Multichannel intraluminal impedance measurement of gastroesophageal reflux in patients with different stages of morbid obesity.

BACKGROUND: Obesity is now one of the world's major chronic diseases. The etiology of the severe comorbid conditions associated with morbid obesity is not fully understood, and in particular the relationship between gastroesophageal reflux and obesity.
METHODS: Sixty-seven patients were enrolled in this prospective study. Patients and control individuals were divided into four subgroups according to their body mass index (BMI). Esophageal motility was assessed using a conventional water-perfused esophageal manometry catheter, and 24-h pH-metry was carried out using multichannel intraluminal impedance equipment.
RESULTS: In the group with the highest BMI (>50), contraction amplitudes in the middle and distal esophagus were significantly higher in comparison both with the control group and groups with a lower BMI (P < 0.05). Lower esophageal sphincter pressure was reduced in the majority of patients with morbid obesity and differed significantly from the control group (P < 0.001). Significant differences between the control group and the patient groups were also observed on 24-h pH-metry (P < 0.05). The 24-h impedance measurements distinguished between acid and nonacid status and between the upright and recumbent positions. The total number of reflux episodes differed significantly between the control and patient groups and between groups III and IV, with lower and higher BMI values (P < 0.008 and P < 0.05, respectively).
CONCLUSIONS: The impedance data obtained in this study confirm that patients with morbid obesity are at risk of developing gastroesophageal reflux disease. However, there is no evidence of a direct correlation between the severity of reflux and the extent of obesity.