We began searching for materials that met this requirement, and realized that standard hematocrit tubes have appropriate dimensions. We ordered a pack of the polycarbonate style (hematocrit tubes are also generally available in glass) and tried updating our design to incorporate these tubes.

Hematocrit capillaries in place

Unfortunately, polycarbonate is a very poor heat conductor, and our attempts to cut the tubes with a fine-blade band-saw resulted in fusing our capillaries shut. As is, we are still looking for suggestions of capillary materials or any premade capillary systems that we could simply cut and plug in to our spirometer.

Ends of capillaries fused by cutter

On the software end, a team of interns has been actively refining computer algorithms that take an array of flow data points and calculate the various spirometry test values. The team is using the raw curve data from the NHANES III and comparing their calculated values with those calculated by NHANES. This process has been challenging as well, as NHANES has used data processing techniques that are not clearly defined to calculate the lung function indices. Our team is currently working on developing a program that will run numerous types of processing techniques, ranging from very low-level to advanced, on the data and compare which methods yield the results closest to those printed by NHANES.

The final front of development is focused on the internal circuitry components of the spirometer. Currently, we are working with the PIC18F13K50 microcontroller which will be responsible for taking the data from our iLite signal conditioner and passing it to the computer via USB. Because USB is an advanced and highly-standardized communication protocol, we’ve been devoting considerable time into learning how to program the microcontroller to successfully identify itself to the computer and then proceed to stream data to it. Also, although our circuitry will have relatively few components, all of them have specific electrical specifications that need to be met by incorporating appropriate accessory components (resistors, capacitors, etc.) into our design. Progress in this area will hopefully allow us to create a Printed Circuit Board (PCB) of our circuitry design by the end of summer.

The multi-faceted nature of the spirometer project has allowed the team to learn a great deal in a wide variety of fields, but we are still far from experts in any one area. Feedback on our design, including critiques of existing work and suggestions for future progress, are always appreciated!

We would like to send this document to a software developer who could help us begin to code it. This document is only the first draft, and any input would be appreciated and would result in better software being produced.  Please comment if you have any suggestions, or email a revised document to openspirometry@gmail.com

Thanks for your input!

• We revised our design from the Venturi design, and we now need to decide whether to build a Lilly or Fleisch type spirometer. Both are currently used in commercial models. We are examining the pros and cons of each design and hope to have a basic prototype of each built by the end of the week. Feedback on the design features and construction is welcome as always. Find out more about these spirometer designs here:

Fleisch – http://spirxpert.com/technical2.htm

Lilly – http://spirxpert.com/technical3.htm

• After much consideration, we have decided to pursue Adobe AIR as the platform for our software. We believe that AIR will provide the smoothest path to a highly-functional graphic interface that is capable of displaying all of the data we want. However, AIR does have its disadvantages, including a large RAM requirement and no direct access to USB devices. We are examining the use of the Merapi Project software to acquire our data through a Java application (allowing USB access), but would be interested to hear other alternatives.  Here is our rationale for choosing Adobe AIR over Microsoft Silverlight, Processing, and Java:

Design matrix for software decision

• We are currently working on correlating input voltages with the output of the ZMD 31014. This process will allow us to correlate the data we see on the screen with the differential pressure recorded by the sensor. Our current setup has been giving unexpected data, but we hope to resolve the problems soon.

Info we need

We want to make our product as functional as possible for our customers, so we want to know as much as we can about the operating environment for our spirometer. Information about the following topics would be greatly appreciated!

• What types of cleaning solutions are available or commonly used in your clinics? Ethanol, Cidex, other?
• How much RAM do your computers generally have?
  • We plan on creating a graphically intensive program to show video and animation and are concerned about the capabilities of the users’ computers.
• Do patients tidal breathe through your spirometer prior to forced exhalation or do they place the spirometer to their lips after their max inhalation?
  • If you have used both types of procedures, which do you prefer? Why?
  • We would prefer NOT to have patients tidal breathe through our spirometer to reduce the risk of cross-contamination.
  • Also, we want training videos to portray the use of our spirometer accurately and ensure that it is consistent with most commercial spirometer procedures.

Thanks for your help! Please send any comments or suggestions to  openspirometry@gmail.com, or leave a comment on this post.

For the past week we’ve been strategizing about the audiovisual materials we hope to build to demonstrate the ideas of standardizing patient preparation, instruction and coaching, including several different types of incentive screens – typically modeled on what we’ve seen in the marketplace.

During a meeting last week with Charlotte – a French student spending a year in Madison who is pitching in to help make the short clips we’ll need -the students came up with some exciting new ideas about the incentive screen.

For example, Jeremy G raised the possibility of making the screen more competitive – taking a game approach a step further.

The discussion led me to wonder whether we could create a competitive animation where the opponent depicted the student’s own predicted values (the expected values for someone of the same age, sex and height).

Charlotte suggested that we think about creatively trying to exploit and encourage the patient to model the behavior of a person demonstrated in the video.

In general, I’ve recently been wondering whether incentive screens might be better seen as something for everyone doing spirometry, rather than just for kids.

Andrew D had done some reading about incentive screens and drew our attention to a debate in the literature about their efficacy. Surprisingly, it turns out that the efficacy of incentive screens hasn’t actually been very well evaluated.

The series of articles he found reveal a small but healthy debate within the respiratory community about whether traditional incentive screens and computer animations improve the quality of measurements in young children – and which parts of the maneuvers they actually affect (effort, reproducibility).

I’ve posted some of Andrew’s comments in the wiki along with links to the articles in the resources area of the wiki. We’d love to hear what others think about the value of the incentive screens, and stimulate some discussion about innovative ways to improve their utility.

Please let us know what you think about the ideas for the incentive screens or suggest some of your own. We’re keeping a list in the wiki and will start build something in the next week or two.

Pressure sensor setup

They’ve started preparing for their upcoming mid-semester presentation on the project which will take place Friday afternoon. I hope to post some of the details of the presentation soon afterwards.

Testing differential pressure sensors

Early on I learned some interesting details about each of their backgrounds and interests and have been wanting to introduce them.

Jeremy G grew up in a little town north of Minocqua (the true Northwoods of Wisconsin) surrounded by trees and lakes and, in his words, “not much else.” He studied abroad in Ireland last semester and spends time here on outdoor activities, especially cross-country skiing in the winter.

Jeremy S is a junior from Waterford, WI, interested in bioinstrumentation and medical imaging, who also gets outdoors as he can to hunt and fish.

Andrew D is a junior BME major in the bioinstrumentation track, who’s made it his goal before graduation to finish a Mickey’s scrambler in one sitting.

Andrew Bremer is a junior studying BME at UW-Madison. Outside of school he is an officer in the UW chapter of the Biomedical Engineering Society and also works as a campus tour guide. Born and raised in Madison, he is a true Madisonian – he enjoys Badger sporting events, Babcock ice cream, (the World’s Largest) Bratfest, cheese, Concerts on the Square, hanging out on the Memorial Union Terrace, and all other things that make Madison unique!

Thanks to each of them for their enthusiasm and hard work so far this semester.