Forced Deflation spirometry has been done here in Pittsburgh for ~30 years. While there are some drawbacks (it requires intubation and either deep sedation or paralysis), it also allows for testing of ventilated patients where that is not feasible with the IPL. For the last 30 years, this has been accomplished with some ... umm.... older technology (recording oscilloscope, polaroid camera, ruler), but just recently we have modernized this to run with a digital signal processing system and laptop (thanks, Joe!). Here, it has been commonly used to test children undergoing VEPTR, but we have used it for other purposes (pre-transplant evaluations in the ICU), or for children going to the OR for some other purpose where obtaining lung function would be helpful.
Do others have any experience with it?
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Which predicteds do you use for this technique?
ReplyDeleteI know that both arm span and length are used, the former being more useful for children with significant spine abnormalities, but do you think there is significant discordance between the predicted values that you get for these two in the same patient?
I suspect it depends on how much discordance there is between AS and Len! In Pittsburgh, we use the predicteds generated by Dr. Motoyama while at Yale (I am not sure if they have been published?), but there have also been predicteds published by Hammer et. al (J Appl Physiol. 2009 Jul;107(1):105-11. Epub 2009 May 14.) which utilize ulnar length! (on the occasions where we have measured ulnar length for a deflation study, I have found it to give very different results than the Motoyama predicteds). Also, somewhere I have plotted graphs of predicted FVC vs length using both Motoyama & Jones/Castile predicteds (they are similar but not the same).
ReplyDeleteI am excited that we have done our first test with our more modern digital system - it went very well, and analysis is a snap! Looking forward to doing 3 more tests next week.
ReplyDeleteI should add that this patient had an IPL study just a week earlier, and had some very similar results.
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