Computer Simulation of Human Interaction with Underwater Breathing Equipment

Abstract

A mathematical model of the human respiratory system is being developed in order to simulate manned diving operations using various types of breathing equipment. A simulation study is presented of a human diving to a depth of 50 m, using a semi-closed re-breathing system with two different oxygen flow settings. A gas supply with 32.5 per cent oxygen concentration results in a safe dive whereas a 60 per cent setting indicates a dangerous diving condition. Typical respiratory model input data are illustrated for the lung, together with dimensional details for the re-breathing counterlung. The simulation results show variations in alveolar and pleural pressures, gas concentrations and partial pressures in the equipment and in the human respiratory system.

Pressure oscillation delivery to the lung: Computer simulation of neonatal breathing parameters

“…Other authors have produced model predictions in pressure, volume and flow at the airway opening that also show good comparison to values measured from real subjects (Athanasiades et al, 2000;Liu et al, 1998;Tomlinson et al, 1994). However, these investigations involve the healthy adult human lung.…”

“…The main driving force for the model F th is the force generated by the ribcage and diaphragm muscles due to the neurogenic signals sent by the brain to drive lung motion to create the tidal volume. Since the tidal volume follows the shape (but not the magnitude) of the (Tomlinson et al, 1994) for each breath, this relationship is used to reconstruct the profile of the thoracic force by setting the maximum value of thoracic force to occur at the peak of inspiration and normalizing other values in the profile relative to it. The profile of the thoracic force is then input into the model via a 'source block' in Simulink TM used to generate input signals by reading an array of values from a data file containing thoracic force values for a breath cycle in 0.001 s increments.…”

“…(12) allows the volume and elastance values at each distending pressure (from 0-40 cm H 2 O in increments of 0.1) to be determined and implemented in the model as ''Look-Up'' tables. Chest wall stiffness [26] and damping coefficients (Tomlinson et al, 1994;Lambert et al, 1982) are estimated from the data with the aid of available relationships.…”

“…Previous models have either concentrated on whole lung (Barbini et al, 2001;Nucci et al, 2002;Tomlinson et al, 1994) or left/right lung ventilation in adults. Neonatal models developed (Costantino and Fiore, 1997;Costantino and Fiore, 2001;DeJongh, 1995; either utilize symmetric branching geometry or are at most two-compartment models.…”

Diagnosis and prognosis of scrubber faults for underwater rebreathers based on stochastic event models

“…A rebreather can be viewed as a system that takes exhalation as an input and produces an output for inhalation. An advanced computer simulation model of the human respiration is dealt with in [14] and its application to semi-closed circuit underwater breathing equipment is discussed in [15]. For rebreather fault simulations, a simplistic respiration model is constructed in this section in accordance with European Standard EN14143:2003 [16].…”