Pathophysiological and Psychosocial Features in Functional Vomiting: Author's Reply.

TO THE EDITOR: We appreciate the comments from Kang. This study was conducted to further understand the pathophysiological and psychosocial features in functional vomiting (FV). Patients diagnosed as FV should fulfill the Rome III criteria,1 which does not require the absence of other functional gastrointestinal disorders. Gastrointestinal symptoms in all FV patients were recorded by questionnaires, which included vomiting symptoms, other upper and lower gastrointestinal symptoms. Recent studies have revealed that overlaps are common in patients with functional gastrointestinal disorders and about two thirds have symptoms of multiple disorders at the same time.2,3 I agree the pathophysiology in our study might reflect both the FV and functional dyspepsia. However, our FV patients presented vomiting as a predominant symptom.

Electrogastrography was used to investigate gastric electric activity instead of gastric emptying study since we wanted to avoid vomiting during testing. Power ratio is the ratio of the postprandial dominant power (DP) divided by the fasting DP. Although average DP increased, there was still 50% abnormal power ratio (< 1), suggesting a poor motor response to the meal.

In our study, psychosocial factors played an important role in FV patients in our study and we paid more attention to the relationship between psychosocial factors and the amount of overlaps or gastric sensorimotor function.

Electric barostat has been regarded as gold standard method to evaluate the gastric accommodation and visceral sensitivity.4 However, it is not physiological, and not available in clinic. Instead, drinking test is easier to perform.5 Most recently, our perfusion nutrition load test (P-NLT) was shown to reflect gastric accommodation more accurately than the drinking test in health subjects and functional dyspepsia.6 Therefore, we used P-NLT in our present study. Further studies are needed to confirm the validation of this method. In addition, further studies with large cases and other sensormotor function test are needed to reinforce the findings in our study.