High-resolution manometry (HRM) is a diagnostic procedure that measures pressure throughout the oesophagus and surrounding sphincters during swallowing. Unlike VFSS or FEES — which visualise bolus movement and airway protection — HRM measures the mechanical forces that propel food and liquid through the oesophagus and across the lower oesophageal sphincter. It is the gold-standard investigation for oesophageal motility disorders, which are a significant and often underdiagnosed cause of dysphagia.
This article is aimed at SLPs, gastroenterologists, and physicians involved in dysphagia management who need a working understanding of HRM’s role in the diagnostic workup.
Most dysphagia assessments — including clinical swallowing examinations, VFSS, and FEES — focus on the oral and pharyngeal phases of swallowing. These investigations are excellent at detecting aspiration, reduced laryngeal closure, impaired tongue base propulsion, and pharyngeal residue.
However, they are not designed to assess the oesophageal phase: the coordinated peristaltic contractions that transport the bolus from the pharynx to the stomach over approximately 7–10 seconds. Patients with oesophageal dysphagia may have entirely normal VFSS and FEES results because their swallowing impairment occurs below the pharynx — in the oesophageal body or at the lower oesophageal sphincter (LOS).
HRM fills this diagnostic gap. It is indicated whenever:
An HRM catheter contains 36 or more circumferential pressure sensors spaced 1 cm apart along its length (typically 35–40 cm). This high sensor density creates a continuous pressure topography map of the entire oesophagus — from the upper oesophageal sphincter (UOS) to the lower oesophageal sphincter (LOS) — during each swallow.
Older conventional manometry systems used 3–8 water-perfused catheters spaced 5 cm apart, producing sparse data and requiring catheter pull-through manoeuvres. HRM eliminates these limitations by capturing the entire oesophagus simultaneously.
The patient experiences mild discomfort during insertion but the catheter is well tolerated during the swallow protocol.
HRM data are displayed as spatiotemporal pressure topography maps — commonly called Clouse plots after their developer. In these plots:
A normal swallow produces a recognisable pattern: relaxation of the UOS, a propagating high-pressure contractile wave (peristalsis) moving from upper to lower oesophagus, complete relaxation of the LOS (integrated relaxation pressure <15 mmHg), and then LOS restoration to resting tone.
The Chicago Classification is the internationally accepted diagnostic framework for interpreting HRM studies. Version 4.0 (2021) introduced a hierarchical diagnostic algorithm and clarified several disputed categories.
Integrated Relaxation Pressure (IRP4): The mean of the 4 seconds of lowest LOS pressure during a 10-second post-swallow window. Normal <15 mmHg. Elevated IRP4 indicates impaired LOS relaxation — the defining feature of achalasia and oesophagogastric junction (OGJ) outflow obstruction.
Distal Contractile Integral (DCI): A measure of the vigour of oesophageal peristalsis. DCI >8,000 mmHg·s·cm = hypercontractile (Jackhammer oesophagus). DCI <450 mmHg·s·cm on >50% of swallows = ineffective peristalsis.
Distal Latency (DL): Time from swallow onset to the contractile deceleration point. DL <4.5 seconds = premature contraction, as seen in distal oesophageal spasm.
Contractile Front Velocity (CFV): Speed of peristaltic propagation. Abnormally rapid (>9 cm/s) propagation in the distal oesophagus may indicate spasm.
Disorders of OGJ Outflow (elevated IRP4):
Major Disorders of Peristalsis (normal IRP4):
Minor Disorders of Peristalsis:
Normal HRM: Normal IRP4, normal peristalsis — no oesophageal motility disorder. In this case, dysphagia may be structural (stricture, ring, web, eosinophilic oesophagitis) and endoscopy is the next investigation.
HRM also captures upper oesophageal sphincter (UOS) function, which is directly relevant to SLPs managing oropharyngeal dysphagia. Key UOS parameters include:
Pharyngeal HRM is a specialised variant used in dysphagia research to measure pharyngeal contraction wave timing and amplitude, though it is not yet widely available outside academic centres.
It does not visualise bolus movement. HRM measures pressure, not bolus transit. Retained material in the oesophagus (stasis) is inferred from pressure patterns, not directly observed. Combined impedance-HRM (pH-impedance-HRM) can track bolus movement alongside pressure.
It assesses the oesophageal phase only. The oral and pharyngeal phases, which are the primary concern in neurological dysphagia, are not fully captured by standard HRM.
Provocative protocols are not standardised. Solid bolus swallows, large volume challenges, and MRS tests vary across centres, limiting cross-site comparison.
Interpretation requires specialist training. CCv4.0 classification requires familiarity with HRM patterns that are not intuitive. Misclassification (particularly of OGJOO vs. achalasia) has direct treatment implications.
Patient factors affect results. Anxiety, excessive swallowing during the resting phase, incomplete catheter positioning, and post-surgical anatomy can confound interpretation.
HRM is available at Hospital Authority tertiary hospitals with gastroenterology departments. In the public system, referral is typically from a gastroenterologist or surgeon following upper endoscopy. SLPs may initiate referral via the relevant physician when VFSS and FEES are unremarkable in a patient with persistent dysphagia, particularly when solid-only dysphagia, chest pain, or regurgitation are present.
In the private sector, HRM is available at most private hospitals with gastroenterology services. Waiting times in the public system can be several months; private studies are typically available within 1–4 weeks.
The procedure is performed by a gastroenterology technician or nurse and interpreted by a gastroenterologist. In academic centres, SLP-gastroenterology joint dysphagia clinics allow co-interpretation of HRM alongside clinical swallowing assessment — a model increasingly adopted in the UK, USA, and Australia.
HRM occupies a specific position in the dysphagia diagnostic pathway:
For patients with dysphagia following neurological injury (stroke, Parkinson’s disease, ALS), VFSS/FEES typically remain the primary investigations. HRM is most impactful in patients with suspected oesophageal dysmotility — those presenting with food sticking, chest pain, nocturnal regurgitation, or dysphagia that is equal for solids and liquids from the outset (suggesting functional rather than mechanical obstruction).