A Systematic Review of Pharyngeal High-Resolution Manometry Normative Data

Purpose: The utilization of high-resolution pharyngeal manometry (HRPM) in the evaluation of pharyngeal dysphagia has been increasing; however, standardization of its use has lagged behind. Without standardization using normative values, it is difficult for clinicians to adopt this emerging technology into meaningful use. Our goal is to map and compare the published normative values for common HRPM metrics in order to help establish consensus reference values. Method: A systematic review was conducted on prospective and retrospective studies that included HRPM metrics, defined by an international working group consensus, in healthy adult populations. Data on the following variables were extracted when available: contractile integrals of the pharynx (PhCI), velopharynx, mesopharynx, and hypopharynx, as well as the upper esophageal sphincter (UES) integrated relaxation pressure (IRP), relaxation time (RT), maximum admittance, and hypopharyngeal intrabolus pressure. Results: Thirty studies were included. Significant variation existed in the technique and equipment used to perform procedures between the different studies. Lower PhCIs and UES IRPs were seen in younger compared to older individuals. Higher UES RTs were found in individuals in the upright position compared to the supine position and in those using larger boluses sizes or smaller catheters. Conclusions: Due to the wide variety of protocols, catheter configurations, manufacturers, and software used in the existing literature, it is difficult to formulate consensus on HPRM normative values using pooled data. Prospective studies adhering to standardized HRPM protocols for specific catheter configurations and manufacturers with larger cohorts of normal individuals are necessary to establish proper reference values for HRPM metrics.