Functional association between proximal and distal gastric motility during fasting and duodenal nutrient stimulation in humans

A functional integration exists between proximal and distal gastric motor activity in dogs but has not been demonstrated in humans. To determine the relationship between proximal and distal gastric motor activity in humans. Concurrent proximal (barostat) and distal (antro-pyloro-duodenal (APD) manometry) gastric motility were recorded in 10 healthy volunteers (28 +/- 3 years) during (i) fasting and (ii) two 60-min duodenal infusions of Ensure((R)) (1 and 2 kcal min(-1)) in random order. Proximal and APD motor activity and the association between fundic and propagated antral waves (PAWs) were determined. During fasting, 32% of fundic waves (FWs) were followed by a PAW. In a dose-dependent fashion, duodenal nutrients (i) increased proximal gastric volume, (ii) reduced fundic and antral wave (total and propagated) activity, and (iii) increased pyloric contractions. The proportion of FWs followed by a distal PAW was similar between both infusions and did not differ from fasting. During nutrient infusion, nearly all PAWs were antegrade, propagated over a shorter distance and less likely to traverse the pylorus, compared with fasting. In humans, a functional association exists between proximal and distal gastric motility during fasting and duodenal nutrient stimulation. This may have a role in optimizing intra-gastric meal distribution.     

Relationship between the mechanism of gastro-oesophageal reflux and oesophageal acid exposure in patients with reflux disease

Abstract  This study investigated the relationship between the oesophageal acid exposure time and the underlying manometric motor events in patients with gastro-oesophageal reflux disease (GORD). In 31 patients, 3-hour oesophageal motility and pH were measured after a test meal. Ten patients underwent 24-hour ambulatory manometry and pH recording. In the 3-hour postprandial study, of 367 reflux episodes 79% was associated with a transient lower oesophageal sphincter relaxation (TLOSR), 14% with absent basal lower oesophageal sphincter (LOS) pressure and the remaining 7% with other mechanisms, representing 62, 28 and 10% of the acid exposure time, respectively. Acid reflux duration per motor mechanism was longer for absent basal LOS pressure than for TLOSR (189 ± 23 s and 41 ± 5 s, respectively, P  < 0.001). In the 24-hour ambulatory study, the contribution of TLOSRs to reflux frequency vs acid exposure time were 65 vs 54% interprandially and 74 vs 53% after the meal. During the night, absence of basal LOS pressure accounted for 36% of reflux events representing 71% of acid exposure time. In conclusion, the duration of oesophageal acid exposure following a TLOSR is shorter than reflux during absent basal LOS pressure. TLOSRs are, the major contributor to oesophageal acid exposure during the day. At night, however, reflux during absent basal LOS pressure is the major contributor to acid exposure.     

Assessment of oesophageal motor function using combined perfusion manometry and multi-channel intra-luminal impedance measurement in normal subjects

Multichannel intraluminal impedance (MII) is being used increasingly to assess oesophageal bolus clearance. However, there is no good standardization of the impedance parameters that define 'effective bolus clearance'. The aim of this study was to define these important impedance parameters and to determine their normal values. Concurrent perfusion manometry and MII were performed in 42 healthy volunteers. Ten, 5-mL liquid (saline) boluses and then, 10x5-mL low impedance viscous boluses were tested in each subject in the right-lateral position. Normal values for bolus presence time (BPT) at each site and total bolus transit time (TBTT) were determined from either 'normal' peristaltic responses (amplitude>or=30 mmHg in distal oesophagus) or 'super-normal' peristaltic responses (amplitudes>or=50 mmHg at all sites). The relationship between BPT and TBTT within a response and per-individual performance was determined. A total of 840 swallows of liquids and viscous responses were analysed. BPT and TBTT of viscous swallows were longer than those for liquids. Non-peristaltic responses were significantly more likely not to clear a viscous than a liquid bolus. Within a response, the number of sites with prolonged BPT strongly predicted the incidence of prolonged TBTT. Using impedance criteria, normal oesophageal bolus clearance is defined when an individual completely clears at least 70% of liquid responses and at least 60% of viscous responses. This study provides normal values for impedance measurement of bolus clearance when combined with perfusion manometry. These values will allow standardization of impedance application in oesophageal function testing, in both research and clinical setting.     

Impact of nadir lower oesophageal sphincter pressure on bolus clearance assessed by combined manometry and multi-channel intra-luminal impedance measurement

Abstract  This study aimed to assess the relationship between nadir lower oesophageal sphincter pressure (LOSP) and wave amplitude (WA) in oesophageal bolus clearance. Concurrent oesophageal manometry and impedance were performed in 146 subjects [41 healthy, 24 non-obstructive dysphagia (NOD) and 81 gastro-oesophageal reflux (GOR)]. Patients with achalasia and diffuse oesophageal spasm were excluded. Swallow responses were categorized by nadir LOSP. For each category of nadir LOSP, WA at the distal 2 recording sites were grouped into bins of 10 mmHg and the proportion of waves in each bin associated with a normal bolus presence time (BPT) was determined. Nadir LOSP, distal BPT, total bolus transit time and the proportion of impaired oesophageal clearance in patients with NOD were greater than those of healthy subjects and patients with GOR. Overall, responses with impaired oesophageal clearance had significantly lower WA (54 ± 1 vs 81 ± 1 mmHg; P  < 0.0001) and higher nadir LOSP (2.7 ± 0.4 vs 1.0 ± 0.1 mmHg, P  < 0.001). For each level of nadir LOSP, there was a direct relationship between distal WA and successful bolus clearance of both liquid and viscous boluses from the distal oesophagus. As nadir LOSP increased, the relationship between WA and bolus clearance shifted to the right and higher amplitudes were required to achieve the same effectiveness of clearance. Hypotensive responses with nadir LOSP ≥3 mmHg were less likely to clear than those with nadir LOSP <3 mmHg, for both liquid (7/29 vs 162/276; P  < 0.001) or viscous boluses (11/46 vs 176/279; P  <   0.0001). Nadir LOSP is an important determinant of bolus clearance from the distal oesophagus, particularly in patients with NOD.