Measuring gastric emptying of semisolids in children using the C-acetate breath test: a validation study

Background and aim. Radioscintigraphy is the gold standard for evaluation of gastric emptying in children, but requires exposure to ionising radiation. Therefore, the aim of the study was to validate the non-radioactive ¹³C-acetate breath test in children in comparison to radioscintigraphy as reference method.Patients. Twenty-nine children with dyspeptic or respiratory symptoms were tested for gastric emptying disorders simultaneously performing the ¹³C-acetate breath test and radioscintigraphy.Methods. A semisolid oatmeal was doubly labelled with 150 mg ¹³C-acetate and 50 MBq ^99mTechnetium. Breath samples were collected every 5–10 min for 4 h. After mass spectrometrical ¹³C-analysis, curve fitting of the ¹³C-cumulative recovery to the modified power exponential function Y=m(1−e^−kt)^β calculated the half emptying times of the breath test (t_1/2^breath). Scintigraphic image acquisition began immediately after the ingestion of the ^99mTechnetium-labelled testmeal at a rate of one frame every 60 s for 1 h.Results. Six children showed delayed gastric emptying in scintigraphy (t_1/2^scinti>60 min). All these children had prolonged half emptying times t_1/2^breath in the ¹³C-acetate breath test. Using a cut-off t_1/2^breath>90 min, the ¹³C-acetate breath test had a sensitivity of 100% and a specificity of 85%. Scintigraphic and breath test half emptying times were linearly correlated (Y=0.80x+47.68, r=0.76, P<0.00001).Conclusions. The ¹³C-acetate breath test proves to be a reliable, non-radioactive alternative for measuring gastric emptying in children.