When to Perform pH-impedance Monitoring and High Resolution Esophageal Manometry (HRM) in Gastroesophageal Reflux Disease? : Table 1

Impedance	Ohm cm (at 1KH2)
Gastric Content	30-100
Bile	90
Saline Solution	100
Saliva	110
Skeletal Muscle	50-700
Milk/Yoghurt	300
Cream/Dessert	400
Drinking Water	1100
Cola	1100
Esophageal Wall	2000
Epidermis	2000 – 100.000
Air	10.000.000