Fig. 12.1
Management algorithm for patients presenting with dysphagia after an antireflux procedure. Patients presenting with symptoms that are severe requiring pain medication and/or associated with regurgitation and weight loss require some evaluation to primarily rule out an anatomic or mechanical problem related to herniation or disruption. A step-wise approach is used that ultimately will lead to a diagnosis consistent with functional dysphagia if both FLIP analysis and HRIM are negative
12.3 High-Resolution Impedance Manometry (HRIM)
Esophageal manometry is recommended for the evaluation of non-obstructive dysphagia and prior to anti-reflux surgery [1]. Although not a primary indication, manometry has been used to assess persistent dysphagia in post-fundoplication patients and extrapolating from protocols for dysphagia appears to be reasonable. High-resolution manometry (HRM) utilizes catheters with pressure sensors spaced 1–2 cm apart that are positioned spanning from the hypopharynx to the stomach to simultaneously measure pressures generated along the entire length of the esophagus. Sophisticated software processes the HRM pressure output to generate esophageal pressure topography (EPT) plots that represent esophageal motility and sphincter function on color-coded, pressure-space-time plots [2]. Analysis of EPT plots is facilitated by objective metrics of esophageal function that can be applied to classify individual swallows and generate esophageal motility diagnosis according to a consensus-generated scheme: the Chicago Classification [3, 4]. Once again, the Chicago Classification was not meant to assess post-fundoplication dysphagia, however, it is reasonable to utilize the current metrics given the fact that asymptomatic post-fundoplication patients appear to have similar normal values when compared to controls [5, 6].
Over the last 5 years, there has been an increased interest in combining HRM technology with impedance and to leverage the information on bolus transit from impedance with the improved accuracy and detail of HRM. Basically, this approach gives you the “best of both worlds” and allows for more sophisticated analysis of esophageal function. Impedance electrodes are usually spaced at 2 cm intervals to straddle pressure sensors and provide an assessment of bolus transit/retention and a more robust assessment of IBP.
12.3.1 HRIM Study Protocol
After catheter calibration and application of topical anesthetic to the patient’s nare and/or throat, the HRM catheter is placed transnasally and positioned with the pressure sensors spanning form the hypopharynx, through the esophagus, and 3–5 cm into the stomach. After a brief period for patient acclimation, a baseline of resting pressures can be obtained over approximately 30 s of easy breathing and without swallows. Confirmation of correct placement of the catheter traversing the esophagogastric junction (EGJ) can be confirmed during this period by recognition of the presence of the pressure inversion point (PIP) , i.e., the point at which the inspiration-associated negative intrathoracic pressure inverts to the positive intra-abdominal pressure. Having the patient take deep breaths facilitates identification of the PIP by augmenting the EGJ pressure and exaggerating the intra-thoracic and intra-abdominal pressures. This can be helpful in patients after hernia repair to determine whether there is recurrence, however, this should usually be noted during endoscopy.
The Chicago classification is based on the analysis of ten supine, liquid (5-mL water) swallows and is validated for use in the non-surgical patient. Since one of the primary objectives in assessing patients after antireflux procedures focuses on defining subtle obstruction, additional components can be added to the manometric protocol to supplement clinical interpretation. Inclusion of upright swallows can be useful to help distinguish if abnormal pressure signals, particularly at the EGJ, are related to anatomic abnormalities, such as vascular artifact or hiatal hernia [7]. Incorporating swallows of different bolus textures (thick liquids or solid) or a test meal may also be beneficial to uncover symptoms and/or abnormal findings of esophageal function [8]. Multiple, rapid swallows (generally 5 swallows of 2-mL water spaced 2–3 s) can also be included to elucidate defects in deglutitive inhibition (if esophageal contractions occur during the course of the multiple swallows) and to assess for peristaltic reserve [9, 10]. Peristaltic reserve can be identified by augmentation of the esophageal contractile vigor following the multiple swallows and may help predict risk of developing post-fundoplication dysphagia or detect an etiology for symptoms in an otherwise normal manometry study [9, 10].
Our institutions standard protocol includes (1) Ten supine, liquid swallows, (2) five upright liquid (5-mL water) swallows, (3) one multiple, rapid swallows (five swallows of 2-mL water spaced 2–3 s), and (4) provocative swallows with a thick liquid (applesauce) and solid (crackers) food bolus based on suspicion for obstruction and a final 200 mL mixed saline swallow to mimic a timed barium esophagram.
12.3.2 HRIM Interpretation
Interpretation of EPT studies in the patient presenting with dysphagia after an antireflux procedure can be performed in a stepwise, hierarchical fashion directed by the Chicago Classification (Figs. 12.2 and 12.3) [4]. There are, however, several caveats to note when applying the Chicago Classification to EPT analysis for patients who have undergone an antireflux procedure. First, the absolute values reported in the Chicago Classification (and in the remainder of this review) are based on normative values generated from supine swallows of 5-mL water using the Sierra HRM assembly (Medtronic Inc., Shoreview, MN). Thus, interpretation using different catheter assemblies, patient positions, and/or boluses, needs to account for expected differences in normative values of EPT metrics, which are summarized in a review by Herregods and colleagues [11]. Additionally, there are studies that have presented data on HRM metric values in patients who are asymptomatic after fundoplication. These values are very similar to what is seen in the published normative ranges for non-surgical controls, however, small elevations in IRP are probably within what would be expected and a careful assessment of bolus transit may help determine whether a slightly elevated IRP is contributing to the current symptoms.
Fig. 12.2
Analysis of esophageal pressure topography and impedance using color isocontours, (Left) An example of a normal swallow with intact peristaltic integrity is provided. The color scales for pressure and impedance are noted on the bottom below the topography plot. Deglutitive lower esophageal sphincter (LES) relaxation is measured by the integrated relaxation pressure (IRP), the mean pressure of the EGJ during the four contiguous or non-contiguous seconds of maximal relaxation (i.e., lowest pressure) during the deglutitive window (10 s after the swallow). The value is 12 mmHg and this is within the normal range, The contractile deceleration point (CDP; red circle) is localized by identifying the point along the 30-mmHg isobaric contour at the intersect of lines (dashed-red) tangent to (1) the trailing edge of the propagating contractile wave distal to the transition zone and (2) the terminal portion of the wave front proximal to the esophagogastric junction (EGJ) . The distal latency is then measured as the time from the onset of swallow to the CDP and is normal at 6 s. Peristaltic vigor is measured by the distal contractile integral (DCI) , a composite metric of pressure amplitude × duration × axial length (mmHg•s•cm) of the distal esophageal contraction (i.e., between the transition zone and the proximal border of the EGJ). The value for this swallow is approximately 1100, which is normal. (Right) An example of a FLIP topography plot with the diameter color scale on the bottom and the pressure and volume tracings on the top. This is a normal study with evidence of repetitive antegrade contractions which represent peristaltic contractions in response to volumetric distention. The distensibility index measured through the EGJ is 8.2 mm2/mmHg and suggests minimal resistance to flow through the EGJ. Values less than 2.8 are consistent with obstruction
Fig. 12.3
HRIM and FLIP topography in two patients after fundoplication. Figure 12.3a represents data from a patient with an obstruction related to a tight wrap. The patient has no evidence of peristalsis on both the HRIM study and the FLIP topography. Additionally, both the HRIM and FLIP study support an obstruction. The HRIM supports a severe obstruction at the EGJ with a borderline IRP and abnormal pressurization on the esophageal topography plot with severe bolus retention. The FLIP study supports obstruction with a very low distensibility index and the inability to reach a diameter above 12.5 mm at pressures greater than 30 mmHg. This patient would benefit from dilation or reoperation. Figure 12.3b represents data acquired in a patient with normal function on both HRIM and FLIP topography and the dysphagia symptoms in this patient are likely functional
More recently, a new analysis paradigm has been introduced that combines the analysis of HRM and impedance. Automated impedance manometry (AIM) utilizes the temporal association of peak pressure, nadir impedance and detailed measures of IBP to determine bolus transit dynamics and this approach does appear to have some value in the post-fundoplication patients with dysphagia. This approach led to the development of other metrics focused on utilization of impedance data with and without pressure information, such as the bolus flow time (BFT) and the esophageal impedance integral (EII).
12.3.2.1 Individual High-Resolution Manometry Metrics
The Chicago Classification is based on the assessment of patients without previous foregut surgery, and thus technically should not be applied to these patients. However, with acknowledgement of these factors, the concepts of EPT interpretation based on the Chicago Classification can be broadly applied.
12.3.2.2 Basal EGJ and Upper Esophageal Sphincter Assessment
Though not incorporated in the Chicago Classification of esophageal motility diagnoses, EGJ morphology and basal pressure are important parameters in the assessment of dysphagia after an anti-reflux procedure. The basal EGJ should be assessed during a period of quiet breathing and absent of swallows. Because the crural diaphragm (CD) contributes to EGJ pressure, both the separation of the LES-CD (i.e., EGJ morphology) and the effect of the respiratory cycle on basal EGJ pressure should be appreciated; greater LES-CD separation and reduced CD augmentation pressures are associated with increased reflux [12, 13]. Elevated basal EGJ pressures are also be observed, but the clinical relevance of this finding remains unclear. Reporting EGJ morphology and basal pressures is more important in the patient with dysphagia after antireflux procedures as the procedure specifically targets the antireflux barrier and the components of the EGJ. Large separation of the LES and CD will be seen in disruption and signifies reherniation. Additionally, abnormal basal EGJ pressure values or high EGJCI values can be associated with obstruction.
12.3.2.3 Deglutitive LES Relaxation
Deglutitive LES relaxation is measured with HRM/EPT using the IRP. Because the IRP is referenced to gastric pressure, the IRP can be affected by abnormal pressurization within the stomach. Thus, we typically place the gastric reference 2 cm below the EGJ, though may adjust the placement of the gastric reference to reflect the esophageal outflow resistance pressure in patients. This measurement is the most important parameter in patients with dysphagia as patients with post-fundoplication as this is where the primary alteration occurred and studies support that patients with post-procedure dysphagia have significantly elevated IRP values compared to controls and asymptomatic post-fundoplication patients [6].
12.3.2.4 Distal Latency
The contractile deceleration point (CDP) has been recognized as an important landmark that represents the physiologic transition from esophageal peristalsis to ampullary formation and emptying [14]. Clinically, identification of this landmark draws its primary importance in defining the distal latency (Fig. 12.1), the essential metric defining spastic contractions [15]. The CDP should represent the transition to the terminal propagating velocity and should be within 3 cm of the EGJ [4, 14]. This metric should not be altered after an antireflux procedure and evidence of abnormal latency intervals may be related to a missed diagnosis of a spastic disorder or narcotic induced.
12.3.2.5 Peristaltic Vigor
Peristaltic vigor is measured in HRM/EPT by the distal contractile integral (DCI; Fig. 12.1). As one of the goals of the most recent update of the Chicago Classification was to simplify the esophageal motility assessment using EPT, the DCI claimed greater importance in the schema for individual swallow assessment [4]. Hypercontractile swallows are defined by a DCI > 8000 mmHg•s•cm, a value previously exceeding any observed DCI in studies of normal controls. Swallows with a DCI < 450 mmHg•s•cm showed strong agreement with ineffective swallows identified on conventional manometry and thus a lower DCI threshold has been incorporated into the classification scheme to define ineffective swallows [4, 16]. One interesting phenomenon of antireflux procedures is the finding of increased peristaltic vigor after the procedure. This augmentation is likely due to the esophagus responding to an increase in outflow resistance [Mittal- animal model paper]. In fact, overt jackhammer esophagus can be related to a tight or disrupted fundoplication and this will improve if the obstruction is removed. Thus, all patients who present with jackhammer esophagus after antireflux procedures should be presumed to have an obstruction until proven otherwise.
12.3.2.6 Peristaltic Integrity
In swallows with a normal DCI, the integrity of the peristaltic wave is assessed by measuring the length of axial breaks in the 20 mmHg isobaric contour. Previous versions of the Chicago Classification differentiated breaks into small (3–5 cm) and large (>5 cm), though the most recent update only classifies swallows with large peristaltic breaks (i.e., >5 cm) as fragmented swallows. Once again, these weak contractions will lead to altered bolus transport that may be accentuated in the context of an antireflux procedure.
12.3.2.7 Pressurization Pattern
The final step in assessing individual swallows in determination of the pressurization pattern. With the IBC set at 30 mmHg, swallows are assessed for panesophageal pressurization, i.e. simultaneous esophageal pressurization extending from the upper esophageal sphincter (UES) to the EGJ, and/or compartmentalized pressurization, i.e., when distal esophageal pressurization extends from the contractile front to the EGJ. An assessment of the degree of compartmentalized pressurization is an important component of the HRIM evaluation of patients with dysphagia after antireflux procedures as this is a more accurate methodology to define obstruction at the EGJ. Although there is no validated approach, using the isobaric contour tool, one is able to scroll up and down to determine the minimal pressurization within the compartmentalized area between the LES and propagating wave. If this value is above 30 mmHg, the patient likely has a significant obstruction. These patients are usually referred for an UGI with a 12.5 mm barium tablet of an endoscopy with FLIP if this was not done previously.
12.3.2.8 Individual Impedance Based Metrics
Bolus Flow Time
A study using concurrent HRIM and esophageal intraluminal ultrasound demonstrated that impedance measurement can assess EGJ opening and esophageal emptying [17]. Based on this concept, our group developed and validated a novel HRIM metric to specifically assess flow across the EGJ: the bolus flow time (BFT) [18]. Utilizing simultaneous videofluoroscopy with HRIM, bolus flow across the EGJ was observed on fluoroscopy when two criteria were met: (1) bolus was present, which was associated with a decrease in impedance and (2) A preferential trans-EGJ pressure gradient existed such that pressure in the distal esophagus was greater than at the crural diaphragm. Both of these criteria were incorporated into a computer-based algorithm for automated calculation of the BFT. To measure the BFT, three impedance and three manometry signals are placed through the EGJ at 1-cm intervals (thus, impedance and pressure signals were interpolated by the analysis software). The distal impedance and manometry signal is positioned within the hiatus as identified by crural contractions [18, 19]. Using the impedance signals, the duration of bolus presence is determined: The onset of bolus presence is defined as the point at which the impedance dropped to 90% of the nadir; the offset of bolus presence is defined as the return to 50% of the impedance baseline. Using the three manometry signals, periods of a trans-EGJ flow-permissive pressure gradient (i.e., when the esophageal pressure was greater than both the crural and intra-gastric pressure signals) are determined. The BFT is then derived as the sum of all periods meeting the criteria of both bolus presence and a flow-permissive pressure gradient time. If the impedance drop is not greater than 50% at each axial location and/or a flow-permissive pressure gradient is not achieved, the BFT is considered to be zero. The median BFT value of the five upright swallows is utilized for each patient. Previous study of asymptomatic volunteers demonstrated a median (interquartile range, IQR) BFT of 3.2 s (2.3–3.9 s) for upright swallows; lower BFT values indicate reduced esophageal emptying [19]. We recently reported that the BFT was a useful measure in patients with suspected achalasia and borderline IRP measures and that BFT had a better symptom-association than basal EGJ pressure (EGJP) or IRP in patients with achalasia prior to intervention [19].
Related posts:
Anterior Versus Posterior Fundoplication, Are They Equal?
Preoperative Diagnostic Workup for GERD and Hiatal Hernia: An Evidence and Experience-Based Approach
Management of Recurrent Paraesophageal Hernia
Preoperative Assessment of Failed Fundoplication with Recurrent Hiatal Hernia
Laparoscopic Repair of Paraesophageal Hiatus Hernia: Suture Cruroplasty or Prosthetic Repair
Quality of Life Following Laparoscopic Antireflux Surgery for Primary and Recurrent Gastroesophageal Reflux Disease
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