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Despite continued surgical advancements in the field of cardiothoracic transplantation, post-operative complications remain a burden for the patient and the multidisciplinary team. Lesser-known complications including swallowing disorders (dysphagia), and voice disorders (dysphonia), are now being reported. Such disorders are known to be associated with increased morbidity and mortality in other medical populations, however their etiology amongst the heart and lung transplant populations has received little attention in the literature. This paper explores the potential mechanisms of oropharyngeal dysphagia and dysphonia following transplantation and discusses optimal modalities of diagnostic evaluation and management. A greater understanding of the implications of swallowing and laryngeal dysfunction in the heart and lung transplant populations is important to expedite early diagnosis and management in order to optimize patient outcomes, minimize allograft injury and improve quality of life.
Heart and/or lung transplantation is the preferred treatment for end stage cardiac and/or pulmonary disease with the provision of increased survival and quality of life. Recent advances in surgical technique and immunosuppressive medications have increased life expectancy, however complications post transplantation such as primary graft dysfunction, rejection, multi-organ failure and infection remain common.
There is now growing interest in the lesser known complication of laryngopharyngeal dysfunction (LD), presenting as swallowing disorders (oropharyngeal dysphagia OPD) and voice disorders (dysphonia).
LD following surgery is frequently associated with incompetence in airway protection with associated risk of aspiration, poor secretion clearance and increased morbidity and mortality.
The potential etiology of voice and swallowing complications in this patient population is poorly understood and has received little attention in the literature. Cardiothoracic transplant surgery and the post-operative course are inherently complex and can involve (1) compromised respiratory function, (2) prolonged intubation,
Murty GE, Smith MC. Recurrent laryngeal nerve palsy following heart-lung transplantation: three cases of vocal cord augmentation in the acute phase. Case reports. J Laryngol Otol. 103:968-9.
All these factors are known to have a direct association with swallowing and voice dysfunction. The immunosuppression requirements following transplantation also leave patients at higher risk for deterioration in respiratory function in the event of glottic incompetence and/or dysphagia. Patients awaiting transplantation are often frail with poor physiological reserve, rendering them more vulnerable and at higher risk of increased hospital length of stay and adverse post-operative outcomes.
The prevalence and impact of pre-transplantation OPD and dysphonia are unknown in this complex population.
The aims of this review paper are to (1) provide a comprehensive discussion of the potential etiology for OPD and dysphonia in heart and/or lung transplantation, (2) explore the methods for diagnosis of these complications and, (3) discuss management strategies to help to reduce the burden of disease for this high-risk patient population.
Normal swallowing and vocal function
Normal swallowing is a highly complex neuromuscular process modulated by the central nervous system. Co-ordination of respiration and swallowing is required via the exhale-swallow-exhale pattern to reduce the risk of aspiration.
Airway protection is a multi-step process, involving movement of the arytenoids to contact the epiglottis, the epiglottis covering the arytenoids and closure of the vocal folds to seal the glottis.
both of which can be impacted by lung and heart transplant surgery. If vocal fold closure is mis-timed or incomplete, there is a risk of food and fluid entry into the airway. Should this occur, the final airway protective mechanism is a cough reflex which requires not only the motor initiation of abdominal, intercostal and diaphragm muscles and glottic closure but also an intact sensory system to detect the need for a motor response.
The RLN supplies all intrinsic muscles of the larynx while the superior laryngeal nerve innervates the cricothyroid muscle to tense and adduct the cords.
The vocal folds must be able to adduct to the midline and sufficient subglottic air pressure must be produced to enable vocal fold vibration and subsequent phonation. Clear voice production can be compromised by structural or functional asymmetry of the true vocal folds and/or recruitment of supraglottic structures, as well as inflammation or scarring of the vibratory layer of the folds.
Given the highly complex integration of sensory and motor function required for swallowing and phonation, disruption to any element of these pathways can result in dysphagia and/or dysphonia. Dysphagia can present as oropharyngeal dysfunction and/or oesophageal dysmotility following heart or lung transplantation and may be identified following extubation in the intensive care unit with pain on swallowing, dyspepsia, chronic cough, difficulty in swallowing secretions, or coughing on intake of food or fluids.
Dysphonia may present as hoarse or absent voice or weak cough and may indicate glottic incompetence, risk of aspiration with associated chest infection and potential for respiratory distress.
The association between respiratory function and swallowing is well established. Following heart and/or lung transplantation, respiratory status frequently remains compromised, at least in the early stages post extubation. Currently there is no literature addressing how the altered respiratory pattern of patients following heart or lung transplantation may affect swallowing function. However, alterations to respiratory physiology, characterized by hypercapnia, tachypnoea or hypoxemia are known to cause a discoordination of the breath swallow cycle and hence an increased risk of laryngeal penetration and/or aspiration, especially amongst the critically ill.
The placement of high flow nasal cannula after weaning from the ventilator is a positive step to enable oral intake, however the literature is contradictory as to whether such support assists swallowing safety or increases the risk of aspiration.
Optimal functioning of the entire respiratory system is also vital for successful voice production. The subglottic vocal tract is responsible for generating the essential airflow which travels between the vocal folds to act as the power source for the voice.
Any surgery that impacts on the structure or function of the principal muscles of inspiration or expiration can have an impact on the power source for the voice.
Although there is a distinct lack of evidence in this field in regard to the association between respiratory compromise and voice production, diseases which affect expiratory airflow, such as asthma or chronic obstructive pulmonary diseases have been shown to have a negative effect on the voice.
The requirement for endotracheal intubation to allow for mechanical ventilation during heart and/or lung transplantation is another mechanism for the development of laryngeal dysfunction and OPD. Laryngeal injury with associated dysphonia, as a result of intubation, is reported to be as high as 83% in patients within the intensive care unit who require mechanical ventilation.
Swallowing dysfunction after cardiac operations: associated adverse outcomes and risk factors including intraoperative transesophageal echocardiography.
Laryngotracheal injuries in this population are common, with the present authors previously reporting dysphonia in 63% of patients referred to speech pathology following transplantation.
Intubation related injuries include granulomas, stenosis, infections, glottic and subglottic oedema and vocal fold motion abnormalities due to arytenoid dislocation or nerve damage.
Injury can occur at the time of tube placement, due to prolonged presence of the tube in the airway or at a later stage due to abnormal healing of the airway mucosa. Location and severity of injury can also be associated with the type of endotracheal tube and cuff volume, pressure and location.
`Prolonged intubation is generally associated with mucosal damage such as ulceration and oedema, however peripheral damage of the RLN can also occur due to longer term compression.
Swallowing dysfunction after cardiac operations: associated adverse outcomes and risk factors including intraoperative transesophageal echocardiography.
Due to the pivotal role of the larynx in the protection of the airway, the presence of laryngeal pathology post extubation can directly impact on swallowing function.
Flexible endoscopic evaluation of swallowing with sensory testing in patients with unilateral vocal fold immobility: incidence and pathophysiology of aspiration.
In addition, laryngopharyngeal sensation can be impacted by the constant pressure of the tube on the chemoreceptors and mechanoreceptors in the pharynx and larynx which have a direct role in the initiation of the swallow.
Silent aspiration, defined as the entry of a food or liquid bolus below the level of the vocal folds with no cough reflex elicited, has been reported to be common in the lung transplant population.
The exact cause for this is unknown, however intubation trauma, laryngopharyngeal reflux, as well as the possibility of direct vagal nerve injury and RLN injury, are all potential contributors.
The most widely reported risk factor for PED is increased duration of intubation.
Within the heart and lung transplant populations, the current authors have previously reported duration of intubation and number of intubations to be significant predictors for referral to speech pathology for the management of OPD and voice complications.
Due to the complexity of heart and/or lung transplantation surgery and the post-operative pathway, it is difficult to determine whether RLN injury or intubation trauma is the primary mechanism for VFP and/or dysphonia. However, the close proximity of the RLN and vagus nerves, which supply all intrinsic muscles of the larynx, sensation for the upper oesophagus and contractility of the digestive tract, to the cardiovascular structures involved in heart and lung transplantation, result in risk of intra-operative injury
Numerous intra-operative mechanisms for RLN injury in cardiac surgery have been reported, including hypothermia, cardiac catheterization and sternal retraction following sternotomy. In addition, extracorporeal membrane oxygenation has been reported to pose a risk, due to the need for manipulation of the common carotid artery and internal jugular vein which can result in injury to the vagus nerve.
Murty GE, Smith MC. Recurrent laryngeal nerve palsy following heart-lung transplantation: three cases of vocal cord augmentation in the acute phase. Case reports. J Laryngol Otol. 103:968-9.
report the nerve to be at greatest risk when removing the recipients organs and that the left recurrent laryngeal branch is at higher risk due to its longer course into the posterior mediastinum. This would appear to be supported by increased rates of left sided VFP.
In addition, Taeneka and colleagues report ventricular assist device implantation to be a high risk for severe VFP which they hypothesize to be potentially related to nerve compression from enlarged cardiovascular structures or direct manipulation and retraction of the heart.
Given an increasing proportion of patients with end stage cardiac failure are now being supported via ventricular assist device's, the implant/explant of these devices is likely to further the risk of RLN damage.
There is a scarcity of literature addressing techniques to minimize RLN injury during transplantation, however Huddleston and colleagues suggest leaving a small island of pulmonary artery at the insertion of the ligamentum arteriosum, (which joins the pulmonary artery to the aorta), during cardiopneumonectomy in order to lessen the risk.
reported that half of their cohort diagnosed with VFP were asymptomatic. This phenomena has also been reported in other surgical procedures which place the RLN at risk.
Hence, it could be argued that pre-operative laryngoscopy should be conducted in patients awaiting transplantation who have a history of thyroid, skull base, carotid, anterior approach to cervical spine, or esophagectomy surgery. In addition, formal screening of vocal fold function for all patients following lung transplantation is recommended.
Patients who experience complications during and following heart and/or lung transplantation are frequently in an induced coma for long periods of time with high levels of sedating medications, high dose corticosteroids, potential sepsis and/or multi organ failure and hence are at high risk of ICU acquired weakness (ICUAW).
ICUAW can manifest as neuromuscular disorders of critical illness polyneuropathy or myopathy which is associated with prolonged weaning from ventilator support and increased length of stay.
Muscle atrophy, as a component of ICUAW, is known to have a profound effect not only on peripheral muscle strength but also inspiratory and expiratory muscles which are required
but there is little information on the specific association between ICUAW and swallowing dysfunction and no data in the area of vocal function. High aspiration rates of liquids and saliva are reported, 78% and 48% respectively.
Ponfick and colleagues reported that dysphagia completely resolved in 95% of their cohort within 4 weeks however other studies report 1 to 2 months was required before the ability to swallow fluids was regained.
The ability to predict pharyngeal dysfunction and risk of aspiration based on muscle strength before and after transplantation could be a useful tool for early intervention in this high risk population. Mirzakhani and colleagues
) showed symptomatic aspiration events and muscle weakness was associated was an almost ten-fold increase in aspiration risk.
Gastric motility disorders
Disorders of gastric motility, including gastroesophageal reflux disease (GERD), esophageal dysmotility and gastroparesis are common in patients with advanced lung disease, including those with idiopathic pulmonary fibrosis and connective tissue disorders.
The etiology is often multifactorial, however vagal nerve injury, which may occur during dissection for pneumonectomy or during implantation of the donor lungs, as well as immunosuppressive medication regimes, are considered to be large contributors.
GERD is a known risk factor for the development of BOS (Bronchiolitis Obliterans Syndrome), the pathologic process of chronic rejection following lung transplantation, and hence increased morbidity and mortality.
GERD leads to an increase in quantity of gastroduodenal contents within the esophagus and esophageal dysmotility, combine with gastroparesis, can lead to delayed clearance of this material. When these factors, combine with supine positioning, high levels of sedating medications, tube-based- enteral feeding, and immunosuppression medications, there is a predisposition to aspiration events.
Furthermore, those undergoing heart and/or lung transplantation are at higher risk of vagal nerve injury which is known to impact on esophageal motility and cause delayed gastric emptying
Laryngopharyngeal reflux (LPR), defined as the retrograde flow of gastric contents into the larynx, oropharynx and/or nasopharynx is a common and potentially debilitating component of GERD.
Presenting features can include oedema of the larynx on laryngoscopy, throat irritation and/or globus pharyngeus. LPR is known to have a direct impact on laryngopharyngeal sensation and hence airway protection during swallowing
and is strongly associated with voice changes. Dysphonia is often cited as the most common extra-esophageal symptom being reported in up to 71% of patients with LPR.
The otolaryngologic manifestations of gastroesophageal reflux disease (GERD): a clinical investigation of 225 patients using ambulatory 24-hour pH monitoring and an experimental investigation of the role of acid and pepsin in the development of laryngeal injury.
Diagnosis of GERD is frequently made based on the presence of symptoms which may be laryngeal and/or pulmonary in nature, however patients with GERD can also be asymptomatic in this population. Given the significant potential impact of GERD on the presence of BOS and associated graft survival, early and more systematic evaluation, including high resolution esophageal manometry, is generally recommended.
Medical management of gastric motility disorders generally involves a combination of lifestyle modifications, (such as diet changes and postural manipulations when eating and sleeping), combined with pharmacological agents such as anti-emetics and prokinetics for gastroparesis
However, because PPI medications do not stop the process of gastroesophageal refux, non -acid refluxate can still be aspirated with an associated concern for injury to the transplanted organs.
For patients that exhibit ongoing GERD symptoms, despite maximal medical therapy, laporoscopic fundoplication may be considered appropriate to reduce chronic damage to the graft and improve survival.
Antireflux surgery preserves lung function in patients with gastroesophageal reflux disease and end-stage lung disease before and after lung transplantation.
Other mechanisms for the development of OPD and/or dysphonia following transplantation include transient alterations to neurological function in the context of sedating medications and ICU related delirium, or more serious longer term insults such as intra or post-operative stroke. There is limited data regarding the impact of altered sensorium on swallowing function; however a greater aspiration risk has been reported for those not oriented to person, place and time.
The impact of medication regimes on pharyngo-oesophageal function following transplantation must also be considered. Immunosuppressant drugs used to prevent allograft rejection, including mycophenolate, steroids, and calcineurin inhibitors are known stomach irritants which also cause gastroparesis.
As a result, it is commonplace to prescribe a PPI and prokinetics to reduce the risk of oesophagitis and micro aspiration of reflux materials as explained above.
Furthermore, medications that cause xerostomia or have a known side effect of oesophageal dysmotility are common. Although these medications may be an essential component of the transplantation journey, the multidisciplinary team need to work together closely to understand the interaction and impact of medications on swallowing function.
Risk factors
Definitive risk factors for the development of OPD and dysphonia following heart and/or lung transplantation are poorly understood (Table 1). As a result of the scant and conflicting nature of the data surrounding pre and post-operative risk factors, robust prospective studies are needed in this field in order to form any conclusions to guide clinical practice.
Table 1Documented risk factors for swallowing and laryngeal dysfunction after lung and heart transplantation
Pre-operative
Post-operative
Complications
GERD
Increased duration of intubation
Effusion or empyema
Lower BMI
Increased ICU LOS
Venous thrombosis
Advanced age
Increased hospital LOS
Acute rejection
Tobacco use
History of cerebrovascular disease
Abbreviations: LOS, length of stay; BMI, body mass index; GERD, gastro-esophageal reflux disease; ICU, intensive care unit
Within Australian transplantation units, assessment of swallowing and voice function is not conducted as a routine element of the transplantation workup process, but rather referral is made to a speech language pathologist (SLP) if any concerns are raised by the patient or the multidisciplinary team. Following transplantation, OPD and dysphonia, may present after extubation and should trigger referral to SLP for formal assessment.
Dysphonia
Screening for dysphonia at the bedside is usually conducted by a SLP following concerns regarding perceptually abnormal voice. Subjective voice tasks can include maximum phonation time, s/z ratios, pitch range, auditory-perceptual evaluation of voice quality in conversational speech, and sustained phonation. These tasks can be easily conducted at the bedside in the ICU, depending on patient cognition and medical status, and can be indicators for potential referral for further investigation by a laryngologist. The s/z ratio has been shown to have significant accuracy for detection of laryngeal pathology amongst dysphonic patients in other clinical populations
However, the predictive accuracy for detection of laryngeal pathology via such subjective measures is currently unknown amongst a cardiothoracic transplant population.
Laryngoscopy via a flexible nasendoscope, conducted by a laryngologist, is considered the optimal diagnostic method and involves assessment of secretion management, mucosal integrity, laryngopharyngeal structure, function and sensation. Ideally, videostroboscopy should be conducted to give a detailed view of vocal fold vibration, especially in cases where the larynx appears structurally normal on white light laryngoscopy.
Recommended protocols for instrumental assessment of voice: American speech-language-hearing association expert panel to develop a protocol for instrumental assessment of vocal function.
Laryngeal electromyography, CT scanning and neck and laryngeal ultrasound can also be used to assess vocal fold movement and RLN function to assist with diagnosis.
Oropharyngeal dysphagia
Screening for OPD in all patients within 24 hours of a stroke is now standardized practice as per National Stroke guidelines.
there is no similar system in place amongst this patient population.
Formal diagnostic assessment is most commonly conducted after extubation via a clinical bedside swallowing examination conducted by a SLP. The assessment is not standardized but typically involves a case history, a cranial nerve examination with a focus on oromuscular structure, function and sensation and oral trials of food and fluid consistencies. Although this is the most frequently used method of assessment, largely for reasons of convenience and ease of accessibility, the sensitivity of this assessment has been reported to be questionable.
Silent aspiration is unable to be confirmed via clinical bedside assessment. Following lung transplantation, rates of silent aspiration are reported to be as high as 77% in those diagnosed with OPD
and the clinical bedside assessment has been shown to have poor ability to detect aspiration in this population with sensitivity to detect aspiration of 60% and specificity of 49%.
Hence, instrumental assessment is strongly recommended to enable accurate diagnosis. This is consistent with the lung transplantation clinical pathway suggested by Baumann and colleagues.
A videofluoroscopic swallow study (VFSS), conducted in the radiology suite, allows radiographic imaging of the dynamic swallow and is considered highly accurate for detection of aspiration.
However this tool may not be a suitable alternative for an unstable patient in the ICU who cannot leave the unit. Furthermore, VFSS does not allow direct visualization of glottic competence and its interaction with swallowing function.
The optimal tool to investigate both swallowing and laryngeal function simultaneously is the flexible endoscopic evaluation of swallowing (FEES) conducted via nasendoscopy. The patient is required to conduct voice tasks followed by trials of food and fluid consistencies. FEES has a high sensitivity for detection of silent aspiration
Interjudge and intrajudge reliabilities in fiberoptic endoscopic evaluation of swallowing (Fees ®) using the penetration–aspiration scale: a replication study.
and enables observation of both laryngeal pathology and sensation, and can be conducted at the bedside. This makes FEES a highly usable tool in the ICU following heart and/or lung transplantation.
Interjudge and intrajudge reliabilities in fiberoptic endoscopic evaluation of swallowing (Fees ®) using the penetration–aspiration scale: a replication study.
These figures render a high likelihood for longer term enteral feeding requirements and/or texture diet modifications, however, resolution of dysphagia appears to be seen in most patients before discharge with low rates of percutaneous endoscopic gastrostomy insertion.
After surgery, the multidisciplinary team strive to reduce the risks of rejection or dysfunction of the allograft, as well as BOS. Infectious complications are common and while not all are caused by retrograde or anterograde aspiration of food, drink, gastric contents and/or saliva, avoidance of aspiration and protection of the allograft lung is clearly critical.
Yet, management of OPD amongst critical care patients is generally underexplored and has not been directly investigated in this transplant population. Dysphagia management generally involves strict oral hygiene regimes, postural changes, texture diet modifications and various therapeutic interventions with newer techniques such as surface electromyography and respiratory muscle strength training being investigated amongst other clinical populations.
The trajectory of recovery for laryngotracheal injuries and the associated treatment plan is directly associated with the severity of dysfunction. Dysphonia associated with intubation trauma, demonstrated by inflammation or granuloma on laryngoscopy, may recover spontaneously,
however it is generally treated by a SLP in conjunction with a laryngologist. Training in vocal care and voice techniques are provided to attain optimal voice quality whilst minimizing further trauma to the vocal folds to avoid longer term voice misuse.
The optimal treatment plan for more severe pathology, such as unilateral VFP, varies depending on severity of injury, expected prognosis for recovery, patient co-morbidities, patient willingness to undergo further invasive interventions and local policy at the specific transplant centre.
Laryngeal electromyography can be used to assist with prognosis for spontaneous recovery of paralysis, however it is not widely available and is not always definitive.
Early injection laryngoplasty, which involves injection of a biocompatible resorbable material to temporarily increase bulk and improve vocal fold closure, can be used short to medium term (see Graphic 2 for images of pre/post laryngoplasty). Laryngeal framework surgery is used in the longer term or where spontaneous recovery is unlikely.
Early injection laryngoplasty has been adopted in some centres based on the concept that compromised glottic function places the patient at higher risk for aspiration related infection. The procedure can be conducted in-office or at the bedside and is considered low risk.
However, the limited available evidence within the heart and lung transplant populations renders argument for direct and early intervention challenging. Seeliger et al
recently reported VFP to be transient in 65% of a cohort of lung transplant patients who recovered spontaneously within a period of 6 months and that VFP did not adversely affect graft function, survival or secondary complication rates.However, Atkins et al
report that 75% of their cohort required medialization. Early medialization via reabsorbable implant has been suggested to reduce the need for later more permanent surgical intervention, (e.g., thyroplasty),
Early hyaluronate injection improves quality of life but not neural recovery in unilateral vocal fold paralysis: an open-label randomized controlled study.
and the accepted consensus in the laryngology literature is that it improves quality of life and patient outcomes whilst waiting for potential recovery of VFP.
Hence, further robust studies within the transplantation field may support the argument for more aggressive VFP management for improved patient outcomes.
Patient outcomes
For those patients diagnosed with OPD and/or dysphonia after transplantation, the literature suggests an increased risk for a prolonged and complicated hospital admission. Increased hospital length of stay,
have been reported. The exact nature of these associations has not yet been explored, however the contribution of factors such as critical illness weakness and extended duration of intubation are likely to play a large role as previously discussed. Post-operative complications such as effusion/empyemas, venous thromboses and acute rejection have also been reported to be increased amongst patients with OPD and dysphonia.
However, there are conflicting results in the literature. Seeliger and colleagues reported that amongst their large cohort of patients following lung transplantation, there was no inferior rates of 3 year graft survival and CLAD survival in those patients with VFP vs no VFP.
The association between repetitive aspiration of gastro-duodenal contents secondary to GERD and the development of BOS, has been well explored in the literature.
However, given the known relationship between GERD and BOS, it appears a strong biological plausibility that recurrent aspiration during the pharyngeal phase of swallowing is also likely to be associated with airway epithelial injury and negative impact on longer term graft function; hence the need for further research in this area.
Conclusions
Evidence of high rates of OPD and dysphonia following heart and/or lung transplantation are now beginning to be reported. This review is the first to identify the potential etiology for these complications and their multifactorial nature in this high risk, immunosuppressed population. This inherent complexity may explain the paucity of robust data to direct clinicians as to the optimal assessment and management approaches. To our knowledge there are no prospective studies to date assessing pre- and post-operative voice and swallowing function. Pre-surgical assessment would allow identification of patients who may be at high risk during and following transplantation and also enable the true incidence of OPD and dysphonia to be determined. Information regarding pre and post-operative risk factors for OPD and dysphonia is scant and conflicting and hence clinicians have limited evidence for early identification to optimize outcomes and minimize secondary complications. These points raise further questions as to the best assessment approach including the need for laryngoscopic assessment of function as a part of the transplantation workup process, accurate identification of those at high risk from pre- and post-operative factors such as respiratory function, intubation duration, reflux status, muscle strength and length of stay, and necessity for routine screening following transplantation. Treatment pathways for voice and swallowing disorders in this population where multiple organ systems are contributing to dysfunction, are not established, and the value of aggressive management of VFP through early intervention to minimize secondary complications is not known. Further research is required to inform the development of a comprehensive best practice protocol, which would be an advancement in understanding for the multidisciplinary team, enabling effective collaboration to reduce aspiration risk and optimize quality of life for the transplant population.
Author contributions
Rebecca Black: Primary author responsible for concept of the manuscript, literature review, writing and editing. Daniel Novakovic: Provision of expert opinion in regard to laryngeal complications and management, graphics, editing. Marshall Plit: Provision of expert opinion in regard to lung transplantation content, editing. Anna Miles: Provision of expert opinion in regard to speech pathology management, editing. Peter MacDonald: Provision of expert opinion in regard to cardiac transplantation, editing. Catherine Madill: Concept of the manuscript in conjunction with the primary author, extensive contributions to writing and editing.
Disclosure statement
The authors have no conflict of interest to declare. This work was conducted at St Vincent's hospital, Sydney and was partially funded from the trust funds of the department of thoracic medicine. The production of the manuscript was supported by the Dr Liang voice programme at the University of Sydney.
References
Maurer JR
Tullis DE
Grossman RF
Vellend H
Winton TL
Patterson GA
Infectious complications following isolated lung transplantation.
Murty GE, Smith MC. Recurrent laryngeal nerve palsy following heart-lung transplantation: three cases of vocal cord augmentation in the acute phase. Case reports. J Laryngol Otol. 103:968-9.
Swallowing dysfunction after cardiac operations: associated adverse outcomes and risk factors including intraoperative transesophageal echocardiography.
Flexible endoscopic evaluation of swallowing with sensory testing in patients with unilateral vocal fold immobility: incidence and pathophysiology of aspiration.
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