CONTEXT: Drink tests constitute an inexpensive and non-invasive tool, which has been proposed to discriminate individuals with altered fluid intake, as dyspeptics. However, their use in everyday clinical practice is still limited as standardization still lacks. OBJECTIVE: To perform a direct, paired comparison between the water and the nutrient drink test in normal volunteers. METHODS: Thirty eight normal volunteers (19 males, 19 females, mean age 24.4 ± 0.4 years) underwent drink test with water and nutrient (Nutridrink) within 7-10 days. Both tests included a loading (consumption of 100 mL/min for water and 15 mL/min for Nutridrink for the longest possible period of time) and a recuperation phase (observation after cessation of fluid intake), being separated by the maximal saturation point. During phases, satiety, fullness, discomfort, bloating, belching, nausea, pain and burning sensation (epigastric and thoracic) were recorded using a 0-100 visual analogue scale score (VAS). For the purpose of configuration, four variables were considered: time (t), VAS score (V), VAS slope (S) for a given time period, and probability of participation (Q) at a given timepoint. RESULTS: The loading phase lasted for 11.6 ± 1.7 min in water (total VAS: 879 ± 123, total VAS slope 72.6 ± 10.9 min-1) and 93.3 ± 18.4 min in Nutridrink test (total VAS: 1462 ± 411, total VAS slope 15.9 ± 3.2 min-1); P<0.001. The mean ingested volume recorded was 1155 ± 164 mL for water and 1399 ± 276 mL for nutrient; P = 0.076. Cessation of fluid intake was mainly attributed to fullness (76.3%) in water and satiety (69.2%) in Nutridrink test. Nausea was recorded only in Nutridrink test (15.4%). No volunteer reported substantial, persistent pain or burning sensation. The recuperation phase lasted 63.6 ± 7.8 min in water (total VAS: 278 ± 75, total VAS slope 3.97 ± 0.95 min-1) and 123.2 ± 17.5 min in Nutridrink test (total VAS: 841 ± 126, total VAS slope 6.81 ± 1.63 min-1); P<0.001. Concerning total VAS scores for both phases of the two tests, fullness and satiety represented a mere four fifths of the total (43% and 36%, respectively). Belching (8%), bloating (6%), nausea (4%), and discomfort (3%) followed, while pain and burning sensation represented <1% of the whole. However, intra- and intertest correlations concerning total and symptom-specific VAS scores revealed statistically significant variations underlying differences in physiology of liquid intake. A multiple regression model considering body mass index, gender and age as dependent variables, and total and symptom-specific VAS scores and slopes for both phases of the two tests as independent variables, did not reveal any primary correlation. The function linking the expected probability of participation Q and symptom-specific VAS score V with time t is approached by the formulas Q(t)=1/[1+(t/c)^k] and V(t)=V0*e^(-t/c), respectively; V0 is the mean symptom-specific VAS score, c, and k are phase- and test- related constants, and e = 2.718 is the base of natural logarithms. CONCLUSION: The comparative standardization of both drink tests in normal individuals might provide a tool for clinical application, targeting the diagnosis and treatment of relevant functional disorders.
Drinking, physiology; Potable water; Stochastic processes
