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

Validation of a novel point-of-care ultrasound method to assess diaphragmatic excursion

INTRODUCTION

Point-of-care ultrasound can assess diaphragmatic function and rule in or rule out paresis of the diaphragm. While this is a useful bedside tool, established methods have significant limitations. This study explores a new method to assess diaphragmatic motion by measuring the excursion of the uppermost point of the zone of apposition (ZOA) at the mid-axillary line using a high-frequency linear ultrasound probe and compares it with two previously established methods: the assessment of the excursion of the dome of the diaphragm (DOD) and the thickening ratio at the ZOA.

METHODS

This is a single-centre, prospective comparative study on elective surgical patients with normal diaphragmatic function. Following research ethics board approval and patient written consent, 75 elective surgical patients with normal diaphragmatic function were evaluated preoperatively. Three ultrasound methods were compared: (1) assessment of the excursion of the DOD using a curvilinear probe through an abdominal window; (2) assessment of the thickening fraction of the ZOA; and (3) assessment of the excursion of the ZOA. The last two methods performed with a linear probe on the lateral aspect of the chest.

RESULTS

Seventy-five patients were studied. We found that the evaluation of the excursion of the ZOA was more consistently successful (100% bilaterally) than the evaluation of the excursion of the DOD (98.7% and 34.7% on the right and left sides, respectively). The absolute values of the excursion of the ZOA were greater than and well correlated with the values of the DOD.

CONCLUSION

Our preliminary data from this exploratory study suggest that the evaluation of the excursion of the ZOA on the lateral aspect of the chest using a linear probe is consistently successful on both right and left sides. Future studies are needed to establish the distribution of normal values and suggest diagnostic criteria for diaphragmatic paresis or paralysis.

TRIAL REGISTRATION NUMBER

NCT03225508.

CT-derived 3D-diaphragm motion in emphysema and IPF compared to normal subjects

Image registration-based local displacement analysis enables evaluation of respiratory motion between two computed tomography-captured lung volumes. The objective of this study was to compare diaphragm movement among emphysema, idiopathic pulmonary fibrosis (IPF) and normal subjects. 29 normal, 50 emphysema, and 51 IPF subjects were included. A mass preserving image registration technique was used to compute displacement vectors of local lung regions at an acinar scale. Movement of the diaphragm was assumed to be equivalent to movement of the basal lung within 5 mm from the diaphragm. Magnitudes and directions of displacement vectors were compared between the groups. Three-dimensional (3D) and apico-basal displacements were smaller in emphysema than normal subjects (P = 0.003, P = 0.002). Low lung attenuation area on expiration scan showed significant correlations with decreased 3D and apico-basal displacements (r = - 0.546, P < 0.0001; r = - 0.521, P < 0.0001) in emphysema patients. Dorsal-ventral displacement was smaller in IPF than normal subjects (P < 0.0001). The standard deviation of the displacement angle was greater in both emphysema and IPF patients than normal subjects (P < 0.0001). In conclusion, apico-basal movement of the diaphragm is reduced in emphysema while dorsal-ventral movement is reduced in IPF. Image registration technique to multi-volume CT scans provides insight into the pathophysiology of limited diaphragmatic motion in emphysema and IPF.

Postoperative acute respiratory failure in cardiac surgery

OBJECTIVE

To evaluate incidence, causes and outcomes of acute respiratory failure (ARF) in patients after cardiac and aortic surgery.

MATERIAL AND METHODS

A retrospective trial included 3972 patients after elective cardiovascular procedures for the period 2013-2017. Inclusion criterion: sustained reduction of pulmonary function (PaO₂/FiO₂<300 mm Hg) in the postoperative period required mechanical ventilation or non-invasive positive pressure mask ventilation for at least 24 h.

RESULTS

ARF developed in 138 (3.5%) cases. It was observed after aortic surgery as a rule (11.2%). Other operations were followed by ARF in 1-3.5% of cases. Incidence of ARF was less after off-pump coronary artery bypass surgery compared with on-pump interventions (1.6 vs. 3.5%, p=0.0469). Acute respiratory distress syndrome was the main reason of ARF (n=37, 26.8%). ARF as a consequence of neurological complications were observed in 25 (18.1%) patients. Exacerbation of COPD and bronchial asthma occurred in 23 (16.1%) patients, paresis of the diaphragm - in 15 (11.7%). In 15 (10.8%) patients, ARF was caused by pneumonia, in 12 (8.7%) cases - pulmonary congestion, in 10 (7.2%) patients - lung injury and haemothorax. Overall ARDS-associated mortality was 21.6%; 15.1% of patients with mild and moderate ARDS died. Severe ARDS was followed by unfavorable outcome in 75% of patients. Nosocomial pneumonia was found in 40.6%, there were no fatal outcomes from this complication.

CONCLUSION

Acute respiratory failure developed in 3.5% of cardiac patients and was common thoracic and thoracoabdominal aortic surgery. The leading cause of mortality was ARDS (mortality rate 15.1% in mild and moderate syndrome, 75% in severe course of ARDS). Nosocomial pneumonia was diagnosed in 1.4% of patients and was not fatal.

Diaphragmatic palsy after cardiac surgery in adult and pediatric patients

Background

Important differences in the mechanism of respiration between adults and children warrant distinction in the management of diaphragmatic paralysis as a complication of cardiac surgery. We describe the management and outcomes of this complication in both groups.

Methods

We retrospectively analyzed 16 patients (5 adults and 11 children) with diaphragmatic paralysis after cardiac surgery performed between 2008 and 2018. Clinical examination, chest radiography, and confirmation with fluoroscopy in selected cases were our modalities of diagnosis. All adults were managed conservatively, whereas plication was performed in all children.

Results

The incidence of diaphragmatic paralysis was 0.98% in pediatric patients and 0.43% in adults. The mean age was 2.33 ± 2.59 years in children and 53.2 ± 17.99 years in adults. All adults were symptomatic. All children showed difficulty in weaning from mechanical ventilation after cardiac surgery. The period of mechanical ventilation before plication was 2–6 days (median 4 days). Death occurred as a result of low cardiac output in a 10-year-old boy, and due to respiratory failure in a 30-year-old woman. Children were successfully weaned from mechanical ventilation after diaphragmatic plication. The median time to extubation after plication was 2.5 days (range 1–13 days). The median period of recovery in adults was 52 days (range 32–85 days). All survivors had acceptable outcomes at 6 months to one year.

Conclusion

Conservative management in adults and early plication in children are viable treatment options for diaphragmatic palsy after cardiac surgery, with acceptable outcomes.

Diaphragm thickening in cardiac surgery: a perioperative prospective ultrasound study

Background

Diaphragm paresis is common after cardiac surgery and may delay the weaning from the ventilator. Our objective was to evaluate diaphragm thickening during weaning and secondly the muscle thickness as a marker of myotrauma.

Methods

Patients undergoing elective cardiac surgery were prospectively included. Ultrasonic index of right hemidiaphragm thickening fraction (TF) was measured as a surrogate criterion of work of breathing. A TF < 20% was defined as a low diaphragm thickening. Measurements of TF were performed during three periods to study diaphragm thickening evolution defined by the difference between two consecutive time line point: preoperative (D − 1), during a spontaneous breathing trial (SBT) in the intensive care unit and postoperative (D + 1). We studied three patterns of diaphragm thickness at end expiration evolution from D − 1 to D + 1: > 10% decrease, stability and > 10% increase. Demographical data, length of surgery, type of surgery, ICU length of stay (LOS) and extubation failure were collected.

Results

Of the 100 consecutively included patients, 75 patients had a low diaphragm thickening during SBT. Compared to TF values at D − 1 (36% ± 18), TF was reduced during SBT (17% ± 14) and D + 1 (12% ± 11) (P < 0.0001). Thickness and TF did not change according to the type of surgery or cooling method. TF at SBT was correlated to the length of surgery (both r = − 0.4; P < 0.0001). Diaphragm thickness as continuous variable did not change over time. Twenty-eight patients (42%) had a > 10% decrease thickness, 19 patients (29%) stability and 19 patients (28%) in > 10% increase, and this thickness evolution pattern was associated with: a longer LOS 3 days [2–5] versus 2 days [2–4] and 2 days [2], respectively (ANOVA P = 0.046), and diaphragm thickening evolution (ANOVA P = 0.02). Two patients experience extubation failure.

Conclusion

These findings indicate that diaphragm thickening is frequently decreased after elective cardiac surgery without impact on respiratory outcome, whereas an altered thickness pattern was associated with a longer length of stay in the ICU. Contractile activity influenced thickness evolution.

Trial registry number ClinicalTrial.gov ID NCT02208479

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0521-z) contains supplementary material, which is available to authorized users.

Topical Ice Slush Adversely Affects Sniff Nasal Inspiratory Force After Coronary Bypass Surgery

BACKGROUND

Topical cooling with ice slush as an adjunct for myocardial protection during cardiac surgery has been shown to cause freezing injury of the phrenic nerves. This can cause diaphragmatic dysfunction and respiratory complications.

METHODS

Twenty (n=20) male patients between the ages of 40 and 60 years were equally randomised to undergo elective coronary artery bypass grafting (CABG) with either cold cardioplegic arrest with topical ice slush cooling or cold cardioplegic arrest without the use of ice slush. The sniff nasal inspiratory force (SNIF) was used to compare inspiratory muscle strength.

RESULTS

There was no difference in the preoperative SNIF in the two randomised groups. In the immediate postoperative period, the ice slush group had worse SNIF (33.5±9.6cm H2O versus 47.8±12.2cm H2O; p=0.009). The pre-home discharge SNIF was still significantly lower for the ice slush group despite a noted improvement in SNIF recovery in both groups (38.3±10.6cm H2O versus 53.5±13.2cm H2O; p=0.011). Two patients in the ice slush group had left diaphragmatic dysfunction with none in the control group.

CONCLUSION

The use of topical ice slush is associated with freezing injury of the phrenic nerves. This will adversely affect the inspiratory muscle force which may lead to respiratory complications after surgery.

Diaphragm Dysfunction: Diagnostic Approaches and Management Strategies

The diaphragm is the main inspiratory muscle, and its dysfunction can lead to significant adverse clinical consequences. The aim of this review is to provide clinicians with an overview of the main causes of uni- and bi-lateral diaphragm dysfunction, explore the clinical and physiological consequences of the disease on lung function, exercise physiology and sleep and review the available diagnostic tools used in the evaluation of diaphragm function. A particular emphasis is placed on the clinical significance of diaphragm weakness in the intensive care unit setting and the use of ultrasound to evaluate diaphragmatic action.

“Other” Neurologic Complications After Cardiac Surgery

Compared to the neurologic morbidity of stroke and cognitive dysfunction, “other” neurologic complications involving injuries to the brachial plexus, phrenic nerve, cranial nerves, other peripheral nerves, as well as the visual pathways, have been disproportionately underrepresented in the cardiac surgery and anesthesiology literature. These injuries are often missed in the early postoperative period when attention is focused principally on recovery from the acute trespass of cardiac surgery and cardiopulmonary bypass. However, when these problems do become apparent, they can cause considerable discomfort and morbidity. An overview of the current concepts of injury mechanisms/etiology, diagnosis, prognosis, and when possible, prevention of these injuries is presented.

Prototype nerve-specific near-infrared fluorophores

Nerve preservation is an important issue during most surgery because accidental transection or injury results in significant morbidity, including numbness, pain, weakness, or paralysis. Currently, nerves are still identified only by gross appearance and anatomical location during surgery, without intraoperative image guidance. Near-infrared (NIR) fluorescent light, in the wavelength range of 650-900 nm, has the potential to provide high-resolution, high-sensitivity, and real-time avoidance of nerve damage, but only if nerve-specific NIR fluorophores can be developed. In this study, we evaluated a series of Oxazine derivatives to highlight various peripheral nerve structures in small and large animals. Among the targeted fluorophores, Oxazine 4 has peak emission near into the NIR, which provided nerve-targeted signal in the brachial plexus and sciatic nerve for up to 12 h after a single intravenous injection. In addition, recurrent laryngeal nerves were successfully identified and highlighted in real time in swine, which could be preserved during the course of thyroid resection. Although optical properties of these agents are not yet optimal, chemical structure analysis provides a basis for improving these prototype nerve-specific NIR fluorophores even further.

Early hemi-diaphragmatic plication through a video assisted mini-thoracotomy in postcardiotomy phrenic nerve paresis

New symptom onset of respiratory distress without other cause, and new hemi-diaphragmatic elevation on chest radiography postcardiotomy, are usually adequate for the diagnosis of phrenic nerve paresis. The symptom severity varies (asymptomatic state to severe respiratory failure) depending on the degree of the lesion (paresis vs. paralysis), the laterality (unilateral or bilateral), the age, and the co-morbidity (respiratory, cardiac disease, morbid obesity, etc). Surgical treatment (hemi-diaphragmatic plication) is indicated only in the presence of symptoms. The established surgical treatment is plication of the affected hemidiaphragm which is generally considered safe and effective. Several techniques and approaches are employed for diaphragmatic plication (thoracotomy, video-assisted thoracoscopic surgery, video-assisted mini-thoracotomy, laparoscopic surgery). The timing of surgery depends on the severity and the progression of symptoms. In infants and young children with postcardiotomy phrenic nerve paresis the clinical status is usually severe (failure to wean from mechanical ventilation), and early plication is indicated. Adults with postcardiotomy phrenic nerve paresis usually suffer from chronic dyspnoea, and, in the absence of respiratory distress, conservative treatment is recommended for 6 months -2 years, since improvement is often observed. Nevertheless, earlier surgical treatment may be indicated in non-resolving respiratory failure. We present early (25(th) day postcardiotomy) right hemi-diaphragm plication, through a video assisted mini-thoracotomy in a high risk patient with postcardiotomy phrenic nerve paresis and respiratory distress. Early surgery with minimal surgical trauma, short operative time, minimal blood loss and postoperative pain, led to fast rehabilitation and avoidance of prolonged hospitalization complications. The relevant literature is discussed.

Can lung volumes and capacities be used as an outcome measure for phrenic nerve recovery after cardiac surgeries?

Phrenic nerve is the main nerve drive to the diaphragm and its injury is a well-known complication following cardiac surgeries. It results in diaphragmatic dysfunction with reduction in lung volumes and capacities. This study aimed to evaluate the objectivity of lung volumes and capacities as an outcome measure for the prognosis of phrenic nerve recovery after cardiac surgeries. In this prospective experimental study, patients were recruited from Cardio-Thoracic Surgery Department, Educational-Hospital of College of Medicine, Cairo University. They were 11 patients with right phrenic nerve injury and 14 patients with left injury. On the basis of receiving low-level laser irradiation, they were divided into irradiated group and non-irradiated group. Measures of phrenic nerve latency, lung volumes and capacities were taken pre and post-operative and at 3-months follow up. After 3 months of low-level laser therapy, the irradiated group showed marked improvement in the phrenic nerve recovery. On the other hand, vital capacity and forced expiratory volume in the first second were the only lung capacity and volume that showed improvement consequent with the recovery of right phrenic nerve (P value <0.001 for both). Furthermore, forced vital capacity was the single lung capacity that showed significant statistical improvement in patients with recovered left phrenic nerve injury (P value <0.001). Study concluded that lung volumes and capacities cannot be used as an objective outcome measure for recovery of phrenic nerve injury after cardiac surgeries.

Incidence and management of diaphragmatic palsy in patients after cardiac surgery

Background:

Diaphragm is the most important part of the respiratory system. Diaphragmatic palsy following cardiac surgery is not uncommon and can cause deterioration of pulmonary functions and attendant pulmonary complications.

Objectives:

Aim of this study was to observe the incidence of diaphragmatic palsy after off pump coronary artery bypass grafting (OPCAB) as compared to conventional CABG and to assess the efficacy of chest physiotherapy on diaphragmatic palsy in post cardiac surgical patients.

Design and Setting:

An observational prospective interventional study done at a tertiary care cardiac centre.

Patients:

2280 consecutive adult patients who underwent cardiac surgery from February 2005 to august 2005.

Results:

30 patients out of 2280 (1.31%) developed diaphragmatic palsy. Patients were divided based on the presence or absence of symptoms viz. breathlessness at rest or exertion or with the change of posture along with hypoxemia and / or hypercapnia. Group I included 14 patients who were symptomatic (CABG n=13, post valve surgery n=1), While Group II included 16 asymptomatic patients (CABG n=12, post valve surgery n=4), 9 patients (64%) from Group I (n=14) and 4 patients (25%) from group II showed complete recovery from diaphragmatic palsy as demonstrated ultrasonographically.

Conclusion:

The incidence of diaphragmatic palsy was remarkably less in our adult cardiac surgical patients because most of the cardiac surgeries were performed off pump and intensive chest physiotherapy beginning shortly after extubation helped in complete or near complete recovery of diaphragmatic palsy. Chest Physiotherapy led to marked improvement in functional outcome following post cardiac surgery diaphragmatic palsy.

We also conclude that ultrasonography is a simple valuable bed-side tool for rapid diagnosis of diaphragmatic palsy

Respiratory movements are altered three months and one year following cardiac surgery

OBJECTIVE

Pulmonary complications following cardiac surgery through sternotomy are well known, but little is known about the proposed alterations of the chest wall mechanism. The purpose of this study was to examine changes in chest wall motion and pulmonary function after cardiac surgery.

DESIGN

The subjects were 20 cardiac surgery patients, 13 men and 7 women, mean age 65 years.

MEASUREMENTS

Bilateral respiratory movements were measured using the Respiratory Movement Measuring Instrument before, 3 and 12 months after the operation. Vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume (FEV1) were measured with the Pulminet III (Gold Godart Ltd Vitalograph Alpha Ltd. Maids Morton, Buckingham, England) preoperatively, 3 and 12 months postoperatively, and radiographs were taken at the same points in time.

ANALYSIS

Descriptive statistics, paired sample t-tests, Mann-Whitney and Wilcoxon Signed Rank tests were used for analyses, p < or = 0.05.

RESULTS

Average abdominal movements 3 months postoperatively were significantly decreased and the difference between right and left side in upper thoracic and abdominal movements was significant. All pulmonary function measurements except the FEV1/FVC showed a significant decrease and a restrictive pattern compared with preoperative values. Twelve months after the operation the upper thoracic movements were significantly increased. Five patients had an abnormal chest x-ray before the operation, eight 3 months and three 12 months after the operation.

CONCLUSION

The motor system of the respiratory organs suffers considerable injury from cardiac surgery, which in part at least can explain the restrictive breathing 3 months postoperatively.

Chest wall motion and pulmonary function are more diminished following cardiac surgery when the internal mammary artery retractor is used

OBJECTIVES

Pulmonary complications following cardiac surgery through sternotomy have been widely studied. The duration of these complications, however, has been less studied and the proposed alterations in chest wall mechanism even less. The purpose of this study was to investigate changes in chest wall motion and pulmonary function of cardiac surgery patients, where both the median and the internal mammary artery retractor was used (IMA group) and cardiac surgery patients, where only the median retractor was used (Median group).

DESIGN

Subjects were 20 cardiac surgery patients with mean age 65 years (12 in the IMA group and 8 in the Median group). Bilateral respiratory movements (RMs) using the Respiratory Movement Measuring Instrument, lung volumes including vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume (FEV1) using the Vitalograph Alpha were measured and pulmonary radiographs analyzed before, 3 and 12 months after the operation.

ANALYSIS

Descriptive statistics, t-tests, Mann-Whitney and Wilcoxon Signed Rank tests were used for analyses, p < or = 0.05.

RESULTS

RMs were symmetrical in both groups prior to the operation and the differences in RMs and lung volumes between the groups were not significant. Three and 12 months postoperatively bilateral abdominal respiratory movements (ARM) were significantly less in the IMA group than in the Median group. Average left ARM were significantly less than the average right ARM in the IMA group 3 months postoperatively, while symmetrical in the Median group. Average FVC and FEV1 were significantly less in the IMA group than in the Median group 3 months postoperatively and FVC was still significantly less in the IMA group 12 months after the operation.

CONCLUSION

The significantly more reduced ARM and lung volumes 3 months postoperatively in the IMA group than in the Median group suggests that the IMA retractor causes greater injury to the rib cage and the diaphragm.

Surgical Anatomy of the Accessory Phrenic Nerve

BACKGROUND

Reports place the frequency of phrenic nerve injury after cardiac operations between 10% and 85%, emphasizing the importance of an accurate anatomic description of the diaphragm's innervating nerves to reduce iatrogenic injury, length of hospitalization, and associated costs. The aim of our study was to explore the anatomic variations of the accessory phrenic nerve and relate these findings to phrenic nerve injury.

METHODS

Eighty adult formalin-fixed cadavers were dissected, resulting in 160 nerve specimens. Fifty nerve specimens were also examined laparoscopically with findings later confirmed through gross dissection. All nerves contributing to the phrenic nerve after crossing the anterior scalene were considered to be accessory phrenic nerves.

RESULTS

The phrenic nerve was present in all specimens, and 99 (61.8%) also had an accessory phrenic nerve. The accessory phrenic nerve arose from the nerve to subclavius in 60 specimens (60.6%), ansa cervicalis in 12 (12.1%), and nerve to sternohyoid in 7 (7%). The accessory phrenic nerve joined with the phrenic nerve in the thorax anterior to the subclavian vein in 45 (45.5%) specimens and posterior in 17 (22.2%). A phrenic-accessory phrenic nerve loop was found around the subclavian vein in 45 (35 on the right, 10 on the left) specimens and around the internal thoracic artery in 38 (31 on the right, 7 on the left).

CONCLUSIONS

To reduce injuries to the diaphragm, the presence of an accessory phrenic nerve should be considered before mobilization and skeletonization of the internal thoracic artery above the second rib.

The effect of oral prednisolone with chronic obstructive pulmonary disease undergoing coronary artery bypass surgery

BACKGROUND

Chronic obstructive pulmonary disease is still one of the most important problems in patients undergoing cardiopulmonary bypass. The purpose of this prospective study was to assess the beneficial effects of oral prednisolone on pulmonary functions in patients undergoing cardiopulmonary bypass.

METHODS

Forty patients with chronic obstructive pulmonary disease were divided into two groups randomly and were given 20 mg oral prednisolone once daily perioperatively (Group I, n = 20) or identical placebo (Group II, n = 20). FEV(1) values, dates of intensive care unit and hospital stays of the two groups were compared.

RESULTS

FEV1 values during the admission to our hospital were similar in each group mean predicted FEV1: 56.7 +/- 5.35% in Group I and 57.2 +/- 4.88% in Group II (p = 0.759). After 10 days of oral prednisolone treatment in Group I, predicted FEV1 values were significantly different between two groups (63.2%+/- 4.24 and 57.9%+/- 4.38) (p = 0.0001). While predicted FEV1 values revealed difference between two groups at the date of discharge (p = 0.0001) the values became similar at the third month (55.6%+/- 4.09 in Group I and 55.45%+/- 3.87 in Group II) (p = 0.897).

CONCLUSION

Various types of complications may occur after cardiopulmonary bypass. Oral prednisolone not only decreases the rates of complications (reintubation, intubation times, and rhythm disturbances) but also decreases the cost of cardiac operations according to shorter hospital stays.

Iatrogenic-induced dysfunction of the neuromuscular respiratory system

In the presence of respiratory symptoms that are associated with alveolar hypoventilation or a restrictive ventilatory defect and in the absence of parenchymal or pleural abnormalities on the chest radiograph, iatrogenic causes must be evoked, exactly as they are in the presence of interstitial lung disease. In most cases, the anamnestic and clinical contexts provide a strong diagnostic presumption. It is important to establish carefully the mechanism of the observed disorders, using the currently available arsenal of diagnostic tools for clinical and prognostic reasons and from a medicolegal standpoint. It is necessary to evaluate precisely the clinical repercussions of the respiratory neuromuscular abnormality to serve as a basis for follow-up and to discuss therapeutic options in certain cases (eg, nocturnal ventilation to correct nocturnal hypoventilation due to diaphragmatic dysfunction, diaphragm plication to alleviate dyspnea after complete phrenic nerve destruction, phrenic nerve pacing), again in the perspective of medicolegal actions.

Laparoscopic diaphragmatic plication: long-term results of a novel surgical technique for postoperative phrenic nerve palsy

BACKGROUND

Paralysis of the diaphragm is a severe complication of cardiothoracic surgery carrying significant morbidity and mortality. This study demonstrates a novel minimally invasive technique for treatment of phrenic nerve injuries presenting with symptomatic eventration of the diaphragm. It also presents long-term results of three patients treated with this operation.

METHODS

Chest x-ray proved eventration of the left diaphragm in all patients. Two patients required treatment due to prolonged respirator therapy/assisted ventilation for 4 weeks after cardiac surgery. One patient suffered from progressive dyspnea caused by increasing left-sided diaphragmatic elevation and underwent surgery 2 years after cardiac surgery. In all cases, a minimally invasive abdominal approach was chosen. During surgery the dome of the diaphragm was pulled down via three percutaneously inserted retention stitches. This resulted in two or three folds of the diaphragm located within the abdomen. These diaphragmatic folds were subsequently tightened using 12 to 15 unresorbable sutures with extracorporally prepared knots. Surgical as well as long-term follow-up results are presented of all patients and a review of the current literature is provided.

RESULTS

Mean operating time was 203 min; mean intraoperative blood loss was 130 ml. No major complications occurred during surgery or the postoperative period. At a median follow-up of 72 months no recurrence was observed.

CONCLUSIONS

Laparoscopic diaphragmatic plication provides excellent relief of symptoms caused by diaphragmatic paralysis. There is no perioperative morbidity, and hospital stay is short. The laparoscopic approach, therefore, is an attractive surgical alternative for the treatment of phrenic nerve palsy and should be considered in all suitable patients.

Brachial plexus injury as an unusual complication of coronary artery bypass graft surgery

Brachial plexus injury is an unusual and under-recognised complication of coronary artery bypass grafting especially when internal mammary artery harvesting takes place. It is believed to be due to sternal retraction resulting in compression of the brachial plexus. Although the majority of cases are transient, there are cases where the injury is permanent and may have severe implications as illustrated in the accompanying case history.

Is phrenic nerve dysfunction after cardiac surgery related to internal mammary harvesting?

BACKGROUND

Although many surgeons feel that internal mammary artery (IMA) harvesting is a risk factor for phrenic nerve dysfunction (PND) following coronary artery bypass grafting surgery (CABG), objective data confirming this are lacking. We sought to compare two groups of cardiac surgical patients to determine if an association exists between IMA harvesting and PND following CABG.

METHODS

Using inpatient medical records and chest radiographs, we performed a retrospective analysis of 25 consecutive CABG patients and 25 consecutive valve procedure patients in order to compare the incidence of PND following cardiac surgery with and without IMA harvesting.

RESULTS

Two patients were excluded. Thirty-one patients underwent IMA harvesting as part of their procedure, of whom 42% had PND evidenced on postextubation chest X-ray. Seventeen patients did not have IMA harvesting, and the incidence of PND in this group was 12% (p = 0.05). Both groups were similar in preoperative variables and operative techniques.

CONCLUSION

This study suggests IMA harvesting is indeed a risk factor for PND following CABG.

Morbid results of prolonged intubation after coronary artery bypass surgery

OBJECTIVES

This study evaluated the morbid results of prolonged intubation after coronary artery bypass grafting (CABG).

METHODS

Over 30 months, 66 of 1,112 patients undergoing CABG required prolonged intubation. They were matched with 66 patients who did not require prolonged intubation. Preoperative and operative variables were evaluated to determine which would predict prolonged intubation. The postoperative courses were then compared to evaluate the effect of prolonged intubation. The study population was divided into three groups: those who underwent early extubation, but required reintubation (n = 24); those who required initial prolonged intubation, but no reintubation (n = 22); and those who required initial prolonged intubation and reintubation (n = 20).

RESULTS

Univariate analysis revealed unstable angina (p = 0.037), elevated creatinine (p = 0.001), reduced FEV(1) (p = 0.019), longer cardiopulmonary bypass time (p = 0.009), and a greater positive fluid balance at 24 h (p = 0.0001) as predictors of postoperative prolonged intubation. Multivariate regression analysis revealed elevated creatinine (p = 0.011), FEV(1) (p = 0.022), and fluid balance (p = 0.001) as predictors of prolonged intubation. The study population had longer ICU and hospital stays (p = 0.0001), with more infectious complications (p = 0.0001) and higher mortality (p = 0. 001). In the subgroups of the study population, patients not requiring reintubation had shorter ICU (p = 0.001) and hospital stays (p = 0.0001), fewer infectious complications (p = 0.0001), and reduced mortality (p = 0.0001).

CONCLUSIONS

Patients undergoing CABG with reduced FEV(1), renal failure, and positive fluid balance 24 h postoperatively are at risk for prolonged intubation. Prolonged intubation results in significant acute and midterm morbidity and mortality. Early extubation followed by reintubation further increases morbidity and mortality rates in these patients.

Topical hypothermia: ineffective and deleterious as adjunct to cardioplegia for myocardial protection

BACKGROUND

Topical hypothermia, an early method developed for myocardial protection by virtue of its reduction of cardiac metabolic rate, is not without sequelae such as phrenic nerve paralysis and pulmonary complications.

METHODS

The hospital records of 505 nonrandomized consecutive patients undergoing coronary artery bypass grafting between 1991 and 1995 at the University of South Alabama were reviewed to evaluate the effectiveness of topical hypothermia and its relationship to pulmonary complications. Group A included 191 patients between 1991 and 1992 who received systemic hypothermia and topical hypothermia with iced slush in addition to cold blood cardioplegia. Group B included 314 patients between 1993 and 1995 who received systemic hypothermia and intermittent cold blood cardioplegia without iced slush.

RESULTS

Myocardial temperature mapping did not reveal any difference between the two groups. Postoperative cardiac morbidity, manifested as intraaortic balloon use, low cardiac output, inotrope use, and perioperative myocardial infarction, was decreased in group B, but the difference failed to achieve statistical significance. Mortality (group A, 3.14%; group B, 3.82%) and rates of significant morbidity such as sternal infection, stroke, reoperation for bleeding, renal failure, and prolonged ventilation were comparable between the two groups. However, there was a statistically significant difference in the incidence of diaphragmatic paralysis between group A and group B. Group A had a 25% incidence of diaphragmatic paralysis on the first postoperative day, 18% on the 15th postoperative day, and 8% at 6 months, as opposed to group B, which had incidences of 2% on the first postoperative day, 1% on the 15th postoperative day, and 1% at 6 months (p < 0.001). Also, there was a significant difference in incidence of pleural effusions (60% versus 25%) and rate of thoracentesis (25% versus 8%) between groups A and B (p < 0.0001).

CONCLUSIONS

We conclude that topical hypothermia did not offer any additional cardioprotective benefit above systemic hypothermia and cold blood cardioplegia alone in coronary bypass patients, but significantly increased the incidence of diaphragmatic paralysis and associated pulmonary complications.