Lungs A Dry Subject For Student

From the Foundation for Research, Science and Technology

LUNGS A DRY SUBJECT FOR STUDENT

Intensive-care patients on ventilators could benefit from a student's research into what happens in their lungs when they breathe.

Merryn Howatson Tawhai, a biomedical engineering student originally from Toko, near Stratford, has developed a computer model for Fisher & Paykel Healthcare that paints a picture of how dry air affects lungs.

The research project has been a joint venture between the University of Auckland and F&P Healthcare, the country's main maker of humidifiers - air-conditioners that are attached to ventilators.

It is supported by Technology New Zealand's Graduates in Industry Fellowship (GRIF), which helps tertiary students do research with businesses. Ms Tawhai divided her time between Fisher & Paykel and the university during the project, which was for her PhD.

"When we breathe normally, the nose or mouth conditions the air to body temperature and saturation," Ms Tawhai says. But when a patient needs artificial ventilation, a tube that goes down the throat bypasses their nose and mouth.

"The conditioning region is bypassed, so the airways in the lungs have to do the conditioning. The surface liquid on the airways evaporates into the dry air, conditioning it to saturation.

"In the process, the surface liquid decreases, so the cillia - little hair-like fronds in the airways that sweep mucous towards the mouth - can't work and eventually die. As a result, the lungs can't clear mucous effectively."

Ms Tawhai says the computer model is a mathematical description of the branches of the lungs.

"Everything's broken down into mathematics, using equations that describe how heat and water vapour interact. Then we can investigate how far down into the lungs cold, dry air can penetrate, and look at the drying of the liquid on the airways' surface."

Bryan Peterson, of Fisher & Paykel Healthcare, says the company wants to know about dry air's penetration of lungs so it can fine-tune its humidifiers, and do simulations with the model to improve the design-prototype cycle.

Peter Hunter, a professor of engineering science at the university and Ms Tawhai's supervisor, says the project has been very successful. "It is going well. There is a benefit to Fisher & Paykel, who see it now as valuable for improving designs of respiratory-related products," he says. "It will also help raise the profile of career opportunities in bioengineering industry in New Zealand.

"We are working with several overseas companies - but we would like to bring more of this work home to New Zealand and generate wealth here. We also propose to start a new degree programme in biomedical engineering next year at the University of Auckland."

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Contact

* Bryan Peterson, clinical research manager, Fisher & Paykel Healthcare, Auckland. Ph: (09) 574-0123. Email: petersb@fphcare.fp.co.nz * Merryn Howatson Tawhai, Engineering Science Department, University of Auckland. Ph: (09) 373-7599 ext 7490, 021 483-259. Email: m.tawhai@auckland.ac.nz * Nigel Metge, Technology New Zealand at the Foundation for Research, Science and Technology (Auckland Office), (09) 912-6730, or 021 454-095. Website: www.technz.co.nz

Prepared on behalf of the Foundation for Research, Science and Technology by ID Communications. Contact: Ian Carson (04) 477-2525, ian@idcomm.co.nz

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