NASAL PRESSURE CHANGES DURING SWALLOWING

AN ANALYSIS OF 1,219 SWALLOWS IN 88 HEALTHY SUBJECTS

¹ Associate Professor of Radiology
² Associate Professor of Medicine
³ Medical Student Summer Fellow in Radiology

Nasal pressure curves during swallowing were recorded 1,219 times in 88 healthy subjects. Of these 940 were satisfactory for analysis and could be grouped into four basic types:

Type I. An initial positive deflection followed by a smooth downward trend to a maximum negative point terminating with an abrupt positive deflection. Incidence 195 (20.7 per cent).

Type II. Similar to Type I but with formation of a plateau in the mid portion of the downward component. Incidence 504 (53.6 per cent).

Type III. Similar to Type I but with a cleft initial peak. Incidence 93 (9.9 per cent).

Type IV. A complex combining the features of Types II and III. Incidence 148 (15.8 per cent).

Nasal pressures during deglutition ranged from 32 mm. Hg above resting nasal pressure during the initial positive deflection to 34 mm. Hg below resting nasal pressure near the termination of swallowing. The duration of the nasal pressure complex was from 0.52 to 2.39 seconds, usually approximately 1 second. Statistical analysis revealed that: (1) variations in the characteristics of the bolus produced variations in the pressure and time of occurrence of events on the nasal pressure curve; (2) similar bolus characteristics evoked similar manometric and temporal responses; (3) larger volumes of bolus were associated with an increase in the duration of the initial positive deflection; and (4) longer nasal pressure complexes were recorded in the supine position.

Nasal pressure curves contained landmarks subdividing the act of deglutition into four functional phases: oral transport, pharyngeal transport, pharyngeal cleansing, and oropharyngeal relaxation. Alteration of the volume of the bolus and subject posture significantly changed the duration of oral transport, whereas the subsequent phases were unaffected by changes in size or consistency of the bolus or position of the subject. This is in agreement with the classical concept that Stage I (oral transport) is voluntary while Stage II (pharyngeal transport, pharyngeal cleansing, and oropharyngeal relaxation) is reflex in nature.

Practice under the conditions of the experiment and a bolus of 10 cc. volume are recommended to produce the lowest failure rate. Barium paste is considered an unsuitable substance for quantitative study of swallowing.

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