Investigation to diagnosis of laryngopharyngeal reflux: (A) Esophageal pH monitoring, (B) Dual probe impedance pH monitoring, (C) Barium esophagram, (D) Scintigraphy
Answer is B. pH monitoring at the level of pharynx is not helpful because the acid refluxed is neutralised by the pharyngeal secretions Hence a dual (bifurcated) catheter measuring both pH and impedance is used across upper oesophageal sphincter thereby permitting detection of pharyngeal reflux Ref: Shackelford 8th edition Pgno: 222