Background: Regurgitation and vomiting are common manifestations of cow's milk protein allergy (CMPA) in infants and are usually ascribed to gastroesophageal reflux (GER). Gastric anaphylaxis can induce antral dysmotility in the rat, and therefore the hypothesis for the current study was that cow's milk in sensitized infants may impair antral motility, thereby promoting GER and reflex vomiting. Methods: Seven vomiting infants with CMPA and nine with primary GER underwent a challenge with cow's milk formula. Electrogastrography (EGG) was used to measure the spectral Frequency (bradygastria = 1.5-2.4 cycles per minute [cpm], normogastria = 2.5-3.9 cpm, tachygastria = 4.0-9.0 cpm) and the postprandial-to-fasting power ratio of gastric electrical activity, whereas gastric half-emptying time (T 1/2) was measured by electrical impedance tomography (EIT). Results: In CMPA and GER. respectively, during fasting, the Frequency distribution (mean +/- SD) of the EGG was as follows: normogastria 47.9% +/- 12.5% versus 52.2% +/- 9.8%, bradygastria 24.1% +/- 5.7% versus 22.8% +/- 8.3%, and tachygastria 28.0% +/- 8.5% versus 25.0% +/- 8.3%. In contrast, after the cow's milk challenge, the difference between the two groups was statistically significant: normogastria 33.1% +/- 8.8% versus 70.6% +/- 8.6% (P < 0.0001), bradygastria 38.0% +/- 15.5% versus 15.7% +/- 5.2% (P = 0.002), and tachygastria 28.9% +/- 10.6% versus 13.4% +/- 4.6% (P = 0.001. The postprandial/ fasting power ratio (mean +/- SD) was 3.2 +/- 1.9 in CMPA and 8.1 +/- 2.1 in GER (P < 0.0001). Gastric T 1/2 (mean +/- SD) of the cow's milk meal was 89.0 +/- 26.3 minutes versus 54.0 +/- 12.6 minutes (P = 0.003). In infants with GER all EGG parameters and gastric T 1/2 were similar to that in 10 healthy control infants. Conclusions: In sensitized infants, cow's milk induces severe gastric dysrhythmia and delayed gastric emptying, which in turn may exacerbate GER and induce reflex vomiting. Electrogastrography and EIT can be useful in the assessment of vomiting, GER, and CMPA in infants.
