the diaphragm to label phrenic motoneurons in all animals. Microglia and astrocytes were labeled with Texas red and fluorescein, respectively, and were visualized simultaneously along with phrenic motoneurons. The results suggest that the microglial and astrocytic response in the superimposed injury model are similar to the glial reactions characteristically seen in a peripheral axotomy alone model. These reactions include proliferation and migration of microglial cells along the perineuronal surface (peaking at 2 weeks) and the hypertrophy of astrocytes (peaking at 4 weeks). In addition, the increase in astrocytic tissue, which is characteristically seen in response to axotomy alone, is significantly enhanced in the superimposed injury model. Also, there is a large and rapid increase in GFAP-positive astrocytes within 24 hours after hemisection alone. The information gained from the present study will aid in determining, predicting, and eventually manipulating central nervous system responses to multiple injuries with the objective of reestablishing function in the damaged CNS.

Diaphragmatic eventration in infants and children: is conservative treatment justified?

PURPOSE

The purpose of this study is to examine the justification of diaphragmatic plication to treat diaphragmatic eventration. A retrospective review of 50 patients who underwent diaphragmatic plication for phrenic nerve injury (PNI) or congenital muscular deficiency (CMD) of the diaphragm was conducted.

METHODS

During the last 26 years, 50 patients, aged 4 days to 7 years, were surgically treated for diaphragmatic eventration. Twenty-five patients had iatrogenic PNI and another 25 had CMD. Respiratory distress developed in all patients who had PNI and 10 required mechanical ventilatory support for 13 to 78 days (mean, 41 days) before operation. Respiratory symptoms developed in 17 of 25 patients who had CMD, and four required ventilatory support. In those who were asymptomatic, we justified surgical repair to optimize future lung growth. All patients underwent diaphragmatic plication by a thoracic approach. Reefing mattress sutures on pledgets were used for the plication.

RESULTS

In patients who had PNI, ventilatory support could be discontinued within 0 to 6 days (mean, 3 days) after operation, with a dramatic improvement in their respiratory status. Two patients required reoperation because the plication was not tight enough. Seven patients died in this series, but none because of the diaphragmatic plication.

CONCLUSION

This study suggests that symptomatic patients who have diaphragmatic eventration should be operated on immediately with an expected dramatic resolution of their respiratory problems.

Chronic hypoxia does not induce synaptic plasticity in the phrenic nucleus

Interruption of the main descending respiratory drive to phrenic motoneurons by cold block or spinal cord hemisection results in morphological modifications of the ipsilateral phrenic nucleus in the rat. The modifications consist of an increase in the number of multiple synapses and dendrodendritic appositions and elongation of the asymmetric and symmetric synaptic active zones. Hemisection and hemispinalization by cold block cause not only "functional deafferentation" of the ipsilateral phrenic neurons (i.e., a loss of ipsilateral descending respiratory drive), but also an increase in the remaining contralateral descending respiratory drive. The contralateral respiratory pathways connect with phrenic motoneurons ipsilateral to cold block or hemisection by decussating collateral axons which cross the spinal cord midline below the hemisection/cold block site. Thus, the phrenic nucleus synaptic plasticity could possibly be induced by functional deafferentation or by an increase of the descending respiratory drive. To differentiate between these two possible inducers of the plasticity, we assessed the synaptic morphology of the phrenic nucleus of nonoperated rats exposed to 48 h of hypoxia in an atmosphere chamber. The hypoxia exposure produces an increased descending respiratory drive without functional deafferentation. The quantitative data extracted from electron micrographs of the phrenic nucleus from four experimental rats were compared with the data from four normal breathing animals. Phrenic nucleus morphometric analysis showed that there was no significant difference in the mean number of single synapses between the samples from control animals (141 +/- 12.12) and the experimental animals (156 +/- 26.73). Similarly, no significant difference was detected in the total number of synaptic active zones of control animals (178.25 +/- 11.13) and experimental animals (195.05 +/- 5.35). Furthermore, the length of synaptic active zones of asymmetrical synapses (0.21 +/- 0.024 micron) or symmetrical synapses (0.22 +/- 0.022 micron) did not change significantly compared to the synaptic active zone length in control animals (0.21 +/- 0.018 micron for asymmetrical and 0.21 +/- 0.010 micron for symmetrical). We conclude that no synaptic plasticity occurs in the phrenic nucleus without functional deafferentation in spite of an increase in descending respiratory drive. Therefore functional deafferentation may be the primary inducer of phrenic nucleus synaptic plasticity occurring after hemisection or cold block.

Morphological plasticity induced in the phrenic nucleus following cervical cold block of descending respiratory drive

Morphological plasticity occurs in the phrenic nucleus within hours following an ipsilateral C2 spinal cord hemisection. The plasticity has been associated with the unmasking of a latent respiratory pathway (the crossed phrenic pathway) which allows recovery of the hemidiaphragm paralyzed by the hemisection during a reflex known as the crossed phrenic phenomenon. This study tests if the plasticity is induced by the generalized effects of spinal cord trauma or the more specific effect of interrupting the main descending respiratory drive to phrenic motoneurons. Electron microscopic quantitative morphometric analysis of the phrenic nucleus neuropil was carried out on four Sprague-Dawley rats (200-250 g) sacrificed 4 h following unilateral reversible cold block of the descending bulbospinal respiratory drive at the second cervical segment of the spinal cord (C2). The data from four sham-operated control animals were compared with those of the experimental group. The following morphological alterations were documented in cold block animals compared to controls: (1) a significant increase in the number of multiple synapses (i.e., terminals with synaptic active zones contacting two or more postsynaptic profiles in the same plane of section), (2) a significant increase in the number of dendrodendritic appositions, and (3) a significant increase in the length of symmetric and asymmetric synaptic active zones. The above changes are similar to the changes induced in the phrenic nucleus following C2 hemisection. We conclude therefore, that injury to the spinal cord is not a requirement for this type of morphological plasticity in the phrenic nucleus, but rather the induced changes are activity-dependent and are likely caused by the interruption of the descending bulbospinal respiratory drive to the phrenic nucleus.

Concomitant cardiac and pulmonary operation. Pulmonary mechanics and outcome of phrenic nerve injury

OBJECTIVE

We describe the postoperative respiratory failure due to the phrenic nerve injury in the setting of concomitant cardiac and pulmonary operation.

EXPERIMENTAL STUDY

Prospective study.

SETTING

Department of Cardiac and Thoracic Surgery Osaka University Medical School.

PATIENTS AND INTERVENTIONS

From January 1984 to December 1993, 5 patients (1.4%) underwent the concomitant cardiac and pulmonary operation out of 359 patients who received surgical treatment for lung cancer at our institution.

MEASURES AND RESULTS

Three (60%) out of 5 patients required prolonged mechanical ventilation despite the absence of cardiac complication, lung edema or pneumonia. Diaphragm function and work of breathing were measured in two patients before and after weaning from mechanical ventilation. Phrenic nerve dysfunction was consistent with the result that trans-diaphragmatic pressure (delta Pdi) was low, a ratio of gastric to esophageal pressure swing (delta Pga/delta Pes) was abnormally negative, and work of breathing (WOB) was high. Phrenic nerve function restored associated with clinical improvement.

CONCLUSIONS

Diaphragm dysfunction and an increase in work of breathing may be potential causes of respiratory failure in patients after concomitant cardiac and pulmonary operation. This compromise in respiratory mechanics should not be overlooked in the postoperative care, which may lead to the best management in postoperative respiratory care.

Right phrenic nerve palsy as a complication of indwelling central venous catheters

Five cases are reported of patients who developed a raised right hemidiaphragm while an indwelling central venous catheter was in situ. The patients were being treated with protracted venous infusions of chemotherapy for colorectal carcinoma. All five patients had a chest radiograph following insertion of the Hickman line which showed normal diaphragmatic positions. A mean of 93 days later (range 55-134 days) elevation of the right hemidiaphragm was noted in these patients on repeat chest radiographs. Two of the patients had a right phrenic nerve palsy demonstrated by magnetic stimulation of the nerve. The remaining three patients had paradoxical motion of the right hemidiaphragm on sonography, but were unable to undergo studies of phrenic nerve function before death from metastatic disease. It is suggested that right phrenic nerve palsy is a late complication of an indwelling central venous catheter.

Phrenic nerve injury after coronary artery grafting: is it always benign?

BACKGROUND

The purpose of this study was to evaluate the effect of phrenic nerve injury (PNI) occurring during coronary artery bypass grafting in patients with major chronic obstructive pulmonary disease (COPD).

METHODS

Over a 42-month period, 1,303 patients underwent primary coronary artery bypass grafting. Sixty-seven (5.14%) had major COPD, and 29 (43.3%) of these 67 sustained PNI (group I). These patients were matched for age and ejection fraction with 29 CABG patients with COPD but without PNI (group II), 29 patients without COPD but with PNI (group III), and 29 patients with neither COPD nor PNI (group IV). The groups were compared on the basis of preoperative and operative factors and immediate and midterm morbidity and mortality.

RESULTS

There were no significant differences between the groups with respect to hypertension, diabetes, ejection fraction, number of grafts, internal mammary artery use, cardiopulmonary bypass time, and ischemic time. Postoperatively, group I had a longer total hospitalization (group I, 11.7 days; group II, 7.8 days; group III, 7.8 days; and group IV, 6 days; p = 0.0001) and stay in the intensive care unit (I, 3.6 days; II, 2.2 days; III, 2.1 days; and IV, 1.2 days; p = 0.0023). More patients in group I required reintubation (I, 37.9%; II, 3.4%; III, 6.9%; and IV, 0%; p < 0.0001). Mean follow-up was 32.8 months (range, 7 to 48 months). Group I had more hospital readmissions (I, 78; II, 50; III, 61; and IV, 28; p < 0.007) and lower cumulative survival (I, 60.6%; II, 93%; III, 96.8%; and IV, 100%; p < 0.0015) compared with the other groups.

CONCLUSIONS

In patients with COPD, PNI during coronary artery bypass grafting has a major negative impact on immediate and midterm results.

[Plication of the diaphragm--a method of surgical treatment of diaphragmatic paralysis in neonates and infants after heart surgery]

The cause of paresis of the diaphragm after cardiosurgery is damage of the phrenic nerve. The diagnosis of paresis is based on X-ray examination, sonography and electromyography of the diaphragm. Plication of the diaphragm is indicated only in those children with paresis of the diaphragm who develop during spontaneous ventilation severe respiratory insufficiency. In the Cardiocentre of the Faculty Hospital Prague-Motol between 1983 and 1996 of 5333 children operated on account of heart disease 29 children were subjected to plication of the diaphragm, incl. five where the operation was made during the neonatal stage (17%), 20 in infant age (69%) and four were older than one year (14%). By the third day after plication 9 children (38%) could be disconnected from the respirator, by the 5th day 20 children (70%) by the 7th day 22 children (75%). In neonates and infants with postoperative paresis of the diaphragm, where spontaneous ventilation cannot be induced, plication of the diaphragm is according to the authors the method of choice. It is a rapid and safe surgical operation which reduces the period of artificial ventilation and its complications.

Clinical implications of phrenic nerve injury after pediatric cardiac surgery

Phrenic nerve injury with resulting diaphragm paralysis occurred in 25 (1.5%) of 1,656 cardiac surgical procedures in children during a 10-year period. Phrenic nerve injury was most commonly noted in patients who had undergone previous cardiac surgery (16 of 165, 10%; P < .0001), typically after a previous Blalock-Taussig shunt (10 of 53, 19%; P = .007). Plication of the diaphragm (7 thoracic, 4 abdominal) was performed in 11 patients (44%). Indications for plication were inability to wean from mechanical ventilation (5 patients) and persistent or recurrent respiratory distress (6 patients). The patients who needed diaphragm plication were significantly younger than those who were managed conservatively (median, 11 months [4 days to 23 months] versus 20 months [4 months to 16 years]; P = .01). All patients older than 2 years were extubated within 3 days (mean, 1.5 days) and did not need any surgical intervention. The median follow-up period was 3.2 years, and no patient has had recurrent respiratory problems. There were no deaths as a direct result of phrenic nerve injury. Phrenic nerve injury after cardiac surgery is a serious complication that often leads to respiratory insufficiency in patients under than 2 years of age. For such patients, early diaphragm plication is a simple and effective procedure that prevents the complications of prolonged mechanical ventilation.

Intraoperative phrenic nerve monitoring in cardiac surgery

BACKGROUND

Left hemidiaphragmatic paralysis due to phrenic nerve lesion is a frequent complication of hypothermic cardiopulmonary bypass. Although this is believed to be caused by cold injury to the phrenic nerve, its exact cause is still not clear.

STUDY OBJECTIVE

To assess feasibility, safety, and usefulness of intraoperative phrenic nerve function monitoring.

SETTING

Elective cardiac surgery in a university hospital.

PATIENTS

Consenting patients scheduled for myocardial revascularization surgery with the use of the left internal mammary artery.

DESIGN

Intraoperative monitoring of compound diaphragmatic action potentials (CDAPs) through transcutaneous stimulation of phrenic nerves.

INTERVENTIONS

Patients were divided in two groups. Group 1 received intracoronary cold St. Thomas's solution as the only cardioplegic method. Group 2 received topical cardiac cooling with ice-cold solutions in addition to intracoronary cardioplegia.

RESULTS

In all group 1 patients, function of phrenic nerves was maintained throughout the surgical procedure. Group 2: in two patients, bilateral, and in one patient, left phrenic nerve conduction was abolished after submersion of the heart in ice-cold solution. In two of them, the action potential of the left hemidiaphragm was absent by the end of surgery. In one, nerve conduction recovered with rewarming of the patient.

DISCUSSION

Intraoperative monitoring of CDAP was safe and easily obtained in the intraoperative setting. It allowed us to observe changes in phrenic nerve conduction occurring during surgery and as a result of cold cardioplegia. Cryogenic lesion of phrenic nerve might explain our findings. However, nerve ischemia cannot be ruled out and it may worsen axonal damage or delay its recovery.

COMMENT

This monitoring method allowed us to predict postoperative diaphragmatic dysfunction. Also, surgeons can be warned of the damaging effects of excessive cooling of the pericardium and surrounding structures; thus, preventive measures can be taken.

Combined left-sided recurrent laryngeal and phrenic nerve palsy after coronary artery operation

BACKGROUND

Ice/saline slush used along with cold cardioplegia for heart arrest in cardiac operations can cause hypothermic damage to certain structures, an important one being the left phrenic nerve, damage of which results in raised left hemidiaphragm and delayed recovery of the patient. In coronary artery bypass grafting, opening of the pleura and collection of the ice/saline slush in the pleural cavity increases the incidence of injury.

METHODS

Three of our nonconsecutive patients underwent coronary artery bypass grafting with cold cardioplegia and open pleura, with collection of ice/saline slush in the pleural cavity for a sufficiently long time.

RESULTS

Simultaneous involvement of left recurrent laryngeal nerve along with left phrenic nerve was found in all patients without any concurrent topical injury around the larynx. the recurrent laryngeal nerve took 8 to 10 months to recover.

CONCLUSIONS

The left recurrent nerve as it arches around aorta lies in the thorax very close to the parietal pleura and may be prone to hypothermic injury by ice/slush collecting in the pleural cavity during cardiac operations. Judicious use of ice/saline slush had helped in eliminating the problem to some extent.

Non-quantal acetylcholine release in the mouse diaphragm after phrenic nerve crush and during recovery

The progressive decline and recovery of spontaneous quantal acetylcholine (ACh) release (miniature endplate potentials, MEPPs) and the H-effect were measured in the mouse diaphragm after nerve crush and during regeneration. The H-effect is the hyperpolarization of the muscle fibre membrane produced by the addition of (+)tubocurarine, which indicates non-quantal ACh release. One hour after nerve crush the H-effect had declined to 50% of control values and 4 h later the H-effect disappeared completely. There were no substantial changes in the MEPP frequency and amplitude during the first 4 h after denervation. MEPP frequency then increased, but after 6 h of denervation it decreased and after 16 h no MEPPs were found in any of the muscle fibres. The times of onset of these denervation changes in the proximal, central and distal parts of diaphragm were similar. During reinnervation, the H-effect was detectable in all muscle parts 3 days before the reappearance of MEPPs. The H-effect developed first on day 8 in the proximal endplates and then, with a delay of 3 and 6 days, in the central and distal areas, respectively. During axonal regrowth the non-quantal release was restored before detectable quantal release. Non-quantal release is the first indication of the ability of the nerve terminal to release ACh in the process of reinnervation.