A numerical model of an intensive care ventilator-humidifier system.
Current intensive care ventilator-humidifier systems neither monitor nor adequately control inspired gas humidity. Problems of low delivered humidity and condensation within ventilator circuitry are commonly encountered. To help to address these problems, a numerical model of a complete ventilator-humidifier-patient intensive care system has been developed. The model, based on a finite difference technique, can predict pressures, flow-rates, temperatures and relative humidities at discrete points throughout the system. A comparison of numerical predictions and measurements in a real system is reported. A strong qualitative agreement is demonstrated in all cases studied, and a good quantitative agreement is obtained in most cases. It is concluded that such models could be used to assess methods of controlling ventilator-humidifier systems to prevent the occurrence of condensation. Similar models could be developed for other medical gas delivery systems.
Drew
T
T
Department of Medical Physics, Ninewells Hospital, Dundee, UK.
Vardy
A
A
Tarnow-Mordi
W
W
Lerski
R
R
D001698:Biomedical Engineering; D003422:Critical Care; D005740:Gases; D006801:Humans; D006813:Humidity; D008168:Lung / Q000502:physiology; D008954:Models, Biological; D008962:Models, Theoretical; D015203:Reproducibility of Results; D012121:Respiration, Artificial / Q000295:instrumentation*; D012984:Software; D013816:Thermodynamics
D005740:Gases