VentMonkey
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We're a Drager family at our service, but actually in the process of getting new vents.
End tidal CO2 questions
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medichopeful
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Here's an excellent lecture on EtCO2 that might answer some of your questions, or at the very least help dispel some myths.
http://emcrit.org/podcasts/etco2-podcast/
http://emcrit.org/podcasts/etco2-podcast/
medichopeful
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Here's an interesting podcast from EMCrit on basically this exact scenario. Of course, it would be almost impossible to do this in the field, but you might find it interesting:
http://emcrit.org/podcasts/tube-severe-acidosis/
VentMonkey
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Excellent podcast @medichopeful, Doc Weingart never disappoints. Kind of back to my original post, and something I think worth reiterating is that DKA is a form of metabolic acidosis. I think in the prehospital setting oftentimes we are so caught up in DKA=Kussmaul breathing; in all actuality it is caused by any form of metabolic acidosis, and at this stage in the game these patients are very sick. I think this is worth bringing up because if you do come across a severe sepsis, or toxic OD with a metabolic compensatory component that may need intubation, they will need to be treated the same as though it was a severe DKA with impending respiratory failure. He mentions it in the podcast in reference to severe ASA toxicity, but here's a quick Merck manual link about it:
https://www.merckmanuals.com/profes...e-regulation-and-disorders/metabolic-acidosis
Again, these patients are extremely sick. An excellent takeaway from this podcast for me was, that while ETCO2 may be a poor indicator of how high the patients actual PaCO2 may be, at the very least you will known where the baseline is.
Something @RRTMedic mentioned earlier was his recommendation for ventilator settings on these patients. Something I think that should be pointed out about vent management (again, I am no RT/ RCP) is that there are so many different takes on proper vent settings for specific patient types. Dr. Weingart makes mention of initially matching the patients respiratory rate. I know @Tigger had brought up a concern about how he would have managed this patient had they required intubation.
If it was me I would think I would carefully count an initial (spontaneous) rate, which optimally would be backed by the in-line ETCO2 (it's recorded, and can be proven for starters), once intubated I would then match the rate to the patient's intrinsic rate/ETCO2 reading pre-RSI, and then pass this along to the hospital. I don't think I would be against keeping these patients paralyzed for the transport as chances are they're in an impending respiratory failure to begin with, so my vent setting would be along the lines of A/C, or even CMV if truly paralyzed, and not just properly sedated with f- initial/ intrinsic rate (f), Vt-4-6 ml/ kg IBW, FiO2 @1.0, and optional Peep @ 5. My vent adjustments would focus on the patient's MV to ensure their ETCO2/ rate again, match what they were at initially before intubating them. The standard bilateral IV's probably goes without saying here, but those as well as Sodium Bicarb would be pretty close to where we could reach it.
Again, severe metabolic acidosis regardless of the etiology yields a very complex management approach in the prehospital setting, and ever there was a time, patient, and place to prove our worth as medical providers this would be it.
https://www.merckmanuals.com/profes...e-regulation-and-disorders/metabolic-acidosis
Again, these patients are extremely sick. An excellent takeaway from this podcast for me was, that while ETCO2 may be a poor indicator of how high the patients actual PaCO2 may be, at the very least you will known where the baseline is.
Something @RRTMedic mentioned earlier was his recommendation for ventilator settings on these patients. Something I think that should be pointed out about vent management (again, I am no RT/ RCP) is that there are so many different takes on proper vent settings for specific patient types. Dr. Weingart makes mention of initially matching the patients respiratory rate. I know @Tigger had brought up a concern about how he would have managed this patient had they required intubation.
If it was me I would think I would carefully count an initial (spontaneous) rate, which optimally would be backed by the in-line ETCO2 (it's recorded, and can be proven for starters), once intubated I would then match the rate to the patient's intrinsic rate/ETCO2 reading pre-RSI, and then pass this along to the hospital. I don't think I would be against keeping these patients paralyzed for the transport as chances are they're in an impending respiratory failure to begin with, so my vent setting would be along the lines of A/C, or even CMV if truly paralyzed, and not just properly sedated with f- initial/ intrinsic rate (f), Vt-4-6 ml/ kg IBW, FiO2 @1.0, and optional Peep @ 5. My vent adjustments would focus on the patient's MV to ensure their ETCO2/ rate again, match what they were at initially before intubating them. The standard bilateral IV's probably goes without saying here, but those as well as Sodium Bicarb would be pretty close to where we could reach it.
Again, severe metabolic acidosis regardless of the etiology yields a very complex management approach in the prehospital setting, and ever there was a time, patient, and place to prove our worth as medical providers this would be it.
VFlutter
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We used those for our MRI and transport vents in the hospital. I hated them, especially for sick patients. We have the Revel on the helicopter.
VentMonkey
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I think this is an Air Methods favorite. It seems their service here also carries them. I'm keeping my fingers crossed we get the Hamilton as our next vent.
VFlutter
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Ya I think all Air Methods programs are phasing out the LTVs and going with Revels. The Hamilton looks awesome.
VentMonkey
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Yeah, a bit tricky to fit in our 407, but we'd make it work. AirLife? Denver has one in theirs, and I agree, it is an awesome vent. I got to toy with the demo they had left a while back and TMK if we get one, the rep will run all of us through the training directly (fingers crossed).
I learned vent basics on the revel. Never really got to use it personally, but I liked what I saw.
VentMonkey
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I liked that it had PRVC, but was a tad disappointed otherwise it was the LTV.
I wished they'd made the screen better with the ability to see flow graphs such as airway pressures etc. (can't always hear them in the aircraft).
I can see that being nice. I had VERY limited exposure to it, so I have little anecdotal experience to compare it with. And I use what tigger uses, so whatever limitations the Revel may have, it is still vastly superior to what I have available now.
RRTMedic
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G
Great point about thinking carefully about initiating spontaneous modes, etc. Again, I am always suffering from 'identity loss' and frequently forget that the ICU is a different place than in the back of an ambulance or aircraft.
Generally, these patient's don't have a ventilatory problem (the respiratory system is wack trying to compensate). Paralyzing is noble, but of course sedation is preferred. Really, you will never fix a metabolic problem with your ventilator, but it is definitely something you want to maintain (low CO2 is what I mean). Often, I've seen these patients move from nasal cannula, to bipap, to ventilator as providers try to fix their metabolic issue with a pulmonary intervention--almost never happens.
I would caution using assist/control modes with these patients as high respiratory rates with demand volumes/pressures may result in air trapping, vent dyssynchrony, etc. This is one of the few times as an RT I would suggest SIMV (or if you're brave a spontaneous mode, provided their current pulmonary status is maintaining).
Great point about thinking carefully about initiating spontaneous modes, etc. Again, I am always suffering from 'identity loss' and frequently forget that the ICU is a different place than in the back of an ambulance or aircraft.
Generally, these patient's don't have a ventilatory problem (the respiratory system is wack trying to compensate). Paralyzing is noble, but of course sedation is preferred. Really, you will never fix a metabolic problem with your ventilator, but it is definitely something you want to maintain (low CO2 is what I mean). Often, I've seen these patients move from nasal cannula, to bipap, to ventilator as providers try to fix their metabolic issue with a pulmonary intervention--almost never happens.
I would caution using assist/control modes with these patients as high respiratory rates with demand volumes/pressures may result in air trapping, vent dyssynchrony, etc. This is one of the few times as an RT I would suggest SIMV (or if you're brave a spontaneous mode, provided their current pulmonary status is maintaining).
RRTMedic
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Ah, PRVC... the 'mindless' mode. You know, in the respiratory profession, it seems that many RTs revert to PRVC because of its automative functions. BUT, it's rare to find personnel who really understand PRVC and what it is doing for the patient.
Here's a challenge: You have a patient who is not tolerating PRVC and obviously needs more flow. You try to decrease the inspiratory time, as you would in Volume or Pressure Control (decrease inspiratory time means increased flow rate in these modes). However, nothing changes. So how do you increase your flow rate in PRVC?
TXmed
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we have the impact AEV where i work.
on these patients are difficult. i have found that with our vent A/C pressure actually makes them more comfortable (i suspect it is because of there tired respiratory muscles) so i will put them on something along the lines of PIP-20 PEEP-5-7 RR - 24-28 and adjust rise time accordingly. i like to use several small doses of ketamine or low dose propofol. then as they regain their drive i will lower the lower the trigger and PIP down to 10 as our vent will let them pull as much volume as they would like and the RR - 20-18 and they seem to self regulate pretty well if they continue to get better i will switch to NIV but ive rarely done that. and titrate sedation lower to only treating for anxiety, i also talk to the patient very regularly.
the main trick is getting them from the hospital vent to ours. that is where i will give ketamine or up the propofol for 1-2 minutes (nothing crazy) to help them go from one breathing system to another a little more comfortable.
im a big believer on making your patient comfortably without just sedation. so i will sit them up, tinker with the vent (such as rise time, trigger level, I:E ratio) talk to them, maybe reduce my vent tubing by cutting it, headset, and talk to them the whole time.
@RRTMedic i use A/C mode on these patients as the SIMV mode will lead me down nothing but alarms every time the patient follows a decent breath with a short rapid breath as the SIMV will not assist them as much as they need to. i think this is vent specific. so ive learned to use A/C and have not encountered any breath stacking as of yet (but i am on the look out). this may be because the impact is pressure triggered instead of low triggered but i am not sure.
on these patients are difficult. i have found that with our vent A/C pressure actually makes them more comfortable (i suspect it is because of there tired respiratory muscles) so i will put them on something along the lines of PIP-20 PEEP-5-7 RR - 24-28 and adjust rise time accordingly. i like to use several small doses of ketamine or low dose propofol. then as they regain their drive i will lower the lower the trigger and PIP down to 10 as our vent will let them pull as much volume as they would like and the RR - 20-18 and they seem to self regulate pretty well if they continue to get better i will switch to NIV but ive rarely done that. and titrate sedation lower to only treating for anxiety, i also talk to the patient very regularly.
the main trick is getting them from the hospital vent to ours. that is where i will give ketamine or up the propofol for 1-2 minutes (nothing crazy) to help them go from one breathing system to another a little more comfortable.
im a big believer on making your patient comfortably without just sedation. so i will sit them up, tinker with the vent (such as rise time, trigger level, I:E ratio) talk to them, maybe reduce my vent tubing by cutting it, headset, and talk to them the whole time.
@RRTMedic i use A/C mode on these patients as the SIMV mode will lead me down nothing but alarms every time the patient follows a decent breath with a short rapid breath as the SIMV will not assist them as much as they need to. i think this is vent specific. so ive learned to use A/C and have not encountered any breath stacking as of yet (but i am on the look out). this may be because the impact is pressure triggered instead of low triggered but i am not sure.
RRTMedic
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Don't get me wrong; I'm a big advocate for assist/control. I don't care what the FP-C exam says about "patient's spontaneously breathing should be placed in SIMV." Assist/control, when good settings are inputted, can do amazing things for patients. Decreased muscle fatigue, normalization of arterial gases, etc. I love love love A/C and will always use it until it isn't tolerated.
And yes, you are very much correct, it does depend on your ventilator. A lot of vents don't give good pressures (ie. ran into a vent today that constantly had the actual PEEP way below the set PEEP). Most of my vent experience has been with a Servo i in the hospital; a great ventilator that provides accurate pressures and when in a spontaneous mode, gives GREAT pressure support.
LTVs are a little disappointing when you need spot on pressures/volumes. Great for a transport environment, not so much for the ICU.
And of course, the transport environment does provide more liberty with gracious amounts of sedation and paralytics... a big no no in the ICU where 'sedation vacation' is a norm.
**sigh** I often forget my place and my audience... it has always been a challenge for me to separate the ICU and the ambulance. Great discussion though! It is encouraging to see my fellow paramedic colleagues care so much about vent management; a step in the right direction in giving the EMS/paramedic profession the place it deserves.
RRTMedic
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Another thing I forgot to mention is pressure support in SIMV... a good pressure support setting in SIMV goes a long way as well. Typically, I start at a pressure support of 10 cmH2O and titrate from there.... definitely helps with muscle fatigue and air hunger.
VentMonkey
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http://www.uthscsa.edu/academics/health-professions/departments/emergency-health-sciences
Decelerating flow patterns is my non-RT guess.
SIMV with a PS of 10 is my go to as well, unless the patient is completely paralyzed then I would default to A/C, but again depending on who you talk to you could argue for either in the prehospital environment as most transport times (excluding LDT's) wouldn't make a huge difference.
I digress however, as I enjoy prehospital vent management and think it takes quite a bit of critical thinking skills.
TXmed
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@RRTMedic I never thought the PEEP could be off like that. something to think about next time i got the vent out.
@VentMonkey i agree with that
@VentMonkey i agree with that
RRTMedic
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So it took me a long time to figure this out, but I eventually got to wrap my head around this.
And yes, decelerating flow is one of the mechanisms that PRVC used to prevent increased peak airway pressure.
But, to increase flow in PRVC, you gotta know the concepts surrounding PRVC. PRVC works based upon patient effort and added vent support. In essence, the ventilator (breath by breath) determines how hard the patient works during a respiratory cycle and then compensates for any slack in the patients spontaneous efforts. This is another mechanism that PRVC uses to decrease peak airway pressures and plateau pressures.
So, if you have a tidal volume set at 350 ml and the patient (for the sake of explanation--its more complicated in reality) makes enough effort to breath at 350 ml, the vent provides little support because the patient is doing much of the work. That means that the flow is DECREASED because the patient is doing all the work. But, in reality, this patient is struggling to take that 350 ml breath and is becoming tired and air hungry... the solution? Increase the flow. How do we do that (in prvc?).... increase the tidal volume. More tidal volume will result in greater flow because the vent will have to add more support if the patient only feels like generating a 350 ml breath.
Hope that makes sense... I'm a visual learner so trying to explain it in words can be a challenge.