Biomechanical properties of duodenal wall and duodenal tone during phase I and phase II of the MMC.
We used a new method, impedance planimetry, to look at variations in compliance, tone, and distension-induced peristaltic activity during phase I and phase II of the migrating myoelectric complex (MMC) in the human duodenum. A balloon was inflated stepwise with pressures up to 30 cmH2O in the duodenum, while the pressure and balloon cross-sectional area (CSA) were measured simultaneously. The biomechanical wall parameters were calculated from these measurements. Nine duodenal phase IIIs were recorded in six subjects. A balloon pressure of 20 cmH2O induced a smaller CSA in early phase I [266 (236-324) mm2] than in late phase II [385 (276-474) mm2] (P < 0.05). Balloon distensions elicited no contractions in phase I, whereas they increased contractile activity 60% (P < 0.05) proximal to the balloon and 4% distal to the balloon in late phase II. Step distensions in phase I with balloon pressures between 10 and 30 cmH2O increased the CSA from 40 (30-81) to 645 (603-704) mm2. It increased circumferential wall tension from 35 (28-63) to 429 (402-466) mm x cmH2O and the pressure elastic modulus from 9.7 (9.0-14.7) to 33.8 (27.6-33.8) cmH2O, respectively. Thus compliance differs from phase I to phase II. This is most likely caused by increased smooth muscle tone during phase I. Duodenal wall stiffness increases with the balloon pressure applied.
Gregersen
H
H
Department of Surgical Gastroenterology L, Aarhus University Hospital, Denmark.
Orvar
K
K
Christensen
J
J
D000328:Adult; D002404:Catheterization; D003187:Compliance; D004386:Duodenum / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009129:Muscle Tonus / Q000502:physiology*; D016065:Myoelectric Complex, Migrating; D011312:Pressure