What is High-Resolution Impedance Manometry
High-Resolution Impedance Manometry (HRIM) is an advanced diagnostic tool used to evaluate esophageal motility and bolus transit. By combining high-resolution pressure sensors with impedance sensors, HRIM provides comprehensive information about both muscular contractions and the flow of swallowed substances through the esophagus
How does High-Resolution Impedance Manometry Work
HRIM employs a catheter embedded with closely spaced pressure sensors (typically 1 cm apart) and impedance electrodes. The pressure sensors measure the peristaltic activity of the esophagus, while the impedance sensors detect bolus movement based on changes in electrical resistance as fluids or solids pass through. The data is displayed in a topographic (color-coded) format known as Clouse plots, which allow for intuitive interpretation of esophageal pressure dynamics.
Indications of High-Resolution Impedance Manometry
High-resolution impedance manometry is indicated in the following cases:
- Evaluation of dysphagia (difficulty swallowing)
- Diagnosis of esophageal motility disorders, such as: achalasia, distal esophageal spasm and ineffective esophageal motility
- Assessment before anti-reflux surgery
- Investigation of non-cardiac chest pain
- Unexplained regurgitation or refractory gastroesophageal reflux
Procedure of High-Resolution Impedance Manometry
High-resolution impedance manometry procedure involves the following
- The procedure is conducted in an outpatient setting.
- You will be usually awake, seated or supine.
- A lubricated catheter is inserted trans nasally into the esophagus and positioned such that it spans from the pharynx to the stomach.
- You are instructed to perform a series of wet swallows (usually 5 mL of water each).
- Real-time pressure and impedance data are recorded and analyzed using software algorithms.
Interpretation Parameters of High-Resolution Impedance Manometry
HRIM provides both pressure and impedance data, allowing for detailed analysis of:
- Integrated Relaxation Pressure (IRP): This indicates lower esophageal sphincter relaxation.
- Distal Contractile Integral (DCI): This measures the strength of esophageal contractions.
- Peristaltic Integrity: This evaluates completeness and coordination of esophageal muscle contractions.
- Bolus Transit: This determines whether the swallowed material passes completely through the esophagus.
Advantages of High-Resolution Impedance Manometry
High-resolution impedance manometry advantages include:
- Combines pressure and bolus transit data in a single test.
- Improved accuracy in diagnosing complex esophageal motility disorders.
- Enhances classification of achalasia subtypes (Type I, II, III).
- Superior to conventional manometry in terms of resolution and diagnostic yield.
Limitations of High-Resolution Impedance Manometry
High-resolution impedance manometry limitations include
- Requires your cooperation and fasting prior to the procedure.
- May cause transient nasal or throat discomfort.
- Interpretation requires specialized training.
- Not useful in evaluating structural abnormalities (e.g., tumors or strictures) — imaging may still be necessary.
Clinical Relevance of High-Resolution Impedance Manometry
HRIM is especially valuable in individuals with unexplained dysphagia where endoscopy and imaging are inconclusive. It guides treatment decisions such as pharmacologic therapy, dilation, or surgical interventions, and plays a critical role in pre-operative assessment for fundoplication or other anti-reflux procedures.
