ABSTRACT
In the quantitative assessment of a system, a description of the low-order transfer function model is important. The objective of this study was to identify the system of a mechanomyogram (MMG) with SubSpace-based State Space model IDentification (4SID). The input data consisted of the electrical stimulation of the common peroneal nerve, which made the anterior tibial muscle contract. The output data consisted of the evoked MMG. We applied Fourier transform to the MMG signal and obtained a power spectrum. The 10th-order model was estimated by the 4SID method. It was suggested that the frequency band separation of the power spectrum reflected the types of recruited muscle fiber. The results suggest that the MMG is a linear system which can be estimated in the lower-order transfer function model by applying the 4SID to each frequency band.
Subject(s)
Electric Stimulation/methods , Models, Biological , Muscle Contraction/physiology , Muscle, Skeletal/innervation , Muscle, Skeletal/physiology , Myography/methods , Peroneal Nerve/physiology , Computer Simulation , HumansABSTRACT
OBJECTIVE: The effects of postprandial water intake on the gastrointestinal tract have not been systematically investigated in humans. MATERIAL AND METHODS: In 8 healthy volunteers, the gastric antral pressure was measured with a strain gauge transducer, while the esophageal and lower esophageal sphincter pressures were measured with an infused catheter with a Dent sleeve. The esophageal pH at 5 cm above the lower sphincter was measured with a microglass electrode. A standard test meal (560 kcal) was eaten and 500 ml water was ingested 1 h later. The plasma cholecystokinin level was assessed at 4-min intervals. As a control, the same study was done on another day with sham water intake. RESULTS: At 4 min after water intake, there was a significant decrease in gastric antral motility and a significant increase in the plasma cholecystokinin level. Water intake also significantly increased the occurrence of gastroesophageal reflux. CONCLUSIONS: The rapid increase in cholecystokinin after water intake may be initiated by a feedback mechanism related to inflow of fatty chyme into the duodenum that inhibits gastric antral activity.
Subject(s)
Cholecystokinin/blood , Drinking/physiology , Gastrointestinal Motility/physiology , Postprandial Period/physiology , Pyloric Antrum/physiology , Adult , Biomarkers/blood , Esophageal Sphincter, Lower/physiology , Fasting/physiology , Gastroesophageal Reflux/metabolism , Gastroesophageal Reflux/physiopathology , Humans , Male , Manometry , Middle Aged , Pyloric Antrum/metabolism , Radioimmunoassay , Reference ValuesABSTRACT
BACKGROUND AND AIM: An early and accurate evaluation by a general practitioner is needed to screen out non-gastroesophageal reflux disease (GERD) patients. A recent questionnaire (QUEST) highlighted problems with specificity and complexity, so the aim of the present study was to design a simplified questionnaire. METHODS: When admitted to hospital to undergo an upper gastrointestinal endoscopy for suspected GERD, 333 patients completed a 50-item questionnaire requiring 'yes/no' answers to different combinations of questions relating to symptoms of upper gastrointestinal tract conditions (e.g. GERD, ulcers and functional dyspepsia) and psychosomatic symptoms. The endoscopic diagnosis was then correlated with the rate of positive answers to each question. RESULTS: Based on the analysis of the 50 items, the 8-10 questions most often answered affirmatively by each of the GERD and non-GERD groups were chosen for the simplified questionnaire. Three draft questionnaires were compiled. After calculating the sensitivity, specificity and accuracy in relation to the diagnosis of GERD and other conditions, it was found that questionnaire B (selection of persons answering 'yes' to at least one of questions 1-5 and exclusion of persons answering 'yes' to at least three of questions 7-10) had a high sensitivity, high specificity and low false positive rate. CONCLUSION: A novel questionnaire was developed. It was designed to detect the symptoms of GERD while simultaneously excluding non-GERD patients. This simplified nine-item simplified questionnaire had a sensitivity of 79.8%, a specificity of 53.6% and an accuracy of 63.4%.
Subject(s)
Gastroesophageal Reflux/diagnosis , Surveys and Questionnaires , Chi-Square Distribution , Diagnosis, Differential , Endoscopy, Gastrointestinal , Female , Humans , Male , Middle Aged , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
BACKGROUND: The aim of this study was to produce a simplified questionnaire for evaluation of the symptoms of gastroesophageal reflux disease (GERD). METHODS: A total of 124 patients with an endoscopic diagnosis of GERD completed a 50-part questionnaire, requiring only "yes" or "no" answers, that covered various symptoms related to the upper gastrointestinal tract, as well as psychosomatic symptoms. The 12 questions to which patients most often answered "yes" were selected, and were assigned scores (never = 0; occasionally = 1; sometimes = 2; often = 3; and always = 4) to produce a frequency scale for symptoms of GERD (FSSG). Sensitivity, specificity, and accuracy of the FSSG questionnaire were evaluated in another group of patients with GERD and non-GERD. The usefulness of this questionnaire was evaluated in 26 other GERD patients who were treated with proton pump inhibitors for 8 weeks. RESULTS: When the cutoff score was set at 8 points, the FSSG showed a sensitivity of 62%, a specificity of 59%, and an accuracy of 60%, whereas a cutoff score of 10 points altered these values to 55%, 69%, and 63%. The score obtained using the questionnaire correlated well with the extent of endoscopic improvement in patients with mild or severe GERD. CONCLUSIONS: This new questionnaire is useful for the objective evaluation of symptoms in GERD patients.
