Hello. I would like to share this very valuable Info so I think with you.
WARNING: THIS IS NOT MY IDEA. ITS SOMETHING I HAVE LEARNED FROM A GREAT GREAT RT WHO'S NAME I WILL NOT SAY, BUT I DO NOT OWN THE INVENTION OF THIS WAY, NOR DO I OWN ANY CREDIT, NOR SHOULD I RECIEVE ANY CREDIT FOR THIS INFO. I AM SIMPLY HERE TO PASS THIS ALONG, BECAUSE MY GOAL IS TO HELP OTHERS BETTER PATIENT CARE, AND WHEN I AM ABLE TO WORK IN THE MEDICAL FIELD AS I'VE WANTED TO SINCE AROUND 4, I WILL DO THIS WONDERFUL WONDERFUL BLESSING ALL RTs, CRNAs, and many other H/C professionals do.
I CANNOT TAKE ANY RESPONSIBILITY OF ANY HARM THAT IS DONE TO PATIENTS DUE TO PERFORMING THIS TASK OF WHICH I WILL BE SPECIFYING BELOW. DO THIS AT YOUR OWN RISK. THANK YOU, GOD BLESS.
Usually to perform a NIF, Negative Inspiratory force, AKA, NIP Negative Inspiratory Pressure, MIF Maximum Inspiratory Force, MIP, Maximum Inspiratory Pressure a patient is asked to suck in as hard as he/she can against an occluded valve. This poses great hazard to patients, not only that, this can and will cause massive amounts of anxiety to patients, and can lead to issues including Cardiovascular Problems, and prolonged ventilatory support. A friend I know learned this very valuable and relativly new technique for obtaning NIF, NIP, MIF, MIP, or whatever you prefer to call it. This can be done with a ventilator in which the sensitivity can be decreased to Negative 20cmH2O Pressure trigger. So here is how to perform this procedure.
1: Explain the procedure to the patient. Hello Mr. Baker. I'm here to perform a Procedure that's going to gell us if you might be ready to get that tube out of your throat, and breathe on your own." I'm going to adjust some settings on the ventilator, and I'm going go have you suck in as hard as you can when I say, and when you do this, Its going to feel like you cannot get that breath, but eventually, If you can suck in hard enough, you will recieve that breath. If you are unable to, I will disconnect the ventilator circuit, and I will reset the ventilator so that you get the breaths again when you breathe in. Do you understand?" and of corse the patient will give ou some means of communication head shake, nod, sign language, etc to notify to you he does understand. OK. Now turn to the ventilator, and we'll begin adjusting the trigger and other settings you are going to need adjusted.
2: Set the ventilator to a low amount of pressure support just enough to give a little bit of pressure to help take away the ristance of the airway being that its a trach tube, an ET tube, etc.
3: Place the patient in a fully spontaneous mode of ventilation, and let them know you are doing so.
4: Adjust pressure trigger to 20cmH2O or greater, or if you are able to on a ventilator that allows trigger to be turned off in a spontaneous mode, you may just turn it off. Now, the key is to watch the PEEP value here, because this is where your NIF is going to come from. Its going to be an Indirect measure of NIF, and the way you will get an almost direct measure is through the calculations to be specified below.:
5: while you are watching the PEEP value, instruct the patient to suck in as hard as he can. Now, observe the PEEP value. Observe the measured PEEP value as it will become negative when the patient sucks in if the patient is able to suck in enough to cause negative PEEP measurements. For this example I had my patient SET at a SET PEEP of 5. cmH2O. Now I asked him to suck in as hard as he could. He hit a Negative PEEP value of -33 cmH2O Now add that up until we get to five. OK. This patient has recieved a NIF of -38. The reason we got this is we subtracted 33 from 5, and this gave us Negative 38. 6: PERFORM THIS STEP 2 TO 3 TIMES IN SUCCESSION AS PATIENT TOLLERATES.
7: REMEBER to set the trigger and other settings back to their previous settings including the mode, and document your findings. This patient was later extubated, and went on to make a full recovery. Thank you.
I think you may be barking up the wrong tree. If you truly believe NIF is an indicator of extubation readiness, you don't need to know what prssures that can be done on request, but the manuever must be mildly asphyxiative, they have to feel as though they cant get air. Sounds mean, but unreliable indices of extubation readiness are also.
Gotta agree with respir8er. I am totally against collecting NIFs except via mask or sniff method to monitor pulmonary muscle strength across time for NM patients, and I generally prefer a insp VC with an incentive spirometer. As a means of assessing for weaning or extubation readiness NIF has no value. If a doc is ordering it, he is probably not aware of the data. I haven't seen an article on assessment of weaning readiness where it was studied that demonstrated any predictive value. I have worked in the past where a NIF was collected every morning on every vent patient. I observed I would have patients that would be able to pull a immeasurable or result greater than the NIF gauge, which went to -70they could not sustain spontaneous respirations more than a couple of minutes and I also observed patients that could not pull more that a -15 that could sustain for hours or even wean. My problem with the NIF besides its weakness as a predictor is that I believe that since most of the theories on VAP indict aspiration of above the cuff secretions as a possible causative factor. If we have the ETT or trach cuff inflated to 25 cm and our patient can pull a normal -50 then they are placing that negative pressure against not only the device we are using to measure, weather NIF gauge or vent via circuit but also against the bottom of that cuff and sucking some amount of those infective secretions down into the trachea below the cuff. I don’t ever recall NIF being directly associated with VAP rates, but circuit breaks certainly are. Most seem to think the VAP comes from contamination of the circuit during the break. I am more inclined to think that it is due to the fact that the patient’s spontaneous respiratory efforts that occur during the time the circuit is off the airway create a negative pressure against the bottom of the cuff and a flow of above the cuff secretions down toward the trachea that does not occur when positive pressure breaths and PEEP are delivered into the trachea. With all of that said against doing NIFs, if one is going to do it, it should be done right. At its basic level a NIF is a pulmonary function value. As we are all taught a pulmonary function result is only useful if produces repeatable results. If one guy is jacking up the vent with some major triggering pressure setting and thinking he is collecting a NIF and I use the standard method of a 20 second airway occlusion against a NIF gauge and a one way valve, and he collects a value a couple of centimeters greater than the maxed out sensitivity pressures he has placed on the vent and I collect a -63 on my NIF gauge, and the next person uses a thumb occlusion adaptor and says “take a deep breath” and gets a -18 on one wimpy effort how useful is this series of data points to the interpreting physician if there were any possibility of it being useful data. I really appreciate the term "asphixiative" in respir8er’s post. That is exactly right. When collecting pulmonary function values maximum effort is the only way to obtain repeatable results. A NIF collected correctly on a patient with an artificial airway requires inducing some level of distress to get maximum inspiratory effort. This is another reason I do not like the test. I will usually contact the physician ant try to talk him or her out of requiring this useless study. To the best of my knowledge, the only useful indicator of readiness to advance spontaneous breathing is to have the patient breath spontaneously and assess their tolerance. At the acute level on most short-term vent patients 30 minutes to an hour of tolerance will usually predict success enough to suggest assessment for extubation. For more long-term patients I like to see them move to a trach collar or T-bar ASAP and manage demonstration of good tolerance for 48 hours before I d/c the vent. If they fail at any point i.e. rapid shallow resp pattern, desaturation, increase HR, increased BP, sustained increased level of resp. distress etc. put them back to settings that are comfortable let them recover and go back at it at the next opportunity. How these steps are structured exactly should be based on a sound protocol and everyone should work them with relatively similar timing and technique, but I have some heavy weaning experience and have successfully managed a staff that produced national best wean times and rates for difficult to wean populations and I would offer that we were able to produce those results without ever assessing NIFs. We did use RSBI and VD/VT as well as assessment of tolerance of SBTs as tools to help us assess readiness to progress, but nary a NIF. As to the guy who adjusts the insp trigger setting to collect what he thinks is a NIF, I would totally disclaim that also. I am pretty sure he is way off the farm and not working to the policies of his department. I believe his manager or director would have no problem justifying firing him, and if he does not drop this he will wind up caught and fired. He should really study up on the literature related to weaning and offer the doc a plan that is based in the science of vent weaning, and not try to find a shortcut to generating patient assessment data. The science really works. I have seen the proof.
I really appreciate both of your posts. Great response respir8er, and EvitaXL I really enjoy your enthusiasm and I hope you keep bringing us these types of conversations. I don’t mean to totally condemn a therapist that you think is really great, but I think this person is misguided and I hope you can see why, but I don’t want to dampen your enthusiasm for posting here at all.