Human lower esophageal sphincter pressure response to increased intra-abdominal pressure

Abstract

We studied the effects of increased intra-abdominal pressure on the lower esophageal sphincter (LES) pressure in 15 healthy subjects. The role of the diaphragm in the genesis of LES pressure during increased intra-abdominal pressure was determined by measuring diaphragm electromyogram (EMG). The latter was recorded using bipolar intraesophageal platinum electrodes that were placed on the nonpressure sensing surface of the sleeve device. We also measured the LES pressure response to increased intra-abdominal pressure during inhibition of the smooth muscles of the LES by intravenous atropine (12 micrograms/kg). Straight-leg raising and abdominal compression were used to increase intra-abdominal pressure. Our results show that the increase in LES pressure during straight-leg raising is greater than the increase in gastric pressure. During abdominal compression, the rate of LES pressure increase is faster than that of the gastric pressure, suggesting an active contraction at the esophagogastric junction. The increase in LES pressure during periods of increased intra-abdominal pressure is associated with a tonic contraction of the crural diaphragm as demonstrated by EMG recording. Atropine inhibited the resting LES pressure by 50-70% in each subject but had no effect either on the peak LES pressure attained during increased intra-abdominal pressure or tonic crural diaphragm EMG. We conclude that 1) there is an active contraction at the esophagogastric junction during periods of increased intra-abdominal pressure and 2) tonic contraction of the crural diaphragm is a mechanism for this LES pressure response.

Abdominal Compression by Waist Belt Aggravates Gastroesophageal Reflux, Primarily by Impairing Esophageal Clearance

“…Previous investigators have examined the effect of waist belt compression on the manometric characteristics of the lower esophageal sphincter (LES) in both healthy volunteers and patients with reflux disease. The rise in IGP caused by the waist belt is accompanied by a rise in LES pressure though sometimes of a lesser magnitude (5,7,8,9,10,11). Waist belt compression in short term studies does not result in the development of, or aggravation of, hiatus hernia or in increased separation of the intrinsic and extrinsic components of the LES (9,12,13).…”

Structure and function of the esophagus of the American alligator(Alligator mississippiensis)

“…The mammalian LES is closely associated with the crural part of the diaphragm, and diaphragmatic contraction exerts a sphincteric action on the LES (Mittal et al, 1988(Mittal et al, , 1990, although the diaphragmatic contribution to LES pressure has been controversial. Crocodilians have a muscle called the 'diaphragmaticus' but it is not homologous to the mammalian diaphragm.…”

Pressure profile along the oesophagus during eructation in sheep

“…This interpretation is unlikely because of the quasi-immediate pressure rise occurring alongside the oesophagus and the decrease in pressure recorded simultaneously within the entire oesophagus when a bolus of gas was relieved. Therefore, it could be suspected that the increase of oesophageal pressure preceding the pharyngeal expulsion of gas was similar to the socalled &dquo;common cavity&dquo; phenomenon described in dogs (Patriokios et al, 1986) and humans (Mittal et al, 1990) (Brasseur and Dodds, 1991 ).…”

“…En (Dent et al, 1988). The competence of the LOS to prevent reflux of gastric acidic chyme or gas into the oesophagus is clinically evaluated by measurement of its basal pressure (Patriokios et al, 1986;Mittal et al, 1990) (Ali and Singleton, 1979). Therefore, using a special X-shaped tracheal cannula (Stevens and Sellers, 1960), the eructated gas flow rate could be measured simultaneously with the pressure events occurring within the oesophagus (Arndorfer et al, 1977).…”