Contact Finite Element with Surface Tension Adhesion - Technologies for Medical Sciences - page 18

Contact Finite Element with Surface
Tension Adhesion

Rudolf A.P. Hellmuth and Raul G. Lima

Abstract This work is a contribution on the development of a computational model
of lung parenchyma capable to simulate mechanical ventilation manoeuvres. This
computational model should be able to represent adhesion caused by surface tension
and be able suffer collapse and alveolar recruitment. Therefore, a contact finite
element was developed and then simulated in a structure with structural properties
of the same order of magnitude of a real alveolus. The simulation was performed
with the non-linear finite element method. The implementation of the arc-length
method was also necessary in order to prevent divergence at limit points. The
numerical results of the simulation of a single alveolus, including the surface tension
and adhesion, are qualitatively similar to experimental data obtained from whole
excised lungs. Both present hysteresis and transmural pressures of the same order
of magnitude.

1 Introduction

Many patients in intensive care units (ICU) are unable to breathe spontaneously and
therefore they can only survive by means of mechanical ventilation. In many clinical
cases the patient's condition is so weak that the physician must choose between a
ventilation manoeuvre or other procedures that would perhaps help in the recovery
of the patient. However, there is a lack of information about the lung's current
condition and the efficacy of such therapeutic procedure can't be well predicted.
So, any improvement in knowledge about the physical and biological phenomena
involved in lung dynamics would be very useful both for critical decisions at the
bedside and for the development of new pulmonary therapy manoeuvres.

R.A.P. Hellmuth ( )•R.G.Lima
Escola Polit´ecnicadaUniversidadedeSao Paulo, Av. Prof. Mello Moraes,
2231 - 05508-970, Sao Paulo, SP, Brazil
e-mail: [e-mail] ; [e-mail]