Primary Motility  Disorders of the  Esophagus
 The Esophageal
 Esophagogastric  Junction

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Volume: Primary Motility Disorders of the Esophagus
Chapter: Manometric observations in the normal subject

Can dry swallows generate a peristaltic sequence ?

J.N. Blackwell (Newtownabbey)

A dry swallow is generally regarded as a voluntary swallow carried out at the request of the medical or technical attendant during a manometric examination.

The swallow is therefore unstimulated by the presence of fluid, saliva or a bolus in the mouth or esophagus. Consequently the « dry swallow » may represent an unphysiological activity with little relationship to normal activity or to clinical disorders of esophageal contraction. Excluding cases of mechanical obstruction of the esophagus, patients extremely rarely complain of symptoms on swallowing in the complete absence of a fluid or solid bolus.

Nonetheless, « dry swallows » have been utilised in manometric studies and were included in a protocol used to determinate qualitative and quantitative parameters of manometry in normal subjects [1]. The results showed that normally co-ordinated peristaltic sequences usually occur when most normal subjects are requested to swallow « dry », but co-ordinated peristalsis occurs with less reliability than after wet swallows (5 ml water).

In this study, the mean figure for peristaltic contractions after dry swallows recorded in normal subjects was 81.9 p. cent (table 1). However 50 p. cent of normal subjects had at least one non-peristaltic sequence during a series of 10 dry swallows.

Table 1. Frequency of peristaltic sequence after wet and dry swallows

Percentage swallows ( X|

± 1 SD)



Wet swallows

94 ± 10.3

6.0 ± 10.3

P < .001

P < .001

Dry swallows

81.9 ± 25,7

18.1 ± 25.7

Only 26 p. cent of these subjects had non-peristaltic sequences after wet swallows. Since the prevalence of non-conducted contractions was similar after both wet and dry swallows, the difference between the outcome of wet and dry swallows was accounted for by a significantly higher frequency of simultaneous contraction after dry swallows (table 2). 37 p. cent of subjects had at least one simultaneous contraction after dry swallows, but only 4 p. cent after wet swallows. Two subjects had 80 p. cent and 100 p. cent of dry swallows resulting in simultaneous contractions, though all their wet swallows were followed by peristaltic contractions.

Table 2. Motor responses after wet and dry swallows


swallows ( X i

1 SD)




Wet swallows

6.0 + 10.3

0.8 ±2.7

5.2± 1,5

P< .001

P< .001


Dry swallows

18.1 + 25.7

12.6 ± 23.6

5.5 ± 12.7

Differences also emerged in the amplitude and velocity of peristalsis following wet or dry swallows (table 3). The mean distal esophageal amplitude of dry swallow induced peristalsis was 71 ± 28 mm Hg (± ISD) compared to 112 ± 39 mm Hg for wet swallows. The velocity of peristalsis was also significantly different, being increased, compared to wet swallows. The mean figures were 4.9 ± 0.3 cm/sec and

3.5 ± 0.8 cm/sec for dry and wet respectively in the distal esophagus. The duration of peristalsis was not significantly different after dry or wet swallows.

The age and sex of the normal subject had no influence on the prevalence of either type of non-peristaltic contraction, nor on the differences with wet swallows in amplitudes duration, or velocity of peristalsis.

Table 3. Quantitative values for distal esophageal peristalsis in normal subjects

Wet swallows

Dry swallows

p Values

Amplitude mmHg X| ± 1 SD

112 ± 39

71± 28

< .001


4.2 ± 0.9

4.1 ± 0.8


sec X| ± 1 SD


3.5 ± 0.9

4.9 ± 0.3

< .001

cm/sec X| ± 1 SD


1. Richter JE, Wu WC, Johns DN, Blackwell JN, Nelson JL, Castell JA, Castell DO (1987) Esophageal manometry in 95 healthy adult volunteers-Variability of pressures with age and frequency of « abnormal » contractions. Dig Dis Sci 32 : 583-592.

Publication date: May 1991 OESO©2015