Related Experiment Video
Updated: Aug 20, 2026

A Protocol for Comprehensive Assessment of Bulbar Dysfunction in Amyotrophic Lateral Sclerosis (ALS)
Published on: February 21, 2011
[Maximum phonation time as a tool of screening respiratory muscle weakness in myopathic patients]
Chizuko Toyoda1, Masafumi Ogawa, Yasushi Oya
1Department of Neurology, Musashi Hospital, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-machi, Kodaira-shi, Tokyo 187-8551, Japan.
Unlabelled:
We examined the relation of maximum phonation time (MPT) and vital capacity (VC) and reviewed the usefulness of MPT as a respiratory function screening.
Subjects:
18 healthy adult subjects (8 men and 10 women), and 32 myopathic patients (24 men and 8 women).
Methods:
MPT and VC were measured in sitting position. Six patients were tested with and without air stacking by glossopharyngeal respiration.
Results:
In healthy subjects, MPT was 29.9 +/- 11.8 seconds in men and 21.7 +/- 7.8 seconds in women. Second trials showed good reproducibility. The healthy group had no correlation between MPT and VC. The patient group showed a significant positive correlation between MPT and VC (r2= 0.25, p=0.003). All patients with MPT less than 15 seconds showed VC less than 1.5 l and %VC less than 50%. Air-stacking by glossopharyngeal respiration significantly increased the MPT.
Conclusions:
MPT is a useful screening test for respiratory muscle weakness. The patients are easily aware of the effect of air-stacking by glossopharyngeal respiration.
Related Concept Videos
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...
Myasthenia Gravis: Diagnostic Tests
The edrophonium test is a diagnostic tool for myasthenia gravis. It involves...
Physical Assessment of the Respiratory Tract II: Palpation
Thoracic Palpation
Thoracic palpation detects tenderness, masses, lesions, respiratory excursions, and vocal fremitus. The nurse assesses...
Physical Assessment of the Respiratory Tract II: Inspection
Chest Configuration
The chest configuration can...
Respiratory System Abnormal Finding II: Palpation and Auscultation
Palpation Findings
During a respiratory assessment, palpation can reveal several vital abnormalities:
Respiratory System Abnormal Finding I: Inspection and Percussion
Inspection Findings
During an inspection, several findings may suggest the presence of respiratory distress or disease. Pursed-lip breathing, where exhalation is slowed by...
