Introduction

Gastroesophageal reflux disease (GERD) is defined as abnormal distal esophageal acid exposure that is associated with patient symptoms, and it is the most common benign condition of the stomach and esophagus. The majority of patients with GERD experience “typical symptoms ” (i.e., heartburn and regurgitation), and their symptoms are managed effectively with medications, specifically proton pump inhibitors (PPIs) . In fact, because PPIs are so effective at decreasing gastric acid production and provide improvement in typical GERD-related symptoms, most patients with GERD who take these medications never undergo a formal diagnostic evaluation. Consequently, an empiric trial of PPI therapy has become viewed as both “diagnostic and therapeutic” for most patients that present with typical GERD symptoms.

In the vast majority of patients, GERD is a disease that affects quality of life and is associated with a low risk of developing life-threatening complications. In these patients, the end point of treatment is symptom management, and in most patients medical therapy is successful at achieving that goal. More recently, however, it has become clear that GERD is a contributing factor to certain types of advanced lung disease presumably due to repetitive micro-aspiration of gastroduodenal contents. Compared to most GERD patients, patients with GERD-related lung disease are unique in two major ways. First, these patients infrequently experience typical symptoms of GERD; therefore, the decision to evaluate these patients for GERD should not be determined based exclusively on patient-reported gastroesophageal symptoms. In fact, many pulmonologists have adopted a liberal approach to testing, or even empirically treating, patients with specific types of pulmonary disease for GERD regardless of the presence of symptoms. Furthermore, improvement in gastroesophageal symptoms should not be the end point of treatment in patients with GERD and chronic lung disease. Second, while PPI therapy is very effective at suppressing gastric acid production, recent evidence suggests that micro-aspiration of pH-neutral gastric contents can cause pulmonary injury. As a result, PPI therapy alone is ineffective at correcting the pathophysiologic mechanism behind GERD-related lung disease – micro-aspiration. Traditionally, antireflux surgery has been employed almost exclusively in patients who experience persistent life-limiting GERD symptoms despite maximal medical therapy (i.e., PPI therapy). However, in patients with GERD-related lung disease, antireflux surgery may be more appropriate than PPI therapy because antireflux surgery is the treatment that comes closest to eradicating all forms of gastroesophageal reflux (GER) with the creation of a mechanical barrier.

The purpose of this chapter is to provide a comprehensive review of GERD in the context of chronic severe pulmonary disease and related conditions, including esophageal dysmotility, connective tissue disorders, and lung transplantation. We discuss the approach to clinical evaluation and management of patients with GERD and GERD-related lung disease, emphasizing the relevant diagnostic testing and treatment options, including antireflux surgery.

Gastroesophageal Reflux Disease: Relevant Anatomy, Physiology, and Pathophysiology

Normal function of the stomach and esophagus is necessary to prevent GERD. The three primary mechanisms that counteract GER are a competent lower esophageal sphincter (LES), effective spontaneous esophageal clearance, and normal gastric emptying. Failure of any of these processes can lead to GERD.

Lower Esophageal Sphincter

The LES is the first defense against preventing reflux of gastric contents into the esophagus. Rather than a distinct anatomic structure, the LES is a zone of high pressure located just cephalad to the gastroesophageal junction (GEJ). This high-pressure zone is readily identified during esophageal manometry (see the section on “Clinical Evaluation of Patients with Suspected Gastroesophageal Reflux Disease”).

The LES is made up of four anatomic structures: (1) The intrinsic musculature of the distal esophagus is normally in a state of tonic contraction. With the initiation of a swallow, these smooth muscle fibers relax and then return to a state of tonic contraction. (2) Sling fibers of the gastric cardia are oriented diagonally from the cardia-fundus junction to the lesser curve of the stomach and contribute significantly to the high-pressure zone of the LES. (3) The crura of the diaphragm surround the esophagus as it passes through the esophageal hiatus. During inspiration, a pressure gradient is created as intrathoracic pressure decreases relative to intraabdominal pressure. To counteract this pressure gradient, the anteroposterior diameter of the crural opening is decreased, compressing the esophagus and increasing pressure at the LES. (4) With the GEJ firmly anchored in the abdominal cavity, increased intraabdominal pressure is transmitted to the GEJ, which increases the pressure on the distal esophagus and prevents reflux of gastric contents.

Gastroesophageal reflux develops when intragastric pressure surpasses the high-pressure zone of the distal esophagus. This occurs under three conditions : (1) LES resting pressure is too low to counteract normal intragastric pressures (i.e., hypotensive LES); (2) LES inappropriately relaxes in the absence of peristaltic contraction of the esophagus (i.e., spontaneous LES relaxation); and (3) intragastric pressure surpasses the normal LES resting pressure [1]. It is important to remember that GER is a normal physiologic process that occurs even in the setting of normal gastroesophageal anatomy and function. The distinction between physiologic reflux (i.e., GER) and pathologic reflux (i.e., GERD) hinges on the total amount of esophageal acid exposure, patient symptoms, and the presence of mucosal damage of the esophagus.

The presence of a hiatal hernia is a common anatomic abnormality that can significantly compromise the LES antireflux mechanism and predispose to GER. A hiatal hernia is the abnormal displacement of the GEJ cephalad to the esophageal hiatus and into the posterior mediastinum. This occurs due to a failure of the phrenoesophageal ligament, a continuation of the peritoneum that reflects onto the esophagus at the hiatus and normally anchors the GEJ in the abdominal cavity. When the GEJ becomes displaced into the distal mediastinum, the LES becomes compromised and is unable to maintain a high-pressure zone to prevent reflux. When a hiatal hernia is present, the most common symptoms attributable to this finding are typical symptoms of GERD. However, many small hiatal hernias are completely asymptomatic, and a hiatal hernia is neither necessary nor sufficient to make the diagnosis of GERD. Therefore, the presence of such a hernia does not constitute an indication for operative correction.

Ineffective Esophageal Motility

The primary functions of the esophagus are to transport liquid and food boluses into the stomach, to clear refluxed gastroduodenal contents back into the stomach, and to prevent abnormal reflux from occurring. For these to be accomplished, the esophagus must generate sufficiently forceful peristaltic contractions, and the lower esophageal sphincter must simultaneously relax. Esophageal dysmotility is a broad term that refers to discoordinated esophageal body contractions, low-amplitude coordinated esophageal contractions, or both. High-resolution esophageal manometry (HRM) (see the section on “Clinical Evaluation of Patients with Suspected Gastroesophageal Reflux Disease”) is the best modality to evaluate for esophageal dysmotility. Based on manometric evaluation , ineffective esophageal motility (IEM) is defined by the Chicago Classification v3.0 of HRM as ≥50% of swallows resulting in a distal esophageal contractile pressure of <450 mmHg (Fig. 17.1a–c) [2]. When esophageal dysmotility is present, the functions of the esophagus may become compromised.

Fig. 17.1
figure 1

(a–c) High-resolution esophageal manometry provides a comprehensive evaluation of esophageal function. (a) Normal esophageal manometry. (b) Ineffective esophageal motility due to hypotensive distal esophageal body contractility. (c) Ineffective esophageal motility due to failed swallows (a–c: Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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Ineffective esophageal motility and GERD are intimately related. When GER occurs, intrinsic esophageal motility should rapidly and effectively clear the refluxate from the distal esophagus back into the stomach. Spontaneous esophageal clearance reduces the amount of time that the distal esophageal mucosa is exposed to acid and other gastroduodenal contents that are caustic to the esophageal mucosa. Furthermore, esophageal motility prevents reflux to the proximal esophagus. With impaired esophageal body motility, this intrinsic clearance mechanism fails to evacuate the esophagus of these refluxed materials. As a result, relatively infrequent GER can lead to prolonged episodes of distal esophageal acid exposure. This can be demonstrated on 24-h pH monitoring (Fig. 17.2a, b). When a patient with IEM is upright, gravity aids in draining the distal esophagus of refluxed gastric contents; however, in the supine position, incomplete esophageal clearance results in a column of fluid that can passively move toward the oropharynx, resulting in severe regurgitation, water brash sensation, and even aspiration.

Fig. 17.2
figure 2

(a, b) Representative portions of a 24-h esophageal pH monitoring tracing demonstrating episodes of reflux in the upright (a) and recumbent (b) positions. Note that in the presence of impaired esophageal clearance of gastric contents, a single episode of reflux can result in prolonged exposure of the distal esophagus to acidic gastric contents (b) (a, b: Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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There is mounting evidence that esophageal dysmotility is prevalent among patients with GERD. In a study of over 1500 patients with abnormal distal esophageal acid exposure on 24-h pH monitoring, patients with abnormal esophageal body peristalsis demonstrated more severe GERD-related symptoms, worse esophagitis, and longer time to clearance of distal esophageal acid [3]. Furthermore, there appears to be an association between the presence of IEM and the severity of GERD: Esophageal dysmotility is more common in patients with esophagitis and Barrett’s esophagus compared to patients with nonerosive reflux disease [4, 5]. Although esophageal dysmotility appears to increase GERD severity, GERD itself may potentiate—or even cause—esophageal dysmotility due to repeated exposure of the esophagus to caustic gastroduodenal contents. In support of this hypothesis, Heider and colleagues demonstrated improvement in esophageal dysmotility following antireflux surgery [6].

There also appears to be a connection among IEM, GERD, and GERD-related respiratory conditions. In patients with GERD-related respiratory symptoms, IEM is the most commonly identified esophageal motility disorder. The logical explanation for this is that incomplete clearance of acid from the esophagus allows for proximal movement of the refluxate and eventual micro-aspiration. Pellegrini and colleagues were the first to systematically study this connection [7]. They evaluated 100 patients with elevated distal esophageal acid exposure on 24-h pH studies and defined aspiration as a drop in esophageal pH followed by patient-reported water brash sensation and coinciding cough or wheeze. Ineffective esophageal motility was identified in 75% of patients who experienced aspiration based on these criteria. A study by Fouad and colleagues further supports the connection between prolonged distal esophageal acid exposure and respiratory symptoms [8]. They demonstrated that in patients with GERD-associated respiratory symptoms, the average duration of an episode of reflux was twice as long compared to patients with typical symptoms of GERD and no respiratory problems. They also found that 41% of patients with chronic cough and 53% of patients with asthma demonstrated IEM on esophageal manometry. Taken together, these findings suggest that IEM leads to longer esophageal acid exposure time, which in turn increases the risk of aspiration .

Since ineffective esophageal motility appears to facilitate aspiration and micro-aspiration is the underlying mechanism behind GERD-related respiratory symptoms and pulmonary disease, it should come as no surprise that the incidence of esophageal dysmotility is greater in patients with end-stage lung disease compared to normal healthy control subjects. In the most comprehensive evaluation of esophageal motor dysfunction in lung transplant candidates to date, Basseri and colleagues [9] performed HRM in 30 consecutive patients undergoing lung transplant evaluation. Compared to healthy control subjects, lung transplant candidates were found to have a higher incidence of hypotensive lower esophageal sphincter (63% vs. 20%, p = 0.028), which places these patients at increased risk for GER. Additionally, 77% of lung transplant candidates demonstrated some form of esophageal body dysfunction, and compared to healthy control subjects, these patients demonstrated fewer peristaltic contractions and a greater incidence of hypotensive peristaltic contractions and of complete esophageal body aperistalsis.

Finally, esophageal motility disorders are common in patients who undergo lung transplantation. Since the performance of the first pneumonectomy in the 1930s, it has been recognized that radical lung surgery is associated with postoperative anatomic and physiologic changes in the esophagus [10]. These changes include a shift of the esophagus to the ipsilateral side of the pneumonectomy, decreased distal esophageal body contractile amplitude, and decreased lower esophageal sphincter resting pressure. In lung transplantation, replacement of the removed organ prevents anatomic shift in the esophagus; however, esophageal dysmotility has been reported in up to 20% of patients following lung transplantation [11]. The reason for esophageal dysmotility following lung transplantation is thought to be due to inadvertent partial or complete vagal nerve injury that can occur during dissection and hemostasis within the posterior mediastinum during recipient pneumonectomy and implantation of the donor lung(s).

Delayed Gastric Emptying

Delayed gastric empting (DGE) is the ineffective clearance of gastric contents from the stomach. In some patients, DGE can result in significant symptoms, including nausea, early satiety, regurgitation, and vomiting. The three most common causes of DGE are diabetic, idiopathic, and postsurgical.

In any patient undergoing evaluation of GERD, it is important to consider whether delayed gastric emptying is present. First, DGE is a cause, albeit rare, of GERD: Delayed emptying of the stomach leads to increased intragastric pressure that overwhelms the antireflux mechanism of the LES and results in GER [12]. Second, in the setting of DGE, traditional GERD management strategies will likely be ineffective or even result in additional symptoms. For example, the performance of antireflux surgery in the setting of gastroparesis can result in severe upper abdominal bloating secondary to a distended stomach and inability to regurgitate or vomit. In this situation, reoperation to undo the fundoplication may be required. In patients without any symptoms of gastroparesis, generally no further testing is required. However, if there is any suspicion that gastric emptying may be abnormal, a radionuclide scintigraphy scan (i.e., gastric emptying study) should be performed.

There is mounting evidence that DGE is common in patients with chronic pulmonary disease, particularly when the pulmonary disease is associated with a connective tissue disorder, and following lung transplantation. Similar to posttransplant esophageal dysfunction, the likely mechanism underlying DGE following lung transplantation is vagal nerve injury incurred during transplantation. In one of the first reports of DGE in lung transplant patients, Berkowitz and colleagues published that 42% of lung transplant recipients reported persistent gastrointestinal symptoms and 24% of lung transplant recipients were ultimately diagnosed with DGE [13]. In the lung transplant population, DGE can easily be overlooked, because these patients require many medications, including immune suppression agents, which can cause gastroesophageal symptoms. Consequently, a high index of suspicion should be had for the presence of gastroparesis in lung transplant patients who present with any upper gastroesophageal symptoms. Identification of DGE in a lung transplant recipient is important, since DGE can lead to regurgitation and aspiration. The presence of delayed gastric emptying in the lung transplant population has led some surgeons to adding a gastric emptying procedure (pyloroplasty) during performance of laparoscopic antireflux surgery in these patients [14], although there is no consensus on whether this should be routinely performed during antireflux surgery.

Clinical Presentation of Gastroesophageal Reflux Disease

Typical Symptoms

Heartburn, regurgitation, and water brash are the three typical esophageal symptoms of GERD, and they are among the most common symptoms reported by patients with GERD (Table 17.1). Heartburn is very specific to GERD and described as epigastric and/or retrosternal caustic or stinging sensation. It is important to ask the patient about his or her symptoms in detail to differentiate typical heartburn from symptoms suggestive of other disease processes, including pancreatitis, acute coronary syndrome, peptic ulcer disease, and cholelithiasis.

Table 17.1 Prevalence of symptoms in 1000 patients with GERD symptom
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The presence of regurgitation often indicates progression of GERD. In severe cases, patients will be unable to bend over without experiencing an episode of regurgitation. Regurgitation of gastric contents to the oropharynx and mouth can produce a sour taste that patients will describe as either “acid” or “bile.” This phenomenon is referred to as water brash. In patients who report regurgitation as a frequent symptom, it is important to distinguish between regurgitation of undigested and digested food. Regurgitation of undigested food is not common in GERD and suggests the presence of a different pathologic process, such as an esophageal diverticulum, achalasia, and gastroparesis.

Extraesophageal Symptoms

Extraesophageal symptoms of GERD arise from the respiratory tract and include both laryngeal and pulmonary symptoms (Box 17.1). Two proposed mechanisms may lead to extraesophageal symptoms of GERD [15]. First, proximal esophageal reflux and micro-aspiration of gastroduodenal contents cause direct caustic injury to the larynx and lower respiratory tract; this is probably the most common mechanism. Second, due to the common vagal innervation of the trachea and esophagus, distal esophageal acid exposure can trigger a vagal nerve reflex that results in bronchospasm and cough.

Box 17.1 Extraesophageal symptoms of GERD

Laryngeal symptoms of reflux:

  1. 1.

    Hoarseness/dysphonia

  2. 2.

    Throat clearing

  3. 3.

    Throat pain

  4. 4.

    Globus

  5. 5.

    Choking

  6. 6.

    Postnasal drip

  7. 7.

    Laryngeal and tracheal stenosis

  8. 8.

    Laryngospasm

  9. 9.

    Contact ulcers

Pulmonary symptoms of reflux:

  1. 1.

    Cough

  2. 2.

    Shortness of breath

  3. 3.

    Wheezing

  4. 4.

    Pulmonary disease (asthma, IPF, chronic bronchitis, and others)

Unlike typical GERD symptoms (i.e., heartburn and regurgitation), extraesophageal symptoms of reflux are much less specific to GERD. Prior to attributing these symptoms to GERD, and certainly before proceeding with antireflux surgery, it is necessary to determine whether a patient’s extraesophageal symptoms are due to abnormal GER or a primary laryngeal-bronchial-pulmonary etiology. This can be challenging. A lack of response of extraesophageal symptoms to a trial of PPI therapy cannot reliably refute GERD as the etiology of extraesophageal symptoms. Although PPI therapy can improve or completely resolve typical GERD symptoms, patients with extraesophageal symptoms experience variable response to medical treatment [16,17,18]. This may be explained by recent evidence that suggests acid is not the only underlying caustic agent that results in laryngeal and pulmonary injury [19,20,21]. PPI therapy will suppress gastric acid production, but micro-aspiration of non-acid refluxate, which contains caustic bile salts, pepsin, and other caustic agents, can cause ongoing injury and symptoms. Therefore, in patients with extraesophageal symptoms of GERD, a mechanical barrier to reflux (i.e., esophagogastric fundoplication created during antireflux surgery) may be necessary to prevent ongoing laryngeal-tracheal-bronchial injury.

In patients who present with abnormal GER and bothersome extraesophageal symptoms, a thorough evaluation must be completed to rule out a primary disorder of their upper or lower respiratory tract. This should be completed whether or not typical GERD symptoms are also present. At the University of Washington Center for Esophageal and Gastric Surgery, we always collaborate with otolaryngologists and pulmonologists to determine if a non-gastrointestinal condition is present. Surgery is only considered as an option for patients in whom GERD is present and highly suspicious of being related to the patient’s extraesophageal symptoms . Based on our results, we counsel these patients that they will have a 70% likelihood of improvement in extraesophageal symptoms following antireflux surgery. It should be noted that these results are inferior to those normally seen in patients treated only for typical symptoms of GERD [22].

Lung Conditions Related to Gastroesophageal Reflux Disease

Increasing evidence suggests GERD is a contributing factor to the pathophysiology of several pulmonary diseases [23, 24].

Asthma

In their extensive review , Bowrey and colleagues [25] examined medical and surgical antireflux therapy in patients with GERD and asthma. In these patients, the use of antisecretory medications was associated with improved respiratory symptoms in only 25–50% of patients with GERD-induced asthma. Furthermore, less than 15% of these patients experienced objective improvement in pulmonary function. One explanation for these results is that most of these studies lasted 3 months or less, which is potentially too short to see any improvement in pulmonary function. Additionally, in several trials, gastric acid secretion was incompletely blocked by acid suppression therapy, and patients experienced ongoing GERD.

In patients with asthma and GERD, antireflux surgery appears to be more effective than medical therapy at managing pulmonary symptoms. Antireflux surgery is associated with improvement in respiratory symptoms in nearly 90% of children and 70% of adults with asthma and GERD. Several randomized trials have compared histamine-2 receptor antagonists and antireflux surgery in the management of GERD-associated asthma. Compared to patients treated with antisecretory medications, patients treated with antireflux surgery were more likely to experience relief of asthma symptoms, discontinue systemic steroid therapy, and improve peak expiratory flow rate. Thus, the presence of GERD in lung transplant recipient may induce airflow obstruction without overt manifestations of asthma and mimic bronchiolitis obliterans syndrome (BOS) and/or cause lung allograft dysfunction.

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe, chronic, and progressive lung disease that generally results in death within 5 years of diagnosis. Recently, the pathophysiology of IPF has been shown to hinge on alveolar epithelial injury followed by abnormal tissue remodeling. Proximal esophageal reflux and micro-aspiration of acid and non-acid gastric contents has been implicated as one possible cause of alveolar epithelial injury that can lead to IPF.

The incidence of GERD in patients with IPF has been reported to be between 35 and 94% [26,27,28,29]. Importantly, typical symptoms of GERD are not sensitive for abnormal reflux in patients with IPF, as many patients with IPF do not experience any heartburn, regurgitation, or acid brash despite having a very abnormal acid exposure [30]. Consequently, the threshold to test for GERD in patients with IPF should be low, as a result several authors have recommended ambulatory pH monitoring in all patients with IPF [31, 32]. It is important to appreciate, however, that several studies have demonstrated that the severity of reflux measured by ambulatory pH monitoring does not appear to be associated with severity of pulmonary disease in patients with IPF [33]. This should not discount the role that GERD plays in the pathophysiology of IPF, as multiple host-response factors are involved in the development of pulmonary dysfunction due to GERD, and the variability in pulmonary dysfunction may be related to one or more of these factors rather than the degree of GERD. This underscores the notion that a better test is needed to determine the relative contribution of GERD to lung dysfunction in patients with chronic lung disease.

Since IPF is a progressive, fatal disease, investigators have studied the effect of GERD treatment on pulmonary function and survival in patients with IPF . In reviewing the charts of 204 patients with IPF, Lee and colleagues [34] used logistic regression to show that both acid suppression therapy and history of Nissen fundoplication were associated with longer survival and slower pulmonary decline. Although PPI use suppresses gastric acid production, it does not prevent reflux of non-acid gastroduodenal contents. As previously stated, non-acid reflux has been implicated in both extraesophageal symptoms of reflux and IPF; thus, it is postulated that perhaps surgery may be more effective than medical treatment in this patient population. In 18 patients with IPF, Kilduff and colleagues [35] demonstrated PPI use was associated with fewer episodes of acid reflux on pH monitoring; however, these patients experienced no change in reported cough severity and were found to have persistent and significant non-acid reflux on esophageal impedance testing. Therefore, in IPF patients with significant GERD, the argument could be made that a mechanical barrier to both acid and non-acid reflux (i.e., antireflux surgery) is more appropriate than PPI therapy.

Antireflux surgery in patients with IPF appears to be safe, provides effective control of distal esophageal acid exposure, and may mitigate progression of pulmonary dysfunction. In the first report on this topic, Raghu and colleagues [36] published their experience with antireflux surgery in one patient with IPF and GERD. During 72 months of follow-up, they demonstrated stabilization of forced vital capacity, diffusion capacity of the lung to carbon monoxide, room air oxygen saturation, and exercise capacity on 6-min walk test. This observation led to a larger retrospective cohort study in which the same group studied the outcome of 27 patients with IPF who underwent laparoscopic antireflux surgery over a 14-year period [37]. Ninety-day mortality was zero, and there were no perioperative pulmonary complications. Distal esophageal acid exposure was normalized in 19 of 20 patients (95%), and only 1 patient underwent reoperation for recurrent GERD at 12 years after the initial antireflux surgery. The decline in pulmonary function (as measured by forced vital capacity [FVC]) was 102 mL over the first year following antireflux surgery. Compared with pulmonary decline published for two leading pharmacotherapies for IPF (nintedanib, 115 mL, and pirfenidone, 235 mL), this pulmonary decline following antireflux surgery was lesser but not statistically significant. With stronger evidence of the benefit of antireflux surgery in the mitigation of IPF-related pulmonary dysfunction and the relative safety of the procedure in these patients, an NIH-sponsored multicenter randomized controlled trial is underway to evaluate the safety and efficacy of laparoscopic antireflux surgery in the treatment of IPF (Treatment of IPF with Laparoscopic Antireflux Surgery [WRAP-IPF], NCT01982968).

Lung Transplantation

Despite advances in medical management, lung transplantation remains the only definitive treatment option for patients with end-stage lung disease. Unfortunately, patient survival following lung transplantation is short compared to survival after other solid organ transplantation. As of 2015, the median survival at 1, 3, and 5 years was 83.1%, 62.1%, and 46.2%, respectively [38].

The main reason for this inferior survival following lung transplantation is the development of bronchiolitis obliterans syndrome (BOS) in the transplanted lungs. BOS develops secondary to both immune and nonimmunologic chronic inflammatory responses to ongoing graft injury. At 5-year posttransplant, BOS can affect up to 80% of lung transplant patients, and by 3-year posttransplant, it accounts for up to 30% of all deaths [39]. Although the specific pathophysiology is incompletely understood, there is mounting evidence that GERD is a contributing factor to BOS. GERD is found in as many as 70% of patients after lung transplant [40], and it is now viewed as a modifiable risk factor for allograft deterioration. Additionally, it has been shown that a negative correlation exists between extent of esophageal acid exposure and graft function as measured by forced expiratory volume in 1 s [41].

Connective Tissue Disorders and Gastroesophageal Reflux Disease

Connective tissue disorders (CTD) are systemic rheumatologic diseases that affect protein-rich tissues, including the fat, bone, and cartilage. CTD typically involve the musculoskeletal system, including the skin, muscles, and joints, but they also can affect other organs, including the gastrointestinal tract and the lungs. Esophageal dysmotility and GERD are the two most common gastrointestinal manifestations of these diseases. Gastroparesis is also prevalent in this patient population. Patti and colleagues reported pathologic reflux in 70% of CTD patients evaluated by 24-h pH monitoring and 83% of CTD patients evaluated by esophageal manometry demonstrated low-amplitude peristalsis; nearly half of those patients had absent esophageal peristalsis [42]. Further, up to 60% of patients with scleroderma were found to have a complication of GERD, including Barrett’s esophagus or peptic stricture [43].

Lung disease is also common in patients with CTD, and up to 60% of patients with CTD and lung involvement ultimately progress to end-stage lung disease and may be considered for transplantation [44]. As discussed in prior sections of this chapter, there is a strong association among esophageal dysmotility, GERD, and some pulmonary conditions, and it is now evident that a similar relationship exists in the CTD patient population. However, the CTD patient population is unique in that CTD patients also have a high prevalence of esophageal dysmotility. In patients with CTD and end-stage lung disease, Patti and colleagues reported an incidence of abnormal esophageal motility of 83%, and nearly half of those patients demonstrated absent peristalsis [45]. This was significantly more common than in patients with isolated CTD (36% abnormal peristalsis; 0% absent peristalsis) and normal healthy control patients with GERD (36% abnormal peristalsis; 0% absent peristalsis). Because of the high prevalence of esophageal dysmotility and severe chronic lung disease in patients with CTD, there has been hesitation to offer these patients lung transplantation due to concern for early graft dysfunction secondary to GERD-related BOS. Because antireflux surgery is very effective at controlling acid- and non-acid GERD, antireflux surgery may provide an opportunity to mitigate GERD-related BOS in this patient population.

Clinical Evaluation of Patients with Suspected GERD

The diagnosis of GERD is frequently made clinically based on the presence of typical GERD symptoms and improvement in those symptoms with PPI therapy. In patients without pulmonary disease or other symptoms that raise concern for an alternative diagnosis (i.e., esophageal stricture, achalasia, malignancy), this approach is acceptable. Since patients with GERD and coexisting pulmonary disease frequently lack gastroesophageal symptoms of GERD and stake of leaving GERD untreated is ongoing lung injury, a more definitive diagnosis of GERD is necessary. The diagnosis of GERD is confirmed by the presence of elevated distal esophageal acid exposure identified on ambulatory esophageal pH testing. Three additional tests—esophageal manometry, barium esophagram, and esophagogastroduodenoscopy—provide a comprehensive evaluation of gastroesophageal anatomy and function. In patients with abnormal esophageal pH testing who are also considering antireflux surgery, including patients with pulmonary disease, all four tests should be completed.

Ambulatory pH and Impedance Monitoring

Ambulatory pH monitoring quantifies distal esophageal acid exposure and is the gold standard test to diagnose GERD. Twenty-four-hour pH monitoring is conducted with a thin catheter that is passed into the esophagus via the patient’s nose. The simplest catheter is a dual-probe pH catheter that is positioned 5 cm proximal to the LES based on esophageal manometry (see next section). Alternatively, 48-h ambulatory pH monitoring can be performed using an endoscopically placed wireless pH monitor. In one study, 48-h system increased sensitivity of detecting GERD by 22% [46].

Ambulatory pH monitoring generates a large amount of data concerning esophageal acid exposure (Fig. 17.3). A composite DeMeester score is calculated based on these data, and a score of ≥14.7 is abnormal. Importantly, patients undergoing esophageal pH monitoring should stop all acid suppression medications for 1 week prior to testing to avoid a false-negative test. Occasionally one may want to repeat the test—once the baseline is obtained—while the patient is on treatment with PPIs to determine the effect of treatment in esophageal acid exposure.

Fig. 17.3
figure 3

Ambulatory 24-h esophageal pH monitoring report. In this patient, abnormal esophageal acid exposure was identified in the upright and recumbent positions and in both the distal and proximal esophagus. A complete report should include a calculated DeMeester composite score and symptom correlation (Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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In addition to the objective data obtained with esophageal pH testing, the patient can keep track of reflux-related symptoms by pressing a button on an electronic data recorder. During the interpretation of the pH study, symptom index and symptom-associated probability are calculated based on the temporal relationship between the symptom event and episodes of distal esophageal acid exposure (Fig. 17.4). A symptom episode that occurs within 2 min of a reflux episode is defined as a close temporal relationship and suggests, but does not confirm, a cause and effect relationship between GER and patient symptoms. While the decision to perform antireflux surgery should not hinge on symptom correlation [47], it can help predict symptom improvement following antireflux surgery [48].

Fig. 17.4
figure 4

Representative portion of a dual-probe 24-h esophageal pH study . Temporal correlation of reflux symptoms (e.g., heartburn and cough) with episodes of esophageal pH <4 is used to calculate symptom index, which can help predict symptom improvement after antireflux surgery (Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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Esophageal impedance monitoring identifies episodes of non-acid reflux by detecting changes in the resistance to flow of an electrical current (i.e., impedance). Impedance increases in the presence of air and decreases in the presence of a liquid bolus. Therefore, this technology can detect both gas and liquid movement in the esophagus. Some impedance catheters also have one or more pH sensor, allowing for the simultaneous detection of acid and non-acid reflux. There also exists a specialized pH-impedance catheter with a very proximal pH sensor that detects pharyngeal acid reflux. This catheter can be useful in the evaluation of patients with extraesophageal symptoms such as cough, throat clearing, hoarseness, and wheezing.

Combined impedance-pH monitoring has been shown to identify reflux episodes with greater sensitivity than pH testing alone [49]. Although there is no consensus on whether impedance-pH testing should be performed on or off acid suppression therapy [50,51,52,53], our practice is to perform all impedance-pH testing off acid suppression. Furthermore, how impedance-pH monitoring should guide the management of GERD is unknown. Patel and colleagues attempted to determine the parameters on esophageal impedance-pH monitoring that predict response of GERD symptoms to both medical and surgical treatment [54]. They showed that acid exposure time, and not the number of non-acid reflux events, best predicted symptom improvement to both medical and surgical therapy. Although the addition of impedance monitoring increased the sensitivity of the study, non-acid reflux measurements alone were unable to accurately predict symptom improvement to medical or surgical therapy for GERD.

Esophageal Manometry

Esophageal manometry is the most effective way to assesses function of the esophageal body and the lower esophageal sphincter. Standard esophageal manometry provides linear tracings of pressure waves of the esophageal body and LES (Fig. 17.5). High-resolution esophageal manometry gathers data using a 32-channel flexible catheter with pressure-sensing devices arranged at 1 cm intervals. The study generates a color contour plot of ten patients’ swallows. It shows the response of the upper and lower esophageal sphincters as well as the esophageal body; time is on the x-axis, esophageal length is on the y-axis, and pressure is represented by a color scale (Fig. 17.6). In patients undergoing evaluation for GERD, esophageal manometry can exclude achalasia and identify patients with ineffective esophageal body peristalsis. Esophageal manometry also measures the LES resting pressure and assesses the LES for appropriate relaxation with deglutition. Because the LES is the major barrier to GER, a defective LES is common in patients with GERD [55].

Fig. 17.5
figure 5

Standard esophageal manometry tracing (Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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Fig. 17.6
figure 6

High-resolution manometry tracing (Courtesy of the University of Washington Center for Esophageal and Gastric Surgery, Seattle, WA)

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Esophagogastroduodenoscopy

Endoscopy is an essential step in the evaluation of patients with GERD to evaluate for evidence of mucosal injury due to GER, including ulcerations, peptic strictures, and Barrett’s esophagus. Endoscopic evaluation should also include an assessment of the integrity of the GEJ flap valve [56] as well as the presence of a hiatal hernia. The hernia should be measured in cranial-caudal, anteroposterior, and lateral dimensions.

Barium Esophagram

Barium esophagram provides a detailed anatomic evaluation of the esophagus and stomach that is useful during preoperative evaluation of patients with GERD. Of particular importance are the presence, size, and anatomic characteristics of a hiatal or paraesophageal hernia (Fig. 17.7). Despite its ability to identify episodes of GER, which can occur spontaneously or in response to patient positioning during the study, barium esophagram cannot confirm or refute the diagnosis of GERD. Additional gastroesophageal conditions that can be identified on barium esophagram are esophageal diverticula, tumors, peptic strictures, achalasia, dysmotility, and gastroparesis. If any one of these is found in a patient undergoing evaluation for GERD, antireflux surgery should be delayed until appropriate evaluation of the unexpected findings is completed.

Fig. 17.7
figure 7

Upper gastrointestinal series (esophagram) demonstrating a paraesophageal hernia. Note that the gastroesophageal junction and a portion of the gastric fundus are herniated cephalad to the diaphragmatic impression on the gastric body/fundus

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Additional Evaluations in Patients with Extraesophageal GERD Symptoms

While there is agreement among gastroenterologists, pulmonolgists, and surgeons that extraesophageal (laryngopharyngeal) reflux exists, a sensitive and specific test to diagnose this condition has yet to be developed. Despite this, in patients with isolated extraesophageal symptoms of GERD, clinical evaluation beyond the four major diagnostic evaluation tools noted above should be performed, particularly if antireflux surgery is being considered. Several questionnaires exist that assess the presence and severity of laryngopharyngeal symptoms. While these are easy to administer and score, they lack sensitivity and specificity to GERD. Collaboration with an otolaryngologist is indispensable when vague, non-specific laryngopharyngeal symptoms are present, including throat clearing, hoarseness, throat pain, postnasal drainage, and globus sensation. Otolaryngologists are uniquely trained to perform a detailed history and examination that may identify a non-GERD etiology of the patient’s symptoms. Furthermore, otolaryngologists can perform awake endoscopic evaluations of the upper aerodigestive tract. Laryngeal inflammation has been identified in patients with as few as three episodes a week of reflux [57], and these inflammatory changes can be identified on laryngoscopy and graded according to the reflux finding score [58]. Pathologic biomarkers, including pepsin, have been identified in laryngeal biopsy [21], bronchoalveolar lavage [59], and even sputum [60]. Additionally, laryngopharyngeal pH testing may identify the presence of proximal reflux of gastric contents. Although no single test may confirm or refute GERD as the cause of extraesophageal symptoms, taken together the results of these studies can help guide treatment, including the decision to pursue antireflux surgery.

Treatment of Gastroesophageal Reflux Disease

Medical Management

For patients that present with typical symptoms of GERD, an 8-week course of PPI therapy is recommended [61, 62]. However, prior to empirically prescribing a PPI, it is necessary to ensure that the patient does not have symptoms that may indicate the presence of a gastroesophageal malignancy or other non-GERD diagnosis, including rapidly progressive dysphagia, regurgitation of undigested food, anemia, extraesophageal symptoms of GERD, or weight loss. If the symptoms improve with PPI therapy, then the trial is considered both diagnostic and therapeutic. If the symptoms persist after a trial of medical therapy, a more extensive evaluation, as described above, is indicated. Although lifestyle modification has been advocated before or as an adjunct to medical therapy, the efficacy of such changes in the treatment of esophagitis has not been proved [63].

Proton pump inhibitors have revolutionized the pharmacologic treatment of GERD. As one of the most widely prescribed drugs worldwide, the annual expenditure on PPI therapy has reached approximately $24 billion [64]. These drugs stop gastric acid production by irreversibly binding the proton pump in the parietal cells of the stomach. The maximal pharmacological effect occurs approximately 4 days after initiation of therapy, and the effect lasts for the life of the parietal cell. For this reason, patients must stop PPI therapy 1 week prior to ambulatory pH monitoring to avoid a false-negative test result.

Proton pump inhibitors are well-tolerated medications. Immediate side effects of PPI therapy are relatively rare and generally mild, including headache, abdominal pain, flatulence, constipation, and diarrhea. This relatively safe side-effect profile and their effectiveness at controlling GERD symptoms have led to overprescription of these medications in both the outpatient and inpatient settings [65]. Although there are published evidence-based recommendations that might limit this practice of overprescription, including on-demand dosing and step-down therapy, clinicians frequently do not follow these guidelines.

Despite their short-term safety, there has been concern over the long-term effects of PPI use since their initial preclinical trials [66]. The most concerning long-term complication of PPI use is hypergastrinemia leading to enterochromaffin cell hyperplasia and ultimately carcinoid tumors. The first case of neuroendocrine tumor of the stomach in patient with 15-year history of PPI use has just been published [67], so it seems that the true risk of this is exceptionally low. However, additional associations have been made between PPI use and enteric infections, antiplatelet medication interactions, bone fractures, nutritional deficiencies, and community-acquired pneumonia [65]. Importantly, however, there have been no cause and effect relationship established, and patients prescribed with PPI therapy have more comorbid conditions than the general population, which may explain some of these associations. Therefore, until further studies better elucidate PPI as a contributing factor to these conditions, the results of these studies should be interpreted with caution.

One shortcoming of PPI therapy is that it actually does nothing to reduce gastroesophageal reflux (i.e., retrograde movement of gastric contents into the esophagus). Proton pump inhibitors render the gastric refluxate less acidic and consequently reduce the caustic injury to the esophagus during episodes of reflux. However, because GER still occurs (albeit with more alkaline gastric contents), patients with long-standing GERD frequently experience symptomatic regurgitation. Furthermore, proximal esophageal reflux of non-acid gastric contents can still be aspirated. This is an important consideration in generating a treatment plan for patients with chronic lung disease and patients undergoing lung transplant evaluation: Aspiration of non-acid refluxate is associated with lung injury that can lead to progression of lung disease or, in the case of a lung transplant patient, graft rejection and/or BOS. As such, surgical creation of a mechanical barrier to reflux may be more appropriate in these patient populations.

Surgical Management

For patients that exhibit elevated distal esophageal acid exposure and persistent typical GERD symptoms despite maximal medical therapy, antireflux surgery should be strongly considered. The application of laparoscopy to antireflux surgery has decreased patient morbidity and hospital length of stay. Furthermore, several studies have shown that antireflux surgery is cost-effective compared to prolonged PPI therapy [68, 69]. In patients that experience absolutely no improvement in their symptoms with the use of PPI, the diagnosis of GERD should be questioned, and surgeons must carefully consider alternative etiologies prior to offering surgical treatment. In patients with extraesophageal symptoms of GERD that do not improve with PPI therapy, consultation with an otolaryngologist and/or pulmonologist is necessary prior to proceeding with antireflux surgery to determine if a primary laryngeal, bronchial, or pulmonary cause of the symptoms is present. Endoscopic evidence of severe esophageal injury (e.g., ulcerations, peptic strictures, and Barrett’s esophagus) can be considered evidence of abnormal distal esophageal acid exposure; however, endoscopic findings by themselves should not be considered an indication for operative therapy by themselves.

Several randomized trials with long-term follow-up have compared medical and surgical therapy for GERD. Spechler and colleagues [70] found that surgical therapy results in good symptom control after 10-year follow-up. Although they reported 62% of patients in the surgical group were taking antisecretory medications at long-term follow-up, the indications for this medication use were not necessarily GERD, and reflux symptoms did not change significantly when these patients stopped taking these medications.

Lundell and colleagues [71] randomized patients with erosive esophagitis into surgical or medical therapy. Treatment failure was defined as moderate or severe symptoms of heartburn, regurgitation, dysphagia, and/or odynophagia, recommencement of PPI therapy, reoperation, or grade 2 esophagitis. At 7-year follow-up, fewer treatment failures were seen in patients managed with fundoplication than omeprazole (33% vs. 53%, p = 0.002). In patients that did not respond to the initial dose of omeprazole, dose escalation was completed; however, surgical intervention remained superior. Patients treated with fundoplication experienced more obstructive and gas bloat symptoms (e.g., dysphagia, flatulence, inability to belch) compared with the medically treated cohort. At 12-year follow-up, the durability of these results remained: Patients who underwent fundoplication had fewer treatment failures compared with patients treated with medical therapy (47% vs. 55%, p = 0.022) [72].

Over the past 25 years, surgeon experience with antireflux surgery has increased dramatically. With increased experience, the durability of symptom improvement has increased, and perioperative complications have decreased. This is especially true in high-volume centers. In one single-institution study that followed 100 patients for 10 years after antireflux surgery, 90% of patients remained free of GERD symptoms [73]. We recently published our experience in a cohort of 288 patients undergoing antireflux surgery. With median follow-up of greater than 5 years, symptom improvement for heartburn was 90% and regurgitation was 92% [74]. These results confirm that antireflux surgery can provide excellent durable relief of GERD when patients are appropriately selected and excellent technique is employed. However, it should be noted that none of the studies mentioned above were limited to patients with GERD and pulmonary disease. While some of the patients in these studies did have respiratory symptoms, the majority did not, and the studies were not centered on the relationship between GERD and pulmonary disease.

Fisichella and associates were the first to comprehensively evaluate symptoms of GERD and gastroesophageal function (esophageal manometry, 24-h pH testing, UGI, EGD, and gastric emptying study) in patients who have undergone lung transplantation. In 35 consecutive lung transplant patients, 51% were found to have GERD (15 with typical symptoms and elevated distal esophageal acid exposure; 3 with typical symptoms and bronchoscopic evidence of aspiration). Although no differences in the manometric profile of the LES were demonstrated between the GERD and non-GERD groups, there were differences in the manometric results of the esophageal body. In GERD patients, the distal esophageal amplitude was significantly lower than in patients without GERD (median 46 mmHg vs. 90 mmHg, P = 0.029), and more patients with GERD demonstrated ineffective esophageal motility (36% vs. 6%, P = 0.04). While this study was performed prior to the adoption of the Chicago Classification v3.0, which is now considered diagnostic standard for high-resolution esophageal manometry, it still demonstrates that the presence of GERD is associated with manometric evidence of esophageal dysfunction. Finally, among all patients with GERD following lung transplantation, there were no hiatal hernias identified on UGI.

Two findings from this study point to interesting differences between lung transplant patients with GERD and those patients with GERD who have not undergone a lung transplant. First, although a hypotensive lower esophageal sphincter is frequently identified in patients with GERD, nearly all patients in this study had a normal LES resting pressure, regardless of the presence of GERD. Second, no hiatal hernias were identified in patients with GERD in this study, whereas type I sliding hiatal hernias are common among patients with GERD. These findings suggest that the pathophysiologic mechanism underlying GERD in lung transplant patients may be different than typical patients with GERD. Specifically, rather than have a baseline underlying low-pressure LES , lung transplant patients may experience more transient LES relaxations that contribute to GER. Additionally, in this study, there was a higher prevalence of ineffective esophageal motility in the GERD patients compared to patients without GERD. From this observational study, it is not possible to determine if this ineffective esophageal motility is a contributing factor to GERD (inability to clear distal esophageal acid when reflux occurs) or a result of GERD (secondary to chronic distal esophageal inflammation). Further, it was not noted whether the patients with ineffective esophageal motility had an underlying disease, such as scleroderma, that could contribute to both lung disease and esophageal dysmotility.

Lung transplant patients are assumed to be at higher risk for an operation. Compared to a matched cohort of patients without pulmonary disease undergoing elective antireflux surgery, they have a higher overall comorbidity burden, higher rates of diabetes mellitus, and chronic renal disease, and pulmonary allografts do not function as well as healthy native lungs [75]. A single-center study found pulmonary transplant patients undergoing antireflux surgery have a longer postoperative length of stay (2.89 vs. 0.71 days) and higher readmission rate (25% vs. 3%) compared to the general population [76]. In a nationwide study using propensity-matched controls without history of lung transplant, Kilic and associates [75] found that lung transplant patients undergoing antireflux surgery had similar rates of postoperative mortality as well as overall and individual morbidity (cardiac, pulmonary, renal, wound, hollow viscous injury). Similar to single-center studies, hospital length of stay and estimated costs of care were higher in lung transplant patients.

In lung transplant patients with GERD, antireflux surgery is associated with improved objective measurement of allograft function. Hoppo and associates [77] retrospectively reviewed their experience with antireflux surgery in 22 lung transplant patients with GERD. After antireflux surgery, 91% of patients experienced significant improvement in forced expiratory volume in 1 s (FEV1). In 12 patients that had decreasing FEV1 before antireflux surgery, 11 patients experienced a reversal of this trend post-antireflux surgery. Additionally, following antireflux surgery, there were fewer episodes of pneumonia and rejection.

Considerations for Surgical Management of GERD in Patients with Ineffective Esophageal Motility and Lung Disease

Ineffective esophageal motility (IEM) refers to impaired distal esophageal contractility (“vigor”) and is defined according to the Chicago Classification v3.0 of high-resolution esophageal manometry as ≥50% of peristaltic contractions having a distal esophageal contractile integral of <450 mmHg-s-cm [2]. At the most extreme end of the spectrum, the esophagus may exhibit absent muscular contractility. As discussed in prior sections, there is a clear association between IEM, GERD, and ESLD, especially among patients with mixed connective tissues disorders. There is a general consensus—emanated more from clinical judgment than scientific data—that impaired esophageal motility (in the most severe cases, absent esophageal contractility) decreases the ability of the esophagus to clear gastric refluxate from the esophagus and, consequently, reflux episodes may travel more proximally than in patients with normal esophageal motility. In theory, this places patients with IEM at increased risk for aspiration from refluxate, though with an intact oropharyngeal swallowing phase, IEM/absent contractility should not result in aspiration when eating or drinking. Therefore, remaining nil per os and receiving enteral nutrition through a gastrostomy tube do not necessarily solve this problem. As detailed in prior sections, aspiration is associated with some chronic lung diseases and BOS, the leading cause of graft failure following lung transplantation. Consequently, many lung transplant teams make IEM, particularly when severe (i.e., complete absence of esophageal body contractility), a contraindication to lung transplantation. Unfortunately, while the connections among these clinical entities appear to be logical, the current literature does not specifically answer the question: “Are IEM and absent esophageal contractility contraindications to lung transplantation?” At the University of Washington, we have observed (anecdotally) that patients with IEM who lack dysphagia do well after transplant. Therefore, in patients with IEM and absent esophageal contractility, we use dysphagia as a marker for the severity of esophageal dysfunction and as an additional criterion to determine whether the patient should remain in the transplant list. Furthermore, we have substantial experience with LARS in patients with IEM. Our studies [78] as well as those from Patti and associates [79] have shown that LARS is safe and effective at controlling GERD. These studies have a relatively small number of patients, and their outcomes are not based on mitigation of pulmonary decline in patients with lung disease. However, they do suggest indirectly that patients with IEM and GERD who are being considered for lung transplantation should not be declined transplantation based solely on the presence of IEM.

Summary

Gastroesophageal reflux disease is a very common condition that is associated with symptoms (like heartburn and regurgitation) that can significantly impair quality of life. Additionally, GERD appears to be a contributing factor to both end-stage lung disease and pulmonary failure after lung transplantation. For patients who experience life-limiting symptoms of GERD and for patients with severe pulmonary disease and GERD, diagnostic testing should be performed to confirm the diagnosis of GERD and evaluate for the presence of esophageal dysmotility. When medical therapy is ineffective or, in the case of GERD-related lung disease, insufficient, antireflux surgery should be considered. Laparoscopic antireflux surgery has a long-standing history of excellent control of typical symptoms of GERD. Recently, antireflux surgery has been shown to mitigate pulmonary decline in end-stage lung disease and prevent BOS in lung transplant recipients. Even in patients with severe pulmonary disease who are at relatively increased risk of undergoing an abdominal operation, antireflux surgery is safe in the hands of experienced gastroesophageal surgeons. For this reason, experienced gastroesophageal surgeons should be an integral member of the multidisciplinary team that manages these patients.