Manometry and Impedance Characteristics of Achalasia. Facts and Myths

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Achalasia is defined manometrically by an aperistaltic esophagus. Variations in the manometric findings occur in achalasia suggesting that all manometric features should not be required to diagnose achalasia. Combined multichannel intraluminal impedance and esophageal manometry (MII-EM) allows both a functional and a manometric evaluation of esophageal motility and identifies chronic fluid retention.


To compare manometric and MII characteristics in patients with achalasia.


Retrospective review of 73 MII-EM tracings from patients with achalasia done in our laboratory between October 2001 and December 2004 (38 females; mean age=53.5 y). Patients with previous esophageal interventions were excluded. Manometric and MII characteristics were identified and compared during 10 liquid and 10 viscous swallows. Patients were also divided into 2 groups: vigorous achalasia (VA) and achalasia.


Twenty-two of the seventy-one (31%) achalasia patients had a hypertensive lower esophageal sphincter (LES). The mean lower esophageal sphincter pressure (LESP) for the 71 patients with achalasia was 37.9±21.2 mm Hg compared with 27.3±9.3 mm Hg (P<0.05) in the 73 patients with normal motility. The mean LESP in patients with achalasia was 36±20.3 mm Hg compared with 47±23.2 mm Hg (P<0.05) in patients with VA. Elevated intraesophageal pressure (IEP) was noted in 45/73 (61.6%). The mean LESP in this group was 41.1±22.9 mm Hg compared with 32.5±17 mm Hg (P<0.05) with normal IEP. The mean baseline impedance for achalasia was 801±732 compared with 1265.2±829.5 Ω (P<0.05) for the VA patients.


Most patients with achalasia have elevated IEP, elevated LES residual pressure, normal LES pressure, and low baseline impedance. All manometric features should not be required to diagnose achalasia. Patients with an elevated IEP are likely to have an elevated LES pressure and LES residual pressure. Low MII values identify chronic fluid retention and helps confirm the diagnosis.

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