My mother is on an LP6plus ventilator. In the past 4 weeks the high pressure alarm keeps going off. She was set at 45 on SIMV and a breathing effort of +1. I called the Doc; he sent an RT and the settings are now Assist Control, pressure limit of 55 (which she is still alarming) and effort of +4. There are no infections showing up, but suctioning has reduced. What does all this mean?

I have only worked very sporadically with the LP6 Ventilator.

An online source can be found by typing in <LP6 KUMC> into a Google source. It's a slide show.

I can't begin to tell you "what it all means". But I can overall describe some things and give you my impression of what the setting changes will do.

The pressure limit was increased from 45 cmH20 to 55cmH2O. This means it will take more pressure for the "high pressure" alarm to sound AND for the ventilator to dump the volume should that occur.

SIMV stands for "syncrhonized intermittant mandatory ventilation". If the patient is set on a rate of 10 then every six seconds the ventilator will give a "mandatory" breath at the specified tidal volume and inspiratory time.

In SIMV mode between the mandatory breaths the patient is basically on their own to draw air through the circuit.

Changing to Assist/Control means that every breath will be assisted with a machine breath at the specified volume/time/flow pattern. This should help to unload the patient's work of breathing if every breath is assisted. It may also help to work up secretions.

The sensitivity settings can be (relative to normal atmosphere) anywhere from negative 10 to plus 10. Is there a Peep valve added to the circuit? If a Peep valve of 5 was added then an increase from negative 1 to positive 4 would make perfect sense. Also if the alarm were at 45 and if the baseline pressure were increased to 5 PLUS PERHAPS the insp. time was reduced to meet patient demand. If the patient is drawing in air fast and then relaxes a pressure of 30 could change to a pressure of 50.

The flow pattern is sine, meaning it starts out slow and ends slow, with a flow spike in the middle. If a patient is in need of more support and really trying to draw in alot of air fast, this type of flow pattern can be a problem. Decreasing the insp. time will then increase the flows all across the sine wave--but at a cost of a higher peak pressure (and especially if the patient relaxes and doesn't suck in for air so much).

Without being there I can't honestly say what the setting changes accomplish, and if the changes be good or bad. I suspect the RT found a patient in need of more support and gave it to her.

I would ask the therapist..."was the change from SIMV to AC so that she could get the support she needs for each breath?"

"Is she on any Peep?" and if so "was that why the sensitivity was changed from +1 to +5?" (was it negative 1 before and +4 now?)

"Did you shorten the inspiratory time to better match the patient's demand for air?". And if so, "is that why the high pressure limit was increased?".

I wasn't going to answer your question but as no one else did I'm doing the best I can.

To answer here you previous question about Psuedomonas that "the rotting flesh smell". Psuedomonas is a pretty tough bacteria, it's good at colonizing the upper airway, and is a bad bug to get infected with ala pneumonia. Recently scientists are finding that it creates a biofilm and it's virulence is enhanced by it's group or colony cooperation between bacteria (i.e. the biofilm it creates). It has it's own smell.

I wouldn't presume to guess what the rotting flesh smell is. I hope that the patient is being turned and doesn't have any skin breakdown or decubiti. Has an RN seen the patient?

As for the rotting flesh I can't help but repeat my favorite Jeffrey Dalmer joke. He had his mother over for dinner. She said "Jeffrey I really don't care for some of your friends.". Jeffrey replied, "OK Mom,then try the salad.".

Thank you for the information. Today she had to go to the hospital due the continued high alarm to check for occlusions. She has very mild pneumonia in rt. lung. They (hospital RT) changed her tidal volume from 500 to 350. I don't understand that. As for the inspiratory time he never changed it. Her new settings at home are Assist Control; Breath Rate 10; Ins. time 1.0; peep valve 5; low alarm 8, high alarm 55; and effort at +4 with 35% O2. The Doc that is treating her wanted to unplug machines last year before trach. Her normal Doc has spinal cancer. As for turning, She is alert and I turn her about every 2 hrs. (even @ night). Sometimes she gets up in her wheelchair on her trach collar @ 35% venti-mask. I'm still trying to learn all of this. My goals are to become an RT for children and infants.

The tidal volume reduction to 350 cc's could be a good or bad move. On the one hand if her right lung is collapsed or blocked one doesn't want the otherwise distributed tidal volume to all to into the left lung--could over distend it and send pulmonary blood flow to the right lung as ventilation goes to the left. Air trapping, etc.

One the other hand, ever since the ARDSnet trial showing improved survival for ARDS patients on low tidal volumes, giving all comers reduced tidal volumes has become a bit of a fad for all.

Is she on the home ventilator while in the hospital?

All things being equal (which they often aren't) whenever I hear that the right lung is affected I suspect aspiration as the anatomy predisposes to anything which goes down the trachea to go right (could be food, vomit, sinus drainage, esophageal reflux, etc.). When I hear the left lung is affected I suspect that laying on one's back, with the heart on the left side, has caused a compression atelectasis and secretion retention. (turn on right side for that).

Does she, or has she, ever used a Passy Muir valve?

At the last AARC Conference one of the more interesting things discussed was the use of Transtracheal Continuous High Flow Gas. A scoop catheter is inserted down the trache and a continous (humidified and at specific O2 from a blender going through a humidifier) flow of 10-12 liters/min is sent down. The patient then has a bit of "power steering" for the vocal cords. By closing the glotis and letting the flow accumulate the patients can use the system to augment ventilation also. THe gas flow also flushes CO2 out of their anatomic deadspace (where CO2 builds up).

If the MD was considering "unplugging" the machines a year ago before the trache...you might want to ask yourself if having the trache is buying time or wasting it. Did you buy time to have more good time? Or waste time in avoiding the necessary end of life preparations?

I'm not there and only you and she can answer it. But at a certain point a line may need to be drawn in the sand as to how far to take it all. I would suggest finding a Palliative Care MD (if around) and discussing end of life issues. THIS DOESN'T mean you necessarily would move into "Hospice Mode", but merely would have a backup plan (one which would avoid unnecessary suffering and shortness of breath) should things get hopelessly futile. Unfortunately in many hospitals are built in critical care "save em all" bias clouds how we approach the various options and paths.

At a certain point the only logical and compassionate goal is to have a good death. I am not making any judgement that this is now the case, only strongly suggesting that you include such a "game change" into your future thinking and planning.

I would suggest you get a copy of the July 1999 issue of Critical Care Nurse and read

HS Chapple
Changing the game in the intensive care unit: letting nature take its course
Crit Care Nurse 1999 19: 25-34.

It really is a description of how nurses and therapists often have clouded and confusing goals in clinical practice. It used to be free online but no more.