A mechanics-based perspective on the pressure-cross-sectional area loop within the esophageal body

Figures

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  FIGURE 1. Diagram showing the FLIP bag and catheter assembly placed within the esophagus, passing through the LES or not. The bag used in this study is 16 cm long and 22 mm diameter. The catheter measures CSA at 16 location and one distal pressure measurement at each time instant.

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  FIGURE 2. P-CSA relationships in the esophagus body for four different contraction cycles with different experimental setups. (A) P-CSA extracted from a 4-cm long FLIP obtained by Gregersen et al. (2011). (B) and (C) P-CSA extracted from a 16-cm long FLIP at 60 ml, where the FLIP bag passes through the LES. These hystereses are plotted from data recorded at a sensor located away from the LES. (D) P-CSA extracted from a 16-cm long FLIP at 60 ml, where the FLIP bag does not cross the LES.

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  FIGURE 3. Activation functions (A) θ p and (B) θ sup (B) plotted as a function of χ at five consecutive time instants.

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  FIGURE 4. Simulation results for a single contraction cycle with muscle activity defined by a traveling peristaltic wave (θ p ). Top left: P-CSA hysteresis loop at χ o . Bottom left: P and CSA vs. time at χ = χ o . Right: tube shape at seven consecutive instants, ordered chronologically.

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  FIGURE 5. Two instants showing the corresponding tube shapes from the same simulation. The locations of point χ = c, regions 1 and 2, and how they change over time are depicted. P-CSA is plotted at χ = χ o and its location does not change with time.

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  FIGURE 6. P-CSA plots obtained from three different contraction cycle simulations. Input parameters are as listed in Table 1 and ψ = 100. (A, B) The FLIP bag does not pass through the LES, w = .25, (C) the FLIP bag passes through the LES, w = .25, and (D) simulation results for a short FLIP bag, w = .75.