What metrics should be measured in pharyngeal manometry?

Guidelines for Metrics to Measure in Pharyngeal Manometry

Pharyngeal manometry should measure pressure dynamics at the velopharynx, tongue base, and upper esophageal sphincter, with specific attention to maximum pressures, relaxation parameters, and timing sequences to accurately assess swallowing function and detect dysphagia.

Key Measurement Locations

• Velopharynx (VP) - critical for measuring the initial phase of pharyngeal swallowing 1
• Tongue base (TB) - essential for evaluating propulsive forces during swallowing 1
• Upper esophageal sphincter (UES) - crucial for assessing sphincter function during swallow 2, 1

Essential Pressure Metrics

Velopharyngeal Measurements

• Maximum velopharyngeal pressure - threshold value of 144.0 mmHg has 96.4% sensitivity and 74.7% specificity for identifying dysphagia 1
• Velopharyngeal pressure duration - critical timing parameter for coordination assessment 3

Tongue Base Measurements

• Maximum tongue base pressure - threshold value of 158.0 mmHg has 96.4% sensitivity and 77.3% specificity for dysphagia detection 1
• Tongue base pressure duration - important for evaluating propulsive phase timing 3

Upper Esophageal Sphincter Measurements

• UES resting pressure - values <75.0 mmHg have 89.3% sensitivity and 90.7% specificity for dysphagia 1
• UES minimal pressure during swallow - threshold of 2.0 mmHg has 74.7% sensitivity and 60.7% specificity for identifying dysphagia 1
• UES relaxation duration - values <0.58 seconds have 85.7% sensitivity and 65.3% specificity for dysphagia 1
• UES integrated relaxation pressure (IRP) at various time points (0.2,0.4,0.6,0.8 seconds) 4

Advanced Integrated Metrics

• Pharyngeal contractile integral (PhCI) - product of mean pharyngeal contractile amplitude, length, and duration; provides a single metric for the vigor of entire pharyngeal contraction 5
  • Normal values in children with normal swallowing: 147.28 ± 53.89 mmHg.s.cm 5
  • Values in children with abnormal swallowing: 82.00 ± 51.90 mmHg.s.cm 5

Timing Sequences

• Total swallow duration - critical for overall coordination assessment 3
• Pressure wave velocity - measures the speed of contraction propagation 3
• Coordination timing between pharyngeal contraction and UES relaxation 2

Quality Control Parameters

• Minimum of three acceptable maneuvers should be performed for reliable assessment 6
• Acceptable repeatability is achieved when the difference between measurements is within established thresholds 6
• Volume-time or flow-volume curves from at least the best three maneuvers must be retained 6

Technical Considerations

• Use solid-state transducers that measure pressures over 360 degrees for UES measurements to account for sphincter asymmetry 2
• Position a second transducer 5 cm proximal to the UES transducer for pharyngeal measurements 2
• Computer-based analysis systems should be used for accurate measurement of rapid pressure changes 2, 3

Common Pitfalls to Avoid

• Single, unoriented transducers may provide inaccurate UES measurements due to sphincter asymmetry 2
• Perfused systems lack the necessary response rate for measuring peak pharyngeal contraction pressures 2
• Failure to account for age-related differences in normal values, particularly in pediatric populations 4, 5