PROLONGED GASTROESOPHAGEAL REFLUX MONITORING BY IMPEDANCE-PHMETRY: A REVIEW OF THE SUBJECT PONDERED WITH OUR EXPERIENCE WITH 1,200 CASES

ABSTRACT BACKGROUND: Prolonged monitoring increased our knowledge on gastroesophageal reflux (GER), and the disease became known as gastroesophageal reflux disease (GERD). Prolonged reflux monitoring permits the diagnosis of GERD when endoscopic findings are not enough to characterize it. OBJECTIVE: The objective of this paper is to review the current knowledge on impedance-pH monitoring, taking into account the published literature and the authors experience with 1,200 exams. METHODS: The different types of prolonged reflux monitoring, namely: conventional pHmetry, catheter-free pHmetry and impedance-pHmetry will be briefly described. The new possibilities of evaluation with impedance-pHmetry are emphasized, namely: the study of symptomatic patients in use of proton pump inhibitors (PPIs); evaluation of patients with symptoms suggestive of GERD although with normal endoscopy and normal pHmetry, diagnostic elucidation of patients with atypical symptoms or supra-esophageal symptoms, mainly chronic cough, study of patients complaining of belch, differentiating gastric and supra-gastric belching, and the proper work-up before anti-reflux surgery. RESULTS: When impedance was associated to pH monitoring, an impressive technological evolution became apparent, when compared to pH monitoring alone. The main advantages of impedance-pHmetry are: the ability to detect all types of reflux: acid, non-acid, liquid, gaseous. In addition, other important measurements can be made: the ability of the esophagus in transporting the bolus, the measurement of basal mucosal impedance and the evaluation of primary peristalsis post reflux. CONCLUSION: Impedance-pHmetry is a promising method, with great advantages over conventional pHmetry. The choice between these two types of monitoring should be very judicious. The authors suggest the importance of careful evaluation of each reflux episode by the physician responsible for the examination, necessary for the correct interpretation of the tracings.

Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates

We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed ( N = 20 premature neonates) at 34.7 and 39.1 wk ( time 1 and time 2). Effects of midesophageal provocation with graded stimuli ( N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation ( P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P < 0.05); 3) media differences were noted with LESR response latency (air vs. liquids, P < 0.02); and 4) infusion flow rate-LESR were different ( P < 0.01 for air and liquids). Mechanistically, 1) frequency of LESR was greater during peristaltic reflexes at both times (vs. none, P < 0.0001); 2) LESR response latency, duration, and time to complete LESR were longer with EDR (all P < 0.05, vs. SP at time 2); and 3) graded stimulus volume LESR were different for air and liquids ( P < 0.01). In conclusion, sensory-motor characteristics of LESR depend on the mechanosensitive properties of the stimulus (media, volume, flow), type of peristaltic reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR.

Terminating motor events for TLESR are influenced by the presence and distribution of refluxate

Transient lower esophageal sphincter relaxation (TLESR) is frequently associated with reflux events and terminates with a primary or secondary peristaltic wave. However, it is unclear whether the presence and properties of the refluxate affect TLESR-termination events. The aims of this study were to determine the pattern of terminating esophageal motor activity after TLESR in healthy subjects and factors affecting the type of terminating motor event. Fifteen healthy subjects (7 men, age 18–56) were studied. High-resolution manometry and impedance/pH monitoring were performed simultaneously in supine position for 2 h after subjects took a 1,000-kcal meal (Awake Study). This procedure was repeated during the night under polysomnographic recording for 6–8 h after consuming a 1,000-kcal meal (Sleep Study). We categorized three types of TLESR-terminating motor events, primary peristalsis (PP), full secondary contraction (FSC), which propagated the entire esophagus, and partial secondary contractions (PSC), which started distal to the upper esophageal sphincter. Overall, 289 TLESR events were found. The percentages of TLESR events terminated by PP, FSC, and PSC were 22%, 14%, and 64%, respectively. TLESR events terminated by PP were less likely to be accompanied by reflux events. TLESR events terminated by FSC were significantly more likely to have evidence for proximal esophageal reflux and esophago-pharyngeal reflux. Findings were similar in awake and sleep states. We concluded that, in healthy recumbent subjects, the most common TLESR-termination event is a secondary contraction, rather than PP. Presence and distribution of the refluxate is a major influence on the type of terminating contraction.