View Full Version : Trached PFT's, how
02-07-2011, 12:32 AM
Anyone know any research on how to do an accurate Pulmonary Function Test for a trached patient? Intention of the test would be to make a guesstimate as to how the patient would fare during the daytime without the trach so preferably it would be done through the mouth/nose and not through a sealed trach.
02-07-2011, 08:28 AM
I'd say it depends on the patient.
When *I* did a PFT, I had to wear some funky scuba-gear looking stuff, and a clip on my nose....and follow directions.
Assuming the patient was capable of following the directions, I'd assume a down-sized trach with a cap and the normal equipment would work. If not...I've heard there's a couple of hospitals that do test infants and toddlers in a sealed chamber, much like an iron lung. It sounded horrible, so we didn't ask any questions further than that.
That said...I'm not sure a PFT would tell you what you need to know. A capped trach would be less hassle....
02-07-2011, 09:16 AM
Back before I had my trach I did the test in some kind of sealed thingy and it wasn't quite like an iron lung but I see how you can get that idea. In the future I would say don't be freaked out by it, most of them have many windows and so it isn't scary.
As for following directions, well I can follow directions well enough.
The issue we keep running into with a capped trach is that in practice it doesn't work well because my trach is unfenestrated. Lets assume my airway has a diameter that is 1.5 to 2 times my trach OD which is 9mm. This means the trach takes up anywhere from 1/4 to 1/3 of the space in the airway so if you cap the trach what you have done is created an obstruction that is 1/4 to 1/3 of the airway space. It is hard for me to imagine my trachea being as fat as 18mm and with or without Muscular Dystrophy if I block off that much of your airway it's going to cause a problem.
There are a few obvious answers hanging around like Fenestrated Trach or Stoma Button which both would alleviate the blockage issue but I figured I first may as well look around and see if there is something we can do without changing up the hardware in my neck.
02-07-2011, 09:29 AM
Fenestrated would be the way to go, I'd think. I know my son (who's only 2 1/2) really could not have tolerated a cap until we went down 2 sizes on his trach. He was so-so with a speaking valve at his original size, and much improved when we went down one size. Clearly, though, we cannot use a ventilator on him at this point if it becomes necessary - his air leak is too large to successfully ventilate just through the trach.
A PFT tells you how much lung capacity, and how much ability to blow in and out (and as you've noted, a trach is going to affect that reading)....and I forget what else, since it's been quite a while since I had one done.
My son has had two types of PFT's -both times he wore a cuffed trach:
he had one that the air was pushed into his lungs via ambu thru trach; and then a vacuum sucked all the air out and measured the volume of air he could hold.
He had another one that he was strapped to a board with a vest type thing around his chest... the lungs were again filled with air via ambu thru trach.. and the vest inflated to squeeze all of the air out of his lungs very quickly (again with a monitor on the trach measuring how much air his lungs held when they were filled to capacity (this method is VERY painful; and he was sedated for it)
My son doesnt have any lung issues; his chest is deformed, causing the lungs to have little space to move or grow(causing the need for a vent)we were testing the lung capacity before deciding on whether to do chest surgery or not. our tests came back well enough to try PMV during day without surgery.
Fenestrated tube or downsizing a couple of sizes would probably be the best way to try any type of capping to determine if you can manage without breathing thru the trach. I understand your thoughts behind the obstruction of the trach in the airway... and I have insisted before we attempt to cap my son he will be downsized at least 2 sizes before I will consent to letting him be tested with a cap(I would prefer to go down 3 sizes-if the ENT will let me get my way)
02-07-2011, 03:22 PM
Scoliosis caused my initial intubation (is that what they call getting a trach?) so I can relate to the deformed chest thing which I think they called Severly Restrictive Pulmonary Disease on paper. I called it: My spine crushing my lungs. Now that my spine is fixed though I am still limited in strength due to having Muscular Dystrophy (which actually caused the spine collapse) so that is where our conundrum is. We don't know how much the MD really affects my breathing capacity.
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